A Treatise of Human Nature
by David Hume · English · Gutenberg #4705 · 1,343,407 chars · public domain (US)
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Title: A Treatise of Human Nature
Author: David Hume
Release date: December 1, 2003 [eBook #4705]
Most recently updated: June 10, 2025
Language: English
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*** START OF THE PROJECT GUTENBERG EBOOK A TREATISE OF HUMAN NATURE ***
A TREATISE OF HUMAN NATURE
By David Hume
CONTENTS
VOLUME I
INTRODUCTION BY THE AUTHOR.
BOOK I OF THE UNDERSTANDING
PART I OF IDEAS, THEIR ORIGIN, COMPOSITION, CONNEXION,
ABSTRACTION, ETC.
SECT. I OF THE ORIGIN OF OUR IDEAS.
SECT. II. DIVISION OF THE SUBJECT.
SECT. III. OF THE IDEAS OF THE MEMORY AND IMAGINATION.
SECT. IV. OF THE CONNECTION OR ASSOCIATION OF IDEAS.
SECT. V. OF RELATIONS.
SECT. VI. OF MODES AND SUBSTANCES
SECT. VII. OF ABSTRACT IDEAS.
PART II. OF THE IDEAS OF SPACE AND TIME.
SECT. I. OF THE INFINITE DIVISIBILITY OF OUR IDEAS OF SPACE AND TIME.
SECT. II. OF THE INFINITE DIVISIBILITY OF SPACE AND TIME.
SECT. III. OF THE OTHER QUALITIES OF OUR IDEA OF SPACE AND TIME.
SECT. IV. OBJECTIONS ANSWERED.
SECT. V. THE SAME SUBJECT CONTINUED.
SECT. VI. OF THE IDEA OF EXISTENCE, AND OF EXTERNAL EXISTENCE.
PART III. OF KNOWLEDGE AND PROBABILITY.
SECT. I. OF KNOWLEDGE.
SECT. II. OF PROBABILITY, AND OF THE IDEA OF CAUSE AND EFFECT.
SECT. III. WHY A CAUSE IS ALWAYS NECESSARY.
SECT. IV. OF THE COMPONENT PARTS OF OUR REASONINGS CONCERNING CAUSE
AND EFFECT.
SECT. V. OF THE IMPRESSIONS OF THE SENSES AND MEMORY.
SECT. VI. OF THE INFERENCE FROM THE IMPRESSION TO THE IDEA.
SECT. VII. OF THE NATURE OF THE IDEA OR BELIEF.
SECT. VIII. OF THE CAUSES OF BELIEF.
SECT. IX. OF THE EFFECTS OF OTHER RELATIONS AND OTHER HABITS.
SECT. X. OF THE INFLUENCE OF BELIEF.
SECT. XI. OF THE PROBABILITY OF CHANCES.
SECT. XII. OF THE PROBABILITY OF CAUSES.
SECT. XIII. OF UNPHILOSOPHICAL PROBABILITY.
SECT. XIV. OF THE IDEA OF NECESSARY CONNECTION.
SECT. XV. RULES BY WHICH TO JUDGE OF CAUSES AND EFFECTS.
SECT. XVI OF THE REASON OF ANIMALS
PART IV. OF THE SCEPTICAL AND OTHER SYSTEMS OF PHILOSOPHY.
SECT. I. OF SCEPTICISM WITH REGARD TO REASON.
SECT. II. OF SCEPTICISM WITH REGARD TO THE SENSES.
SECT. III. OF THE ANTIENT PHILOSOPHY.
SECT. IV. OF THE MODERN PHILOSOPHY.
SECT. V. OF THE IMMATERIALITY OF THE SOUL.
SECT. VI. OF PERSONAL IDENTITY
SECT. VII. CONCLUSION OF THIS BOOK.
VOLUME II
BOOK II OF THE PASSIONS
PART I OF PRIDE AND HUMILITY
SECT. I DIVISION OF THE SUBJECT
SECT. II OF PRIDE AND HUMILITY, THEIR OBJECTS AND CAUSES
SECT. III WHENCE THESE OBJECTS AND CAUSES ARE DERIVED
SECT. IV OF THE RELATIONS OF IMPRESSIONS AND IDEAS
SECT. V OF THE INFLUENCE OF THESE RELATIONS ON PRIDE AND HUMILITY
SECT. VI LIMITATIONS OF THIS SYSTEM
SECT. VII OF VICE AND VIRTUE
SECT. VIII OF BEAUTY AND DEFORMITY
SECT. IX OF EXTERNAL ADVANTAGES AND DISADVANTAGES
SECT. X OF PROPERTY AND RICHES
SECT. XI OF THE LOVE OF FAME
SECT. XII OF THE PRIDE AND HUMILITY OF ANIMALS
PART II OF LOVE AND HATRED
SECT. I OF THE OBJECT AND CAUSES OF LOVE AND HATRED
SECT. II EXPERIMENTS TO CONFIRM THIS SYSTEM
SECT. III DIFFICULTIES SOLVED
SECT. IV OF THE LOVE OF RELATIONS
SECT. V OF OUR ESTEEM FOR THE RICH AND POWERFUL
SECT. VI OF BENEVOLENCE AND ANGER
SECT. VII OF COMPASSION
SECT. VIII OF MALICE AND ENVY
SECT. IX OF THE MIXTURE OF BENEVOLENCE AND ANGER WITH COMPASSION
AND MALICE
SECT. X OF RESPECT AND CONTEMPT
SECT. XI OF THE AMOROUS PASSION, OR LOVE BETWIXT THE SEXES
SECT. XII OF THE LOVE AND HATRED OF ANIMALS
PART III OF THE WILL AND DIRECT PASSIONS
SECT. I OF LIBERTY AND NECESSITY
SECT. II THE SAME SUBJECT CONTINUED
SECT. III OF THE INFLUENCING MOTIVES OF THE WILL
SECT. IV OF THE CAUSES OF THE VIOLENT PASSIONS
SECT. V OF THE EFFECTS OF CUSTOM
SECT. VI OF THE INFLUENCE OF THE IMAGINATION ON THE PASSIONS
SECT. VII OF CONTIGUITY AND DISTANCE IN SPACE AND TIME
SECT. VIII THE SAME SUBJECT CONTINUED
SECT. IX OF THE DIRECT PASSIONS
SECT. X OF CURIOSITY, OR THE LOVE OF TRUTH
BOOK III OF MORALS
PART I OF VIRTUE AND VICE IN GENERAL
SECT. I MORAL DISTINCTIONS NOT DERIVED FROM REASON
SECT. II MORAL DISTINCTIONS DERIVED FROM A MORAL SENSE
PART II OF JUSTICE AND INJUSTICE
SECT. I JUSTICE, WHETHER A NATURAL OR ARTIFICIAL VIRTUE?
SECT. II OF THE ORIGIN OF JUSTICE AND PROPERTY
SECT. III OF THE RULES WHICH DETERMINE PROPERTY
SECT. IV OF THE TRANSFERENCE OF PROPERTY BY CONSENT
SECT. V OF THE OBLIGATION OF PROMISES
SECT. VI SOME FARTHER REFLECTIONS CONCERNING JUSTICE AND INJUSTICE
SECT. VII OF THE ORIGIN OF GOVERNMENT
SECT. VIII OF THE SOURCE OF ALLEGIANCE
SECT. IX OF THE MEASURES OF ALLEGIANCE
SECT. X OF THE OBJECTS OF ALLEGIANCE
SECT. XI OF THE LAWS OF NATIONS
SECT. XII OF CHASTITY AND MODESTY
PART III OF THE OTHER VIRTUES AND VICES
SECT. I OF THE ORIGIN OF THE NATURAL VIRTUES AND VICES
SECT. II OF GREATNESS OF MIND
SECT. III OF GOODNESS AND BENEVOLENCE
SECT. IV OF NATURAL ABILITIES
SECT. V SOME FARTHER REFLECTIONS CONCERNING THE NATURAL VIRTUES
SECT. VI CONCLUSION OF THIS BOOK
APPENDIX TO THE TREATISE OF HUMAN NATURE
* * * * *
VOL. I OF THE UNDERSTANDING.
ADVERTISEMENT.
My design in the present work is sufficiently explained in the
Introduction. The reader must only observe, that all the subjects I have
there planned out to myself, are not treated of in these two volumes.
The subjects of the Understanding and Passions make a compleat chain
of reasoning by themselves; and I was willing to take advantage of this
natural division, in order to try the taste of the public. If I have the
good fortune to meet with success, I shall proceed to the examination
of Morals, Politics, and Criticism; which will compleat this Treatise of
Human Nature. The approbation of the public I consider as the greatest
reward of my labours; but am determined to regard its judgment, whatever
it be, as my best instruction.
INTRODUCTION.
Nothing is more usual and more natural for those, who pretend to
discover anything new to the world in philosophy and the sciences, than
to insinuate the praises of their own systems, by decrying all those,
which have been advanced before them. And indeed were they content with
lamenting that ignorance, which we still lie under in the most important
questions, that can come before the tribunal of human reason, there are
few, who have an acquaintance with the sciences, that would not readily
agree with them. It is easy for one of judgment and learning, to
perceive the weak foundation even of those systems, which have obtained
the greatest credit, and have carried their pretensions highest
to accurate and profound reasoning. Principles taken upon trust,
consequences lamely deduced from them, want of coherence in the parts,
and of evidence in the whole, these are every where to be met with in
the systems of the most eminent philosophers, and seem to have drawn
disgrace upon philosophy itself.
Nor is there required such profound knowledge to discover the present
imperfect condition of the sciences, but even the rabble without doors
may, judge from the noise and clamour, which they hear, that all goes
not well within. There is nothing which is not the subject of debate,
and in which men of learning are not of contrary opinions. The most
trivial question escapes not our controversy, and in the most momentous
we are not able to give any certain decision. Disputes are multiplied,
as if every thing was uncertain; and these disputes are managed with the
greatest warmth, as if every thing was certain. Amidst all this bustle
it is not reason, which carries the prize, but eloquence; and no
man needs ever despair of gaining proselytes to the most extravagant
hypothesis, who has art enough to represent it in any favourable
colours. The victory is not gained by the men at arms, who manage the
pike and the sword; but by the trumpeters, drummers, and musicians of
the army.
From hence in my opinion arises that common prejudice against
metaphysical reasonings of all kinds, even amongst those, who profess
themselves scholars, and have a just value for every other part of
literature. By metaphysical reasonings, they do not understand those on
any particular branch of science, but every kind of argument, which is
any way abstruse, and requires some attention to be comprehended. We
have so often lost our labour in such researches, that we commonly
reject them without hesitation, and resolve, if we must for ever be a
prey to errors and delusions, that they shall at least be natural and
entertaining. And indeed nothing but the most determined scepticism,
along with a great degree of indolence, can justify this aversion to
metaphysics. For if truth be at all within the reach of human capacity,
it is certain it must lie very deep and abstruse: and to hope we shall
arrive at it without pains, while the greatest geniuses have failed
with the utmost pains, must certainly be esteemed sufficiently vain
and presumptuous. I pretend to no such advantage in the philosophy I am
going to unfold, and would esteem it a strong presumption against it,
were it so very easy and obvious.
It is evident, that all the sciences have a relation, greater or less,
to human nature: and that however wide any of them may seem to run from
it, they still return back by one passage or another. Even. Mathematics,
Natural Philosophy, and Natural Religion, are in some measure dependent
on the science of MAN; since they lie under the cognizance of men, and
are judged of by their powers and faculties. It is impossible to tell
what changes and improvements we might make in these sciences were we
thoroughly acquainted with the extent and force of human understanding,
and could explain the nature of the ideas we employ, and of the
operations we perform in our reasonings. And these improvements are
the more to be hoped for in natural religion, as it is not content with
instructing us in the nature of superior powers, but carries its views
farther, to their disposition towards us, and our duties towards them;
and consequently we ourselves are not only the beings, that reason, but
also one of the objects, concerning which we reason.
If therefore the sciences of Mathematics, Natural Philosophy, and
Natural Religion, have such a dependence on the knowledge of man, what
may be expected in the other sciences, whose connexion with human nature
is more close and intimate? The sole end of logic is to explain the
principles and operations of our reasoning faculty, and the nature of
our ideas: morals and criticism regard our tastes and sentiments: and
politics consider men as united in society, and dependent on each other.
In these four sciences of Logic, Morals, Criticism, and Politics, is
comprehended almost everything, which it can any way import us to be
acquainted with, or which can tend either to the improvement or ornament
of the human mind.
Here then is the only expedient, from which we can hope for success in
our philosophical researches, to leave the tedious lingering method,
which we have hitherto followed, and instead of taking now and then a
castle or village on the frontier, to march up directly to the capital
or center of these sciences, to human nature itself; which being once
masters of, we may every where else hope for an easy victory. From this
station we may extend our conquests over all those sciences, which more
intimately concern human life, and may afterwards proceed at leisure
to discover more fully those, which are the objects of pore curiosity.
There is no question of importance, whose decision is not comprised in
the science of man; and there is none, which can be decided with any
certainty, before we become acquainted with that science. In pretending,
therefore, to explain the principles of human nature, we in effect
propose a compleat system of the sciences, built on a foundation almost
entirely new, and the only one upon which they can stand with any
security.
And as the science of man is the-only solid foundation for the other
sciences, so the only solid foundation we can give to this science
itself must be laid on experience and observation. It is no astonishing
reflection to consider, that the application of experimental philosophy
to moral subjects should come after that to natural at the distance of
above a whole century; since we find in fact, that there was about the
same interval betwixt the origins of these sciences; and that reckoning
from THALES to SOCRATES, the space of time is nearly equal to that
betwixt, my Lord Bacon and some late philosophers in England,[1] who
have begun to put the science of man on a new footing, and have engaged
the attention, and excited the curiosity of the public. So true it is,
that however other nations may rival us in poetry, and excel us in some
other agreeable arts, the improvements in reason and philosophy can
only be owing to a land of toleration and of liberty.
[1] Mr. _Locke_, my Lord _Shaftesbury_, Dr. _Mandeville_, Mr.
_Hutchinson_, Dr. _Butler_, etc.
Nor ought we to think, that this latter improvement in the science of
man will do less honour to our native country than the former in natural
philosophy, but ought rather to esteem it a greater glory, upon account
of the greater importance of that science, as well as the necessity it
lay under of such a reformation. For to me it seems evident, that the
essence of the mind being equally unknown to us with that of external
bodies, it must be equally impossible to form any notion of its powers
and qualities otherwise than from careful and exact experiments, and the
observation of those particular effects, which result from its different
circumstances and situations. And though we must endeavour to render all
our principles as universal as possible, by tracing up our experiments
to the utmost, and explaining all effects from the simplest and fewest
causes, it is still certain we cannot go beyond experience; and any
hypothesis, that pretends to discover the ultimate original qualities
of human nature, ought at first to be rejected as presumptuous and
chimerical.
I do not think a philosopher, who would apply himself so earnestly to
the explaining the ultimate principles of the soul, would show himself a
great master in that very science of human nature, which he pretends to
explain, or very knowing in what is naturally satisfactory to the mind
of man. For nothing is more certain, than that despair has almost the
same effect upon us with enjoyment, and that we are no sooner acquainted
with the impossibility of satisfying any desire, than the desire itself
vanishes. When we see, that we have arrived at the utmost extent of
human reason, we sit down contented, though we be perfectly satisfied in
the main of our ignorance, and perceive that we can give no reason for
our most general and most refined principles, beside our experience
of their reality; which is the reason of the mere vulgar, and what it
required no study at first to have discovered for the most particular
and most extraordinary phænomenon. And as this impossibility of making
any farther progress is enough to satisfy the reader, so the writer
may derive a more delicate satisfaction from the free confession of his
ignorance, and from his prudence in avoiding that error, into which so
many have fallen, of imposing their conjectures and hypotheses on the
world for the most certain principles. When this mutual contentment and
satisfaction can be obtained betwixt the master and scholar, I know not
what more we can require of our philosophy.
But if this impossibility of explaining ultimate principles should be
esteemed a defect in the science of man, I will venture to affirm, that
it is a defect common to it with all the sciences, and all the arts, in
which we can employ ourselves, whether they be such as are cultivated
in the schools of the philosophers, or practised in the shops of the
meanest artizans. None of them can go beyond experience, or establish
any principles which are not founded on that authority. Moral philosophy
has, indeed, this peculiar disadvantage, which is not found in natural,
that in collecting its experiments, it cannot make them purposely, with
premeditation, and after such a manner as to satisfy itself concerning
every particular difficulty which may be. When I am at a loss to know
the effects of one body upon another in any situation, I need only put
them in that situation, and observe what results from it. But should
I endeavour to clear up after the same manner any doubt in moral
philosophy, by placing myself in the same case with that which I
consider, it is evident this reflection and premeditation would so
disturb the operation of my natural principles, as must render it
impossible to form any just conclusion from the phenomenon. We must
therefore glean up our experiments in this science from a cautious
observation of human life, and take them as they appear in the common
course of the world, by men's behaviour in company, in affairs, and
in their pleasures. Where experiments of this kind are judiciously
collected and compared, we may hope to establish on them a science which
will not be inferior in certainty, and will be much superior in utility
to any other of human comprehension.
BOOK I. OF THE UNDERSTANDING
PART I. OF IDEAS, THEIR ORIGIN, COMPOSITION, CONNEXION, ABSTRACTION,
ETC.
SECT. I. OF THE ORIGIN OF OUR IDEAS.
All the perceptions of the human mind resolve themselves into two
distinct kinds, which I shall call IMPRESSIONS and IDEAS. The difference
betwixt these consists in the degrees of force and liveliness, with
which they strike upon the mind, and make their way into our thought
or consciousness. Those perceptions, which enter with most force and
violence, we may name impressions: and under this name I comprehend
all our sensations, passions and emotions, as they make their first
appearance in the soul. By ideas I mean the faint images of these in
thinking and reasoning; such as, for instance, are all the perceptions
excited by the present discourse, excepting only those which arise from
the sight and touch, and excepting the immediate pleasure or uneasiness
it may occasion. I believe it will not be very necessary to employ many
words in explaining this distinction. Every one of himself will readily
perceive the difference betwixt feeling and thinking. The common degrees
of these are easily distinguished; though it is not impossible but in
particular instances they may very nearly approach to each other. Thus
in sleep, in a fever, in madness, or in any very violent emotions of
soul, our ideas may approach to our impressions, As on the other hand
it sometimes happens, that our impressions are so faint and low, that
we cannot distinguish them from our ideas. But notwithstanding this near
resemblance in a few instances, they are in general so very different,
that no-one can make a scruple to rank them under distinct heads, and
assign to each a peculiar name to mark the difference.[1]
[1] I here make use of these terms, _impression and idea_, in a
sense different from what is usual, and I hope this liberty will be
allowed me. Perhaps I rather restore the word, idea, to its
original sense, from which Mr Locke had perverted it, in making it
stand for all our perceptions. By the terms of impression I would
not be understood to express the manner, in which our lively
perceptions are produced in the soul, but merely the perceptions
themselves; for which there is no particular name either in the
_English_ or any other language, that I know of.
There is another division of our perceptions, which it will be
convenient to observe, and which extends itself both to our impressions
and ideas. This division is into SIMPLE and COMPLEX. Simple perceptions
or impressions and ideas are such as admit of no distinction nor
separation. The complex are the contrary to these, and may be
distinguished into parts. Though a particular colour, taste, and smell,
are qualities all united together in this apple, it is easy to perceive
they are not the same, but are at least distinguishable from each other.
Having by these divisions given an order and arrangement to our objects,
we may now apply ourselves to consider with the more accuracy their
qualities and relations. The first circumstance, that strikes my eye, is
the great resemblance betwixt our impressions and ideas in every other
particular, except their degree of force and vivacity. The one seem to
be in a manner the reflexion of the other; so that all the perceptions
of the mind are double, and appear both as impressions and ideas. When
I shut my eyes and think of my chamber, the ideas I form are exact
representations of the impressions I felt; nor is there any circumstance
of the one, which is not to be found in the other. In running over my
other perceptions, I find still the same resemblance and representation.
Ideas and impressions appear always to correspond to each other. This
circumstance seems to me remarkable, and engages my attention for a
moment.
Upon a more accurate survey I find I have been carried away too far by
the first appearance, and that I must make use of the distinction of
perceptions into simple and complex, to limit this general decision,
that all our ideas and impressions are resembling. I observe, that many
of our complex ideas never had impressions, that corresponded to them,
and that many of our complex impressions never are exactly copied in
ideas. I can imagine to myself such a city as the New Jerusalem, whose
pavement is gold and walls are rubies, though I never saw any such.
I have seen Paris; but shall I affirm I can form such an idea of that
city, as will perfectly represent all its streets and houses in their
real and just proportions?
I perceive, therefore, that though there is in general a great,
resemblance betwixt our complex impressions and ideas, yet the rule is
not universally true, that they are exact copies of each other. We may
next consider how the case stands with our simple, perceptions. After
the most accurate examination, of which I am capable, I venture to
affirm, that the rule here holds without any exception, and that every
simple idea has a simple impression, which resembles it, and every
simple impression a correspondent idea. That idea of red, which we form
in the dark, and that impression which strikes our eyes in sun-shine,
differ only in degree, not in nature. That the case is the same with
all our simple impressions and ideas, it is impossible to prove by a
particular enumeration of them. Every one may satisfy himself in this
point by running over as many as he pleases. But if any one should deny
this universal resemblance, I know no way of convincing him, but by
desiring him to shew a simple impression, that has not a correspondent
idea, or a simple idea, that has not a correspondent impression. If he
does not answer this challenge, as it is certain he cannot, we may from
his silence and our own observation establish our conclusion.
Thus we find, that all simple ideas and impressions resemble each other;
and as the complex are formed from them, we may affirm in general,
that these two species of perception are exactly correspondent. Having
discovered this relation, which requires no farther examination, I am
curious to find some other of their qualities. Let us consider how they
stand with regard to their existence, and which of the impressions and
ideas are causes, and which effects.
The full examination of this question is the subject of the present
treatise; and therefore we shall here content ourselves with
establishing one general proposition, THAT ALL OUR SIMPLE IDEAS IN
THEIR FIRST APPEARANCE ARE DERIVED FROM SIMPLE IMPRESSIONS, WHICH ARE
CORRESPONDENT TO THEM, AND WHICH THEY EXACTLY REPRESENT.
In seeking for phenomena to prove this proposition, I find only those
of two kinds; but in each kind the phenomena are obvious, numerous, and
conclusive. I first make myself certain, by a new, review, of what I
have already asserted, that every simple impression is attended with
a correspondent idea, and every simple idea with a correspondent
impression. From this constant conjunction of resembling perceptions
I immediately conclude, that there is a great connexion betwixt our
correspondent impressions and ideas, and that the existence of the one
has a considerable influence upon that of the other. Such a constant
conjunction, in such an infinite number of instances, can never arise
from chance; but clearly proves a dependence of the impressions on the
ideas, or of the ideas on the impressions. That I may know on which side
this dependence lies, I consider the order of their first appearance;
and find by constant experience, that the simple impressions always take
the precedence of their correspondent ideas, but never appear in the
contrary order. To give a child an idea of scarlet or orange, of sweet
or bitter, I present the objects, or in other words, convey to him these
impressions; but proceed not so absurdly, as to endeavour to produce
the impressions by exciting the ideas. Our ideas upon their appearance
produce not their correspondent impressions, nor do we perceive any
colour, or feel any sensation merely upon thinking of them. On the
other hand we find, that any impression either of the mind or body
is constantly followed by an idea, which resembles it, and is only
different in the degrees of force and liveliness. The constant
conjunction of our resembling perceptions, is a convincing proof,
that the one are the causes of the other; and this priority of the
impressions is an equal proof, that our impressions are the causes of
our ideas, not our ideas of our impressions.
To confirm this I consider Another plain and convincing phænomenon;
which is, that, where-ever by any accident the faculties, which give
rise to any impressions, are obstructed in their operations, as when one
is born blind or deaf; not only the impressions are lost, but also their
correspondent ideas; so that there never appear in the mind the least
traces of either of them. Nor is this only true, where the organs of
sensation are entirely destroyed, but likewise where they have never
been put in action to produce a particular impression. We cannot form
to ourselves a just idea of the taste of a pine apple, without having
actually tasted it.
There is however one contradictory phænomenon, which may prove, that it
is not absolutely impossible for ideas to go before their correspondent
impressions. I believe it will readily be allowed that the several
distinct ideas of colours, which enter by the eyes, or those of sounds,
which are conveyed by the hearing, are really different from each other,
though at the same time resembling. Now if this be true of different
colours, it must be no less so of the different shades of the same
colour, that each of them produces a distinct idea, independent of the
rest. For if this should be denied, it is possible, by the continual
gradation of shades, to run a colour insensibly into what is most remote
from it; and if you will not allow any of the means to be different,
you cannot without absurdity deny the extremes to be the same. Suppose
therefore a person to have enjoyed his sight for thirty years, and
to have become perfectly well acquainted with colours of all kinds,
excepting one particular shade of blue, for instance, which it never
has been his fortune to meet with. Let all the different shades of
that colour, except that single one, be placed before him, descending
gradually from the deepest to the lightest; it is plain, that he will
perceive a blank, where that shade is wanting, said will be sensible,
that there is a greater distance in that place betwixt the contiguous
colours, than in any other. Now I ask, whether it is possible for him,
from his own imagination, to supply this deficiency, and raise up to
himself the idea of that particular shade, though it had never been
conveyed to him by his senses? I believe there are few but will be
of opinion that he can; and this may serve as a proof, that the simple
ideas are not always derived from the correspondent impressions; though
the instance is so particular and singular, that it is scarce worth
our observing, and does not merit that for it alone we should alter our
general maxim.
But besides this exception, it may not be amiss to remark on this head,
that the principle of the priority of impressions to ideas must be
understood with another limitation, viz., that as our ideas are images
of our impressions, so we can form secondary ideas, which are images of
the primary; as appears from this very reasoning concerning them.
This is not, properly speaking, an exception to the rule so much as
an explanation of it. Ideas produce the images of themselves in
new ideas; but as the first ideas are supposed to be derived from
impressions, it still remains true, that all our simple ideas proceed
either mediately or immediately, from their correspondent impressions.
This then is the first principle I establish in the science of human
nature; nor ought we to despise it because of the simplicity of its
appearance. For it is remarkable, that the present question concerning
the precedency of our impressions or ideas, is the same with what has
made so much noise in other terms, when it has been disputed whether
there be any INNATE IDEAS, or whether all ideas be derived from
sensation and reflexion. We may observe, that in order to prove the
ideas of extension and colour not to be innate, philosophers do nothing
but shew that they are conveyed by our senses. To prove the ideas
of passion and desire not to be innate, they observe that we have a
preceding experience of these emotions in ourselves. Now if we carefully
examine these arguments, we shall find that they prove nothing but that
ideas are preceded by other more lively perceptions, from which the
are derived, and which they represent. I hope this clear stating of the
question will remove all disputes concerning it, and win render this
principle of more use in our reasonings, than it seems hitherto to have
been.
SECT. II. DIVISION OF THE SUBJECT.
Since it appears, that our simple impressions are prior to their
correspondent ideas, and that the exceptions are very rare, method seems
to require we should examine our impressions, before we consider our
ideas. Impressions may be divided into two kinds, those Of SENSATION and
those of REFLEXION. The first kind arises in the soul originally, from
unknown causes. The second is derived in a great measure from our ideas,
and that in the following order. An impression first strikes upon the
senses, and makes us perceive heat or cold, thirst or hunger, pleasure
or pain of some kind or other. Of this impression there is a copy taken
by the mind, which remains after the impression ceases; and this we call
an idea. This idea of pleasure or pain, when it returns upon the soul,
produces the new impressions of desire and aversion, hope and fear,
which may properly be called impressions of reflexion, because derived
from it. These again are copied by the memory and imagination, and
become ideas; which perhaps in their turn give rise to other impressions
and ideas. So that the impressions of reflexion are only antecedent
to their correspondent ideas; but posterior to those of sensation, and
derived from them. The examination of our sensations belongs more to
anatomists and natural philosophers than to moral; and therefore shall
not at present be entered upon. And as the impressions of reflexion,
viz. passions, desires, and emotions, which principally deserve our
attention, arise mostly from ideas, it will be necessary to reverse that
method, which at first sight seems most natural; and in order to explain
the nature and principles of the human mind, give a particular account
of ideas, before we proceed to impressions. For this reason I have here
chosen to begin with ideas.
SECT. III. OF THE IDEAS OF THE MEMORY AND IMAGINATION.
We find by experience, that when any impression has been present with
the mind, it again makes its appearance there as an idea; and this it
may do after two different ways: either when in its new appearance it
retains a considerable degree of its first vivacity, and is somewhat
intermediate betwixt an impression and an idea: or when it entirely
loses that vivacity, and is a perfect idea. The faculty, by which we
repeat our impressions in the first manner, is called the MEMORY, and
the other the IMAGINATION. It is evident at first sight, that the
ideas of the memory are much more lively and strong than those of the
imagination, and that the former faculty paints its objects in more
distinct colours, than any which are employed by the latter. When we
remember any past event, the idea of it flows in upon the mind in a
forcible manner; whereas in the imagination the perception is faint and
languid, and cannot without difficulty be preserved by the mind
steddy and uniform for any considerable time. Here then is a sensible
difference betwixt one species of ideas and another. But of this more
fully hereafter.[2]
[2] Part III, Sect. 5.
There is another difference betwixt these two kinds of ideas, which is
no less evident, namely that though neither the ideas, of the memory
nor imagination, neither the lively nor faint ideas can make their
appearance in the mind, unless their correspondent impressions have
gone before to prepare the way for them, yet the imagination is not
restrained to the same order and form with the original impressions;
while the memory is in a manner tied down in that respect, without any
power of variation.
It is evident, that the memory preserves the original form, in which
its objects were presented, and that where-ever we depart from it in
recollecting any thing, it proceeds from some defect or imperfection
in that faculty. An historian may, perhaps, for the more convenient
Carrying on of his narration, relate an event before another, to which
it was in fact posterior; but then he takes notice of this disorder, if
he be exact; and by that means replaces the idea in its due position. It
is the same case in our recollection of those places and persons, with
which we were formerly acquainted. The chief exercise of the memory
is not to preserve the simple ideas, but their order and position. In
short, this principle is supported by such a number of common and vulgar
phaenomena, that we may spare ourselves the trouble of insisting on it
any farther.
The same evidence follows us in our second principle, OF THE LIBERTY OF
THE IMAGINATION TO TRANSPOSE AND CHANGE ITS IDEAS. The fables we meet
with in poems and romances put this entirely out of the question. Nature
there is totally confounded, and nothing mentioned but winged horses,
fiery dragons, and monstrous giants. Nor will this liberty of the fancy
appear strange, when we consider, that all our ideas are copyed from
our impressions, and that there are not any two impressions which
are perfectly inseparable. Not to mention, that this is an evident
consequence of the division of ideas into simple and complex. Where-ever
the imagination perceives a difference among ideas, it can easily
produce a separation.
SECT. IV. OF THE CONNEXION OR ASSOCIATION OF IDEAS.
As all simple ideas may be separated by the imagination, and may
be united again in what form it pleases, nothing would be more
unaccountable than the operations of that faculty, were it not guided
by some universal principles, which render it, in some measure, uniform
with itself in all times and places. Were ideas entirely loose and
unconnected, chance alone would join them; and it is impossible the same
simple ideas should fall regularly into complex ones (as they Commonly
do) without some bond of union among them, some associating quality,
by which one idea naturally introduces another. This uniting principle
among ideas is not to be considered as an inseparable connexion; for
that has been already excluded from the imagination: Nor yet are we to
conclude, that without it the mind cannot join two ideas; for nothing
is more free than that faculty: but we are only to regard it as a
gentle force, which commonly prevails, and is the cause why, among other
things, languages so nearly correspond to each other; nature in a manner
pointing out to every one those simple ideas, which are most proper to
be united in a complex one. The qualities, from which this association
arises, and by which the mind is after this manner conveyed from one
idea to another, are three, viz. RESEMBLANCE, CONTIGUITY in time or
place, and CAUSE and EFFECT.
I believe it will not be very necessary to prove, that these qualities
produce an association among ideas, and upon the appearance of one idea
naturally introduce another. It is plain, that in the course of our
thinking, and in the constant revolution of our ideas, our imagination
runs easily from one idea to any other that resembles it, and that this
quality alone is to the fancy a sufficient bond and association. It
is likewise evident that as the senses, in changing their objects,
are necessitated to change them regularly, and take them as they lie
CONTIGUOUS to each other, the imagination must by long custom acquire
the same method of thinking, and run along the parts of space and time
in conceiving its objects. As to the connexion, that is made by the
relation of cause and effect, we shall have occasion afterwards to
examine it to the bottom, and therefore shall not at present insist
upon it. It is sufficient to observe, that there is no relation, which
produces a stronger connexion in the fancy, and makes one idea more
readily recall another, than the relation of cause and effect betwixt
their objects.
That we may understand the full extent of these relations, we must
consider, that two objects are connected together in the imagination,
not only when the one is immediately resembling, contiguous to, or the
cause of the other, but also when there is interposed betwixt them a
third object, which bears to both of them any of these relations. This
may be carried on to a great length; though at the same time we may
observe, that each remove considerably weakens the relation. Cousins in
the fourth degree are connected by causation, if I may be allowed to
use that term; but not so closely as brothers, much less as child and
parent. In general we may observe, that all the relations of blood
depend upon cause and effect, and are esteemed near or remote, according
to the number of connecting causes interposed betwixt the persons.
Of the three relations above-mentioned this of causation is the most
extensive. Two objects may be considered as placed in this relation,
as well when one is the cause of any of the actions or motions of the
other, as when the former is the cause of the existence of the
latter. For as that action or motion is nothing but the object itself,
considered in a certain light, and as the object continues the same
in all its different situations, it is easy to imagine how such
an influence of objects upon one another may connect them in the
imagination.
We may carry this farther, and remark, not only that two objects are
connected by the relation of cause and effect, when the one produces
a motion or any action in the other, but also when it has a power
of producing it. And this we may observe to be the source of all the
relation, of interest and duty, by which men influence each other in
society, and are placed in the ties of government and subordination. A
master is such-a-one as by his situation, arising either from force or
agreement, has a power of directing in certain particulars the actions
of another, whom we call servant. A judge is one, who in all disputed
cases can fix by his opinion the possession or property of any thing
betwixt any members of the society. When a person is possessed of any
power, there is no more required to convert it into action, but the
exertion of the will; and that in every case is considered as possible,
and in many as probable; especially in the case of authority, where the
obedience of the subject is a pleasure and advantage to the superior.
These are therefore the principles of union or cohesion among our simple
ideas, and in the imagination supply the place of that inseparable
connexion, by which they are united in our memory. Here is a kind
of ATTRACTION, which in the mental world will be found to have as
extraordinary effects as in the natural, and to shew itself in as many
and as various forms. Its effects are every where conspicuous; but as to
its causes, they are mostly unknown, and must be resolved into original
qualities of human nature, which I pretend not to explain. Nothing is
more requisite for a true philosopher, than to restrain the intemperate
desire of searching into causes, and having established any doctrine
upon a sufficient number of experiments, rest contented with that, when
he sees a farther examination would lead him into obscure and uncertain
speculations. In that case his enquiry would be much better employed in
examining the effects than the causes of his principle.
Amongst the effects of this union or association of ideas, there are
none more remarkable, than those complex ideas, which are the common
subjects of our thoughts and reasoning, and generally arise from some
principle of union among our simple ideas. These complex ideas may be
divided into Relations, Modes, and Substances. We shall briefly examine
each of these in order, and shall subjoin some considerations concerning
our general and particular ideas, before we leave the present subject,
which may be considered as the elements of this philosophy.
SECT. V. OF RELATIONS.
The word RELATION is commonly used in two senses considerably different
from each other. Either for that quality, by which two ideas are
connected together in the imagination, and the one naturally introduces
the other, after the manner above-explained: or for that particular
circumstance, in which, even upon the arbitrary union of two ideas in
the fancy, we may think proper to compare them. In common language the
former is always the sense, in which we use the word, relation; and it
is only in philosophy, that we extend it to mean any particular subject
of comparison, without a connecting principle. Thus distance will be
allowed by philosophers to be a true relation, because we acquire an
idea of it by the comparing of objects: But in a common way we say, THAT
NOTHING CAN BE MORE DISTANT THAN SUCH OR SUCH THINGS FROM EACH OTHER,
NOTHING CAN HAVE LESS RELATION: as if distance and relation were
incompatible.
It may perhaps be esteemed an endless task to enumerate all those
qualities, which make objects admit of comparison, and by which the
ideas of philosophical relation are produced. But if we diligently
consider them, we shall find that without difficulty they may be
comprised under seven general heads, which may be considered as the
sources of all philosophical relation.
(1) The first is RESEMBLANCE: And this is a relation, without which
no philosophical relation can exist; since no objects will admit
of comparison, but what have some degree of resemblance. But though
resemblance be necessary to all philosophical relation, it does not
follow, that it always produces a connexion or association of ideas.
When a quality becomes very general, and is common to a great many
individuals, it leads not the mind directly to any one of them; but
by presenting at once too great a choice, does thereby prevent the
imagination from fixing on any single object.
(2) IDENTITY may be esteemed a second species of relation. This relation
I here consider as applied in its strictest sense to constant and
unchangeable objects; without examining the nature and foundation
of personal identity, which shall find its place afterwards. Of all
relations the most universal is that of identity, being common to every
being whose existence has any duration.
(3) After identity the most universal and comprehensive relations are
those of SPACE and TIME, which are the sources of an infinite number of
comparisons, such as distant, contiguous, above, below, before, after,
etc.
(4) All those objects, which admit of QUANTITY, or NUMBER, may be
compared in that particular; which is another very fertile source of
relation.
(5) When any two objects possess the same QUALITY in common, the
DEGREES, in which they possess it, form a fifth species of relation.
Thus of two objects, which are both heavy, the one may be either of
greater, or less weight than the other. Two colours, that are of the
same kind, may yet be of different shades, and in that respect admit of
comparison.
(6) The relation of CONTRARIETY may at first sight be regarded as an
exception to the rule, THAT NO RELATION OF ANY KIND CAN SUBSIST WITHOUT
SOME DEGREE OF RESEMBLANCE. But let us consider, that no two ideas are
in themselves contrary, except those of existence and non-existence,
which are plainly resembling, as implying both of them an idea of the
object; though the latter excludes the object from all times and places,
in which it is supposed not to exist.
(7) All other objects, such as fire and water, heat and cold, are only
found to be contrary from experience, and from the contrariety of their
causes or effects; which relation of cause and effect is a seventh
philosophical relation, as well as a natural one. The resemblance
implied in this relation, shall be explained afterwards.
It might naturally be expected, that I should join DIFFERENCE to the
other relations. But that I consider rather as a negation of relation,
than as anything real or positive. Difference is of two kinds as opposed
either to identity or resemblance. The first is called a difference of
number; the other of KIND.
SECT. VI. OF MODES AND SUBSTANCES
I would fain ask those philosophers, who found so much of their
reasonings on the distinction of substance and accident, and imagine we
have clear ideas of each, whether the idea of substance be derived from
the impressions of sensation or of reflection? If it be conveyed to us
by our senses, I ask, which of them; and after what manner? If it be
perceived by the eyes, it must be a colour; if by the ears, a sound; if
by the palate, a taste; and so of the other senses. But I believe none
will assert, that substance is either a colour, or sound, or a taste.
The idea, of substance must therefore be derived from an impression
of reflection, if it really exist. But the impressions of reflection
resolve themselves into our passions and emotions: none of which can
possibly represent a substance. We have therefore no idea of substance,
distinct from that of a collection of particular qualities, nor have we
any other meaning when we either talk or reason concerning it.
The idea of a substance as well as that of a mode, is nothing but a
collection of Simple ideas, that are united by the imagination, and have
a particular name assigned them, by which we are able to recall, either
to ourselves or others, that collection. But the difference betwixt
these ideas consists in this, that the particular qualities, which form
a substance, are commonly referred to an unknown something, in which
they are supposed to inhere; or granting this fiction should not take
place, are at least supposed to be closely and inseparably connected by
the relations of contiguity and causation. The effect of this is, that
whatever new simple quality we discover to have the same connexion with
the rest, we immediately comprehend it among them, even though it did
not enter into the first conception of the substance. Thus our idea of
gold may at first be a yellow colour, weight, malleableness, fusibility;
but upon the discovery of its dissolubility in aqua regia, we join that
to the other qualities, and suppose it to belong to the substance as
much as if its idea had from the beginning made a part of the compound
one. The principal of union being regarded as the chief part of the
complex idea, gives entrance to whatever quality afterwards occurs, and
is equally comprehended by it, as are the others, which first presented
themselves.
That this cannot take place in modes, is evident from considering their
nature. The simple ideas of which modes are formed, either represent
qualities, which are not united by contiguity and causation, but are
dispersed in different subjects; or if they be all united together, the
uniting principle is not regarded as the foundation of the complex idea.
The idea of a dance is an instance of the first kind of modes; that
of beauty of the second. The reason is obvious, why such complex
ideas cannot receive any new idea, without changing the name, which
distinguishes the mode.
SECT. VII. OF ABSTRACT IDEAS.
A very material question has been started concerning ABSTRACT or
GENERAL ideas, WHETHER THEY BE GENERAL OR PARTICULAR IN THE MIND'S
CONCEPTION OF THEM. A great philosopher [3] has disputed the received
opinion in this particular, and has asserted, that all general ideas
are nothing but particular ones, annexed to a certain term, which gives
them a more extensive signification, and makes them recall upon
occasion other individuals, which are similar to them. As I look upon
this to be one of the greatest and most valuable discoveries that has
been made of late years in the republic of letters, I shall here
endeavour to confirm it by some arguments, which I hope will put it
beyond all doubt and controversy.
[3] Dr. Berkeley. [Introd.: to ‘Principles of Human Knowledge,’
secs. 18 &c. Cf. also Introd. to this volume paragraphs 183 and
ff.—Ed.]
It is evident, that in forming most of our general ideas, if not all of
them, we abstract from every particular degree of quantity and quality,
and that an object ceases not to be of any particular species on
account of every small alteration in its extension, duration and other
properties. It may therefore be thought, that here is a plain dilemma,
that decides concerning the nature of those abstract ideas, which have
afforded so much speculation to philosophers. The abstract idea of a man
represents men of all sizes and all qualities; which it is concluded it
cannot do, but either by representing at once all possible sizes and all
possible qualities, or by, representing no particular one at all. Now
it having been esteemed absurd to defend the former proposition, as
implying an infinite capacity in the mind, it has been commonly inferred
in favour of the latter: and our abstract ideas have been supposed to
represent no particular degree either of quantity or quality. But that
this inference is erroneous, I shall endeavour to make appear, first,
by proving, that it is utterly impossible to conceive any quantity or
quality, without forming a precise notion of its degrees: And secondly
by showing, that though the capacity of the mind be not infinite, yet
we can at once form a notion of all possible degrees of quantity and
quality, in such a manner at least, as, however imperfect, may serve all
the purposes of reflection and conversation.
To begin with the first proposition, THAT THE MIND CANNOT FORM ANY
NOTION OF QUANTITY OR QUALITY WITHOUT FORMING A PRECISE NOTION OF
DEGREES OF EACH; we may prove this by the three following arguments.
First, We have observed, that whatever objects are different are
distinguishable, and that whatever objects are distinguishable are
separable by the thought and imagination. And we may here add, that
these propositions are equally true in the inverse, and that whatever
objects are separable are also distinguishable, and that whatever
objects are distinguishable, are also different. For how is it possible
we can separate what is not distinguishable, or distinguish what is not
different? In order therefore to know, whether abstraction implies a
separation, we need only consider it in this view, and examine, whether
all the circumstances, which we abstract from in our general ideas, be
such as are distinguishable and different from those, which we retain
as essential parts of them. But it is evident at first sight, that the
precise length of a line is not different nor distinguishable from the
line itself nor the precise degree of any quality from the quality.
These ideas, therefore, admit no more of separation than they do of
distinction and difference. They are consequently conjoined with
each other in the conception; and the general idea of a line,
notwithstanding all our abstractions and refinements, has in its
appearance in the mind a precise degree of quantity and quality; however
it may be made to represent others, which have different degrees of
both.
Secondly, it is contest, that no object can appear to the senses; or in
other words, that no impression can become present to the mind, without
being determined in its degrees both of quantity and quality. The
confusion, in which impressions are sometimes involved, proceeds only
from their faintness and unsteadiness, not from any capacity in the mind
to receive any impression, which in its real existence has no particular
degree nor proportion. That is a contradiction in terms; and even
implies the flattest of all contradictions, viz. that it is possible for
the same thing both to be and not to be.
Now since all ideas are derived from impressions, and are nothing but
copies and representations of them, whatever is true of the one must be
acknowledged concerning the other. Impressions and ideas differ only in
their strength and vivacity. The foregoing conclusion is not founded on
any particular degree of vivacity. It cannot therefore be affected by
any variation in that particular. An idea is a weaker impression; and
as a strong impression must necessarily have a determinate quantity and
quality, the case must be the same with its copy or representative.
Thirdly, it is a principle generally received in philosophy that
everything in nature is individual, and that it is utterly absurd to
suppose a triangle really existent, which has no precise proportion of
sides and angles. If this therefore be absurd in fact and reality, it
must also be absurd in idea; since nothing of which we can form a clear
and distinct idea is absurd and impossible. But to form the idea of an
object, and to form an idea simply, is the same thing; the reference
of the idea to an object being an extraneous denomination, of which in
itself it bears no mark or character. Now as it is impossible to form an
idea of an object, that is possest of quantity and quality, and yet
is possest of no precise degree of either; it follows that there is an
equal impossibility of forming an idea, that is not limited and confined
in both these particulars. Abstract ideas are therefore in themselves
individual, however they may become general in their representation.
The image in the mind is only that of a particular object, though the
application of it in our reasoning be the same, as if it were universal.
This application of ideas beyond their nature proceeds from our
collecting all their possible degrees of quantity and quality in such
an imperfect manner as may serve the purposes of life, which is the
second proposition I proposed to explain. When we have found a
resemblance[4] among several objects, that often occur to us, we apply
the same name to all of them, whatever differences we may observe in
the degrees of their quantity and quality, and whatever other
differences may appear among them. After we have acquired a custom of
this kind, the hearing of that name revives the idea of one of these
objects, and makes the imagination conceive it with all its particular
circumstances and proportions. But as the same word is supposed to have
been frequently applied to other individuals, that are different in
many respects from that idea, which is immediately present to the mind;
the word not being able to revive the idea of all these individuals,
but only touches the soul, if I may be allowed so to speak, and revives
that custom, which we have acquired by surveying them. They are not
really and in fact present to the mind, but only in power; nor do we
draw them all out distinctly in the imagination, but keep ourselves in
a readiness to survey any of them, as we may be prompted by a present
design or necessity. The word raises up an individual idea, along with
a certain custom; and that custom produces any other individual one,
for which we may have occasion. But as the production of all the ideas,
to which the name may be applied, is in most eases impossible, we
abridge that work by a more partial consideration, and find but few
inconveniences to arise in our reasoning from that abridgment.
[4] It is evident, that even different simple ideas
may have a similarity or resemblance to each other; nor is
it necessary, that the point or circumstance of resemblance
shoud be distinct or separable from that in which they
differ. BLUE and GREEN are different simple ideas, but are
more resembling than BLUE and SCARLET; tho their perfect
simplicity excludes all possibility of separation or
distinction. It is the same case with particular sounds, and
tastes and smells. These admit of infinite resemblances upon
the general appearance and comparison, without having any
common circumstance the same. And of this we may be certain,
even from the very abstract terms SIMPLE IDEA. They
comprehend all simple ideas under them. These resemble each
other in their simplicity. And yet from their very nature,
which excludes all composition, this circumstance, In which
they resemble, Is not distinguishable nor separable from the
rest. It is the same case with all the degrees In any
quality. They are all resembling and yet the quality, In any
individual, Is not distinct from the degree.
For this is one of the most extraordinary circumstances in the present
affair, that after the mind has produced an individual idea, upon which
we reason, the attendant custom, revived by the general or abstract
term, readily suggests any other individual, if by chance we form any
reasoning, that agrees not with it. Thus should we mention the
word triangle, and form the idea of a particular equilateral one to
correspond to it, and should we afterwards assert, that the three
angles of a triangle are equal to each other, the other individuals of a
scalenum and isosceles, which we overlooked at first, immediately crowd
in upon us, and make us perceive the falshood of this proposition,
though it be true with relation to that idea, which we had formed. If
the mind suggests not always these ideas upon occasion, it proceeds
from some imperfection in its faculties; and such a one as is often the
source of false reasoning and sophistry. But this is principally the
case with those ideas which are abstruse and compounded. On other
occasions the custom is more entire, and it is seldom we run into such
errors.
Nay so entire is the custom, that the very same idea may be annext to
several different words, and may be employed in different reasonings,
without any danger of mistake. Thus the idea of an equilateral triangle
of an inch perpendicular may serve us in talking of a figure, of a
rectilinear figure, of a regular figure, of a triangle, and of an
equilateral triangle. All these terms, therefore, are in this case
attended with the same idea; but as they are wont to be applied in a
greater or lesser compass, they excite their particular habits, and
thereby keep the mind in a readiness to observe, that no conclusion be
formed contrary to any ideas, which are usually comprized under them.
Before those habits have become entirely perfect, perhaps the mind may
not be content with forming the idea of only one individual, but may run
over several, in order to make itself comprehend its own meaning, and
the compass of that collection, which it intends to express by the
general term. That we may fix the meaning of the word, figure, we may
revolve in our mind the ideas of circles, squares, parallelograms,
triangles of different sizes and proportions, and may not rest on one
image or idea. However this may be, it is certain that we form the idea
of individuals, whenever we use any general term; that we seldom or
never can exhaust these individuals; and that those, which remain,
are only represented by means of that habit, by which we recall them,
whenever any present occasion requires it. This then is the nature of
our abstract ideas and general terms; and it is after this manner we
account for the foregoing paradox, THAT SOME IDEAS ARE PARTICULAR IN
THEIR NATURE, BUT GENERAL IN THEIR REPRESENTATION. A particular idea
becomes general by being annexed to a general term; that is, to a
term, which from a customary conjunction has a relation to many other
particular ideas, and readily recalls them in the imagination.
The only difficulty, that can remain on this subject, must be with
regard to that custom, which so readily recalls every particular idea,
for which we may have occasion, and is excited by any word or sound, to
which we commonly annex it. The most proper method, in my opinion,
of giving a satisfactory explication of this act of the mind, is
by producing other instances, which are analogous to it, and other
principles, which facilitate its operation. To explain the ultimate
causes of our mental actions is impossible. It is sufficient, if we can
give any satisfactory account of them from experience and analogy.
First then I observe, that when we mention any great number, such as
a thousand, the mind has generally no adequate idea of it, but only a
power of producing such an idea, by its adequate idea of the decimals,
under which the number is comprehended. This imperfection, however,
in our ideas, is never felt in our reasonings; which seems to be an
instance parallel to the present one of universal ideas.
Secondly, we have several instances of habits, which may be revived
by one single word; as when a person, who has by rote any periods of a
discourse, or any number of verses, will be put in remembrance of
the whole, which he is at a loss to recollect, by that single word or
expression, with which they begin.
Thirdly, I believe every one, who examines the situation of his mind in
reasoning will agree with me, that we do not annex distinct and compleat
ideas to every term we make use of, and that in talking of government,
church, negotiation, conquest, we seldom spread out in our minds all the
simple ideas, of which these complex ones are composed. It is however
observable, that notwithstanding this imperfection we may avoid talking
nonsense on these subjects, and may perceive any repugnance among
the ideas, as well as if we had a fall comprehension of them. Thus
if instead of saying, that in war the weaker have always recourse to
negotiation, we should say, that they have always recourse to conquest,
the custom, which we have acquired of attributing certain relations to
ideas, still follows the words, and makes us immediately perceive the
absurdity of that proposition; in the same manner as one particular idea
may serve us in reasoning concerning other ideas, however different from
it in several circumstances.
Fourthly, As the individuals are collected together, said placed under
a general term with a view to that resemblance, which they bear to each
other, this relation must facilitate their entrance in the imagination,
and make them be suggested more readily upon occasion. And indeed if
we consider the common progress of the thought, either in reflection
or conversation, we shall find great reason to be satisfyed in this
particular. Nothing is more admirable, than the readiness, with which
the imagination suggests its ideas, and presents them at the very
instant, in which they become necessary or useful. The fancy runs from
one end of the universe to the other in collecting those ideas, which
belong to any subject. One would think the whole intellectual world of
ideas was at once subjected to our view, and that we did nothing but
pick out such as were most proper for our purpose. There may not,
however, be any present, beside those very ideas, that are thus
collected by a kind of magical faculty in the soul, which, though it be
always most perfect in the greatest geniuses, and is properly what we
call a genius, is however inexplicable by the utmost efforts of human
understanding.
Perhaps these four reflections may help to remove an difficulties to
the hypothesis I have proposed concerning abstract ideas, so contrary to
that, which has hitherto prevailed in philosophy, But, to tell the truth
I place my chief confidence in what I have already proved concerning
the impossibility of general ideas, according to the common method of
explaining them. We must certainly seek some new system on this head,
and there plainly is none beside what I have proposed. If ideas be
particular in their nature, and at the same time finite in their number,
it is only by custom they can become general in their representation,
and contain an infinite number of other ideas under them.
Before I leave this subject I shall employ the same principles to
explain that distinction of reason, which is so much talked of, and is
so little understood, in the schools. Of this kind is the distinction
betwixt figure and the body figured; motion and the body moved. The
difficulty of explaining this distinction arises from the principle
above explained, that all ideas, which are different, are separable. For
it follows from thence, that if the figure be different from the body,
their ideas must be separable as well as distinguishable: if they be
not different, their ideas can neither be separable nor distinguishable.
What then is meant by a distinction of reason, since it implies neither
a difference nor separation.
To remove this difficulty we must have recourse to the foregoing
explication of abstract ideas. It is certain that the mind would never
have dreamed of distinguishing a figure from the body figured, as being
in reality neither distinguishable, nor different, nor separable; did it
not observe, that even in this simplicity there might be contained many
different resemblances and relations. Thus when a globe of white marble
is presented, we receive only the impression of a white colour disposed
in a certain form, nor are we able to separate and distinguish the
colour from the form. But observing afterwards a globe of black marble
and a cube of white, and comparing them with our former object, we
find two separate resemblances, in what formerly seemed, and really is,
perfectly inseparable. After a little more practice of this kind, we
begin to distinguish the figure from the colour by a distinction of
reason; that is, we consider the figure and colour together, since they
are in effect the same and undistinguishable; but still view them in
different aspects, according to the resemblances, of which they are
susceptible. When we would consider only the figure of the globe of
white marble, we form in reality an idea both of the figure and colour,
but tacitly carry our eye to its resemblance with the globe of black
marble: And in the same manner, when we would consider its colour only,
we turn our view to its resemblance with the cube of white marble. By
this means we accompany our ideas with a kind of reflection, of which
custom renders us, in a great measure, insensible. A person, who desires
us to consider the figure of a globe of white marble without thinking on
its colour, desires an impossibility but his meaning is, that we should
consider the figure and colour together, but still keep in our eye the
resemblance to the globe of black marble, or that to any other globe of
whatever colour or substance.
PART II. OF THE IDEAS OF SPACE AND TIME.
SECT. I. OF THE INFINITE DIVISIBILITY OF OUR IDEAS OF SPACE AND TIME.
Whatever has the air of a paradox, and is contrary to the first and
most unprejudiced notions of mankind, is often greedily embraced by
philosophers, as shewing the superiority of their science, which could
discover opinions so remote from vulgar conception. On the other hand,
anything proposed to us, which causes surprize and admiration, gives
such a satisfaction to the mind, that it indulges itself in those
agreeable emotions, and will never be persuaded that its pleasure is
entirely without foundation. From these dispositions in philosophers and
their disciples arises that mutual complaisance betwixt them; while the
former furnish such plenty of strange and unaccountable opinions, and
the latter so readily believe them. Of this mutual complaisance I
cannot give a more evident instance than in the doctrine of infinite
divisibility, with the examination of which I shall begin this subject
of the ideas of space and time.
It is universally allowed, that the capacity of the mind is limited, and
can never attain a full and adequate conception of infinity: And though
it were not allowed, it would be sufficiently evident from the plainest
observation and experience. It is also obvious, that whatever is capable
of being divided in infinitum, must consist of an infinite number of
parts, and that it is impossible to set any bounds to the number of
parts, without setting bounds at the same time to the division. It
requires scarce any, induction to conclude from hence, that the idea,
which we form of any finite quality, is not infinitely divisible, but
that by proper distinctions and separations we may run up this idea
to inferior ones, which will be perfectly simple and indivisible. In
rejecting the infinite capacity of the mind, we suppose it may arrive at
an end in the division of its ideas; nor are there any possible means of
evading the evidence of this conclusion.
It is therefore certain, that the imagination reaches a minimum, and
may raise up to itself an idea, of which it cannot conceive any
sub-division, and which cannot be diminished without a total
annihilation. When you tell me of the thousandth and ten thousandth
part of a grain of sand, I have a distinct idea of these numbers and of
their different proportions; but the images, which I form in my mind to
represent the things themselves, are nothing different from each other,
nor inferior to that image, by which I represent the grain of sand
itself, which is supposed so vastly to exceed them. What consists of
parts is distinguishable into them, and what is distinguishable is
separable. But whatever we may imagine of the thing, the idea of a grain
of sand is not distinguishable, nor separable into twenty, much less
into a thousand, ten thousand, or an infinite number of different ideas.
It is the same case with the impressions of the senses as with the ideas
of the imagination. Put a spot of ink upon paper, fix your eye upon that
spot, and retire to such a distance, that, at last you lose sight of it;
it is plain, that the moment before it vanished the image or impression
was perfectly indivisible. It is not for want of rays of light striking
on our eyes, that the minute parts of distant bodies convey not any
sensible impression; but because they are removed beyond that distance,
at which their impressions were reduced to a minimum, and were incapable
of any farther diminution. A microscope or telescope, which renders them
visible, produces not any new rays of light, but only spreads those,
which always flowed from them; and by that means both gives parts to
impressions, which to the naked eye appear simple and uncompounded, and
advances to a minimum, what was formerly imperceptible.
We may hence discover the error of the common opinion, that the capacity
of the mind is limited on both sides, and that it is impossible for
the imagination to form an adequate idea, of what goes beyond a certain
degree of minuteness as well as of greatness. Nothing can be more
minute, than some ideas, which we form in the fancy; and images, which
appear to the senses; since there are ideas and images perfectly simple
and indivisible. The only defect of our senses is, that they give
us disproportioned images of things, and represent as minute and
uncompounded what is really great and composed of a vast number of
parts. This mistake we are not sensible of: but taking the impressions
of those minute objects, which appear to the senses, to be equal or
nearly equal to the objects, and finding by reason, that there are other
objects vastly more minute, we too hastily conclude, that these are
inferior to any idea of our imagination or impression of our senses.
This however is certain, that we can form ideas, which shall be no
greater than the smallest atom of the animal spirits of an insect a
thousand times less than a mite: And we ought rather to conclude, that
the difficulty lies in enlarging our conceptions so much as to form a
just notion of a mite, or even of an insect a thousand times less than a
mite. For in order to form a just notion of these animals, we must have
a distinct idea representing every part of them, which, according to the
system of infinite divisibility, is utterly impossible, and, recording
to that of indivisible parts or atoms, is extremely difficult, by reason
of the vast number and multiplicity of these parts.
SECT. II. OF THE INFINITE DIVISIBILITY OF SPACE AND TIME.
Wherever ideas are adequate representations of objects, the relations,
contradictions and agreements of the ideas are all applicable to the
objects; and this we may in general observe to be the foundation of all
human knowledge. But our ideas are adequate representations of the
most minute parts of extension; and through whatever divisions and
subdivisions we may suppose these parts to be arrived at, they can never
become inferior to some ideas, which we form. The plain consequence is,
that whatever appears impossible and contradictory upon the comparison
of these ideas, must be really impossible and contradictory, without any
farther excuse or evasion.
Every thing capable of being infinitely divided contains an infinite
number of parts; otherwise the division would be stopt short by the
indivisible parts, which we should immediately arrive at. If therefore
any finite extension be infinitely divisible, it can be no contradiction
to suppose, that a finite extension contains an infinite number of
parts: And vice versa, if it be a contradiction to suppose, that
a finite extension contains an infinite number of parts, no finite
extension can be infinitely divisible. But that this latter supposition
is absurd, I easily convince myself by the consideration of my clear
ideas. I first take the least idea I can form of a part of extension,
and being certain that there is nothing more minute than this idea, I
conclude, that whatever I discover by its means must be a real quality
of extension. I then repeat this idea once, twice, thrice, &c., and find
the compound idea of extension, arising from its repetition, always
to augment, and become double, triple, quadruple, &c., till at last it
swells up to a considerable bulk, greater or smaller, in proportion as I
repeat more or less the same idea. When I stop in the addition of parts,
the idea of extension ceases to augment; and were I to carry on the
addition in infinitum, I clearly perceive, that the idea of extension
must also become infinite. Upon the whole, I conclude, that the idea of
all infinite number of parts is individually the same idea with that of
an infinite extension; that no finite extension is capable of containing
an infinite number of parts; and consequently that no finite extension
is infinitely divisible.[1]
[1] It has been objected to me, that infinite divisibility supposes
only an infinite number of PROPORTIONAL not of ALIQIOT parts, and
that an infinite number of proportional parts does not form an
infinite extension. But this distinction is entirely frivolous.
Whether these parts be calld ALIQUOT or PROPORTIONAL, they cannot
be inferior to those minute parts we conceive; and therefore cannot
form a less extension by their conjunction.
I may subjoin another argument proposed by a noted author,[2] which
seems to me very strong and beautiful. It is evident, that existence in
itself belongs only to unity, and is never applicable to number, but on
account of the unites, of which the number is composed. Twenty men may
be said to exist; but it is only because one, two, three, four, &c. are
existent, and if you deny the existence of the latter, that of the
former falls of course. It is therefore utterly absurd to suppose any
number to exist, and yet deny the existence of unites; and as extension
is always a number, according to the common sentiment of
metaphysicians, and never resolves itself into any unite or indivisible
quantity, it follows, that extension can never at all exist. It is in
vain to reply, that any determinate quantity of extension is an unite;
but such-a-one as admits of an infinite number of fractions, and is
inexhaustible in its sub-divisions. For by the same rule these twenty
men may be considered as a unit. The whole globe of the earth, nay the
whole universe, may be considered as a unit. That term of unity is
merely a fictitious denomination, which the mind may apply to any
quantity of objects it collects together; nor can such an unity any
more exist alone than number can, as being in reality a true number.
But the unity, which can exist alone, and whose existence is necessary
to that of all number, is of another kind, and must be perfectly
indivisible, and incapable of being resolved into any lesser unity.
[2] Mons. MALEZIEU
All this reasoning takes place with regard to time; along with an
additional argument, which it may be proper to take notice of. It is a
property inseparable from time, and which in a manner constitutes its
essence, that each of its parts succeeds another, and that none of them,
however contiguous, can ever be co-existent. For the same reason, that
the year 1737 cannot concur with the present year 1738 every moment must
be distinct from, and posterior or antecedent to another. It is certain
then, that time, as it exists, must be composed of indivisible moments.
For if in time we could never arrive at an end of division, and if
each moment, as it succeeds another, were not perfectly single and
indivisible, there would be an infinite number of co-existent moments,
or parts of time; which I believe will be allowed to be an arrant
contradiction.
The infinite divisibility of space implies that of time, as is evident
from the nature of motion. If the latter, therefore, be impossible, the
former must be equally so.
I doubt not but, it will readily be allowed by the most obstinate
defender of the doctrine of infinite divisibility, that these arguments
are difficulties, and that it is impossible to give any answer to them
which will be perfectly clear and satisfactory. But here we may
observe, that nothing can be more absurd, than this custom of calling a
difficulty what pretends to be a demonstration, and endeavouring by that
means to elude its force and evidence. It is not in demonstrations as
in probabilities, that difficulties can take place, and one argument
counter-ballance another, and diminish its authority. A demonstration,
if just, admits of no opposite difficulty; and if not just, it is a
mere sophism, and consequently can never be a difficulty. It is either
irresistible, or has no manner of force. To talk therefore of objections
and replies, and ballancing of arguments in such a question as this, is
to confess, either that human reason is nothing but a play of words, or
that the person himself, who talks so, has not a Capacity equal to such
subjects. Demonstrations may be difficult to be comprehended, because of
abstractedness of the subject; but can never have such difficulties as
will weaken their authority, when once they are comprehended.
It is true, mathematicians are wont to say, that there are here equally
strong arguments on the other side of the question, and that the
doctrine of indivisible points is also liable to unanswerable
objections. Before I examine these arguments and objections in detail,
I will here take them in a body, and endeavour by a short and decisive
reason to prove at once, that it is utterly impossible they can have any
just foundation.
It is an established maxim in metaphysics, That whatever the mind
clearly conceives, includes the idea of possible existence, or in other
words, that nothing we imagine is absolutely impossible. We can form the
idea of a golden mountain, and from thence conclude that such a mountain
may actually exist. We can form no idea of a mountain without a valley,
and therefore regard it as impossible.
Now it is certain we have an idea of extension; for otherwise why do we
talk and reason concerning it? It is likewise certain that this idea,
as conceived by the imagination, though divisible into parts or inferior
ideas, is not infinitely divisible, nor consists of an infinite number
of parts: For that exceeds the comprehension of our limited capacities.
Here then is an idea of extension, which consists of parts or inferior
ideas, that are perfectly, indivisible: consequently this idea implies
no contradiction: consequently it is possible for extension really to
exist conformable to it: and consequently all the arguments employed
against the possibility of mathematical points are mere scholastick
quibbles, and unworthy of our attention.
These consequences we may carry one step farther, and conclude that all
the pretended demonstrations for the infinite divisibility of extension
are equally sophistical; since it is certain these demonstrations cannot
be just without proving the impossibility of mathematical points; which
it is an evident absurdity to pretend to.
SECT. III. OF THE OTHER QUALITIES OF OUR IDEA OF SPACE AND TIME.
No discovery could have been made more happily for deciding all
controversies concerning ideas, than that abovementioned, that
impressions always take the precedency of them, and that every idea,
with which the imagination is furnished, first makes its appearance in a
correspondent impression. These latter perceptions are all so clear and
evident, that they admit of no controversy; though many of our ideas are
so obscure, that it is almost impossible even for the mind, which forms
them, to tell exactly their nature and composition. Let us apply this
principle, in order to discover farther the nature of our ideas of space
and time.
Upon opening my eyes, and turning them to the surrounding objects,
I perceive many visible bodies; and upon shutting them again, and
considering the distance betwixt these bodies, I acquire the idea of
extension. As every idea is derived from some impression, which
is exactly similar to it, the impressions similar to this idea of
extension, must either be some sensations derived from the sight, or
some internal impressions arising from these sensations.
Our internal impressions are our passions, emotions, desires and
aversions; none of which, I believe, will ever be asserted to be the
model, from which the idea of space is derived. There remains therefore
nothing but the senses, which can convey to us this original impression.
Now what impression do oar senses here convey to us? This is the
principal question, and decides without appeal concerning the nature of
the idea.
The table before me is alone sufficient by its view to give me the idea
of extension. This idea, then, is borrowed from, and represents some
impression, which this moment appears to the senses. But my senses
convey to me only the impressions of coloured points, disposed in a
certain manner. If the eye is sensible of any thing farther, I desire
it may be pointed out to me. But if it be impossible to shew any thing
farther, we may conclude with certainty, that the idea of extension is
nothing but a copy of these coloured points, and of the manner of their
appearance.
Suppose that in the extended object, or composition of coloured points,
from which we first received the idea of extension, the points were of
a purple colour; it follows, that in every repetition of that idea we
would not only place the points in the same order with respect to each
other, but also bestow on them that precise colour, with which alone we
are acquainted. But afterwards having experience of the other colours of
violet, green, red, white, black, and of all the different compositions
of these, and finding a resemblance in the disposition of coloured
points, of which they are composed, we omit the peculiarities of
colour, as far as possible, and found an abstract idea merely on that
disposition of points, or manner of appearance, in which they agree. Nay
even when the resemblance is carryed beyond the objects of one sense,
and the impressions of touch are found to be Similar to those of sight
in the disposition of their parts; this does not hinder the abstract
idea from representing both, upon account of their resemblance. All
abstract ideas are really nothing but particular ones, considered in
a certain light; but being annexed to general terms, they are able to
represent a vast variety, and to comprehend objects, which, as they are
alike in some particulars, are in others vastly wide of each other.
The idea of time, being derived from the succession of our perceptions
of every kind, ideas as well as impressions, and impressions of
reflection as well as of sensations will afford us an instance of an
abstract idea, which comprehends a still greater variety than that of
space, and yet is represented in the fancy by some particular individual
idea of a determinate quantity and quality.
As it is from the disposition of visible and tangible objects we receive
the idea of space, so from the succession of ideas and impressions we
form the idea of time, nor is it possible for time alone ever to make
its appearance, or be taken notice of by the mind. A man in a sound
sleep, or strongly occupyed with one thought, is insensible of time;
and according as his perceptions succeed each other with greater or
less rapidity, the same duration appears longer or shorter to his
imagination. It has been remarked by a great philosopher, that our
perceptions have certain bounds in this particular, which are fixed by
the original nature and constitution of the mind, and beyond which no
influence of external objects on the senses is ever able to hasten or
retard our thought. If you wheel about a burning coal with rapidity, it
will present to the senses an image of a circle of fire; nor will there
seem to be any interval of time betwixt its revolutions; meerly because
it is impossible for our perceptions to succeed each other with the same
rapidity, that motion may be communicated to external objects. Wherever
we have no successive perceptions, we have no notion of time, even
though there be a real succession in the objects. From these phenomena,
as well as from many others, we may conclude, that time cannot make
its appearance to the mind, either alone, or attended with a steady
unchangeable object, but is always discovered some PERCEIVABLE
succession of changeable objects.
To confirm this we may add the following argument, which to me seems
perfectly decisive and convincing. It is evident, that time or duration
consists of different parts: For otherwise we could not conceive a
longer or shorter duration. It is also evident, that these parts are not
co-existent: For that quality of the co-existence of parts belongs to
extension, and is what distinguishes it from duration. Now as time is
composed of parts, that are not coexistent: an unchangeable object,
since it produces none but coexistent impressions, produces none that
can give us the idea of time; and consequently that idea must be
derived from a succession of changeable objects, and time in its first
appearance can never be severed from such a succession.
Having therefore found, that time in its first appearance to the mind
is always conjoined with a succession of changeable objects, and that
otherwise it can never fall under our notice, we must now examine
whether it can be conceived without our conceiving any succession
of objects, and whether it can alone form a distinct idea in the
imagination.
In order to know whether any objects, which are joined in impression,
be inseparable in idea, we need only consider, if they be different
from each other; in which case, it is plain they may be conceived apart.
Every thing, that is different is distinguishable: and everything,
that is distinguishable, may be separated, according to the maxims
above-explained. If on the contrary they be not different, they are
not distinguishable: and if they be not distinguishable, they cannot be
separated. But this is precisely the case with respect to time, compared
with our successive perceptions. The idea of time is not derived from a
particular impression mixed up with others, and plainly distinguishable
from them; but arises altogether from the manner, in which impressions
appear to the mind, without making one of the number. Five notes played
on a flute give us the impression and idea of time; though time be not
a sixth impression, which presents itself to the hearing or any other of
the senses. Nor is it a sixth impression, which the mind by reflection
finds in itself. These five sounds making their appearance in this
particular manner, excite no emotion in the mind, nor produce an
affection of any kind, which being observed by it can give rise to a new
idea. For that is necessary to produce a new idea of reflection, nor can
the mind, by revolving over a thousand times all its ideas of sensation,
ever extract from them any new original idea, unless nature has so
framed its faculties, that it feels some new original impression arise
from such a contemplation. But here it only takes notice of the manner,
in which the different sounds make their appearance; and that it may
afterwards consider without considering these particular sounds, but
may conjoin it with any other objects. The ideas of some objects it
certainly must have, nor is it possible for it without these ideas ever
to arrive at any conception of time; which since it, appears not as any
primary distinct impression, can plainly be nothing but different
ideas, or impressions, or objects disposed in a certain manner, that is,
succeeding each other.
I know there are some who pretend, that the idea of duration
is applicable in a proper sense to objects, which are perfectly
unchangeable; and this I take to be the common opinion of philosophers
as well as of the vulgar. But to be convinced of its falsehood we need
but reflect on the foregoing conclusion, that the idea of duration is
always derived from a succession of changeable objects, and can never
be conveyed to the mind by any thing stedfast and unchangeable. For it
inevitably follows from thence, that since the idea of duration cannot
be derived from such an object, it can never-in any propriety or
exactness be applied to it, nor can any thing unchangeable be ever said
to have duration. Ideas always represent the Objects or impressions,
from which they are derived, and can never without a fiction represent
or be applied to any other. By what fiction we apply the idea of time,
even to what is unchangeable, and suppose, as is common, that duration
is a measure of rest as well as of motion, we shall consider
afterwards.[3]
[3] Sect 5.
There is another very decisive argument, which establishes the present
doctrine concerning our ideas of space and time, and is founded only on
that simple principle, that our ideas of them are compounded of parts,
which are indivisible. This argument may be worth the examining.
Every idea, that is distinguishable, being also separable, let us take
one of those simple indivisible ideas, of which the compound one of
extension is formed, and separating it from all others, and considering
it apart, let us form a judgment of its nature and qualities.
It is plain it is not the idea of extension. For the idea of extension
consists of parts; and this idea, according to the supposition, is
perfectly simple and indivisible. Is it therefore nothing? That is
absolutely impossible. For as the compound idea of extension, which is
real, is composed of such ideas; were these so many non-entities, there
would be a real existence composed of non-entities; which is absurd.
Here therefore I must ask, What is our idea of a simple and indivisible
point? No wonder if my answer appear somewhat new, since the question
itself has scarce ever yet been thought of. We are wont to dispute
concerning the nature of mathematical points, but seldom concerning the
nature of their ideas.
The idea of space is conveyed to the mind by two senses, the sight
and touch; nor does anything ever appear extended, that is not either
visible or tangible. That compound impression, which represents
extension, consists of several lesser impressions, that are indivisible
to the eye or feeling, and may be called impressions of atoms or
corpuscles endowed with colour and solidity. But this is not all. It is
not only requisite, that these atoms should be coloured or tangible,
in order to discover themselves to our senses; it is also necessary
we should preserve the idea of their colour or tangibility in order to
comprehend them by our imagination. There is nothing but the idea of
their colour or tangibility, which can render them conceivable by the
mind. Upon the removal of the ideas of these sensible qualities, they
are utterly annihilated to the thought or imagination.
Now such as the parts are, such is the whole. If a point be not
considered as coloured or tangible, it can convey to us no idea; and
consequently the idea of extension, which is composed of the ideas of
these points, can never possibly exist. But if the idea of extension
really can exist, as we are conscious it does, its parts must also
exist; and in order to that, must be considered as coloured or tangible.
We have therefore no idea of space or extension, but when we regard it
as an object either of our sight or feeling.
The same reasoning will prove, that the indivisible moments of time must
be filled with some real object or existence, whose succession forms the
duration, and makes it be conceivable by the mind.
SECT. IV. OBJECTIONS ANSWERED.
Our system concerning space and time consists of two parts, which
are intimately connected together. The first depends on this chain of
reasoning. The capacity of the mind is not infinite; consequently no
idea of extension or duration consists of an infinite number of parts
or inferior ideas, but of a finite number, and these simple and
indivisible: It is therefore possible for space and time to exist
conformable to this idea: And if it be possible, it is certain they
actually do exist conformable to it; since their infinite divisibility
is utterly impossible and contradictory.
The other part of our system is a consequence of this. The parts, into
which the ideas of space and time resolve themselves, become at last
indivisible; and these indivisible parts, being nothing in themselves,
are inconceivable when not filled with something real and existent. The
ideas of space and time are therefore no separate or distinct ideas, but
merely those of the manner or order, in which objects exist: Or in
other words, it is impossible to conceive either a vacuum and extension
without matter, or a time, when there was no succession or change in any
real existence. The intimate connexion betwixt these parts of our system
is the reason why we shall examine together the objections, which have
been urged against both of them, beginning with those against the finite
divisibility of extension.
I. The first of these objections, which I shall take notice of, is more
proper to prove this connexion and dependence of the one part upon the
other, than to destroy either of them. It has often been maintained in
the schools, that extension must be divisible, in infinitum, because
the system of mathematical points is absurd; and that system is absurd,
because a mathematical point is a non-entity, and consequently can never
by its conjunction with others form a real existence. This would
be perfectly decisive, were there no medium betwixt the infinite
divisibility of matter, and the non-entity of mathematical points. But
there is evidently a medium, viz. the bestowing a colour or solidity on
these points; and the absurdity of both the extremes is a demonstration
of the truth and reality of this medium. The system of physical points,
which is another medium, is too absurd to need a refutation. A real
extension, such as a physical point is supposed to be, can never exist
without parts, different from each other; and wherever objects are
different, they are distinguishable and separable by the imagination.
II. The second objection is derived from the necessity there would be of
PENETRATION, if extension consisted of mathematical points. A simple and
indivisible atom, that touches another, must necessarily penetrate it;
for it is impossible it can touch it by its external parts, from the
very supposition of its perfect simplicity, which excludes all parts. It
must therefore touch it intimately, and in its whole essence, SECUNDUM
SE, TOTA, ET TOTALITER; which is the very definition of penetration.
But penetration is impossible: Mathematical points are of consequence
equally impossible.
I answer this objection by substituting a juster idea of penetration.
Suppose two bodies containing no void within their circumference, to
approach each other, and to unite in such a manner that the body, which
results from their union, is no more extended than either of them; it
is this we must mean when we talk of penetration. But it is evident this
penetration is nothing but the annihilation of one of these bodies, and
the preservation of the other, without our being able to distinguish
particularly which is preserved and which annihilated. Before the
approach we have the idea of two bodies. After it we have the idea
only of one. It is impossible for the mind to preserve any notion of
difference betwixt two bodies of the same nature existing in the same
place at the same time.
Taking then penetration in this sense, for the annihilation of one body
upon its approach to another, I ask any one, if he sees a necessity,
that a coloured or tangible point should be annihilated upon the
approach of another coloured or tangible point? On the contrary, does
he not evidently perceive, that from the union of these points there
results an object, which is compounded and divisible, and may be
distinguished into two parts, of which each preserves its existence
distinct and separate, notwithstanding its contiguity to the other? Let
him aid his fancy by conceiving these points to be of different colours,
the better to prevent their coalition and confusion. A blue and a red
point may surely lie contiguous without any penetration or annihilation.
For if they cannot, what possibly can become of them? Whether shall the
red or the blue be annihilated? Or if these colours unite into one, what
new colour will they produce by their union?
What chiefly gives rise to these objections, and at the same time
renders it so difficult to give a satisfactory answer to them, is the
natural infirmity and unsteadiness both of our imagination and senses,
when employed on such minute objects. Put a spot of ink upon paper, and
retire to such a distance, that the spot becomes altogether invisible;
you will find, that upon your return and nearer approach the spot
first becomes visible by short intervals; and afterwards becomes always
visible; and afterwards acquires only a new force in its colouring
without augmenting its bulk; and afterwards, when it has encreased to
such a degree as to be really extended, it is still difficult for
the imagination to break it into its component parts, because of the
uneasiness it finds in the conception of such a minute object as a
single point. This infirmity affects most of our reasonings on the
present subject, and makes it almost impossible to answer in an
intelligible manner, and in proper expressions, many questions which may
arise concerning it.
III. There have been many objections drawn from the mathematics against
the indivisibility of the parts of extension: though at first sight that
science seems rather favourable to the present doctrine; and if it
be contrary in its DEMONSTRATIONS, it is perfectly conformable in its
definitions. My present business then must be to defend the definitions,
and refute the demonstrations.
A surface is DEFINed to be length and breadth without depth: A line
to be length without breadth or depth: A point to be what has neither
length, breadth nor depth. It is evident that all this is perfectly
unintelligible upon any other supposition than that of the composition
of extension by indivisible points or atoms. How else could any thing
exist without length, without breadth, or without depth?
Two different answers, I find, have been made to this argument; neither
of which is in my opinion satisfactory. The first is, that the objects
of geometry, those surfaces, lines and points, whose proportions and
positions it examines, are mere ideas in the mind; and not only never
did, but never can exist in nature. They never did exist; for no one
will pretend to draw a line or make a surface entirely conformable to
the definition: They never can exist; for we may produce demonstrations
from these very ideas to prove, that they are impossible.
But can anything be imagined more absurd and contradictory than this
reasoning? Whatever can be conceived by a clear and distinct idea
necessarily implies the possibility of existence; and he who pretends
to prove the impossibility of its existence by any argument derived from
the clear idea, in reality asserts, that we have no clear idea of
it, because we have a clear idea. It is in vain to search for a
contradiction in any thing that is distinctly conceived by the mind. Did
it imply any contradiction, it is impossible it could ever be conceived.
There is therefore no medium betwixt allowing at least the possibility
of indivisible points, and denying their idea; and it is on this latter
principle, that the second answer to the foregoing argument is founded.
It has been[4] pretended, that though it be impossible to conceive a
length without any breadth, yet by an abstraction without a separation,
we can consider the one without regarding the other; in the same manner
as we may think of the length of the way betwixt two towns, and
overlook its breadth. The length is inseparable from the breadth both
in nature and in our minds; but this excludes not a partial
consideration, and a distinction of reason, after the manner above
explained.
[4] L'Art de penser.
In refuting this answer I shall not insist on the argument, which I have
already sufficiently explained, that if it be impossible for the mind
to arrive at a minimum in its ideas, its capacity must be infinite, in
order to comprehend the infinite number of parts, of which its idea of
any extension would be composed. I shall here endeavour to find some new
absurdities in this reasoning.
A surface terminates a solid; a line terminates a surface; a point
terminates a line; but I assert, that if the ideas of a point, line or
surface were not indivisible, it is impossible we should ever conceive
these terminations: For let these ideas be supposed infinitely
divisible; and then let the fancy endeavour to fix itself on the idea of
the last surface, line or point; it immediately finds this idea to break
into parts; and upon its seizing the last of these parts, it loses its
hold by a new division, and so on in infinitum, without any possibility
of its arriving at a concluding idea. The number of fractions bring
it no nearer the last division, than the first idea it formed. Every
particle eludes the grasp by a new fraction; like quicksilver, when we
endeavour to seize it. But as in fact there must be something, which
terminates the idea of every finite quantity; and as this terminating
idea cannot itself consist of parts or inferior ideas; otherwise it
would be the last of its parts, which finished the idea, and so on; this
is a clear proof, that the ideas of surfaces, lines and points admit
not of any division; those of surfaces in depth; of lines in breadth and
depth; and of points in any dimension.
The school were so sensible of the force of this argument, that some of
them maintained, that nature has mixed among those particles of matter,
which are divisible in infinitum, a number of mathematical points, in
order to give a termination to bodies; and others eluded the force of
this reasoning by a heap of unintelligible cavils and distinctions. Both
these adversaries equally yield the victory. A man who hides himself,
confesses as evidently the superiority of his enemy, as another, who
fairly delivers his arms.
Thus it appears, that the definitions of mathematics destroy the
pretended demonstrations; and that if we have the idea of indivisible
points, lines and surfaces conformable to the definition, their
existence is certainly possible: but if we have no such idea, it is
impossible we can ever conceive the termination of any figure; without
which conception there can be no geometrical demonstration.
But I go farther, and maintain, that none of these demonstrations
can have sufficient weight to establish such a principle, as this of
infinite divisibility; and that because with regard to such minute
objects, they are not properly demonstrations, being built on ideas,
which are not exact, and maxims, which are not precisely true. When
geometry decides anything concerning the proportions of quantity, we
ought not to look for the utmost precision and exactness. None of its
proofs extend so far. It takes the dimensions and proportions of
figures justly; but roughly, and with some liberty. Its errors are never
considerable; nor would it err at all, did it not aspire to such an
absolute perfection.
I first ask mathematicians, what they mean when they say one line or
surface is EQUAL to, or GREATER or LESS than another? Let any of them
give an answer, to whatever sect he belongs, and whether he maintains
the composition of extension by indivisible points, or by quantities
divisible in infinitum. This question will embarrass both of them.
There are few or no mathematicians, who defend the hypothesis of
indivisible points; and yet these have the readiest and justest answer
to the present question. They need only reply, that lines or surfaces
are equal, when the numbers of points in each are equal; and that as
the proportion of the numbers varies, the proportion of the lines and
surfaces is also varyed. But though this answer be just, as well as
obvious; yet I may affirm, that this standard of equality is entirely
useless, and that it never is from such a comparison we determine
objects to be equal or unequal with respect to each other. For as the
points, which enter into the composition of any line or surface, whether
perceived by the sight or touch, are so minute and so confounded with
each other, that it is utterly impossible for the mind to compute their
number, such a computation will Never afford us a standard by which we
may judge of proportions. No one will ever be able to determine by an
exact numeration, that an inch has fewer points than a foot, or a foot
fewer than an ell or any greater measure: for which reason we seldom or
never consider this as the standard of equality or inequality.
As to those, who imagine, that extension is divisible in infinitum, it
is impossible they can make use of this answer, or fix the equality of
any line or surface by a numeration of its component parts. For since,
according to their hypothesis, the least as well as greatest figures
contain an infinite number of parts; and since infinite numbers,
properly speaking, can neither be equal nor unequal with respect to each
other; the equality or inequality of any portions of space can never
depend on any proportion in the number of their parts. It is true, it
may be said, that the inequality of an ell and a yard consists in the
different numbers of the feet, of which they are composed; and that of
a foot and a yard in the number of the inches. But as that quantity we
call an inch in the one is supposed equal to what we call an inch in
the other, and as it is impossible for the mind to find this equality by
proceeding in infinitum with these references to inferior quantities: it
is evident, that at last we must fix some standard of equality different
from an enumeration of the parts.
There are some[5], who pretend, that equality is best defined by
congruity, and that any two figures are equal, when upon the placing of
one upon the other, all their parts correspond to and touch each other.
In order to judge of this definition let us consider, that since
equality is a relation, it is not, strictly speaking, a property in the
figures themselves, but arises merely from the comparison, which the
mind makes betwixt them. If it consists, therefore, in this imaginary
application and mutual contact of parts, we must at least have a
distinct notion of these parts, and must conceive their contact. Now it
is plain, that in this conception we would run up these parts to the
greatest minuteness, which can possibly be conceived; since the contact
of large parts would never render the figures equal. But the minutest
parts we can conceive are mathematical points; and consequently this
standard of equality is the same with that derived from the equality of
the number of points; which we have already determined to be a just but
an useless standard. We must therefore look to some other quarter for a
solution of the present difficulty.
[5] See Dr. Barrow's mathematical lectures.
There are many philosophers, who refuse to assign any standard of
equality, but assert, that it is sufficient to present two objects, that
are equal, in order to give us a just notion of this proportion. All
definitions, say they, are fruitless, without the perception of such
objects; and where we perceive such objects, we no longer stand in need
of any definition. To this reasoning, I entirely agree; and assert, that
the only useful notion of equality, or inequality, is derived from the
whole united appearance and the comparison of particular objects.
It is evident, that the eye, or rather the mind is often able at one
view to determine the proportions of bodies, and pronounce them equal
to, or greater or less than each other, without examining or comparing
the number of their minute parts. Such judgments are not only common,
but in many cases certain and infallible. When the measure of a yard and
that of a foot are presented, the mind can no more question, that the
first is longer than the second, than it can doubt of those principles,
which are the most clear and self-evident.
There are therefore three proportions, which the mind distinguishes
in the general appearance of its objects, and calls by the names of
greater, less and equal. But though its decisions concerning these
proportions be sometimes infallible, they are not always so; nor are our
judgments of this kind more exempt from doubt and error than those on
any other subject. We frequently correct our first opinion by a review
and reflection; and pronounce those objects to be equal, which at first
we esteemed unequal; and regard an object as less, though before it
appeared greater than another. Nor is this the only correction, which
these judgments of our senses undergo; but we often discover our error
by a juxtaposition of the objects; or where that is impracticable, by
the use of some common and invariable measure, which being successively
applied to each, informs us of their different proportions. And even
this correction is susceptible of a new correction, and of different
degrees of exactness, according to the nature of the instrument,
by which we measure the bodies, and the care which we employ in the
comparison.
When therefore the mind is accustomed to these judgments and their
corrections, and finds that the same proportion which makes two figures
have in the eye that appearance, which we call equality, makes them also
correspond to each other, and to any common measure, with which they
are compared, we form a mixed notion of equality derived both from the
looser and stricter methods of comparison. But we are not content with
this. For as sound reason convinces us that there are bodies vastly more
minute than those, which appear to the senses; and as a false reason
would perswade us, that there are bodies infinitely more minute; we
clearly perceive, that we are not possessed of any instrument or art of
measuring, which can secure us from ill error and uncertainty. We are
sensible, that the addition or removal of one of these minute parts,
is not discernible either in the appearance or measuring; and as we
imagine, that two figures, which were equal before, cannot be equal
after this removal or addition, we therefore suppose some imaginary
standard of equality, by which the appearances and measuring are exactly
corrected, and the figures reduced entirely to that proportion. This
standard is plainly imaginary. For as the very idea of equality is that
of such a particular appearance corrected by juxtaposition or a common
measure. The notion of any correction beyond what we have instruments
and art to make, is a mere fiction of the mind, and useless as well
as incomprehensible. But though this standard be only imaginary, the
fiction however is very natural; nor is anything more usual, than for
the mind to proceed after this manner with any action, even after the
reason has ceased, which first determined it to begin. This appears very
conspicuously with regard to time; where though it is evident we have no
exact method of determining the proportions of parts, not even so exact
as in extension, yet the various corrections of our measures, and their
different degrees of exactness, have given as an obscure and implicit
notion of a perfect and entire equality. The case is the same in many
other subjects. A musician finding his ear becoming every day more
delicate, and correcting himself by reflection and attention, proceeds
with the same act of the mind, even when the subject fails him, and
entertains a notion of a compleat TIERCE or OCTAVE, without being able
to tell whence he derives his standard. A painter forms the same fiction
with regard to colours. A mechanic with regard to motion. To the one
light and shade; to the other swift and slow are imagined to be capable
of an exact comparison and equality beyond the judgments of the senses.
We may apply the same reasoning to CURVE and RIGHT lines. Nothing is
more apparent to the senses, than the distinction betwixt a curve and a
right line; nor are there any ideas we more easily form than the ideas
of these objects. But however easily we may form these ideas, it is
impossible to produce any definition of them, which will fix the precise
boundaries betwixt them. When we draw lines upon paper, or any continued
surface, there is a certain order, by which the lines run along from one
point to another, that they may produce the entire impression of a
curve or right line; but this order is perfectly unknown, and nothing
is observed but the united appearance. Thus even upon the system of
indivisible points, we can only form a distant notion of some unknown
standard to these objects. Upon that of infinite divisibility we cannot
go even this length; but are reduced meerly to the general appearance,
as the rule by which we determine lines to be either curve or right
ones. But though we can give no perfect definition of these lines, nor
produce any very exact method of distinguishing the one from the other;
yet this hinders us not from correcting the first appearance by a more
accurate consideration, and by a comparison with some rule, of whose
rectitude from repeated trials we have a greater assurance. And it is
from these corrections, and by carrying on the same action of the mind,
even when its reason fails us, that we form the loose idea of a perfect
standard to these figures, without being able to explain or comprehend
it.
It is true, mathematicians pretend they give an exact definition of a
right line, when they say, it is the shortest way betwixt two points.
But in the first place I observe, that this is more properly the
discovery of one of the properties of a right line, than a just
deflation of it. For I ask any one, if upon mention of a right line he
thinks not immediately on such a particular appearance, and if it is not
by accident only that he considers this property? A right line can be
comprehended alone; but this definition is unintelligible without a
comparison with other lines, which we conceive to be more extended. In
common life it is established as a maxim, that the straightest way is
always the shortest; which would be as absurd as to say, the shortest
way is always the shortest, if our idea of a right line was not
different from that of the shortest way betwixt two points.
Secondly, I repeat what I have already established, that we have no
precise idea of equality and inequality, shorter and longer, more than
of a right line or a curve; and consequently that the one can never
afford us a perfect standard for the other. An exact idea can never be
built on such as are loose and undetermined.
The idea of a plain surface is as little susceptible of a precise
standard as that of a right line; nor have we any other means of
distinguishing such a surface, than its general appearance. It is in
vain, that mathematicians represent a plain surface as produced by the
flowing of a right line. It will immediately be objected, that our idea
of a surface is as independent of this method of forming a surface, as
our idea of an ellipse is of that of a cone; that the idea of a right
line is no more precise than that of a plain surface; that a right line
may flow irregularly, and by that means form a figure quite different
from a plane; and that therefore we must suppose it to flow along two
right lines, parallel to each other, and on the same plane; which is a
description, that explains a thing by itself, and returns in a circle.
It appears, then, that the ideas which are most essential to geometry,
viz. those of equality and inequality, of a right line and a plain
surface, are far from being exact and determinate, according to our
common method of conceiving them. Not only we are incapable of telling,
if the case be in any degree doubtful, when such particular figures are
equal; when such a line is a right one, and such a surface a plain one;
but we can form no idea of that proportion, or of these figures, which
is firm and invariable. Our appeal is still to the weak and fallible
judgment, which we make from the appearance of the objects, and correct
by a compass or common measure; and if we join the supposition of
any farther correction, it is of such-a-one as is either useless or
imaginary. In vain should we have recourse to the common topic, and
employ the supposition of a deity, whose omnipotence may enable him to
form a perfect geometrical figure, and describe a right line without any
curve or inflexion. As the ultimate standard of these figures is derived
from nothing but the senses and imagination, it is absurd to talk of
any perfection beyond what these faculties can judge of; since the true
perfection of any thing consists in its conformity to its standard.
Now since these ideas are so loose and uncertain, I would fain ask any
mathematician what infallible assurance he has, not only of the more
intricate, and obscure propositions of his science, but of the most
vulgar and obvious principles? How can he prove to me, for instance,
that two right lines cannot have one common segment? Or that it is
impossible to draw more than one right line betwixt any two points?
should he tell me, that these opinions are obviously absurd, and
repugnant to our clear ideas; I would answer, that I do not deny, where
two right lines incline upon each other with a sensible angle, but it is
absurd to imagine them to have a common segment. But supposing these two
lines to approach at the rate of an inch in twenty leagues, I perceive
no absurdity in asserting, that upon their contact they become one. For,
I beseech you, by what rule or standard do you judge, when you assert,
that the line, in which I have supposed them to concur, cannot make
the same right line with those two, that form so small an angle betwixt
them? You must surely have some idea of a right line, to which this line
does not agree. Do you therefore mean that it takes not the points in
the same order and by the same rule, as is peculiar and essential to a
right line? If so, I must inform you, that besides that in judging after
this manner you allow, that extension is composed of indivisible points
(which, perhaps, is more than you intend) besides this, I say, I must
inform you, that neither is this the standard from which we form the
idea of a right line; nor, if it were, is there any such firmness in our
senses or imagination, as to determine when such an order is violated or
preserved. The original standard of a right line is in reality nothing
but a certain general appearance; and it is evident right lines may be
made to concur with each other, and yet correspond to this standard,
though corrected by all the means either practicable or imaginable.
To whatever side mathematicians turn, this dilemma still meets them.
If they judge of equality, or any other proportion, by the accurate and
exact standard, viz. the enumeration of the minute indivisible parts,
they both employ a standard, which is useless in practice, and actually
establish the indivisibility of extension, which they endeavour to
explode. Or if they employ, as is usual, the inaccurate standard,
derived from a comparison of objects, upon their general appearance,
corrected by measuring and juxtaposition; their first principles,
though certain and infallible, are too coarse to afford any such subtile
inferences as they commonly draw from them. The first principles are
founded on the imagination and senses: The conclusion, therefore, can
never go beyond, much less contradict these faculties.
This may open our eyes a little, and let us see, that no geometrical
demonstration for the infinite divisibility of extension can have so
much force as what we naturally attribute to every argument, which is
supported by such magnificent pretensions. At the same time we may learn
the reason, why geometry falls of evidence in this single point, while
all its other reasonings command our fullest assent and approbation.
And indeed it seems more requisite to give the reason of this exception,
than to shew, that we really must make such an exception, and regard
all the mathematical arguments for infinite divisibility as utterly
sophistical. For it is evident, that as no idea of quantity is
infinitely divisible, there cannot be imagined a more glaring absurdity,
than to endeavour to prove, that quantity itself admits of such a
division; and to prove this by means of ideas, which are directly
opposite in that particular. And as this absurdity is very glaring in
itself, so there is no argument founded on it which is not attended
with a new absurdity, and involves not an evident contradiction.
I might give as instances those arguments for infinite divisibility,
which are derived from the point of contact. I know there is no
mathematician, who will not refuse to be judged by the diagrams he
describes upon paper, these being loose draughts, as he will tell us,
and serving only to convey with greater facility certain ideas, which
are the true foundation of all our reasoning. This I am satisfyed with,
and am willing to rest the controversy merely upon these ideas. I desire
therefore our mathematician to form, as accurately as possible,
the ideas of a circle and a right line; and I then ask, if upon the
conception of their contact he can conceive them as touching in a
mathematical point, or if he must necessarily imagine them to concur
for some space. Whichever side he chuses, he runs himself into equal
difficulties. If he affirms, that in tracing these figures in his
imagination, he can imagine them to touch only in a point, he allows
the possibility of that idea, and consequently of the thing. If he says,
that in his conception of the contact of those lines he must make
them concur, he thereby acknowledges the fallacy of geometrical
demonstrations, when carryed beyond a certain degree of minuteness;
since it is certain he has such demonstrations against the concurrence
of a circle and a right line; that is, in other words, he can prove an
idea, viz. that of concurrence, to be INCOMPATIBLE with two other
ideas, those of a circle and right line; though at the same time he
acknowledges these ideas to be inseparable.
SECT. V. THE SAME SUBJECT CONTINUED.
If the second part of my system be true, that the idea of space
or extension is nothing but the idea of visible or tangible points
distributed in a certain order; it follows, that we can form no idea
of a vacuum, or space, where there is nothing visible or tangible. This
gives rise to three objections, which I shall examine together, because
the answer I shall give to one is a consequence of that which I shall
make use of for the others.
First, It may be said, that men have disputed for many ages concerning
a vacuum and a plenum, without being able to bring the affair to a
final decision; and philosophers, even at this day, think themselves
at liberty to take part on either side, as their fancy leads them. But
whatever foundation there may be for a controversy concerning the things
themselves, it may be pretended, that the very dispute is decisive
concerning the idea, and that it is impossible men could so long reason
about a vacuum, and either refute or defend it, without having a notion
of what they refuted or defended.
Secondly, If this argument should be contested, the reality or at least
the possibility of the idea of a vacuum may be proved by the following
reasoning. Every idea is possible, which is a necessary and infallible
consequence of such as are possible. Now though we allow the world to be
at present a plenum, we may easily conceive it to be deprived of motion;
and this idea will certainly be allowed possible. It must also be
allowed possible, to conceive the annihilation of any part of matter by
the omnipotence of the deity, while the other parts remain at rest. For
as every idea, that is distinguishable, is separable by the imagination;
and as every idea, that is separable by the imagination, may be
conceived to be separately existent; it is evident, that the existence
of one particle of matter, no more implies the existence of another,
than a square figure in one body implies a square figure in every one.
This being granted, I now demand what results from the concurrence of
these two possible ideas of rest and annihilation, and what must we
conceive to follow upon the annihilation of all the air and subtile
matter in the chamber, supposing the walls to remain the same, without
any motion or alteration? There are some metaphysicians, who answer,
that since matter and extension are the same, the annihilation of one
necessarily implies that of the other; and there being now no distance
betwixt the walls of the chamber, they touch each other; in the same
manner as my hand touches the paper, which is immediately before me.
But though this answer be very common, I defy these metaphysicians to
conceive the matter according to their hypothesis, or imagine the floor
and roof, with all the opposite sides of the chamber, to touch each
other, while they continue in rest, and preserve the same position. For
how can the two walls, that run from south to north, touch each other,
while they touch the opposite ends of two walls, that run from east
to west? And how can the floor and roof ever meet, while they are
separated by the four walls, that lie in a contrary position? If you
change their position, you suppose a motion. If you conceive any thing
betwixt them, you suppose a new creation. But keeping strictly to the
two ideas of rest and annihilation, it is evident, that the idea, which
results from them, is not that of a contact of parts, but something
else; which is concluded to be the idea of a vacuum.
The third objection carries the matter still farther, and not only
asserts, that the idea of a vacuum is real and possible, but also
necessary and unavoidable. This assertion is founded on the motion we
observe in bodies, which, it is maintained, would be impossible and
inconceivable without a vacuum, into which one body must move in order
to make way for another.. I shall not enlarge upon this objection,
because it principally belongs to natural philosophy, which lies without
our present sphere.
In order to answer these objections, we must take the matter pretty
deep, and consider the nature and origin of several ideas, lest we
dispute without understanding perfectly the subject of the controversy.
It is evident the idea of darkness is no positive idea, but merely the
negation of light, or more properly speaking, of coloured and visible
objects. A man, who enjoys his sight, receives no other perception from
turning his eyes on every side, when entirely deprived of light, than
what is common to him with one born blind; and it is certain such-a-one
has no idea either of light or darkness. The consequence of this is,
that it is not from the mere removal of visible objects we receive
the impression of extension without matter; and that the idea of utter
darkness can never be the same with that of vacuum.
Suppose again a man to be supported in the air, and to be softly
conveyed along by some invisible power; it is evident he is sensible of
nothing, and never receives the idea of extension, nor indeed any idea,
from this invariable motion. Even supposing he moves his limbs to
and fro, this cannot convey to him that idea. He feels in that case a
certain sensation or impression, the parts of which are successive to
each other, and may give him the idea of time: But certainly are not
disposed in such a manner, as is necessary to convey the idea of space
or the idea of space or extension.
Since then it appears, that darkness and motion, with the utter removal
of every thing visible and tangible, can never give us the idea of
extension without matter, or of a vacuum; the next question is, whether
they can convey this idea, when mixed with something visible and
tangible?
It is commonly allowed by philosophers, that all bodies, which discover
themselves to the eye, appear as if painted on a plain surface, and that
their different degrees of remoteness from ourselves are discovered
more by reason than by the senses. When I hold up my hand before me, and
spread my fingers, they are separated as perfectly by the blue colour
of the firmament, as they could be by any visible object, which I could
place betwixt them. In order, therefore, to know whether the sight can
convey the impression and idea of a vacuum, we must suppose, that amidst
an entire darkness, there are luminous bodies presented to us, whose
light discovers only these bodies themselves, without giving us any
impression of the surrounding objects.
We must form a parallel supposition concerning the objects of our
feeling. It is not proper to suppose a perfect removal of all tangible
objects: we must allow something to be perceived by the feeling; and
after an interval and motion of the hand or other organ of sensation,
another object of the touch to be met with; and upon leaving that,
another; and so on, as often as we please. The question is, whether
these intervals do not afford us the idea of extension without body?
To begin with the first case; it is evident, that when only two luminous
bodies appear to the eye, we can perceive, whether they be conjoined or
separate: whether they be separated by a great or small distance; and if
this distance varies, we can perceive its increase or diminution, with
the motion of the bodies. But as the distance is not in this case any
thing coloured or visible, it may be thought that there is here a vacuum
or pure extension, not only intelligible to the mind, but obvious to the
very senses.
This is our natural and most familiar way of thinking; but which we
shall learn to correct by a little reflection. We may observe, that
when two bodies present themselves, where there was formerly an entire
darkness, the only change, that is discoverable, is in the appearance
of these two objects, and that all the rest continues to be as before, a
perfect negation of light, and of every coloured or visible object. This
is not only true of what may be said to be remote from these bodies, but
also of the very distance; which is interposed betwixt them; that being
nothing but darkness, or the negation of light; without parts, without
composition, invariable and indivisible. Now since this distance causes
no perception different from what a blind man receives from his eyes, or
what is conveyed to us in the darkest night, it must partake of the
same properties: And as blindness and darkness afford us no ideas of
extension, it is impossible that the dark and undistinguishable distance
betwixt two bodies can ever produce that idea.
The sole difference betwixt an absolute darkness and the appearance of
two or more visible luminous objects consists, as I said, in the objects
themselves, and in the manner they affect our senses. The angles, which
the rays of light flowing from them, form with each other; the motion
that is required in the eye, in its passage from one to the other; and
the different parts of the organs, which are affected by them; these
produce the only perceptions, from which we can judge of the distance.
But as these perceptions are each of them simple and indivisible, they
can never give us the idea of extension.
We may illustrate this by considering the sense of feeling, and the
imaginary distance or interval interposed betwixt tangible or solid
objects. I suppose two cases, viz. that of a man supported in the air,
and moving his limbs to and fro, without meeting any thing tangible; and
that of a man, who feeling something tangible, leaves it, and after a
motion, of which he is sensible, perceives another tangible object; and
I then ask, wherein consists the difference betwixt these two cases?
No one will make any scruple to affirm, that it consists meerly in the
perceiving those objects, and that the sensation, which arises from the
motion, is in both cases the same: And as that sensation is not capable
of conveying to us an idea of extension, when unaccompanyed with some
other perception, it can no more give us that idea, when mixed with
the impressions of tangible objects; since that mixture produces no
alteration upon it.
But though motion and darkness, either alone, or attended with tangible
and visible objects, convey no idea of a vacuum or extension without
matter, yet they are the causes why we falsly imagine we can form such
an idea. For there is a close relation betwixt that motion and darkness,
and a real extension, or composition of visible and tangible objects.
First, We may observe, that two visible objects appearing in the midst
of utter darkness, affect the senses in the same manner, and form the
same angle by the rays, which flow from them, and meet in the eye, as if
the distance betwixt them were find with visible objects, that give us
a true idea of extension. The sensation of motion is likewise the same,
when there is nothing tangible interposed betwixt two bodies, as when
we feel a compounded body, whose different parts are placed beyond each
other.
Secondly, We find by experience, that two bodies, which are so placed
as to affect the senses in the same manner with two others, that have a
certain extent of visible objects interposed betwixt them, are
capable of receiving the same extent, without any sensible impulse or
penetration, and without any change on that angle, under which they
appear to the senses. In like manner, where there is one object, which
we cannot feel after another without an interval, and the perceiving
of that sensation we call motion in our hand or organ of sensation;
experience shews us, that it is possible the same object may be felt
with the same sensation of motion, along with the interposed impression
of solid and tangible objects, attending the sensation. That is, in
other words, an invisible and intangible distance may be converted into
a visible and tangible one, without any change on the distant objects.
Thirdly, We may observe, as another relation betwixt these two kinds
of distance, that they have nearly the same effects on every natural
phænomenon. For as all qualities, such as heat, cold, light,
attraction, &c. diminish in proportion to the distance; there is but
little difference observed, whether this distance be marled out by
compounded and sensible objects, or be known only by the manner, in
which the distant objects affect the senses.
Here then are three relations betwixt that distance, which conveys the
idea of extension, and that other, which is not filled with any coloured
or solid object. The distant objects affect the senses in the same
manner, whether separated by the one distance or the other; the second
species of distance is found capable of receiving the first; and they
both equally diminish the force of every quality.
These relations betwixt the two kinds of distance will afford us an easy
reason, why the one has so often been taken for the other, and why we
imagine we have an idea of extension without the idea of any object
either of the sight or feeling. For we may establish it as a general
maxim in this science of human nature, that wherever there is a close
relation betwixt two ideas, the mind is very apt to mistake them, and
in all its discourses and reasonings to use the one for the other. This
phænomenon occurs on so many occasions, and is of such consequence,
that I cannot forbear stopping a moment to examine its causes. I shall
only premise, that we must distinguish exactly betwixt the phænomenon
itself, and the causes, which I shall assign for it; and must not
imagine from any uncertainty in the latter, that the former is also
uncertain. The phænomenon may be real, though my explication be
chimerical. The falshood of the one is no consequence of that of the
other; though at the same time we may observe, that it is very natural
for us to draw such a consequence; which is an evident instance of that
very principle, which I endeavour to explain.
When I received the relations of resemblance, contiguity and causation,
as principles of union among ideas, without examining into their causes,
it was more in prosecution of my first maxim, that we must in the end
rest contented with experience, than for want of something specious and
plausible, which I might have displayed on that subject. It would have
been easy to have made an imaginary dissection of the brain, and have
shewn, why upon our conception of any idea, the animal spirits run
into all the contiguous traces, and rouze up the other ideas, that are
related to it. But though I have neglected any advantage, which I might
have drawn from this topic in explaining the relations of ideas, I am
afraid I must here have recourse to it, in order to account for the
mistakes that arise from these relations. I shall therefore observe,
that as the mind is endowed with a power of exciting any idea it
pleases; whenever it dispatches the spirits into that region of the
brain, in which the idea is placed; these spirits always excite the
idea, when they run precisely into the proper traces, and rummage that
cell, which belongs to the idea. But as their motion is seldom direct,
and naturally turns a little to the one side or the other; for this
reason the animal spirits, falling into the contiguous traces, present
other related ideas in lieu of that, which the mind desired at first to
survey. This change we are not always sensible of; but continuing
still the same train of thought, make use of the related idea, which is
presented to us, and employ it in our reasoning, as if it were the same
with what we demanded. This is the cause of many mistakes and sophisms
in philosophy; as will naturally be imagined, and as it would be easy to
show, if there was occasion.
Of the three relations above-mentioned that of resemblance is the most
fertile source of error; and indeed there are few mistakes in reasoning,
which do not borrow largely from that origin. Resembling ideas are not
only related together, but the actions of the mind, which we employ
in considering them, are so little different, that we are not able to
distinguish them. This last circumstance is of great consequence, and we
may in general observe, that wherever the actions of the mind in forming
any two ideas are the same or resembling, we are very apt to confound
these ideas, and take the one for the other. Of this we shall see many
instances in the progress of this treatise. But though resemblance be
the relation, which most readily produces a mistake in ideas, yet
the others of causation and contiguity may also concur in the same
influence. We might produce the figures of poets and orators, as
sufficient proofs of this, were it as usual, as it is reasonable, in
metaphysical subjects to draw our arguments from that quarter. But lest
metaphysicians should esteem this below their dignity, I shall borrow
a proof from an observation, which may be made on most of their own
discourses, viz. that it is usual for men to use words for ideas, and
to talk instead of thinking in their reasonings. We use words for ideas,
because they are commonly so closely connected that the mind easily
mistakes them. And this likewise is the reason, why we substitute
the idea of a distance, which is not considered either as visible or
tangible, in the room of extension, which is nothing but a composition
of visible or tangible points disposed in a certain order. In
causing this mistake there concur both the relations of causation and
resemblance. As the first species of distance is found to be convertible
into the second, it is in this respect a kind of cause; and the
similarity of their manner of affecting the senses, and diminishing
every quality, forms the relation of resemblance.
After this chain of reasoning and explication of my principles, I am now
prepared to answer all the objections that have been offered, whether
derived from metaphysics or mechanics. The frequent disputes concerning
a vacuum, or extension without matter prove not the reality of the idea,
upon which the dispute turns; there being nothing more common, than to
see men deceive themselves in this particular; especially when by means
of any close relation, there is another idea presented, which may be the
occasion of their mistake.
We may make almost the same answer to the second objection, derived from
the conjunction of the ideas of rest and annihilation. When every thing
is annihilated in the chamber, and the walls continue immoveable, the
chamber must be conceived much in the same manner as at present, when
the air that fills it, is not an object of the senses. This annihilation
leaves to the eye, that fictitious distance, which is discovered by the
different parts of the organ, that are affected, and by the degrees of
light and shade;--and to the feeling, that which consists in a sensation
of motion in the hand, or other member of the body. In vain should we.
search any farther. On whichever side we turn this subject, we shall
find that these are the only impressions such an object can produce
after the supposed annihilation; and it has already been remarked, that
impressions can give rise to no ideas, but to such as resemble them.
Since a body interposed betwixt two others may be supposed to be
annihilated, without producing any change upon such as lie on each
hand of it, it is easily conceived, how it may be created anew, and yet
produce as little alteration. Now the motion of a body has much the same
effect as its creation. The distant bodies are no more affected in the
one case, than in the other. This suffices to satisfy the imagination,
and proves there is no repugnance in such a motion. Afterwards
experience comes in play to persuade us that two bodies, situated in the
manner above-described, have really such a capacity of receiving body
betwixt them, and that there is no obstacle to the conversion of the
invisible and intangible distance into one that is visible and tangible.
However natural that conversion may seem, we cannot be sure it is
practicable, before we have had experience of it.
Thus I seem to have answered the three objections above-mentioned;
though at the same time I am sensible, that few will be satisfyed
with these answers, but will immediately propose new objections and
difficulties. It will probably be said, that my reasoning makes nothing
to the matter in hands and that I explain only the manner in which
objects affect the senses, without endeavouring to account for their
real nature and operations. Though there be nothing visible or tangible
interposed betwixt two bodies, yet we find BY EXPERIENCE, that the
bodies may be placed in the same manner, with regard to the eye, and
require the same motion of the hand in passing from one to the other,
as if divided by something visible and tangible. This invisible and
intangible distance is also found by experience to contain a capacity of
receiving body, or of becoming visible and tangible. Here is the whole
of my system; and in no part of it have I endeavoured to explain the
cause, which separates bodies after this manner, and gives them a
capacity of receiving others betwixt them, without any impulse or
penetration.
I answer this objection, by pleading guilty, and by confessing that my
intention never was to penetrate into the nature of bodies, or explain
the secret causes of their operations. For besides that this belongs not
to my present purpose, I am afraid, that such an enterprise is beyond
the reach of human understanding, and that we can never pretend to
know body otherwise than by those external properties, which discover
themselves to the senses. As to those who attempt any thing farther, I
cannot approve of their ambition, till I see, in some one instance at
least, that they have met with success. But at present I content myself
with knowing perfectly the manner in which objects affect my senses, and
their connections with each other, as far as experience informs me of
them. This suffices for the conduct of life; and this also suffices for
my philosophy, which pretends only to explain the nature and causes of
our perceptions, or impressions and ideas.[6]
[6] As long as we confine our speculations to the appearances of
objects to our senses, without entering into disquisitions
concerning their real nature and operations, we are safe from all
difficulties, and can never be embarrassed by any question. Thus,
if it be asked, if the invisible and intangible distance,
interposed betwixt two objects, be something or nothing: It is easy
to answer, that it is SOMETHING, VIZ. a property of the objects,
which affect the SENSES after such a particular manner. If it be
asked whether two objects, having such a distance betwixt them,
touch or not: it may be answered, that this depends upon the
definition of the word, TOUCH. If objects be said to touch, when
there is nothing SENSIBLE interposed betwixt them, these objects
touch: it objects be said to touch, when their IMAGES strike
contiguous parts of the eye, and when the hand FEELS both objects
successively, without any interposed motion, these objects do not
touch. The appearances of objects to our senses are all consistent;
and no difficulties can ever arise, but from the obscurity of the
terms we make use of.
If we carry our enquiry beyond the appearances of objects to the
senses, I am afraid, that most of our conclusions will be full of
scepticism and uncertainty. Thus if it be asked, whether or not the
invisible and intangible distance be always full of body, or of
something that by an improvement of our organs might become visible
or tangible, I must acknowledge, that I find no very decisive
arguments on either side; though I am inclined to the contrary
opinion, as being more suitable to vulgar and popular notions. If
THE NEWTONIAN philosophy be rightly understood, it will be found to
mean no more. A vacuum is asserted: That is, bodies are said to be
placed after such a manner, is to receive bodies betwixt them,
without impulsion or penetration. The real nature of this position
of bodies is unknown. We are only acquainted with its effects on
the senses, and its power of receiving body. Nothing is more
suitable to that philosophy, than a modest scepticism to a certain
degree, and a fair confession of ignorance in subjects, that exceed
all human capacity.
I shall conclude this subject of extension with a paradox, which will
easily be explained from the foregoing reasoning. This paradox is, that
if you are pleased to give to the in-visible and intangible distance,
or in other words, to the capacity of becoming a visible and tangible
distance, the name of a vacuum, extension and matter are the same, and
yet there is a vacuum. If you will not give it that name, motion
is possible in a plenum, without any impulse in infinitum, without
returning in a circle, and without penetration. But however we may
express ourselves, we must always confess, that we have no idea of any
real extension without filling it with sensible objects, and conceiving
its parts as visible or tangible.
As to the doctrine, that time is nothing but the manner, in which
some real objects exist; we may observe, that it is liable to the same
objections as the similar doctrine with regard to extension. If it be a
sufficient proof, that we have the idea of a vacuum, because we dispute
and reason concerning it; we must for the same reason have the idea
of time without any changeable existence; since there is no subject of
dispute more frequent and common. But that we really have no such idea,
is certain. For whence should it be derived? Does it arise from an
impression of sensation or of reflection? Point it out distinctly to us,
that we may know its nature and qualities. But if you cannot point
out any such impression, you may be certain you are mistaken, when you
imagine you have any such idea.
But though it be impossible to shew the impression, from which the idea
of time without a changeable existence is derived; yet we can easily
point out those appearances, which make us fancy we have that idea. For
we may observe, that there is a continual succession of perceptions in
our mind; so that the idea of time being for ever present with us; when
we consider a stedfast object at five-a-clock, and regard the same at
six; we are apt to apply to it that idea in the same manner as if every
moment were distinguished by a different position, or an alteration
of the object. The first and second appearances of the object, being
compared with the succession of our perceptions, seem equally removed as
if the object had really changed. To which we may add, what experience
shews us, that the object was susceptible of such a number of changes
betwixt these appearances; as also that the unchangeable or rather
fictitious duration has the same effect upon every quality, by
encreasing or diminishing it, as that succession, which is obvious to
the senses. From these three relations we are apt to confound our ideas,
and imagine we can form the idea of a time and duration, without any
change or succession.
SECT. VI. OF THE IDEA OF EXISTENCE, AND OF EXTERNAL EXISTENCE.
It may not be amiss, before we leave this subject, to explain the ideas
of existence and of external existence; which have their difficulties,
as well as the ideas of space and time. By this means we shall be the
better prepared for the examination of knowledge and probability, when
we understand perfectly all those particular ideas, which may enter into
our reasoning.
There is no impression nor idea of any kind, of which we have any
consciousness or memory, that is not conceived as existent; and it
is evident, that from this consciousness the most perfect idea and
assurance of being is derived. From hence we may form a dilemma, the
most clear and conclusive that can be imagined, viz. that since we never
remember any idea or impression without attributing existence to it,
the idea of existence must either be derived from a distinct impression,
conjoined with every perception or object of our thought, or must be the
very same with the idea of the perception or object.
As this dilemma is an evident consequence of the principle, that every
idea arises from a similar impression, so our decision betwixt the
propositions of the dilemma is no more doubtful. So far from there being
any distinct impression, attending every impression and every idea,
that I do not think there are any two distinct impressions, which are
inseparably conjoined. Though certain sensations may at one time be
united, we quickly find they admit of a separation, and may be presented
apart. And thus, though every impression and idea we remember be
considered as existent, the idea of existence is not derived from any
particular impression.
The idea of existence, then, is the very same with the idea of what we
conceive to be existent. To reflect on any thing simply, and to reflect
on it as existent, are nothing different from each other. That idea,
when conjoined with the idea of any object, makes no addition to it.
Whatever we conceive, we conceive to be existent. Any idea we please
to form is the idea of a being; and the idea of a being is any idea we
please to form.
Whoever opposes this, must necessarily point out that distinct
impression, from which the idea of entity is derived, and must prove,
that this impression is inseparable from every perception we believe to
be existent. This we may without hesitation conclude to be impossible.
Our foregoing reasoning[7] concerning the distinction of ideas without
any real difference will not here serve us in any stead. That kind of
distinction is founded on the different resemblances, which the same
simple idea may have to several different ideas. But no object can be
presented resembling some object with respect to its existence, and
different from others in the same particular; since every object, that
is presented, must necessarily be existent.
[7] Part I. Sect. 7.
A like reasoning will account for the idea of external existence. We may
observe, that it is universally allowed by philosophers, and is besides
pretty obvious of itself, that nothing is ever really present with the
mind but its perceptions or impressions and ideas, and that external
objects become known to us only by those perceptions they occasion. To
hate, to love, to think, to feel, to see; all this is nothing but to
perceive.
Now since nothing is ever present to the mind but perceptions, and since
all ideas are derived from something antecedently present to the mind;
it follows, that it is impossible for us so much as to conceive or form
an idea of any thing specifically different from ideas and impressions.
Let us fix our attention out of ourselves as much as possible: Let us
chase our imagination to the heavens, or to the utmost limits of the
universe; we never really advance a step beyond ourselves, nor can
conceive any kind of existence, but those perceptions, which
have appeared in that narrow compass. This is the universe of the
imagination, nor have we any idea but what is there produced.
The farthest we can go towards a conception of external objects, when
supposed SPECIFICALLY different from our perceptions, is to form a
relative idea of them, without pretending to comprehend the related
objects. Generally speaking we do not suppose them specifically
different; but only attribute to them different relations, connections
and durations. But of this more fully hereafter.[8]
[8] Part IV, Sect. 2.
PART III. OF KNOWLEDGE AND PROBABILITY.
SECT. I. OF KNOWLEDGE.
There are seven[1] different kinds of philosophical relation, viz.
RESEMBLANCE, IDENTITY, RELATIONS OF TIME AND PLACE, PROPORTION IN
QUANTITY OR NUMBER, DEGREES IN ANY QUALITY, CONTRARIETY and CAUSATION.
These relations may be divided into two classes; into such as depend
entirely on the ideas, which we compare together, and such as may be
changed without any change in the ideas. It is from the idea of a
triangle, that we discover the relation of equality, which its three
angles bear to two right ones; and this relation is invariable, as long
as our idea remains the same. On the contrary, the relations of
contiguity and distance betwixt two objects may be changed merely by an
alteration of their place, without any change on the objects themselves
or on their ideas; and the place depends on a hundred different
accidents, which cannot be foreseen by the mind. It is the same case
with identity and causation. Two objects, though perfectly resembling
each other, and even appearing in the same place at different times,
may be numerically different: And as the power, by which one object
produces another, is never discoverable merely from their idea, it is
evident cause and effect are relations, of which we receive information
from experience, and not from any abstract reasoning or reflection.
There is no single phænomenon, even the most simple, which can be
accounted for from the qualities of the objects, as they appear to us;
or which we could foresee without the help of our memory and
experience.
[1] Part I. Sect. 5.
It appears, therefore, that of these seven philosophical relations,
there remain only four, which depending solely upon ideas, can be
the objects of knowledge and certainty. These four are RESEMBLANCE,
CONTRARIETY, DEGREES IN QUALITY, and PROPORTIONS IN QUANTITY OR NUMBER.
Three of these relations are discoverable at first sight, and fall more
properly under the province of intuition than demonstration. When any
objects resemble each other, the resemblance will at first strike the
eye, or rather the mind; and seldom requires a second examination. The
case is the same with contrariety, and with the degrees of any quality.
No one can once doubt but existence and non-existence destroy each
other, and are perfectly incompatible and contrary. And though it be
impossible to judge exactly of the degrees of any quality, such as
colour, taste, heat, cold, when the difference betwixt them is very
small: yet it is easy to decide, that any of them is superior or
inferior to another, when their difference is considerable. And this
decision we always pronounce at first sight, without any enquiry or
reasoning.
We might proceed, after the same manner, in fixing the proportions
of quantity or number, and might at one view observe a superiority
or inferiority betwixt any numbers, or figures; especially where the
difference is very great and remarkable. As to equality or any exact
proportion, we can only guess at it from a single consideration; except
in very short numbers, or very limited portions of extension; which are
comprehended in an instant, and where we perceive an impossibility of
falling into any considerable error. In all other cases we must settle
the proportions with some liberty, or proceed in a more artificial
manner.
I have already observed, that geometry, or the art, by which we fix
the proportions of figures; though it much excels both in universality
and exactness, the loose judgments of the senses and imagination; yet
never attains a perfect precision and exactness. It's first principles
are still drawn from the general appearance of the objects; and that
appearance can never afford us any security, when we examine, the
prodigious minuteness of which nature is susceptible. Our ideas seem
to give a perfect assurance, that no two right lines can have a common
segment; but if we consider these ideas, we shall find, that they always
suppose a sensible inclination of the two lines, and that where the
angle they form is extremely small, we have no standard of a I @ right
line so precise as to assure us of the truth of this proposition. It is
the same case with most of the primary decisions of the mathematics.
There remain, therefore, algebra and arithmetic as the only sciences, in
which we can carry on a chain of reasoning to any degree of intricacy,
and yet preserve a perfect exactness and certainty. We are possest of a
precise standard, by which we can judge of the equality and proportion
of numbers; and according as they correspond or not to that standard,
we determine their relations, without any possibility of error. When two
numbers are so combined, as that the one has always an unite answering
to every unite of the other, we pronounce them equal; and it is for want
of such a standard of equality in extension, that geometry can scarce be
esteemed a perfect and infallible science.
But here it may not be amiss to obviate a difficulty, which may arise
from my asserting, that though geometry falls short of that perfect
precision and certainty, which are peculiar to arithmetic and algebra,
yet it excels the imperfect judgments of our senses and imagination. The
reason why I impute any defect to geometry, is, because its original and
fundamental principles are derived merely from appearances; and it may
perhaps be imagined, that this defect must always attend it, and keep it
from ever reaching a greater exactness in the comparison of objects or
ideas, than what our eye or imagination alone is able to attain. I own
that this defect so far attends it, as to keep it from ever aspiring to
a full certainty: But since these fundamental principles depend on
the easiest and least deceitful appearances, they bestow on their
consequences a degree of exactness, of which these consequences are
singly incapable. It is impossible for the eye to determine the angles
of a chiliagon to be equal to 1996 right angles, or make any conjecture,
that approaches this proportion; but when it determines, that right
lines cannot concur; that we cannot draw more than one right line
between two given points; it's mistakes can never be of any consequence.
And this is the nature and use of geometry, to run us up to such
appearances, as, by reason of their simplicity, cannot lead us into any
considerable error.
I shall here take occasion to propose a second observation concerning
our demonstrative reasonings, which is suggested by the same subject of
the mathematics. It is usual with mathematicians, to pretend, that
those ideas, which are their objects, are of so refined and spiritual a
nature, that they fall not under the conception of the fancy, but must
be comprehended by a pure and intellectual view, of which the superior
faculties of the soul are alone capable. The same notion runs through
most parts of philosophy, and is principally made use of to explain oar
abstract ideas, and to shew how we can form an idea of a triangle,
for instance, which shall neither be an isoceles nor scalenum, nor be
confined to any particular length and proportion of sides. It is easy to
see, why philosophers are so fond of this notion of some spiritual
and refined perceptions; since by that means they cover many of their
absurdities, and may refuse to submit to the decisions of clear ideas,
by appealing to such as are obscure and uncertain. But to destroy this
artifice, we need but reflect on that principle so oft insisted on, that
all our ideas are copyed from our impressions. For from thence we may
immediately conclude, that since all impressions are clear and precise,
the ideas, which are copyed from them, must be of the same nature, and
can never, but from our fault, contain any thing so dark and intricate.
An idea is by its very nature weaker and fainter than an impression;
but being in every other respect the same, cannot imply any very great
mystery. If its weakness render it obscure, it is our business to
remedy that defect, as much as possible, by keeping the idea steady and
precise; and till we have done so, it is in vain to pretend to reasoning
and philosophy.
SECT. II. OF PROBABILITY, AND OF THE IDEA OF CAUSE AND EFFECT.
This is all I think necessary to observe concerning those four
relations, which are the foundation of science; but as to the other
three, which depend not upon the idea, and may be absent or present
even while that remains the same, it will be proper to explain them more
particularly. These three relations are identity, the situations in time
and place, and causation.
All kinds of reasoning consist in nothing but a comparison, and a
discovery of those relations, either constant or inconstant, which two
or more objects bear to each other. This comparison we may make, either
when both the objects are present to the senses, or when neither of them
is present, or when only one. When both the objects are present to the
senses along with the relation, we call this perception rather than
reasoning; nor is there in this case any exercise of the thought, or
any action, properly speaking, but a mere passive admission of the
impressions through the organs of sensation. According to this way of
thinking, we ought not to receive as reasoning any of the observations
we may make concerning identity, and the relations of time and place;
since in none of them the mind can go beyond what is immediately present
to the senses, either to discover the real existence or the relations
of objects. It is only causation, which produces such a connexion, as
to give us assurance from the existence or action of one object, that it
was followed or preceded by any other existence or action; nor can the
other two relations be ever made use of in reasoning, except so far
as they either affect or are affected by it. There is nothing in any
objects to perswade us, that they are either always remote or always
contiguous; and when from experience and observation we discover, that
their relation in this particular is invariable, we, always conclude
there is some secret cause, which separates or unites them. The same
reasoning extends to identity. We readily suppose an object may continue
individually the same, though several times absent from and present
to the senses; and ascribe to it an identity, notwithstanding the
interruption of the perception, whenever we conclude, that if we had
kept our eye or hand constantly upon it, it would have conveyed an
invariable and uninterrupted perception. But this conclusion beyond the
impressions of our senses can be founded only on the connexion of cause
and effect; nor can we otherwise have any security, that the object is
not changed upon us, however much the new object may resemble that which
was formerly present to the senses. Whenever we discover such a perfect
resemblance, we consider, whether it be common in that species of
objects; whether possibly or probably any cause could operate in
producing the change and resemblance; and according as we determine
concerning these causes and effects, we form our judgment concerning the
identity of the object.
Here then it appears, that of those three relations, which depend not
upon the mere ideas, the only one, that can be traced beyond our senses
and informs us of existences and objects, which we do not see or feel,
is causation. This relation, therefore, we shall endeavour to explain
fully before we leave the subject of the understanding.
To begin regularly, we must consider the idea of causation, and see from
what origin it is derived. It is impossible to reason justly, without
understanding perfectly the idea concerning which we reason; and it is
impossible perfectly to understand any idea, without tracing it up to
its origin, and examining that primary impression, from which it arises.
The examination of the impression bestows a clearness on the idea;
and the examination of the idea bestows a like clearness on all our
reasoning.
Let us therefore cast our eye on any two objects, which we call
cause and effect, and turn them on all sides, in order to find that
impression, which produces an idea, of such prodigious consequence.
At first sight I perceive, that I must not search for it in any of
the particular qualities of the objects; since which-ever of these
qualities I pitch on, I find some object, that is not possessed of it,
and yet falls under the denomination of cause or effect. And indeed
there is nothing existent, either externally or internally, which is
not to be considered either as a cause or an effect; though it is plain
there is no one quality, which universally belongs to all beings, and
gives them a title to that denomination.
The idea, then, of causation must be derived from some relation among
objects; and that relation we must now endeavour to discover. I find in
the first place, that whatever objects are considered as causes or
effects, are contiguous; and that nothing can operate in a time or
place, which is ever so little removed from those of its existence.
Though distant objects may sometimes seem productive of each other,
they are commonly found upon examination to be linked by a chain of
causes, which are contiguous among themselves, and to the distant
objects; and when in any particular instance we cannot discover this
connexion, we still presume it to exist. We may therefore consider the
relation of CONTIGUITY as essential to that of causation; at least may
suppose it such, according to the general opinion, till we can find a
more[2] proper occasion to clear up this matter, by examining what
objects are or are not susceptible of juxtaposition and conjunction.
[2] Part IV. Sect. 5.
The second relation I shall observe as essential to causes and effects,
is not so universally acknowledged, but is liable to some controversy.
It is that of PRIORITY Of time in the cause before the effect. Some
pretend that it is not absolutely necessary a cause should precede its
effect; but that any object or action, in the very first moment of its
existence, may exert its productive quality, and give rise to another
object or action, perfectly co-temporary with itself. But beside that
experience in most instances seems to contradict this opinion, we may
establish the relation of priority by a kind of inference or reasoning.
It is an established maxim both in natural and moral philosophy, that
an object, which exists for any time in its full perfection without
producing another, is not its sole cause; but is assisted by some other
principle, which pushes it from its state of inactivity, and makes it
exert that energy, of which it was secretly possest. Now if any cause
may be perfectly co-temporary with its effect, it is certain, according
to this maxim, that they must all of them be so; since any one of them,
which retards its operation for a single moment, exerts not itself
at that very individual time, in which it might have operated; and
therefore is no proper cause. The consequence of this would be no less
than the destruction of that succession of causes, which we observe in
the world; and indeed, the utter annihilation of time. For if one cause
were co-temporary with its effect, and this effect with its effect, and
so on, it is plain there would be no such thing as succession, and all
objects must be co-existent.
If this argument appear satisfactory, it is well. If not, I beg the
reader to allow me the same liberty, which I have used in the preceding
case, of supposing it such. For he shall find, that the affair is of no
great importance.
Having thus discovered or supposed the two relations of contiguity and
succession to be essential to causes and effects, I find I am stopt
short, and can proceed no farther in considering any single instance
of cause and effect. Motion in one body is regarded upon impulse as the
cause of motion in another. When we consider these objects with utmost
attention, we find only that the one body approaches the other; and that
the motion of it precedes that of the other, but without any, sensible
interval. It is in vain to rack ourselves with farther thought and
reflection upon this subject. We can go no farther in considering this
particular instance.
Should any one leave this instance, and pretend to define a cause, by
saying it is something productive of another, it is evident he would say
nothing. For what does he mean by production? Can he give any definition
of it, that will not be the same with that of causation? If he can; I
desire it may be produced. If he cannot; he here runs in a circle, and
gives a synonimous term instead of a definition.
Shall we then rest contented with these two relations of contiguity and
succession, as affording a complete idea of causation? By, no means. An
object may be contiguous and prior to another, without being considered
as its cause. There is a NECESSARY CONNEXION to be taken into
consideration; and that relation is of much greater importance, than any
of the other two above-mentioned.
Here again I turn the object on all sides, in order to discover
the nature of this necessary connexion, and find the impression, or
impressions, from which its idea may be derived. When I cast my eye on
the known Qualities of objects, I immediately discover that the relation
of cause and effect depends not in the least on them. When I consider
their relations, I can find none but those of contiguity and succession;
which I have already regarded as imperfect and unsatisfactory. Shall the
despair of success make me assert, that I am here possest of an idea,
which is not preceded by any similar impression? This would be too
strong a proof of levity and inconstancy; since the contrary principle
has been already so firmly established, as to admit of no farther doubt;
at least, till we have more fully examined the present difficulty.
We must, therefore, proceed like those, who being in search of any
thing, that lies concealed from them, and not finding it in the place
they expected, beat about all the neighbouring fields, without any
certain view or design, in hopes their good fortune will at last guide
them to what they search for. It is necessary for us to leave the
direct survey of this question concerning the nature of that necessary
connexion, which enters into our idea of cause and effect; and endeavour
to find some other questions, the examination of which will perhaps
afford a hint, that may serve to clear up the present difficulty. Of
these questions there occur two, which I shall proceed to examine, viz.
First, For what reason we pronounce it necessary, that every thing whose
existence has a beginning, should also have a cause.
Secondly, Why we conclude, that such particular causes must necessarily
have such particular effects; and what is the nature of that inference
we draw from the one to the other, and of the belief we repose in it?
I shall only observe before I proceed any farther, that though the ideas
of cause and effect be derived from the impressions of reflection as
well as from those of sensation, yet for brevity's sake, I commonly
mention only the latter as the origin of these ideas; though I desire
that whatever I say of them may also extend to the former. Passions are
connected with their objects and with one another; no less than external
bodies are connected together. The same relation, then, of cause and
effect, which belongs to one, must be common to all of them.
SECT. III. WHY A CAUSE IS ALWAYS NECESSARY.
To begin with the first question concerning the necessity of a cause:
It is a general maxim in philosophy, that whatever begins to exist, must
have a cause of existence. This is commonly taken for granted in all
reasonings, without any proof given or demanded. It is supposed to be
founded on intuition, and to be one of those maxims, which though they
may be denyed with the lips, it is impossible for men in their hearts
really to doubt of. But if we examine this maxim by the idea of
knowledge above-explained, we shall discover in it no mark of any such
intuitive certainty; but on the contrary shall find, that it is of a
nature quite foreign to that species of conviction.
All certainty arises from the comparison of ideas, and from the
discovery of such relations as are unalterable, so long as the ideas
continue the same. These relations are RESEMBLANCE, PROPORTIONS IN
QUANTITY AND NUMBER, DEGREES OF ANY QUALITY, and CONTRARIETY; none of
which are implyed in this proposition, Whatever has a beginning has
also a cause of existence. That proposition therefore is not intuitively
certain. At least any one, who would assert it to be intuitively
certain, must deny these to be the only infallible relations, and must
find some other relation of that kind to be implyed in it; which it will
then be time enough to examine.
But here is an argument, which proves at once, that the foregoing
proposition is neither intuitively nor demonstrably certain. We can
never demonstrate the necessity of a cause to every new existence, or
new modification of existence, without shewing at the same time the
impossibility there is, that any thing can ever begin to exist without
some productive principle; and where the latter proposition cannot be
proved, we must despair of ever being able to prove the former. Now that
the latter proposition is utterly incapable of a demonstrative proof,
we may satisfy ourselves by considering that as all distinct ideas are
separable from each other, and as the ideas of cause and effect are
evidently distinct, it will be easy for us to conceive any object to be
non-existent this moment, and existent the next, without conjoining to
it the distinct idea of a cause or productive principle. The separation,
therefore, of the idea of a cause from that of a beginning of existence,
is plainly possible for the imagination; and consequently the actual
separation of these objects is so far possible, that it implies no
contradiction nor absurdity; and is therefore incapable of being refuted
by any reasoning from mere ideas; without which it is impossible to
demonstrate the necessity of a cause.
Accordingly we shall find upon examination, that every demonstration,
which has been produced for the necessity of a cause, is fallacious and
sophistical. All the points of time and place, say some
philosophers,[3] in which we can suppose any object to begin to exist,
are in themselves equal; and unless there be some cause, which is
peculiar to one time and to one place, and which by that means
determines and fixes the existence, it must remain in eternal suspence;
and the object can never begin to be, for want of something to fix its
beginning. But I ask; Is there any more difficulty in supposing the
time and place to be fixed without a cause, than to suppose the
existence to be determined in that manner? The first question that
occurs on this subject is always, whether the object shall exist or
not: The next, when and where it shall begin to exist. If the removal
of a cause be intuitively absurd in the one case, it must be so in the
other: And if that absurdity be not clear without a proof in the one
case, it will equally require one in the other. The absurdity, then, of
the one supposition can never be a proof of that of the other; since
they are both upon the same footing, and must stand or fall by the same
reasoning.
[3] Mr. Hobbes.
The second argument,[4] which I find used on this head, labours under
an equal difficulty. Every thing, it is said, must have a cause; for if
any thing wanted a cause, it would produce ITSELF; that is, exist
before it existed; which is impossible. But this reasoning is plainly
unconclusive; because it supposes, that in our denial of a cause we
still grant what we expressly deny, viz. that there must be a cause;
which therefore is taken to be the object itself; and that, no doubt,
is an evident contradiction. But to say that any thing is produced, or
to express myself more properly, comes into existence, without a cause,
is not to affirm, that it is itself its own cause; but on the contrary
in excluding all external causes, excludes a fortiori the thing itself,
which is created. An object, that exists absolutely without any cause,
certainly is not its own cause; and when you assert, that the one
follows from the other, you suppose the very point in questions and
take it for granted, that it is utterly impossible any thing can ever
begin to exist without a cause, but that, upon the exclusion of one
productive principle, we must still have recourse to another.
[4] Dr. Clarke and others.
It is exactly the same case with the third argument,[5] which has been
employed to demonstrate the necessity of a cause. Whatever is produced
without any cause, is produced by nothing; or in other words, has
nothing for its cause. But nothing can never be a cause, no more than
it can be something, or equal to two right angles. By the same
intuition, that we perceive nothing not to be equal to two right
angles, or not to be something, we perceive, that it can never be a
cause; and consequently must perceive, that every object has a real
cause of its existence.
[5] Mr. Locke.
I believe it will not be necessary to employ many words in shewing the
weakness of this argument, after what I have said of the foregoing. They
are all of them founded on the same fallacy, and are derived from the
same turn of thought. It is sufficient only to observe, that when
we exclude all causes we really do exclude them, and neither suppose
nothing nor the object itself to be the causes of the existence;
and consequently can draw no argument from the absurdity of these
suppositions to prove the absurdity of that exclusion. If every thing
must have a cause, it follows, that upon the exclusion of other causes
we must accept of the object itself or of nothing as causes. But it is
the very point in question, whether every thing must have a cause or
not; and therefore, according to all just reasoning, it ought never to
be taken for granted.
They are still more frivolous, who say, that every effect must have a
cause, because it is implyed in the very idea of effect. Every effect
necessarily pre-supposes a cause; effect being a relative term, of which
cause is the correlative. But this does not prove, that every being must
be preceded by a cause; no more than it follows, because every husband
must have a wife, that therefore every man must be marryed. The true
state of the question is, whether every object, which begins to exist,
must owe its existence to a cause: and this I assert neither to be
intuitively nor demonstratively certain, and hope to have proved it
sufficiently by the foregoing arguments.
Since it is not from knowledge or any scientific reasoning, that we
derive the opinion of the necessity of a cause to every new production,
that opinion must necessarily arise from observation and experience. The
next question, then, should naturally be, how experience gives rise to
such a principle? But as I find it will be more convenient to sink this
question in the following, Why we conclude, that such particular
causes must necessarily have such particular erects, and why we form
an inference from one to another? we shall make that the subject of our
future enquiry. It will, perhaps, be found in the end, that the same
answer will serve for both questions.
SECT. IV. OF THE COMPONENT PARTS OF OUR REASONINGS CONCERNING CAUSE AND EFFECT.
Though the mind in its reasonings from causes or effects carries its
view beyond those objects, which it sees or remembers, it must never
lose sight of them entirely, nor reason merely upon its own ideas,
without some mixture of impressions, or at least of ideas of the memory,
which are equivalent to impressions. When we infer effects from causes,
we must establish the existence of these causes; which we have only
two ways of doing, either by an immediate perception of our memory or
senses, or by an inference from other causes; which causes again we must
ascertain in the same manner, either by a present impression, or by an
inference from their causes, and so on, till we arrive at some object,
which we see or remember. It is impossible for us to carry on our
inferences IN INFINITUM; and the only thing, that can stop them, is an
impression of the memory or senses, beyond which there is no room for
doubt or enquiry.
To give an instance of this, we may chuse any point of history, and
consider for what reason we either believe or reject it. Thus we believe
that Caesar was killed in the senate-house on the ides of March; and
that because this fact is established on the unanimous testimony of
historians, who agree to assign this precise time and place to that
event. Here are certain characters and letters present either to our
memory or senses; which characters we likewise remember to have been
used as the signs of certain ideas; and these ideas were either in the
minds of such as were immediately present at that action, and received
the ideas directly from its existence; or they were derived from the
testimony of others, and that again from another testimony, by a
visible gradation, it will we arrive at those who were eyewitnesses and
spectators of the event. It is obvious all this chain of argument or
connexion of causes and effects, is at first founded on those characters
or letters, which are seen or remembered, and that without the authority
either of the memory or senses our whole reasoning would be chimerical
and without foundation. Every link of the chain would in that case hang
upon another; but there would not be any thing fixed to one end of it,
capable of sustaining the whole; and consequently there would be no
belief nor evidence. And this actually is the case with all hypothetical
arguments, or reasonings upon a supposition; there being in them,
neither any present impression, nor belief of a real existence.
I need not observe, that it is no just objection to the present
doctrine, that we can reason upon our past conclusions or principles,
without having recourse to those impressions, from which they first
arose. For even supposing these impressions should be entirely effaced
from the memory, the conviction they produced may still remain; and it
is equally true, that all reasonings concerning causes and effects are
originally derived from some impression; in the same manner, as the
assurance of a demonstration proceeds always from a comparison of ideas,
though it may continue after the comparison is forgot.
SECT. V. OF THE IMPRESSIONS OF THE SENSES AND MEMORY.
In this kind of reasoning, then, from causation, we employ materials,
which are of a mixed and heterogeneous nature, and which, however
connected, are yet essentially different from each other. All our
arguments concerning causes and effects consist both of an impression of
the memory or, senses, and of the idea of that existence, which produces
the object of the impression, or is produced by it. Here therefore
we have three things to explain, viz. First, The original impression.
Secondly, The transition to the idea of the connected cause or effect.
Thirdly, The nature and qualities of that idea.
As to those impressions, which arise from the senses, their ultimate
cause is, in my opinion, perfectly inexplicable by human reason, and it
will always be impossible to decide with certainty, whether they arise
immediately from the object, or are produced by the creative power of
the mind, or are derived from the author of our being. Nor is such a
question any way material to our present purpose. We may draw inferences
from the coherence of our perceptions, whether they be true or false;
whether they represent nature justly, or be mere illusions of the
senses.
When we search for the characteristic, which distinguishes the memory
from the imagination, we must immediately perceive, that it cannot lie
in the simple ideas it presents to us; since both these faculties borrow
their simple ideas from the impressions, and can never go beyond these
original perceptions. These faculties are as little distinguished from
each other by the arrangement of their complex ideas. For though it be
a peculiar property of the memory to preserve the original order and
position of its ideas, while the imagination transposes and changes
them, as it pleases; yet this difference is not sufficient to
distinguish them in their operation, or make us know the one from the
other; it being impossible to recal the past impressions, in order to
compare them with our present ideas, and see whether their arrangement
be exactly similar. Since therefore the memory, is known, neither by
the order of its complex ideas, nor the nature of its simple ones; it
follows, that the difference betwixt it and the imagination lies in its
superior force and vivacity. A man may indulge his fancy in feigning
any past scene of adventures; nor would there be any possibility of
distinguishing this from a remembrance of a like kind, were not the
ideas of the imagination fainter and more obscure.
It frequently happens, that when two men have been engaged in any scene
of action, the one shall remember it much better than the other,
and shall have all the difficulty in the world to make his companion
recollect it. He runs over several circumstances in vain; mentions the
time, the place, the company, what was said, what was done on all sides;
till at last he hits on some lucky circumstance, that revives the whole,
and gives his friend a perfect memory of every thing. Here the person
that forgets receives at first all the ideas from the discourse of
the other, with the same circumstances of time and place; though he
considers them as mere fictions of the imagination. But as soon as the
circumstance is mentioned, that touches the memory, the very same ideas
now appear in a new light, and have, in a manner, a different feeling
from what they had before. Without any other alteration, beside that
of the feeling, they become immediately ideas of the memory, and are
assented to.
Since, therefore, the imagination can represent all the same objects
that the memory can offer to us, and since those faculties are only
distinguished by the different feeling of the ideas they present, it
may be proper to consider what is the nature of that feeling. And here
I believe every one will readily agree with me, that the ideas of the
memory are more strong and lively than those of the fancy.
A painter, who intended to represent a passion or emotion of any kind,
would endeavour to get a sight of a person actuated by a like emotion,
in order to enliven his ideas, and give them a force and vivacity
superior to what is found in those, which are mere fictions of the
imagination. The more recent this memory is, the clearer is the idea;
and when after a long interval he would return to the contemplation of
his object, he always finds its idea to be much decayed, if not wholly
obliterated. We are frequently in doubt concerning the ideas of the
memory, as they become very weak and feeble; and are at a loss to
determine whether any image proceeds from the fancy or the memory,
when it is not drawn in such lively colours as distinguish that latter
faculty. I think, I remember such an event, says one; but am not sure.
A long tract of time has almost worn it out of my memory, and leaves me
uncertain whether or not it be the pure offspring of my fancy.
And as an idea of the memory, by losing its force and vivacity,
may degenerate to such a degree, as to be taken for an idea of the
imagination; so on the other hand an idea of the imagination may acquire
such a force and vivacity, as to pass for an idea of the memory, and
counterfeit its effects on the belief and judgment. This is noted in
the case of liars; who by the frequent repetition of their lies, come at
last to believe and remember them, as realities; custom and habit having
in this case, as in many others, the same influence on the mind as
nature, and infixing the idea with equal force and vigour.
Thus it appears, that the belief or assent, which always attends the
memory and senses, is nothing but the vivacity of those perceptions they
present; and that this alone distinguishes them from the imagination. To
believe is in this case to feel an immediate impression of the senses,
or a repetition of that impression in the memory. It is merely the force
and liveliness of the perception, which constitutes the first act of the
judgment, and lays the foundation of that reasoning, which we build upon
it, when we trace the relation of cause and effect.
SECT. VI. OF THE INFERENCE FROM THE IMPRESSION TO THE IDEA.
It is easy to observe, that in tracing this relation, the inference we
draw from cause to effect, is not derived merely from a survey of these
particular objects, and from such a penetration into their essences
as may discover the dependance of the one upon the other. There is no
object, which implies the existence of any other if we consider these
objects in themselves, and never look beyond the ideas which we form of
them. Such an inference would amount to knowledge, and would imply
the absolute contradiction and impossibility of conceiving any thing
different. But as all distinct ideas are separable, it is evident
there can be no impossibility of that kind. When we pass from a present
impression to the idea of any object, we might possibly have separated
the idea from the impression, and have substituted any other idea in its
room.
It is therefore by EXPERIENCE only, that we can infer the existence of
one object from that of another. The nature of experience is this. We
remember to have had frequent instances of the existence of one species
of objects; and also remember, that the individuals of another species
of objects have always attended them, and have existed in a regular
order of contiguity and succession with regard to them. Thus we
remember, to have seen that species of object we call flame, and to have
felt that species of sensation we call heat. We likewise call to mind
their constant conjunction in all past instances. Without any farther
ceremony, we call the one cause and the other effect, and infer the
existence of the one from that of the other. In all those instances,
from which we learn the conjunction of particular causes and effects,
both the causes and effects have been perceived by the senses, and are
remembered. But in all cases, wherein we reason concerning them, there
is only one perceived or remembered, and the other is supplyed in
conformity to our past experience.
Thus in advancing we have insensibly discovered a new relation betwixt
cause and effect, when we least expected it, and were entirely employed
upon another subject. This relation is their CONSTANT CONJUNCTION.
Contiguity and succession are not sufficient to make us pronounce any
two objects to be cause and effect, unless we perceive, that these
two relations are preserved in several instances. We may now see the
advantage of quitting the direct survey of this relation, in order
to discover the nature of that necessary connexion, which makes so
essential a part of it. There are hopes, that by this means we may
at last arrive at our proposed end; though to tell the truth, this
new-discovered relation of a constant conjunction seems to advance us
but very little in our way. For it implies no more than this, that like
objects have always been placed in like relations of contiguity and
succession; and it seems evident, at least at first sight, that by this
means we can never discover any new idea, and can only multiply, but not
enlarge the objects of our mind. It may be thought, that what we learn
not from one object, we can never learn from a hundred, which are all
of the same kind, and are perfectly resembling in every circumstance. As
our senses shew us in one instance two bodies, or motions, or qualities
in certain relations of success and contiguity; so our memory presents
us only with a multitude of instances, wherein we always find like
bodies, motions, or qualities in like relations. From the mere
repetition of any past impression, even to infinity, there never will
arise any new original idea, such as that of a necessary connexion; and
the number of impressions has in this case no more effect than if we
confined ourselves to one only. But though this reasoning seems just and
obvious; yet as it would be folly to despair too soon, we shall continue
the thread of our discourse; and having found, that after the discovery
of the constant conjunction of any objects, we always draw an inference
from one object to another, we shall now examine the nature of that
inference, and of the transition from the impression to the idea.
Perhaps it will appear in the end, that the necessary connexion depends
on the inference, instead of the inference's depending on the necessary
connexion.
Since it appears, that the transition from an impression present to
the memory or senses to the idea of an object, which we call cause or
effect, is founded on past experience, and on our remembrance of their
constant conjunction, the next question is, Whether experience produces
the idea by means of the understanding or imagination; whether we are
determined by reason to make the transition, or by a certain association
and relation of perceptions. If reason determined us, it would proceed
upon that principle, that instances, of which we have had no experience,
must resemble those, of which we have had experience, and that the
course of nature continues always uniformly the same. In order therefore
to clear up this matter, let us consider all the arguments, upon which
such a proposition may be supposed to be founded; and as these must be
derived either from knowledge or probability, let us cast our eye on
each of these degrees of evidence, and see whether they afford any just
conclusion of this nature.
Our foregoing method
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