Kant's Theory of Knowledge
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Title: Kant's Theory of Knowledge
Author: H. A. Prichard
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Language: English
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KANT'S THEORY OF KNOWLEDGE
by
H. A. PRICHARD
Fellow of Trinity College, Oxford
Oxford
At the Clarendon Press
1909
Henry Frowde, M.A.
Publisher to the University of Oxford
London, Edinburgh, New York
Toronto and Melbourne
PREFACE
This book is an attempt to think out the nature and tenability of
Kant's Transcendental Idealism, an attempt animated by the conviction
that even the elucidation of Kant's meaning, apart from any criticism,
is impossible without a discussion on their own merits of the main
issues which he raises.
My obligations are many and great: to Caird's _Critical Philosophy of
Kant_ and to the translations of Meiklejohn, Max Müller, and Professor
Mahaffy; to Mr. J. A. Smith, Fellow of Balliol College, and to Mr. H.
W. B. Joseph, Fellow of New College, for what I have learned from them
in discussion; to Mr. A. J. Jenkinson, Fellow of Brasenose College,
for reading and commenting on the first half of the MS.; to Mr. H. H.
Joachim, Fellow of Merton College, for making many important
suggestions, especially with regard to matters of translation; to Mr.
Joseph, for reading the whole of the proofs and for making many
valuable corrections; and, above all, to my wife for constant and
unfailing help throughout, and to Professor Cook Wilson, to have been
whose pupil I count the greatest of philosophical good fortunes. Some
years ago it was my privilege to be a member of a class with which
Professor Cook Wilson read a portion of Kant's _Critique of Pure
Reason_, and subsequently I have had the advantage of discussing with
him several of the more important passages. I am especially indebted
to him in my discussion of the following topics: the distinction
between the Sensibility and the Understanding (pp. 27-31, 146-9,
162-6), the term 'form of perception' (pp. 37, 40, 133 fin.-135), the
_Metaphysical Exposition of Space_ (pp. 41-8), Inner Sense (Ch. V,
and pp. 138-9), the _Metaphysical Deduction of the Categories_ (pp.
149-53), Kant's account of 'the reference of representations to an
object' (pp. 178-86), an implication of perspective (p. 90), the
impossibility of a 'theory' of knowledge (p. 245), and the points
considered, pp. 200 med.-202 med., 214 med.-215 med., and 218. The
views expressed in the pages referred to originated from Professor
Cook Wilson, though it must not be assumed that he would accept them
in the form in which they are there stated.
CONTENTS
CHAPTER I PAGE
THE PROBLEM OF THE _Critique_ 1
CHAPTER II
THE SENSIBILITY AND THE UNDERSTANDING 27
CHAPTER III
SPACE 36
CHAPTER IV
PHENOMENA AND THINGS IN THEMSELVES 71
NOTE
THE FIRST ANTINOMY 101
CHAPTER V
TIME AND INNER SENSE 103
CHAPTER VI
KNOWLEDGE AND REALITY 115
CHAPTER VII
THE METAPHYSICAL DEDUCTION OF THE CATEGORIES 140
CHAPTER VIII
THE TRANSCENDENTAL DEDUCTION OF THE CATEGORIES 161
CHAPTER IX
GENERAL CRITICISM OF THE TRANSCENDENTAL DEDUCTION OF THE
CATEGORIES 214
CHAPTER X
THE SCHEMATISM OF THE CATEGORIES 246
CHAPTER XI
THE MATHEMATICAL PRINCIPLES 260
CHAPTER XII
THE ANALOGIES OF EXPERIENCE 268
CHAPTER XIII
THE POSTULATES OF EMPIRICAL THOUGHT 308
NOTE
THE REFUTATION OF IDEALISM 319
REFERENCES
A = First edition of the _Critique of Pure Reason_.
B = Second edition of the _Critique of Pure Reason_.
Prol. = Kant's _Prolegomena to any future Metaphysic_.
M = Meiklejohn's Translation of the _Critique of Pure Reason_.
Mah. = Mahaffy. Translation of Kant's _Prolegomena to any future
Metaphysic_. (The pages referred to are those of the first
edition; these are also to be found in the text of the
second edition.)
Caird = Caird's _Critical Philosophy of Kant_.
CHAPTER I
THE PROBLEM OF THE _CRITIQUE_
The problem of the _Critique_ may be stated in outline and
approximately in Kant's own words as follows.
Human reason is called upon to consider certain questions, which it
cannot decline, as they are presented by its own nature, but which it
cannot answer. These questions relate to God, freedom of the will, and
immortality. And the name for the subject which has to deal with these
questions is metaphysics. At one time metaphysics was regarded as the
queen of all the sciences, and the importance of its aim justified the
title. At first the subject, propounding as it did a dogmatic system,
exercised a despotic sway. But its subsequent failure brought it into
disrepute. It has constantly been compelled to retrace its steps;
there has been fundamental disagreement among philosophers, and no
philosopher has successfully refuted his critics. Consequently the
current attitude to the subject is one of weariness and indifference.
Yet humanity cannot really be indifferent to such problems; even those
who profess indifference inevitably make metaphysical assertions; and
the current attitude is a sign not of levity but of a refusal to put
up with the illusory knowledge offered by contemporary philosophy. Now
the objects of metaphysics, God, freedom, and immortality, are not
objects of experience in the sense in which a tree or a stone is an
object of experience. Hence our views about them cannot be due to
experience; they must somehow be apprehended by pure reason, i. e. by
thinking and without appeal to experience. Moreover, it is in fact by
thinking that men have always tried to solve the problems concerning
God, freedom, and immortality. What, then, is the cause of the
unsatisfactory treatment of these problems and men's consequent
indifference? It must, in some way, lie in a failure to attain the
sure scientific method, and really consists in the neglect of an
inquiry which should be a preliminary to all others in metaphysics.
Men ought to have begun with a critical investigation of pure reason
itself. Reason should have examined its own nature, to ascertain in
general the extent to which it is capable of attaining knowledge
without the aid of experience. This examination will decide whether
reason is able to deal with the problems of God, freedom, and
immortality at all; and without it no discussion of these problems
will have a solid foundation. It is this preliminary investigation
which the _Critique of Pure Reason_ proposes to undertake. Its aim is
to answer the question, 'How far can reason go, without the material
presented and the aid furnished by experience?' and the result
furnishes the solution, or at least the key to the solution, of all
metaphysical problems.
Kant's problem, then, is similar to Locke's. Locke states[1] that his
purpose is to inquire into the original, certainty, and extent of
human knowledge; and he says, "If, by this inquiry into the nature of
the understanding I can discover the powers thereof; how far they
reach, to what things they are in any degree proportionate, and where
they fail us; I suppose it may be of use to prevail with the busy mind
of man, to be more cautious in meddling with things exceeding its
comprehension; to stop when it is at the utmost extent of its tether;
and to sit down in a quiet ignorance of those things, which, upon
examination, are found to be beyond the reach of our capacities."
Thus, to use Dr. Caird's analogy,[2] the task which both Locke and
Kant set themselves resembled that of investigating a telescope,
before turning it upon the stars, to determine its competence for the
work.
[1] Locke's _Essay_, i, 1, §§ 2, 4.
[2] Caird, i, 10.
The above outline of Kant's problem is of course only an outline. Its
definite formulation is expressed in the well-known question, 'How are
_a priori_ synthetic judgements possible?'[3] To determine the meaning
of this question it is necessary to begin with some consideration of
the terms '_a priori_' and 'synthetic'.
[3] B. 19, M. 12.
While there is no difficulty in determining what Kant would have
recognized as an _a priori_ judgement, there is difficulty in
determining what he meant by calling such a judgement _a priori_. The
general account is given in the first two sections of the
Introduction. An _a priori_ judgement is introduced as something
opposed to an _a posteriori_ judgement, or a judgement which has its
source in experience. Instances of the latter would be 'This body is
heavy', and 'This body is hot'. The point of the word 'experience' is
that there is direct apprehension of some individual, e. g. an
individual body. To say that a judgement has its source in experience
is of course to imply a distinction between the judgement and
experience, and the word 'source' may be taken to mean that the
judgement depends for its validity upon the experience of the
individual thing to which the judgement relates. An _a priori_
judgement, then, as first described, is simply a judgement which is
not _a posteriori_. It is independent of all experience; in other
words, its validity does not depend on the experience of individual
things. It might be illustrated by the judgement that all three-sided
figures must have three angles. So far, then, no positive meaning has
been given to _a priori_.[4]
[4] Kant is careful to exclude from the class of _a priori_
judgements proper what may be called relatively _a priori_
judgements, viz. judgements which, though not independent of
all experience, are independent of experience of the facts to
which they relate. "Thus one would say of a man who
undermined the foundations of his house that he might have
known _a priori_ that it would fall down, i. e. that he did
not need to wait for the experience of its actual falling
down. But still he could not know this wholly _a priori_, for
he had first to learn through experience that bodies are
heavy and consequently fall, if their supports are taken
away." (B. 2, M. 2.)
Kant then proceeds, not as we should expect, to state the positive
meaning of _a priori_; but to give tests for what is _a priori_. Since
a test implies a distinction between itself and what is tested, it is
implied that the meaning of _a priori_ is already known.[5]
[5] It may be noted that in this passage (Introduction, §§ 1
and 2) Kant is inconsistent in his use of the term 'pure'.
Pure knowledge is introduced as a species of _a priori_
knowledge: "_A priori_ knowledge, if nothing empirical is
mixed with it, is called pure". (B. 3, M. 2, 17.) And in
accordance with this, the proposition 'every change has a
cause' is said to be _a priori_ but impure, because the
conception of change can only be derived from experience. Yet
immediately afterwards, pure, being opposed in general to
empirical, can only mean _a priori_. Again, in the phrase
'pure _a priori_' (B. 4 fin., M. 3 med.), the context shows
that 'pure' adds nothing to '_a priori_', and the proposition
'every change must have a cause' is expressly given as an
instance of pure _a priori_ knowledge. The inconsistency of
this treatment of the causal rule is explained by the fact
that in the former passage he is thinking of the conception
of change as empirical, while in the latter he is thinking of
the judgement as not empirical. At bottom in this passage
'pure' simply means _a priori_.
The tests given are necessity and strict universality.[6] Since
judgements which are necessary and strictly universal cannot be based
on experience, their existence is said to indicate another source of
knowledge. And Kant gives as illustrations, (1) any proposition in
mathematics, and (2) the proposition 'Every change must have a cause'.
[6] In reality, these tests come to the same thing, for
necessity means the necessity of connexion between the
subject and predicate of a judgement, and since empirical
universality, to which strict universality is opposed, means
numerical universality, as illustrated by the proposition
'All bodies are heavy', the only meaning left for strict
universality is that of a universality reached not through an
enumeration of instances, but through the apprehension of a
necessity of connexion.
So far Kant has said nothing which determines the positive meaning of
_a priori_. A clue is, however, to be found in two subsequent phrases.
He says that we may content ourselves with having established as a
fact the pure use of our faculty of knowledge.[7] And he adds that not
only in judgements, but even in conceptions, is an _a priori_ origin
manifest.[8] The second statement seems to make the _a priori_
character of a judgement consist in its origin. As this origin cannot
be experience, it must, as the first statement implies, lie in our
faculty of knowledge. Kant's point is that the existence of universal
and necessary judgements shows that we must possess a faculty of
knowledge capable of yielding knowledge without appeal to experience.
The term _a priori_, then, has some reference to the existence of this
faculty; in other words, it gives expression to a doctrine of 'innate
ideas'. Perhaps, however, it is hardly fair to press the phrase
'_test_ of _a priori_ judgements'. If so, it may be said that on the
whole, by _a priori_ judgements Kant really means judgements which are
universal and necessary, and that he regards them as implying a
faculty which gives us knowledge without appeal to experience.
[7] B. 5, M. 4.
[8] Ibid.
We may now turn to the term 'synthetic judgement'. Kant distinguishes
analytic and synthetic judgements thus. In any judgement the predicate
B either belongs to the subject A, as something contained (though
covertly) in the conception A, or lies completely outside the
conception A, although it stands in relation to it. In the former case
the judgement is called analytic, in the latter synthetic.[9] 'All
bodies are extended' is an analytic judgement; 'All bodies are heavy'
is synthetic. It immediately follows that only synthetic judgements
extend our knowledge; for in making an analytic judgement we are only
clearing up our conception of the subject. This process yields no new
knowledge, for it only gives us a clearer view of what we know
already. Further, all judgements based on experience are synthetic,
for it would be absurd to base an analytical judgement on experience,
when to make the judgement we need not go beyond our own conceptions.
On the other hand, _a priori_ judgements are sometimes analytic and
sometimes synthetic. For, besides analytical judgements, all
judgements in mathematics and certain judgements which underlie
physics are asserted independently of experience, and they are
synthetic.
[9] B. 10, M. 7.
Here Kant is obviously right in vindicating the synthetic character of
mathematical judgements. In the arithmetical judgement 7 + 5 = 12, the
thought of certain units as a group of twelve is no mere repetition of
the thought of them as a group of five added to a group of seven.
Though the same units are referred to, they are regarded differently.
Thus the thought of them as twelve means either that we think of them
as formed by adding one unit to a group of eleven, or that we think of
them as formed by adding two units to a group of ten, and so on. And
the assertion is that the same units, which can be grouped in one way,
can also be grouped in another. Similarly, Kant is right in pointing
out that the geometrical judgement, 'A straight line between two
points is the shortest,' is synthetic, on the ground that the
conception of straightness is purely qualitative,[10] while the
conception of shortest distance implies the thought of quantity.
[10] Straightness means identity of direction.
It should now be an easy matter to understand the problem expressed
by the question, 'How are _a priori_ synthetic judgements possible?'
Its substance may be stated thus. The existence of _a posteriori_
synthetic judgements presents no difficulty. For experience is
equivalent to perception, and, as we suppose, in perception we are
confronted with reality, and apprehend it as it is. If I am asked,
'How do I know that my pen is black or my chair hard?' I answer that
it is because I see or feel it to be so. In such cases, then, when my
assertion is challenged, I appeal to my experience or perception of
the reality to which the assertion relates. My appeal raises no
difficulty because it conforms to the universal belief that if
judgements are to rank as knowledge, they must be made to conform to
the nature of things, and that the conformity is established by appeal
to actual experience of the things. But do _a priori_ synthetic
judgements satisfy this condition? Apparently not. For when I assert
that every straight line is the shortest way between its extremities,
I have not had, and never can have, experience of all possible
straight lines. How then can I be sure that all cases will conform to
my judgement? In fact, how can I anticipate my experience at all? How
can I make an assertion about any individual until I have had actual
experience of it? In an _a priori_ synthetic judgement the mind in
some way, in virtue of its own powers and independently of experience,
makes an assertion to which it claims that reality must conform. Yet
why should reality conform? _A priori_ judgements of the other
kind, viz. analytic judgements, offer no difficulty, since they
are at bottom tautologies, and consequently denial of them is
self-contradictory and meaningless. But there is difficulty where a
judgement asserts that a term B is connected with another term A, B
being neither identical with nor a part of A. In this case there is no
contradiction in asserting that A is not B, and it would seem that
only experience can determine whether all A is or is not B. Otherwise
we are presupposing that things must conform to our ideas about them.
Now metaphysics claims to make _a priori_ synthetic judgements, for it
does not base its results on any appeal to experience. Hence, before
we enter upon metaphysics, we really ought to investigate our right to
make _a priori_ synthetic judgements at all. Therein, in fact, lies
the importance to metaphysics of the existence of such judgements in
mathematics and physics. For it shows that the difficulty is not
peculiar to metaphysics, but is a general one shared by other
subjects; and the existence of such judgements in mathematics is
specially important because there their validity or certainty has
never been questioned.[11] The success of mathematics shows that at any
rate under certain conditions _a priori_ synthetic judgements are
valid, and if we can determine these conditions, we shall be able to
decide whether such judgements are possible in metaphysics. In this
way we shall be able to settle a disputed case of their validity by
examination of an undisputed case. The general problem, however, is
simply to show what it is which makes _a priori_ synthetic judgements
as such possible; and there will be three cases, those of mathematics,
of physics, and of metaphysics.
[11] Kant points out that this certainty has usually been
attributed to the analytic character of mathematical
judgements, and it is of course vital to his argument that
he should be successful in showing that they are really
synthetic.
The outline of the solution of this problem is contained in the
Preface to the Second Edition. There Kant urges that the key is to be
found by consideration of mathematics and physics. If the question be
raised as to what it is that has enabled these subjects to advance, in
both cases the answer will be found to lie in a change of method.
"Since the earliest times to which the history of human reason
reaches, mathematics has, among that wonderful nation the Greeks,
followed the safe road of a science. Still it is not to be supposed
that it was as easy for this science to strike into, or rather to
construct for itself, that royal road, as it was for logic, in which
reason has only to do with itself. On the contrary, I believe that it
must have remained long in the stage of groping (chiefly among the
Egyptians), and that this change is to be ascribed to a _revolution_,
due to the happy thought of one man, through whose experiment the path
to be followed was rendered unmistakable for future generations, and
the certain way of a science was entered upon and sketched out once
for all.... A new light shone upon the first man (Thales, or whatever
may have been his name) who demonstrated the properties of the
isosceles triangle; for he found that he ought not to investigate
that which he saw in the figure or even the mere conception of the
same, and learn its properties from this, but that he ought to produce
the figure by virtue of that which he himself had thought into it _a
priori_ in accordance with conceptions and had represented (by means
of a construction), and that in order to know something with certainty
_a priori_ he must not attribute to the figure any property other than
that which necessarily follows from that which he has himself
introduced into the figure, in accordance with his conception."[12]
[12] B. x-xii, M. xxvi.
Here Kant's point is as follows. Geometry remained barren so long as
men confined themselves either to the empirical study of individual
figures, of which the properties were to be discovered by observation,
or to the consideration of the mere conception of various kinds of
figure, e. g. of an isosceles triangle. In order to advance, men had
in some sense to produce the figure through their own activity, and in
the act of constructing it to recognize that certain features were
necessitated by those features which they had given to the figure in
constructing it. Thus men had to make a triangle by drawing three
straight lines so as to enclose a space, and then to recognize that
three angles must have been made by the same process. In this way the
mind discovered a general rule, which must apply to all cases, because
the mind itself had determined the nature of the cases. A property B
follows from a nature A; all instances of A must possess the property
B, because they have solely that nature A which the mind has given
them and whatever is involved in A. The mind's own rule holds good in
all cases, because the mind has itself determined the nature of the
cases.
Kant's statements about physics, though not the same, are analogous.
Experiment, he holds, is only fruitful when reason does not follow
nature in a passive spirit, but compels nature to answer its own
questions. Thus, when Torricelli made an experiment to ascertain
whether a certain column of air would sustain a given weight, he had
previously calculated that the quantity of air was just sufficient to
balance the weight, and the significance of the experiment lay in his
expectation that nature would conform to his calculations and in the
vindication of this expectation. Reason, Kant says, must approach
nature not as a pupil but as a judge, and this attitude forms the
condition of progress in physics.
The examples of mathematics and physics suggest, according to Kant,
that metaphysics may require a similar revolution of standpoint, the
lack of which will account for its past failure. An attempt should
therefore be made to introduce such a change into metaphysics. The
change is this. Hitherto it has been assumed that our knowledge must
conform to objects. This assumption is the real cause of the failure
to extend our knowledge _a priori_, for it limits thought to the
analysis of conceptions, which can only yield tautological judgements.
Let us therefore try the effect of assuming that objects must conform
to our knowledge. Herein lies the Copernican revolution. We find that
this reversal of the ordinary view of the relation of objects to the
mind enables us for the first time to understand the possibility of _a
priori_ synthetic judgements, and even to demonstrate certain laws
which lie at the basis of nature, e. g. the law of causality. It is
true that the reversal also involves the surprising consequence that
our faculty of knowledge is incapable of dealing with the objects of
metaphysics proper, viz. God, freedom, and immortality, for the
assumption limits our knowledge to objects of possible experience. But
this very consequence, viz. the impossibility of metaphysics, serves
to test and vindicate the assumption. For the view that our knowledge
conforms to objects as things in themselves leads us into an insoluble
contradiction when we go on, as we must, to seek for the
unconditioned; while the assumption that objects must, as phenomena,
conform to our way of representing them, removes the contradiction[13].
Further, though the assumption leads to the denial of speculative
knowledge in the sphere of metaphysics, it is still possible that
reason in its practical aspect may step in to fill the gap. And the
negative result of the assumption may even have a positive value. For
if, as is the case, the moral reason, or reason in its practical
aspect, involves certain postulates concerning God, freedom, and
immortality, which are rejected by the speculative reason, it is
important to be able to show that these objects fall beyond the scope
of the speculative reason. And if we call reliance on these
postulates, as being presuppositions of morality, faith, we may say
that knowledge must be abolished to make room for faith.
[13] Cf. pp. 101-2.
This answer to the main problem, given in outline in the Preface, is
undeniably plausible. Yet examination of it suggests two criticisms
which affect Kant's general position.
In the first place, the parallel of mathematics which suggests the
'Copernican' revolution does not really lead to the results which Kant
supposes. Advance in mathematics is due to the adoption not of any
conscious assumption but of a certain procedure, viz. that by which we
draw a figure and thereby see the necessity of certain relations
within it. To preserve the parallel, the revolution in metaphysics
should have consisted in the adoption of a similar procedure, and
advance should have been made dependent on the application of an at
least quasi-mathematical method to the objects of metaphysics.
Moreover, since these objects are God, freedom, and immortality, the
conclusion should have been that we ought to study God, freedom, and
immortality by somehow constructing them in perception and thereby
gaining insight into the necessity of certain relations. Success or
failure in metaphysics would therefore consist simply in success or
failure to see the necessity of the relations involved. Kant, however,
makes the condition of advance in metaphysics consist in the adoption
not of a method of procedure but of an assumption, viz. that objects
conform to the mind. And it is impossible to see how this assumption
can assist what, on Kant's theory, it ought to have assisted, viz. the
study of God, freedom, and immortality, or indeed the study of
anything. In geometry we presuppose that individual objects conform to
the universal rules of relation which we discover. Now suppose we
describe a geometrical judgement, e. g. that two straight lines cannot
enclose a space, as a mental law, because we are bound to think it
true. Then we may state the presupposition by saying that objects,
e. g. individual pairs of straight lines, must conform to such a mental
law. But the explicit recognition of this presupposition and the
conscious assertion of it in no way assist the solution of particular
geometrical problems. The presupposition is really a condition of
geometrical thinking at all. Without it there is no geometrical
thinking, and the recognition of it places us in no better position
for the study of geometrical problems. Similarly, if we wish to think
out the nature of God, freedom, and immortality, we are not assisted
by assuming that these objects must conform to the laws of our
thinking. We must presuppose this conformity if we are to think at
all, and consciousness of the presupposition puts us in no better
position. What is needed is an insight similar to that which we have
in geometry, i. e. an insight into the necessity of the relations
under consideration such as would enable us to see, for example, that
being a man, as such, involves living for ever.
Kant has been led into the mistake by a momentary change in the
meaning given to 'metaphysics'. For the moment he is thinking of
metaphysics, not as the inquiry concerned with God, freedom, and
immortality, but as the inquiry which has to deal with the problem as
to how we can know _a priori_. This problem is assisted, at any rate
prima facie, by the assumption that things must conform to the mind.
And this assumption can be said to be suggested by mathematics,
inasmuch as the mathematician presupposes that particular objects must
correspond to the general rules discovered by the mind. From this
point of view Kant's only mistake, if the parallelism is to be
maintained, is that he takes for an assumption which enables the
mathematician to advance a metaphysical presupposition of the advance,
on which the mathematician never reflects, and awareness of which
would in no way assist his mathematics.
In the second place the 'Copernican' revolution is not strictly the
revolution which Kant supposes it to be. He speaks as though his aim
is precisely to reverse the ordinary view of the relation of the mind
to objects. Instead of the mind being conceived as having to conform
to objects, objects are to be conceived as having to conform to the
mind. But if we consider Kant's real position, we see that these views
are only verbally contrary, since the word object refers to something
different in each case. On the ordinary view objects are something
outside the mind, in the sense of independent of it, and the ideas,
which must conform to objects, are something within the mind, in the
sense of dependent upon it. The conformity then is of something within
the mind to something outside it. Again, the conformity means that one
of the terms, viz. the object, exists first and that then the other
term, the idea, is fitted to or made to correspond to it. Hence the
real contrary of this view is that ideas, within the mind, exist first
and that objects outside the mind, coming into existence afterwards,
must adapt themselves to the ideas. This of course strikes us as
absurd, because we always think of the existence of the object as the
presupposition of the existence of the knowledge of it; we do not
think the existence of the knowledge as the presupposition of the
existence of the object. Hence Kant only succeeds in stating the
contrary of the ordinary view with any plausibility, because in doing
so he makes the term object refer to something which like 'knowledge'
is within the mind. His position is that objects within the mind must
conform to our general ways of knowing. For Kant, therefore, the
conformity is not between something within and something without the
mind, but between two realities within the mind, viz. the individual
object, as object of perception, i. e. a phenomenon, and our general
ways of perceiving and thinking. But this view is only verbally the
contrary of the ordinary view, and consequently Kant does not succeed
in reversing the ordinary view that we know objects independent of or
outside the mind, by bringing our ideas into conformity with them. In
fact, his conclusion is that we do not know this object, i. e. the
thing in itself, at all. Hence his real position should be stated by
saying not that the ordinary view puts the conformity between mind and
things in the wrong way, but that we ought not to speak of conformity
at all. For the thing in itself being unknowable, our ideas can never
be made to conform to it. Kant then only reaches a conclusion which is
apparently the reverse of the ordinary view by substituting another
object for the thing in itself, viz. the phenomenon or appearance of
the thing in itself to us.
Further, this second line of criticism, if followed out, will be found
to affect his statement of the problem as well as that of its
solution. It will be seen that the problem is mis-stated, and that the
solution offered presupposes it to be mis-stated. His statement of the
problem takes the form of raising a difficulty which the existence of
_a priori_ knowledge presents to the ordinary view, according to which
objects are independent of the mind, and ideas must be brought into
conformity with them. In a synthetic _a priori_ judgement we claim to
discover the nature of certain objects by an act of our thinking, and
independently of actual experience of them. Hence if a supporter of
the ordinary view is asked to justify the conformity of this judgement
or idea with the objects to which it relates, he can give no answer.
The judgement having _ex hypothesi_ been made without reference to the
objects, the belief that the objects must conform to it is the merely
arbitrary supposition that a reality independent of the mind must
conform to the mind's ideas. But Kant, in thus confining the
difficulty to _a priori_ judgements, implies that empirical judgements
present no difficulty to the ordinary view; since they rest upon
actual experience of the objects concerned, they are conformed to the
objects by the very process through which they arise. He thereby fails
to notice that empirical judgements present a precisely parallel
difficulty. It can only be supposed that the conformity of empirical
judgements to their objects is guaranteed by the experience upon which
they rest, if it be assumed that in experience we apprehend objects as
they are. But our experience or perception of individual objects is
just as much mental as the thinking which originates _a priori_
judgements. If we can question the truth of our thinking, we can
likewise question the truth of our perception. If we can ask whether
our ideas must correspond to their objects, we can likewise ask
whether our perceptions must correspond to them. The problem relates
solely to the correspondence between something within the mind and
something outside it; it applies equally to perceiving and thinking,
and concerns all judgements alike, empirical as well as _a priori_.
Kant, therefore, has no right to imply that empirical judgements raise
no problem, if he finds difficulty in _a priori_ judgements. He is
only able to draw a distinction between them, because, without being
aware that he is doing so, he takes account of the relation of the
object to the subject in the case of an _a priori_ judgement, while in
the case of an empirical judgement he ignores it. In other words, in
dealing with the general connexion between the qualities of an
object, he takes into account the fact that we are thinking it, but,
in dealing with the perception of the coexistence of particular
qualities of an object, he ignores the fact that we are perceiving it.
Further, that the real problem concerns all synthetic judgements alike
is shown by the solution which he eventually reaches. His conclusion
turns out to be that while both empirical and _a priori_ judgements
are valid of phenomena, they are not valid of things in themselves;
i. e. that of things in themselves we know nothing at all, not even
their particular qualities. Since, then, his conclusion is that even
empirical judgements are not valid of things in themselves, it shows
that the problem cannot be confined to _a priori_ judgements, and
therefore constitutes an implicit criticism of his statement of the
problem.
Must there not, however, be some problem peculiar to _a priori_
judgements? Otherwise why should Kant have been led to suppose that
his problem concerned them only? Further consideration will show that
there is such a problem, and that it was only owing to the mistake
indicated that Kant treated this problem as identical with that of
which he actually offered a solution. In the universal judgements of
mathematics we apprehend, as we think, general rules of connexion
which must apply to all possible cases. Such judgements, then,
presuppose a conformity between the connexions which we discover and
all possible instances. Now Kant's treatment of this conformity as a
conformity between our ideas and things has two implications. In the
first place, it implies, as has been pointed out, that relation to the
subject, as thinking, is taken into account in the case of the
universal connexion, and that relation to the subject, as perceiving,
is ignored in the case of the individual thing. In the second place,
it implies that what is related to the subject as the object of its
thought must be subjective or mental; that because we have to think
the general connexion, the connexion is only our own idea, the
conformity of things to which may be questioned. But the treatment, to
be consistent, should take account of relation to the subject in both
cases or in neither. If the former alternative be accepted, then the
subjective character attributed by Kant in virtue of this relation to
what is object of thought, and equally attributable to what is object
of perception, reduces the problem to that of the conformity in
general of all ideas, including perceptions, within the mind to things
outside it; and this problem does not relate specially to _a priori_
judgements. To discover the problem which relates specially to them,
the other alternative must be accepted, that of ignoring relation to
the subject in both cases. The problem then becomes 'What renders
possible or is presupposed by the conformity of individual things to
certain laws of connexion?' And, inasmuch as to deny the conformity is
really to deny that there are laws of connexion,[14] the problem
reduces itself to the question, 'What is the presupposition of the
existence of definite laws of connexion in the world?' And the only
answer possible is that reality is a system or a whole of connected
parts, in other words, that nature is uniform. Thus it turns out that
the problem relates to the uniformity of nature, and that the
question 'How are _a priori_ synthetic judgements possible?' has in
reality nothing to do with the problem of the relation of reality to
the knowing subject, but is concerned solely with the nature of
reality.
[14] To object that the laws in question, being laws which we
have thought, may not be the true laws, and that therefore
there may still be other laws to which reality conforms, is
of course to reintroduce relation to the thinking subject.
Further, it is important to see that the alternative of ignoring
relation to the subject is the right one, not only from the point of
view of the problem peculiar to _a priori_ judgements, but also from
the point of view of the nature of knowledge in general. Perceiving
and thinking alike presuppose that reality is immediately object of
the mind, and that the act of apprehension in no way affects or enters
into the nature of what we apprehend about reality. If, for instance,
I assert on the strength of perception that this table is round, I
imply that I see the table, and that the shape which I judge it to
have is not affected by the fact that I am perceiving it; for I mean
that the table really is round. If some one then convinces me that I
have made a mistake owing to an effect of foreshortening, and that the
table is really oval, I amend my assertion, not by saying that the
table is round but only to my apprehension, but by saying that it
looks round. Thereby I cease to predicate roundness of the table
altogether; for I mean that while it still looks round, it is not
really so. The case of universal judgements is similar. The statement
that a straight line is the shortest distance between its extremities
means that it really is so. The fact is presupposed to be in no way
altered by our having apprehended it. Moreover, reality is here just
as much implied to be directly object of the mind as it is in the case
of the singular judgement. Making the judgement consists, as we say,
in _seeing_ the connexion between the direction between two points
and the shortest distance between them. The connexion of real
characteristics is implied to be directly object of thought.[16] Thus
both perceiving and thinking presuppose that the reality to which they
relate is directly object of the mind, and that the character of it
which we apprehend in the resulting judgement is not affected or
altered by the fact that we have had to perceive or conceive the
reality.[17]
[15] Cf. Bosanquet, _Logic_, vol. ii, p. 2.
[16] In saying that a universal judgement is an immediate
apprehension of fact, it is of course not meant that it can
be actualized by itself or, so to say, _in vacuo_. Its
actualization obviously presupposes the presentation of
individuals in perception or imagination. Perception or
imagination thus forms the necessary occasion of a universal
judgement, and in that sense mediates it. Moreover, the
universal judgement implies an act of abstraction by which
we specially attend to those universal characters of the
individuals perceived or imagined, which enter into the
judgement. But, though our apprehension of a universal
connexion thus implies a process, and is therefore mediated,
yet the connexion, when we apprehend it, is immediately our
object. There is nothing between it and us.
[17] For a fuller discussion of the subject see Chh. IV and
VI.
Kant in the formulation of his problem implicitly admits this
presupposition in the case of perception. He implies that empirical
judgements involve no difficulty, because they rest upon the
perception or experience of the objects to which they relate. On the
other hand, he does not admit the presupposition in the case of
conception, for he implies that in _a priori_ judgements we are not
confronted with reality but are confined to our own ideas. Hence we
ought to ask why Kant is led to adopt an attitude in the latter case
which he does not adopt in the former. The answer appears to be
twofold. In the first place, there is an inveterate tendency to think
of universals, and therefore of the connexions between them, as being
not objective realities[18] but mere ideas. In other words, we tend to
adopt the conceptualist attitude, which regards individuals as the
only reality, and universals as mental fictions. In consequence, we
are apt to think that while in perception, which is of the individual,
we are confronted by reality, in universal judgements, in which we
apprehend connexions between universals, we have before us mere ideas.
Kant may fairly be supposed to have been unconsciously under the
influence of this tendency. In the second place, we apprehend a
universal connexion by the operation of thinking. Thinking is
essentially an activity; and since activity in the ordinary sense in
which we oppose action to knowledge originates something, we tend to
think of the activity of thinking as also originating something, viz.
that which is our object when we think. Hence, since we think of what
is real as independent of us and therefore as something which we may
discover but can in no sense make, we tend to think of the object of
thought as only an idea. On the other hand, what is ordinarily called
perception, though it involves the activity of thinking, also involves
an element in respect of which we are passive. This is the fact
pointed to by Kant's phrase 'objects are _given_ in perception'. In
virtue of this passive element we are inclined to think that in
perception we simply stand before the reality in a passive attitude.
The reality perceived is thought to be, so to say, there, existing
independently of us; relation to the subject is unnoticed because of
our apparently wholly passive attitude. At times, and especially when
he is thinking of the understanding as a faculty of spontaneity, Kant
seems to have been under the influence of this second tendency.
[18] i. e. as not having a place in the reality which, as we
think, exists independently of the mind.
The preceding summary of the problem of the _Critique_ represents the
account given in the two Prefaces and the Introduction. According to
this account, the problem arises from the unquestioned existence of _a
priori_ knowledge in mathematics and physics and the problematic
existence of such knowledge in metaphysics, and Kant's aim is to
determine the range within which _a priori_ knowledge is possible.
Thus the problem is introduced as relating to _a priori_ knowledge as
such, no distinction being drawn between its character in different
cases. Nevertheless the actual discussion of the problem in the body
of the _Critique_ implies a fundamental distinction between the nature
of _a priori_ knowledge in mathematics and its nature in physics, and
in order that a complete view of the problem may be given, this
distinction must be stated.
The 'Copernican' revolution was brought about by consideration of the
facts of mathematics. Kant accepted as an absolute starting-point the
existence in mathematics of true universal and necessary judgements.
He then asked, 'What follows as to the nature of the objects known in
mathematics from the fact that we really know them?' Further, in his
answer he accepted a distinction which he never examined or even
questioned, viz. the distinction between things in themselves and
phenomena.[19] This distinction assumed, Kant inferred from the truth
of mathematics that things in space and time are only phenomena.
According to him mathematicians are able to make the true judgements
that they do make only because they deal with phenomena. Thus Kant in
no way sought to _prove_ the truth of mathematics. On the contrary, he
argued from the truth of mathematics to the nature of the world which
we thereby know. The phenomenal character of the world being thus
established, he was able to reverse the argument and to regard the
phenomenal character of the world as _explaining_ the validity of
mathematical judgements. They are valid, because they relate to
phenomena. And the consideration which led Kant to take mathematics
as his starting-point seems to have been the self-evidence of
mathematical judgements. As we directly apprehend their necessity,
they admit of no reasonable doubt.
[19] Cf. Ch. IV. This distinction should of course have been
examined by one whose aim it was to determine how far our
knowledge can reach.
[20] For the self-evidence of mathematics to Kant compare B.
120, M. 73 and B. 200, M. 121.
On the other hand, the general principles underlying physics, e. g.
that every change must have a cause, or that in all change the quantum
of matter is constant, appeared to Kant in a different light. Though
certainly not based on experience, they did not seem to him
self-evident.[21] Hence,[22] in the case of these principles, he
sought to give what he did not seek to give in the case of
mathematical judgements, viz. a proof of their truth.[23] The nerve of
the proof lies in the contention that these principles are involved
not merely in any general judgement in physics, e. g. 'All bodies are
heavy,' but even in any singular judgement, e. g. 'This body is
heavy,' and that the validity of singular judgements is universally
conceded. Thus here the fact upon which he takes his stand is not the
admitted truth of the universal judgements under consideration, but
the admitted truth of any singular judgement in physics. His
treatment, then, of the universal judgements of mathematics and that
of the principles underlying physics are distinguished by the fact
that, while he accepts the former as needing no proof, he seeks to
prove the latter from the admitted validity of singular judgements in
physics. At the same time the acceptance of mathematical judgements
and the proof of the _a priori_ principles of physics have for Kant a
common presupposition which distinguishes mathematics and physics from
metaphysics. Like universal judgements in mathematics, singular
judgements in physics, and therefore the principles which they
presuppose, are true only if the objects to which they relate are
phenomena. Both in mathematics and physics, therefore, it is a
condition of _a priori_ knowledge that it relates to phenomena and not
to things in themselves. But, just for this reason, metaphysics is in
a different position; since God, freedom, and immortality can never be
objects of experience, _a priori_ knowledge in metaphysics, and
therefore metaphysics itself, is impossible. Thus for Kant the very
condition, the realization of which justifies the acceptance of
mathematical judgements and enables us to prove the principles of
physics, involves the impossibility of metaphysics.
[21] This is stated B. 200, M. 121. It is also implied B.
122, M. 75, B. 263-4, M. 160, and by the argument of the
_Analytic_ generally.
[22] This appears to be the real cause of the difference of
treatment, though it is not the reason assigned by Kant
himself, cf. B. 120, M. 73-4.
[23] His remarks about pure natural science in B. 20, M. 13
and Prol. § 4 sub fin., do not represent the normal attitude
of the _Critique_.
Further, the distinction drawn between _a priori_ judgements in
mathematics and in physics is largely responsible for the difficulty
of understanding what Kant means by _a priori_. His unfortunate
tendency to explain the term negatively could be remedied if it could
be held either that the term refers solely to mathematical judgements
or that he considers the truth of the law of causality to be
apprehended in the same way that we see that two and two are four. For
an _a priori_ judgement could then be defined as one in which the
mind, on the presentation of an individual in perception or
imagination, and in virtue of its capacity of thinking, apprehends the
necessity of a specific relation. But this definition is precluded by
Kant's view that the law of causality and similar principles, though
_a priori_, are not self-evident.
CHAPTER II
THE SENSIBILITY AND THE UNDERSTANDING
The distinction between the sensibility and the understanding[1] is
to Kant fundamental both in itself and in relation to the conclusions
which he reaches. An outline, therefore, of this distinction must
precede any statement or examination of the details of his position.
Unfortunately, in spite of its fundamental character, Kant never
thinks of questioning or criticizing the distinction in the form in
which he draws it, and the presence of certain confusions often
renders it difficult to be sure of his meaning.
[1] Cf. B. 1, 29, 33, 74-5, 75, 92-4; M. 1, 18, 21, 45-46,
57.
The distinction may be stated in his own words thus: "There are two
stems of human knowledge, which perhaps spring from a common but to us
unknown root, namely sensibility and understanding."[2] "Our knowledge
springs from two fundamental sources of the mind; the first receives
representations[3] (receptivity for impressions); the second is the
power of knowing an object by means of these representations
(spontaneity of conceptions). Through the first an object is _given_
to us; through the second the object is _thought_ in relation to the
representation (which is a mere determination of the mind). Perception
and conceptions constitute, therefore, the elements of all our
knowledge, so that neither conceptions without a perception in some
way corresponding to them, nor perception without conceptions can
yield any knowledge.... Neither of these qualities has a preference
over the other. Without sensibility no object would be given to us,
and without understanding no object would be thought. Thoughts without
content are empty, perceptions without conceptions are blind. Hence it
is as necessary for the mind to make its conceptions sensuous (i. e.
to add to them the object in perception) as to make its perceptions
intelligible (i. e. to bring them under conceptions). Neither of these
powers or faculties can exchange its function. The understanding
cannot perceive, and the senses cannot think. Only by their union can
knowledge arise."[4]
[2] B. 29, M. 18
[3] For the sake of uniformity _Vorstellung_ has throughout
been translated by 'representation', though sometimes, as in
the present passage, it would be better rendered by
'presentation'.
[4] B. 74-5, M. 45-6.
The distinction so stated appears straightforward and, on the
whole,[5] sound. And it is fairly referred to by Kant as the
distinction between the faculties of perceiving and conceiving or
thinking, provided that the terms perceiving and conceiving or
thinking be taken to indicate a distinction within perception in the
ordinary sense of the word. His meaning can be stated thus: 'All
knowledge requires the realization of two conditions; an individual
must be presented to us in perception, and we as thinking beings must
bring this individual under or recognize it as an instance of some
universal. Thus, in order to judge 'This is a house' or 'That is red'
we need the presence of the house or of the red colour in perception,
and we must 'recognize' the house or the colour, i. e. apprehend the
individual as a member of a certain kind. Suppose either condition
unrealized. Then if we suppose a failure to conceive, i. e. to
apprehend the individual as a member of some kind, we see that our
perception--if it could be allowed to be anything at all--would be
blind i. e. indeterminate, or a mere 'blur'. What we perceived would
be for us as good as nothing. In fact, we could not even say that we
were perceiving. Again, if we suppose that we had merely the
conception of a house, and neither perceived nor had perceived an
individual to which it applied, we see that the conception, being
without application, would be neither knowledge nor an element in
knowledge. Moreover, the content of a conception is derived from
perception; it is only through its relation to perceived individuals
that we become aware of a universal. To know the meaning of 'redness'
we must have experienced individual red things; to know the meaning of
'house' we must at least have had experience of individual men and of
their physical needs. Hence 'conceptions' without 'perceptions' are
void or empty. The existence of conceptions presupposes experience of
corresponding individuals, even though it also implies the activity of
thinking in relation to these individuals.'[6]
[5] Cf. p. 29, note 1.
[6] Kant's account implies that he has in view only empirical
knowledge; in any case it only applies to empirical
conceptions.
Further, it is true to say that as perceiving we are passive; we do
not do anything. This, as has been pointed out, is the element of
truth contained in the statement that objects are _given_ to us. On
the other hand, it may be truly said that as conceiving, in the sense
of bringing an individual under a universal, we are essentially
active. This is presupposed by the notice or attention involved in
perception ordinarily so called, i. e. perception in the full sense
in which it includes conceiving as well as perceiving.[7] Kant,
therefore, is justified in referring to the sensibility as a
'receptivity' and to the understanding as a 'spontaneity'.
[7] This distinction within perception is of course
compatible with the view that the elements so distinguished
are inseparable.
The distinction, so stated, appears, as has been already said,
intelligible and, in the main[8], valid. Kant, however, renders the
elucidation of his meaning difficult by combining with this view of
the distinction an incompatible and unwarranted theory of perception.
He supposes,[9] without ever questioning the supposition, that
perception is due to the operation of things outside the mind, which
act upon our sensibility and thereby produce sensations. On this
supposition, what we perceive is not, as the distinction just stated
implies, the thing itself, but a sensation produced by it.
Consequently a problem arises as to the meaning on this supposition of
the statements 'by the sensibility objects are given to us' and 'by
the understanding they are thought'. The former statement must mean
that when a thing affects us there is a sensation. It cannot mean that
by the sensibility we know that there exists a thing which causes the
sensation, for this knowledge would imply the activity of thinking;
nor can it mean that in virtue of the sensibility the thing itself is
presented to us. The latter statement must mean that when sensation
arises, the understanding judges that there is something causing it;
and this assertion must really be _a priori_, because not dependent
upon experience. Unfortunately the two statements so interpreted are
wholly inconsistent with the account of the functions of the
sensibility and the understanding which has just been quoted.
[8] See p. 29, note 1.
[9] Cf. B. 1, M. 1.
Further, this theory of perception has two forms. In its first form
the theory is physical rather than metaphysical, and is based upon
our possession of physical organs. It assumes that the reality to be
apprehended is the world of space and time, and it asserts that by the
action of bodies upon our physical organs our sensibility is affected,
and that thereby sensations are originated in us. Thereupon a problem
arises. For if the contribution of the sensibility to our knowledge
of the physical world is limited to a succession of sensations,
explanation must be given of the fact that we have succeeded with
an experience confined to these sensations in acquiring knowledge
of a world which does not consist of sensations.[10] Kant, in fact,
in the _Aesthetic_ has this problem continually before him, and
tries to solve it. He holds that the mind, by means of its forms of
perception and its conceptions of the understanding, superinduces upon
sensations, as data, spatial and other relations, in such a way that
it acquires knowledge of the spatial world.
[10] Cf. B. 1 init., M. 1 init.; B. 34, M. 21 sub fin.
An inherent difficulty, however, of this 'physical' theory of
perception leads to a transformation of it. If, as the theory
supposes, the cause of sensation is outside or beyond the mind, it
cannot be known. Hence the initial assumption that this cause is the
physical world has to be withdrawn, and the cause of sensation comes
to be thought of as the thing in itself of which we can know nothing.
This is undoubtedly the normal form of the theory in Kant's mind.
It may be objected that to attribute to Kant at any time the physical
form of the theory is to accuse him of an impossibly crude confusion
between things in themselves and the spatial world, and that he can
never have thought that the cause of sensation, being as it is outside
the mind, is spatial. But the answer is to be found in the fact that
the problem just referred to as occupying Kant's attention in the
_Aesthetic_ is only a problem at all so long as the cause of sensation
is thought of as a physical body. For the problem 'How do we,
beginning with mere sensation, come to know a spatial and temporal
world?' is only a problem so long as it is supposed that the cause of
sensation is a spatial and temporal world or a part of it, and that
this world is what we come to know. If the cause of sensation, as
being beyond the mind, is held to be unknowable and so not known to be
spatial or temporal, the problem has disappeared. Corroboration is
given by certain passages[11] in the _Critique_ which definitely
mention 'the senses', a term which refers to bodily organs, and by
others[12] to which meaning can be given only if they are taken to
imply that the objects which affect our sensibility are not unknown
things in themselves, but things known to be spatial. Even the use of
the plural in the term 'things in themselves' implies a tendency to
identify the unknowable reality beyond the mind with bodies in space.
For the implication that different sensations are due to different
things in themselves originates in the view that different sensations
are due to the operation of different spatial bodies.
[11] E. g. B. 1 init., M. 1 init., and B. 75 fin., M. 46,
lines 12, 13 [for 'the sensuous faculty' should be
substituted 'the senses'].
[12] E. g. B. 42, lines 11, 12; M. 26, line 13; A. 100, Mah.
195 ('even in the absence of the object'). Cf. B. 182-3, M.
110-1 (see pp. 257-8, and note p. 257), and B. 207-10, M.
126-8 (see pp. 263-5).
It is now necessary to consider how the distinction between the
sensibility and the understanding contributes to articulate the
problem 'How are _a priori_ synthetic judgements possible?' As has
been pointed out, Kant means by this question, 'How is it possible
that the mind is able, in virtue of its own powers, to make universal
and necessary judgements which anticipate its experience of objects?'
To this question his general answer is that it is possible and only
possible because, so far from ideas, as is generally supposed, having
to conform to things, the things to which our ideas or judgements
relate, viz. phenomena, must conform to the nature of the mind. Now,
if the mind's knowing nature can be divided into the sensibility and
the understanding, the problem becomes 'How is it possible for the
mind to make such judgements in virtue of its sensibility and its
understanding?' And the answer will be that it is possible because the
things concerned, i. e. phenomena, must conform to the sensibility and
the understanding, i. e. to the mind's perceiving and thinking nature.
But both the problem and the answer, so stated, give no clue to the
particular _a priori_ judgements thus rendered possible nor to the
nature of the sensibility and the understanding in virtue of which we
make them. It has been seen, however, that the judgements in question
fall into two classes, those of mathematics and those which form the
presuppositions of physics. And it is Kant's aim to relate these
classes to the sensibility and the understanding respectively. His
view is that mathematical judgements, which, as such, deal with
spatial and temporal relations, are essentially bound up with our
perceptive nature, i. e. with our sensibility, and that the principles
underlying physics are the expression of our thinking nature, i. e. of
our understanding. Hence if the vindication of this relation between
our knowing faculties and the judgements to which they are held to
give rise is approached from the side of our faculties, it must be
shown that our sensitive nature is such as to give rise to
mathematical judgements, and that our understanding or thinking nature
is such as to originate the principles underlying physics. Again, if
the account of this relation is to be adequate, it must be shown to be
exhaustive, i. e. it must be shown that the sensibility and the
understanding give rise to no other judgements. Otherwise there may be
other _a priori_ judgements bound up with the sensibility and the
understanding which the inquiry will have ignored. Kant, therefore, by
his distinction between the sensibility and the understanding, sets
himself another problem, which does not come into sight in the first
formulation of the general question 'How are _a priori_ synthetic
judgements possible?' He has to determine what _a priori_ judgements
are related to the sensibility and to the understanding respectively.
At the same time the distinction gives rise to a division within the
main problem. His chief aim is to discover how it is that _a priori_
judgements are universally applicable. But, as Kant conceives
the issue, the problem requires different treatment according
as the judgements in question are related to the sensibility or
to the understanding. Hence arises the distinction between the
_Transcendental Aesthetic_ and the _Transcendental Analytic_, the
former dealing with the _a priori_ judgements of mathematics, which
relate to the sensibility, and the latter dealing with the _a priori_
principles of physics, which originate in the understanding. Again,
within each of these two divisions we have to distinguish two
problems, viz. 'What _a priori_ judgements are essentially related to
the faculty in question?' and 'How is it that they are applicable to
objects?'
It is important, however, to notice that the distinction between the
sensibility and the understanding, in the form in which it serves as a
basis for distinguishing the _Aesthetic_ and the _Analytic_, is not
identical with or even compatible with the distinction, as Kant states
it when he is considering the distinction in itself and is not
thinking of any theory which is to be based upon it. In the latter
case the sensibility and the understanding are represented as
inseparable faculties involved in _all_ knowledge.[13] Only from the
union of both can knowledge arise. But, regarded as a basis for the
distinction between the _Aesthetic_ and the _Analytic_, they are
implied to be the source of different kinds of knowledge, viz.
mathematics and the principles of physics. It is no answer to this to
urge that Kant afterwards points out that space as an object
presupposes a synthesis which does not belong to sense. No doubt this
admission implies that even the apprehension of spatial relations
involves the activity of the understanding. But the implication is
really inconsistent with the existence of the _Aesthetic_ as a
distinct part of the subject dealing with a special class of _a
priori_ judgements.
[13] B. 74-5, M. 45-6; cf. pp. 27-9.
[14] B. 160 note, M. 98 note.
CHAPTER III
SPACE
It is the aim of the _Aesthetic_ to deal with the _a priori_ knowledge
which relates to the sensibility. This knowledge, according to Kant,
is concerned with space and time. Hence he has to show _firstly_ that
our apprehension of space and time is _a priori_, i. e. that it is not
derived from experience but originates in our apprehending nature; and
_secondly_ that within our apprehending nature this apprehension
belongs to the sensibility and not to the understanding, or, in his
language, that space and time are forms of perception or sensibility.
Further, if his treatment is to be exhaustive, he should also show
_thirdly_ that space and time are the only forms of perception. This,
however, he makes no attempt to do except in one passage,[1] where the
argument fails. The first two points established, Kant is able to
develop his main thesis, viz. that it is a condition of the validity
of the _a priori_ judgements which relate to space and time that these
are characteristics of phenomena, and not of things in themselves.
[1] B. 58, M. 35.
It will be convenient to consider his treatment of space and time
separately, and to begin with his treatment of space. It is necessary,
however, first of all to refer to the term 'form of perception'. As
Kant conceives a form of perception, it involves three antitheses.
(1) As a _form_ of perception it is opposed, as a way or mode of
perceiving, to particular perceptions.
(2) As a form or mode of _perception_ it is opposed to a form or mode
of _conception_.
(3) As a form of _perception_ it is also opposed, as a way in which we
apprehend things, to a way in which things are.
While we may defer consideration of the second and third antitheses,
we should at once give attention to the nature of the first, because
Kant confuses it with two other antitheses. There is no doubt that in
general a _form_ of perception means for Kant a general capacity of
perceiving which, as such, is opposed to the actual perceptions in
which it is manifested. For according to him our spatial perceptions
are not foreign to us, but manifestations of our general perceiving
nature; and this view finds expression in the assertion that space is
a form of perception or of sensibility.[2]
[2] Cf. B. 43 init., M. 26 med.
Unfortunately, however, Kant frequently speaks of this form of
perception as if it were the same thing as the actual perception of
empty space.[3] In other words, he implies that such a perception is
possible, and confuses it with a potentiality, i. e. the power of
perceiving that which is spatial. The confusion is possible because it
can be said with some plausibility that a perception of empty
space--if its possibility be allowed--does not inform us about actual
things, but only informs us what must be true of things, if there
prove to be any; such a perception, therefore, can be thought of as a
possibility of knowledge rather than as actual knowledge.
[3] e. g. B. 34, 35, M. 22; B. 41, M. 25; _Prol._ §§ 9-11.
The commonest expression of the confusion is to be found in
the repeated assertion that space is a pure perception.
The second confusion is closely related to the first, and arises from
the fact that Kant speaks of space not only as a form of _perception_,
but also as the form of _phenomena_ in opposition to sensation as
their matter. "That which in the phenomenon corresponds to[4] the
sensation I term its matter; but that which effects that the manifold
of the phenomenon can be arranged under certain relations I call the
form of the phenomenon. Now that in which alone our sensations can be
arranged and placed in a certain form cannot itself be sensation.
Hence while the matter of all phenomena is only given to us _a
posteriori_, their form [i. e. space] must lie ready for them all
together _a priori_ in the mind."[5] Here Kant is clearly under the
influence of his theory of perception.[6] He is thinking that, given
the origination of sensations in us by the thing in itself, it is the
business of the mind to arrange these sensations spatially in order to
attain knowledge of the spatial world.[7] Space being, as it were,
a kind of empty vessel in which sensations are arranged, is said
to be the form of phenomena.[8] Moreover, if we bear in mind that
ultimately bodies in space are for Kant only spatial arrangements
of sensations,[9] we see that the assertion that space is the form
of phenomena is only Kant's way of saying that all bodies are
spatial.[10] Now Kant, in thus asserting that space is the form of
phenomena, is clearly confusing this assertion with the assertion that
space is a form of perception, and he does so in consequence of the
first confusion, viz. that between a capacity of perceiving and an
actual perception of empty space. For in the passage last quoted he
continues thus: "I call all representations[11] _pure_ (in the
transcendental sense) in which nothing is found which belongs to
sensation. Accordingly there will be found _a priori_ in the mind the
pure form of sensuous perceptions in general, wherein all the manifold
of phenomena is perceived in certain relations. This pure form of
sensibility will also itself be called _pure perception_. Thus,
if I abstract from the representation of a body that which the
understanding thinks respecting it, such as substance, force,
divisibility, &c., and also that which belongs to sensation, such as
impenetrability, hardness, colour, &c., something is still left over
for me from this empirical perception, viz. extension and shape. These
belong to pure perception, which exists in the mind _a priori_, even
without an actual object of the senses or a sensation, as a mere form
of sensibility." Here Kant has passed, without any consciousness of a
transition, from treating space as that in which the manifold of
sensation is arranged to treating it as a capacity of perceiving.
Moreover, since Kant in this passage speaks of space as a perception,
and thereby identifies space with the perception of it,[12] the
confusion may be explained thus. The form of phenomena is said to be
the space in which all sensations are arranged, or in which all bodies
are; space, apart from all sensations or bodies, i. e. empty, being
the object of a pure perception, is treated as identical with a pure
perception, viz. the perception of empty space; and the perception of
empty space is treated as identical with a capacity of perceiving that
which is spatial.[13]
[4] 'Corresponds to' must mean 'is'.
[5] B. 34, M. 21.
[6] Cf. pp. 30-2.
[7] It is impossible, of course, to see how such a process
can give us knowledge of the spatial world, for, whatever
bodies in space are, they are not arrangements of sensations.
Nevertheless, Kant's theory of perception really precludes
him from holding that bodies are anything else than
arrangements of sensations, and he seems at times to accept
this view explicitly, e. g. B. 38, M. 23 (quoted p. 41),
where he speaks of our representing sensations as external
to and next to each other, and, therefore, as in different
places.
[8] It may be noted that it would have been more natural to
describe the particular shape of the phenomenon (i. e. the
particular spatial arrangement of the sensations) rather than
space as the form of the phenomenon; for the matter to which
the form is opposed is said to be sensation, and that of
which it is the matter is said to be the phenomenon, i. e.
a body in space.
[9] Cf. note 4, p. 38.
[10] Cf. _Prol._ § 11 and p. 137.
[11] Cf. p. 41, note 1.
[12] Cf. p. 51, note 1.
[13] The same confusion (and due to the same cause) is
implied _Prol_. § 11, and B. 42 (b), M. 26 (b) first
paragraph. Cf. B. 49 (b), M. 30 (b).
The existence of the confusion, however, is most easily realized by
asking, 'How did Kant come to think of space and time as the _only_
forms of perception?' It would seem obvious that the perception of
_anything_ implies a form of perception in the sense of a mode or
capacity of perceiving. To perceive colours implies a capacity for
seeing; to hear noises implies a capacity for hearing. And these
capacities may fairly be called forms of perception. As soon as this
is realized, the conclusion is inevitable that Kant was led to think
of space and time as the only forms of perception, because in this
connexion he was thinking of each as a form of phenomena, i. e. as
something in which all bodies or their states are, or, from the point
of view of our knowledge, as that in which sensuous material is to be
arranged; for there is nothing except space and time in which such
arrangement could plausibly be said to be carried out.
As has been pointed out, Kant's argument falls into two main parts,
one of which prepares the way for the other. The aim of the former is
to show _firstly_ that our apprehension of space is _a priori_, and
_secondly_ that it belongs to perception and not to conception. The
aim of the latter is to conclude from these characteristics of our
apprehension of space that space is a property not of things in
themselves but only of phenomena. These arguments may be considered in
turn.
The really valid argument adduced by Kant for the _a priori_ character
of our apprehension of space is based on the nature of geometrical
judgements. The universality of our judgements in geometry is not
based upon experience, i. e. upon the observation of individual things
in space. The necessity of geometrical relations is apprehended
directly in virtue of the mind's own apprehending nature.
Unfortunately in the present context Kant ignores this argument and
substitutes two others, both of which are invalid.
1. "Space is no empirical conception[14] which has been derived from
external[15] experiences. For in order that certain sensations may be
related to something external to me (that is, to something in a
different part of space from that in which I am), in like manner, in
order that I may represent them as external to and next to each other,
and consequently as not merely different but as in different places,
the representation of space must already exist as a foundation.
Consequently, the representation of space cannot be borrowed from the
relations of external phenomena through experience; but, on the
contrary, this external experience is itself first possible only
through the said representation."[16] Here Kant is thinking that in
order to apprehend, for example, that A is to the right of B we must
first apprehend empty space. He concludes that our apprehension of
space is _a priori_, because we apprehend empty space _before_ we
become aware of the spatial relations of individual objects in it.
[14] _Begriff_ (conception) here is to be understood loosely
not as something opposed to _Anschauung_ (perception), but as
equivalent to the genus of which _Anschauung_ and _Begriff_
are species, i. e. _Vorstellung_, which maybe rendered by
'representation' or 'idea', in the general sense in which
these words are sometimes used to include 'thought' and
'perception'.
[15] The next sentence shows that 'external' means, not
'produced by something external to the mind', but simply
'spatial'.
[16] B. 38, M. 23-4.
To this the following reply may be made. (_a_) The term _a priori_
applied to an apprehension should mean, not that it arises prior to
experience, but that its validity is independent of experience. (_b_)
That to which the term _a priori_ should be applied is not the
apprehension of empty space, which is individual, but the apprehension
of the nature of space in general, which is universal. (_c_) We do not
apprehend empty space before we apprehend individual spatial relations
of individual bodies or, indeed, at any time. (_d_) Though we come to
apprehend _a priori_ the nature of space in general, the apprehension
is not prior but posterior in time to the apprehension of individual
spatial relations. (_e_) It does not follow from the temporal priority
of our apprehension of individual spatial relations that our
apprehension of the nature of space in general is 'borrowed from
experience', and is therefore not _a priori_.
2. "We can never represent to ourselves that there is no space, though
we can quite well think that no objects are found in it. It must,
therefore, be considered as the condition of the possibility of
phenomena, and not as a determination dependent upon them, and it is
an _a priori_ representation, which necessarily underlies external
phenomena."[17]
[17] B. 38, M. 24.
Here the premise is simply false. If 'represent' or 'think' means
'believe', we can no more represent or think that there are no
objects in space than that there is no space. If, on the other hand,
'represent' or 'think' means 'make a mental picture of', the assertion
is equally false. Kant is thinking of empty space as a kind of
receptacle for objects, and the _a priori_ character of our
apprehension of space lies, as before, in the supposed fact that
in order to apprehend objects in space we must begin with the
apprehension of empty space.
The examination of Kant's arguments for the _perceptive_ character
of our apprehension of space is a more complicated matter. By way of
preliminary it should be noticed that they presuppose the possibility
in general of distinguishing features of objects which belong to the
perception of them from others which belong to the conception of them.
In particular, Kant holds that our apprehension of a body as a
substance, as exercising force and as divisible, is due to our
understanding as conceiving it, while our apprehension of it as
extended and as having a shape is due to our sensibility as perceiving
it.[18] The distinction, however, will be found untenable in
principle; and if this be granted, Kant's attempt to distinguish in
this way the extension and shape of an object from its other features
can be ruled out on general grounds. In any case, it must be conceded
that the arguments fail by which he seeks to show that space in
particular belongs to perception.
[18] B. 35, M. 22 (quoted p. 39). It is noteworthy (1) that
the passage contains no _argument_ to show that extension and
shape are not, equally with divisibility, _thought_ to belong
to an object, (2) that impenetrability, which is here said
to belong to sensation, obviously cannot do so, and (3) that
(as has been pointed out, p. 39) the last sentence of the
paragraph in question presupposes that we have a perception
of empty space, and that this is a _form_ of perception.
There appears to be no way of distinguishing perception and conception
as the apprehension of different realities[19] except as the
apprehension of the individual and of the universal respectively.
Distinguished in this way, the faculty of perception is that in virtue
of which we apprehend the individual, and the faculty of conception is
that power of reflection in virtue of which a universal is made the
explicit object of thought.[20] If this be granted, the only test for
what is perceived is that it is individual, and the only test for what
is conceived is that it is universal. These are in fact the tests
which Kant uses. But if this be so, it follows that the various
characteristics of objects cannot be divided into those which are
perceived and those which are conceived. For the distinction between
universal and individual is quite general, and applies to all
characteristics of objects alike. Thus, in the case of colour, we can
distinguish colour in general and the individual colours of individual
objects; or, to take a less ambiguous instance, we can distinguish a
particular shade of redness and its individual instances. Further, it
may be said that perception is of the individual shade of red of the
individual object, and that the faculty by which we become explicitly
aware of the particular shade of red in general is that of conception.
The same distinction can be drawn with respect to hardness, or shape,
or any other characteristic of objects. The distinction, then,
between perception and conception can be drawn with respect to any
characteristic of objects, and does not serve to distinguish one from
another.
[19] And _not_ as mutually involved in the apprehension
of any individual reality.
[20] This distinction is of course different to that
previously drawn _within_ perception in the full sense
between perception in a narrow sense and conception
(pp. 28-9).
Kant's arguments to show that our apprehension of space belongs to
perception are two in number, and both are directed to show not, as
they should, that space is a _form_ of perception, but that it is a
_perception_.[21] The first runs thus: "Space is no discursive, or, as
we say, general conception of relations of things in general, but a
pure perception. For, in the first place, we can represent to
ourselves only one space, and if we speak of many spaces we mean
thereby only parts of one and the same unique space. Again, these
parts cannot precede the one all-embracing space as the component
parts, as it were, out of which it can be composed, but can be thought
only in it. Space is essentially one; the manifold in it, and
consequently the general conception of spaces in general, rests solely
upon limitations."[22]
[21] Kant uses the phrase 'pure perception'; but 'pure' can
only mean 'not containing sensation', and consequently adds
nothing relevant.
[22] B. 39, M. 24. The concluding sentences of the paragraph
need not be considered.
Here Kant is clearly taking the proper test of perception. Its object,
as being an individual, is unique; there is only one of it, whereas
any conception has a plurality of instances. But he reaches his
conclusion by supposing that we first perceive empty space and then
become aware of its parts by dividing it. Parts of space are
essentially limitations of the one space; therefore to apprehend them
we must first apprehend space. And since space is _one_, it must be
object of perception; in other words, space, in the sense of the one
all-embracing space, i. e. the totality of individual spaces, is
something perceived.
The argument appears open to two objections. In the _first_ place, we
do _not_ perceive space as a whole, and then, by dividing it, come to
apprehend individual spaces. We perceive individual spaces, or,
rather, individual bodies occupying individual spaces.[23] We then
apprehend that these spaces, as spaces, involve an infinity of other
spaces. In other words, it is reflection on the general nature of
space, the apprehension of which is involved in our apprehension of
individual spaces or rather of bodies in space, which gives rise to
the apprehension of the totality[24] of spaces, the apprehension being
an act, not of perception, but of thought or conception. It is
necessary, then, to distinguish (_a_) individual spaces, which we
perceive; (_b_) the nature of space in general, of which we become
aware by reflecting upon the character of perceived individual spaces,
and which we conceive; (_c_) the totality of individual spaces, the
thought of which we reach by considering the nature of space in
general.
[23] This contention is not refuted by the objection that our
distinct apprehension of an individual space is always bound
up with an indistinct apprehension of the spaces immediately
surrounding it. For our indistinct apprehension cannot be
supposed to be of the whole of the surrounding space.
[24] It is here assumed that a whole or a totality can be
infinite. Cf. p. 102.
In the _second_ place, the distinctions just drawn afford no ground
for distinguishing space as something perceived from any other
characteristic of objects as something conceived; for any other
characteristic admits of corresponding distinctions. Thus, with
respect to colour it is possible to distinguish (_a_) individual
colours which we perceive; (_b_) colouredness in general, which we
conceive by reflecting on the common character exhibited by individual
colours and which involves various kinds or species of colouredness;
(_c_) the totality of individual colours, the thought of which is
reached by considering the nature of colouredness in general.[25]
[25] For a possible objection and the answer thereto, see
note, p. 70.
Both in the case of colour and in that of space there is to be found
the distinction between universal and individual, and therefore also
that between conception and perception. It may be objected that after
all, as Kant points out, there is only one space, whereas there are
many individual colours. But the assertion that there is only one
space simply means that all individual bodies in space are related
spatially. This will be admitted, if the attempt be made to think of
two bodies as in different spaces and therefore as not related
spatially. Moreover, there is a parallel in the case of colour, since
individual coloured bodies are related by way of colour, e. g. as
brighter and duller; and though such a relation is different from a
relation of bodies in respect of space, the difference is due to the
special nature of the universals conceived, and does not imply a
difference between space and colour in respect of perception and
conception. In any case, space as a whole is not object of perception,
which it must be if Kant is to show that space, as being one, is
perceived; for space in this context must mean the totality of
individual spaces.
Kant's second argument is stated as follows: "Space is represented as
an infinite _given_ magnitude. Now every conception must indeed be
considered as a representation which is contained in an infinite
number of different possible representations (as their common mark),
and which therefore contains these _under itself_, but no conception
can, as such, be thought of as though it contained _in itself_ an
infinite number of representations. Nevertheless, space is so
conceived, for all parts of space _ad infinitum_ exist simultaneously.
Consequently the original representation of space is an _a priori
perception_ and not a _conception_." In other words, while a
conception implies an infinity of individuals which come under it, the
elements which constitute the conception itself (e. g. that of
triangularity or redness) are not infinite; but the elements which go
to constitute space are infinite, and therefore space is not a
conception but a perception.
Though, however, space in the sense of the infinity of spaces may be
said to contain an infinite number of spaces if it be meant that it
_is_ these infinite spaces, it does not follow, nor is it true, that
space in this sense is object of perception.
The aim of the arguments just considered, and stated in § 2 of
the _Aesthetic_, is to establish the two characteristics of our
apprehension of space,[26] from which it is to follow that space is a
property of things only as they appear to us and not as they are in
themselves. This conclusion is drawn in § 4. §§ 2 and 4 therefore
complete the argument. § 3, a passage added in the second edition
of the _Critique_, interrupts the thought, for ignoring § 2, it once
more establishes the _a priori_ and perceptive character of our
apprehension of space, and independently draws the conclusion drawn in
§ 4. Since, however, Kant draws the final conclusion in the same way
in § 3 and in § 4, and since a passage in the _Prolegomena_,[27] of
which § 3 is only a summary, gives a more detailed account of Kant's
thought, attention should be concentrated on § 3, together with the
passage in the _Prolegomena_.
[26] viz. that it is _a priori_ and a pure perception.
[27] §§ 6-11.
It might seem at the outset that since the arguments upon which Kant
bases the premises for his final argument have turned out invalid, the
final argument itself need not be considered. The argument, however,
of § 3 ignores the preceding arguments for the _a priori_ and
perceptive character of our apprehension of space. It returns to the
_a priori_ synthetic character of geometrical judgements, upon which
stress is laid in the Introduction, and appeals to this as the
justification of the _a priori_ and perceptive character of our
apprehension of space.
The argument of § 3 runs as follows: "Geometry is a science which
determines the properties of space synthetically and yet _a priori_.
What, then, must be the representation of space, in order that such a
knowledge of it may be possible? It must be originally perception, for
from a mere conception no propositions can be deduced which go beyond
the conception, and yet this happens in geometry. But this perception
must be _a priori_, i. e. it must occur in us before all
sense-perception of an object, and therefore must be pure, not
empirical perception. For geometrical propositions are always
apodeictic, i. e. bound up with the consciousness of their necessity
(e. g. space has only three dimensions), and such propositions cannot
be empirical judgements nor conclusions from them."
"Now how can there exist in the mind an external perception[28] which
precedes[29] the objects themselves, and in which the conception of
them can be determined _a priori_? Obviously not otherwise than in so
far as it has its seat in the subject only, as the formal nature of
the subject to be affected by objects and thereby to obtain _immediate
representation_, i. e. _perception_ of them, and consequently only as
the form of the external sense in general."[30]
[28] 'External perception' can only mean perception of what
is spatial.
[29] _Vorhergeht._
[30] 'Formal nature _to be affected by objects_' is not
relevant to the context.
Here three steps are taken. From the _synthetic_ character of
geometrical judgements it is concluded that space is not something
which we _conceive_, but something which we _perceive_. From their _a
priori_ character, i. e. from the consciousness of necessity involved,
it is concluded that the perception of space must be _a priori_ in a
new sense, that of taking place _before_ the perception of objects in
it.[31] From the fact that we perceive space before we perceive
objects in it, and thereby are able to anticipate the spatial
relations which condition these objects, it is concluded that space is
only a characteristic of our perceiving nature, and consequently that
space is a property not of things in themselves, but only of things as
perceived by us.[32]
[31] Cf. B. 42, M. 26 (a) fin., (b) second sentence.
[32] Cf. B. 43, M. 26-7.
Two points in this argument are, even on the face of it, paradoxical.
Firstly, the term _a priori_, as applied not to geometrical judgements
but to the perception of space, is given a temporal sense; it means
not something whose validity is independent of experience and which is
the manifestation of the nature of the mind, but something which takes
place before experience. Secondly, the conclusion is not that the
perception of space _is the manifestation of_ the mind's perceiving
nature, but that it _is_ the mind's perceiving nature. For the
conclusion is that space[33] is the formal nature of the subject to be
affected by objects, and therefore the form of the external sense in
general. Plainly, then, Kant here confuses an actual perception and a
form or way of perceiving. These points, however, are more explicit in
the corresponding passage in the _Prolegomena_.[34]
[33] Kant draws no distinction between space and the
perception of space, or, rather, habitually speaks of space
as a perception. No doubt he considers that his view that
space is only a characteristic of phenomena justifies
the identification of space and the perception of it.
Occasionally, however, he distinguishes them. Thus he
sometimes speaks of the representation of space (e. g.
B. 38-40, M. 23-4); in _Prol._, § 11, he speaks of a pure
perception of space and time; and in B. 40, M. 25, he says
that our representation of space must be perception. But this
language is due to the pressure of the facts, and not to his
general theory; cf. pp. 135-6.
[34] §§ 6-11.
It begins thus: "Mathematics carries with it thoroughly apodeictic
certainty, that is, absolute necessity, and, therefore, rests on no
empirical grounds, and consequently is a pure product of reason, and,
besides, is thoroughly synthetical. How, then, is it possible for
human reason to accomplish such knowledge entirely _a priori_?... But
we find that all mathematical knowledge has this peculiarity, that it
must represent its conception previously in _perception_, and indeed
_a priori_, consequently in a perception which is not empirical but
pure, and that otherwise it cannot take a single step. Hence its
judgements are always _intuitive_.... This observation on the nature
of mathematics at once gives us a clue to the first and highest
condition of its possibility, viz. that there must underlie it _a pure
perception_ in which it can exhibit or, as we say, _construct_ all its
conceptions in the concrete and yet _a priori_. If we can discover
this pure perception and its possibility, we may thence easily explain
how _a priori_ synthetical propositions in pure mathematics are
possible, and consequently also how the science itself is possible.
For just as empirical perception enables us without difficulty to
enlarge synthetically in experience the conception which we frame of
an object of perception through new predicates which perception itself
offers us, so pure perception also will do the same, only with the
difference that in this case the synthetical judgement will be _a
priori_ certain and apodeictic, while in the former case it will be
only _a posteriori_ and empirically certain; for the latter [i. e. the
empirical perception on which the _a posteriori_ synthetic judgement
is based] contains only that which is to be found in contingent
empirical perception, while the former [i. e. the pure perception on
which the _a priori_ synthetic judgement is based] contains that which
is bound to be found in pure perception, since, as _a priori_
perception, it is inseparably connected with the conception _before
all experience_ or individual sense-perception."
This passage is evidently based upon the account which Kant gives in
the _Doctrine of Method_ of the method of geometry.[35] According to
this account, in order to apprehend, for instance, that a three-sided
figure must have three angles, we must draw in imagination or on paper
an individual figure corresponding to the conception of a three-sided
figure. We then see that the very nature of the act of construction
involves that the figure constructed must possess three angles as well
as three sides. Hence, perception being that by which we apprehend the
individual, a perception is involved in the act by which we form a
geometrical judgement, and the perception can be called _a priori_, in
that it is guided by our _a priori_ apprehension of the necessary
nature of the act of construction, and therefore of the figure
constructed.
[35] B. 740 ff., M. 434 ff. Compare especially the following:
"_Philosophical_ knowledge is _knowledge of reason_ by means
of _conceptions_; mathematical knowledge is knowledge by
means of the _construction_ of conceptions. But the
_construction_ of a conception means the _a priori_
presentation of a perception corresponding to it. The
construction of a conception therefore demands a
_non-empirical_ perception, which, therefore, as a
perception, is an _individual_ object, but which none the
less, as the construction of a conception (a universal
representation), must express in the representation universal
validity for all possible perceptions which come under that
conception. Thus I construct a triangle by presenting the
object corresponding to the conception, either by mere
imagination in pure perception, or also, in accordance with
pure perception, on paper in empirical perception, but in
both cases completely _a priori_, without having borrowed
the pattern of it from any experience. The individual drawn
figure is empirical, but nevertheless serves to indicate the
conception without prejudice to its universality, because in
this empirical perception we always attend only to the act of
construction of the conception, to which many determinations,
e. g. the magnitude of the sides and of the angles, are
wholly indifferent, and accordingly abstract from these
differences, which do not change the conception of the
triangle."
The account in the _Prolegomena_, however, differs from that of the
_Doctrine of Method_ in one important respect. It asserts that the
perception involved in a mathematical judgement not only may, but
must, be pure, i. e. must be a perception in which no spatial object
is present, and it implies that the perception must take place
_before_ all experience of actual objects.[36] Hence _a priori_,
applied to perception, has here primarily, if not exclusively, the
temporal meaning that the perception takes place _antecedently to all
experience_.[37]
[36] This becomes more explicit in § 8 and ff.
[37] This is also, and more obviously, implied in §§ 8-11.
The thought of the passage quoted from the _Prolegomena_ can be stated
thus: 'A mathematical judgement implies the perception of an
individual figure antecedently to all experience. This may be said to
be the first condition of the possibility of mathematical judgements
which is revealed by reflection. There is, however, a prior or higher
condition. The perception of an individual figure involves as its
basis another pure perception. For we can only construct and therefore
perceive an individual figure in empty space. Space is that _in which_
it must be constructed and perceived. A perception[38] of empty space
is, therefore, necessary. If, then, we can discover how this
perception is possible, we shall be able to explain the possibility of
_a priori_ synthetical judgements of mathematics.'
[38] _Pure_ perception only means that the space perceived is
empty.
Kant continues as follows: "But with this step the difficulty seems to
increase rather than to lessen. For henceforward the question is '_How
is it possible to perceive anything a priori?_' A perception is such a
representation as would immediately depend upon the presence of the
object. Hence it seems impossible _originally_ to perceive _a priori_,
because perception would in that case have to take place without an
object to which it might refer, present either formerly or at the
moment, and accordingly could not be perception.... How can
_perception_ of the object precede the object itself?"[39] Kant here
finds himself face to face with the difficulty created by the
preceding section. Perception, as such, involves the actual presence
of an object; yet the pure perception of space involved by
geometry--which, as pure, is the perception of empty space, and which,
as the perception of empty space, is _a priori_ in the sense of
temporally prior to the perception of actual objects--presupposes that
an object is not actually present.
[39] _Prol._ § 8.
The solution is given in the next section. "Were our perception
necessarily of such a kind as to represent things _as they are in
themselves_, no perception would take place _a priori_, but would
always be empirical. For I can only know what is contained in the
object in itself, if it is present and given to me. No doubt it is
even then unintelligible how the perception of a present thing should
make me know it as it is in itself, since its qualities cannot migrate
over into my faculty of representation; but, even granting this
possibility, such a perception would not occur _a priori_, i. e.
before the object was presented to me; for without this presentation,
no basis of the relation between my representation and the object can
be imagined; the relation would then have to rest upon inspiration. It
is therefore possible only in one way for my perception to precede the
actuality of the object and to take place as _a priori_ knowledge,
viz. _if it contains nothing but the form of the sensibility, which
precedes in me, the subject, all actual impressions through which I am
affected by objects_. For I can know _a priori_ that objects of the
senses can only be perceived in accordance with this form of the
sensibility. Hence it follows that propositions which concern merely
this form of sensuous perception will be possible and valid for
objects of the senses, and in the same way, conversely, that
perceptions which are possible _a priori_ can never concern any things
other than objects of our senses."
This section clearly constitutes the turning-point in Kant's argument,
and primarily expresses, in an expanded form, the central doctrine of
§ 3 of the _Aesthetic_, that an external perception anterior to
objects themselves, and in which our conceptions of objects can be
determined _a priori_, is possible, if, and only if, it has its seat
in the subject as its formal nature of being affected by objects, and
consequently as the form of the external sense in general. It argues
that, since this is true, and since geometrical judgements involve
such a perception anterior to objects, space must be only the[40] form
of sensibility.
[40] _The_ and not _a_, because, for the moment, time is
ignored.
Now why does Kant think that this conclusion follows? Before we can
answer this question we must remove an initial difficulty. In this
passage Kant unquestionably identifies a form of perception with an
actual perception. It is at once an actual perception and a capacity
of perceiving. This is evident from the words, "It is possible only in
one way for my perception to precede the actuality of the object ...
viz. _if it contains nothing but the form of the sensibility_."[41]
The identification becomes more explicit a little later. "A pure
perception (of space and time) can underlie the empirical perception
of objects, because it is nothing but the mere form of the
sensibility, which precedes the actual appearance of the objects, in
that it in fact first makes them possible. Yet this faculty of
perceiving _a priori_ affects not the matter of the phenomenon, i. e.
that in it which is sensation, for this constitutes that which is
empirical, but only its form, viz. space and time."[42] His argument,
however, can be successfully stated without this identification. It is
only necessary to re-write his cardinal assertion in the form 'the
perception of space must be nothing but the _manifestation_ of the
form of the sensibility'. Given this modification, the question
becomes, 'Why does Kant think that the perception of empty space,
involved by geometrical judgements, can be only a manifestation of our
perceiving nature, and not in any way the apprehension of a real
quality of objects?' The answer must be that it is because he thinks
that, while in empirical perception a real object is present, in the
perception of empty space a real object is not present. He regards
this as proving that the latter perception is only of something
subjective or mental. "Space and time, by being pure _a priori_
perceptions, prove that they are mere forms of our sensibility which
must precede all empirical perception, i. e. sense-perception of
actual objects."[43] His main conclusion now follows easily enough. If
in perceiving empty space we are only apprehending a manifestation of
our perceiving nature, what we apprehend in a geometrical judgement is
really a law of our perceiving nature, and therefore, while it _must_
apply to our perceptions of objects or to objects as perceived, it
_cannot_ apply to objects apart from our perception, or, at least,
there is no ground for holding that it does so.
[41] _Prol._, § 9.
[42] _Prol._, § 11.
[43] _Prol._, § 10.
If, however, this fairly represents Kant's thought, it must be allowed
that the conclusion which he should have drawn is different, and even
that the conclusion which he does draw is in reality incompatible with
his starting-point.
His starting-point is the view that the truth of geometrical
judgements presupposes a perception of empty space, in virtue of which
we can discover rules of spatial relation which must apply to all
spatial objects subsequently perceived. His problem is to discover the
presupposition of this presupposition. The proper answer must be, not
that space is a form of sensibility or a way in which objects appear
to us, but that space is the form of all objects, i. e. that all
objects are spatial.[44] For in that case they must be subject to the
laws of space, and therefore if we can discover these laws by a study
of empty space, the only condition to be satisfied, if the objects of
subsequent perception are to conform to the laws which we discover, is
that all objects should be spatial. Nothing is implied which enables
us to decide whether the objects are objects as they are in themselves
or objects as perceived; for in either case the required result
follows. If in empirical perception we apprehend things only as they
appear to us, and if space is the form of them as they appear to us,
it will no doubt be true that the laws of spatial relation which we
discover must apply to things as they appear to us. But on the other
hand, if in empirical perception we apprehend things as they are, and
if space is their form, i. e. if things are spatial, it will be
equally true that the laws discovered by geometry must apply to things
as they are.
[44] Kant expresses the assertion that space is the form of
all objects by saying that space is the form of _phenomena_.
This of course renders easy an unconscious transition from
the thesis that space is the form of objects to the quite
different thesis that space is the form of sensibility; cf.
p. 39.
Again, Kant's starting-point really commits him to the view that space
is a characteristic of things as they are. For--paradoxical though it
may be--his problem is to explain the possibility of _perceiving a
priori_, i. e. of _perceiving_ the characteristics of an object
anterior to the actual presence of the object in perception.[45] This
implies that _empirical_ perception, which involves the actual
presence of the object, involves no difficulty; in other words, it is
implied that empirical perception is of objects as they are. And we
find Kant admitting this to the extent of allowing _for the sake of
argument_ that the perception of a present thing can make us know the
thing as it is in itself.[46] But if empirical perception gives us
things as they are, and if, as is the case, and as Kant really
presupposes, the objects of empirical perception are spatial, then,
since space is their form, the judgements of geometry must relate to
things as they are. It is true that on this view Kant's first
presupposition of geometrical judgements has to be stated by saying
that we are able to perceive a real characteristic of things in space,
before we perceive the things; and, no doubt, Kant thinks this
impossible. According to him, when we perceive empty space no object
is present, and therefore what is before the mind must be merely
mental. But no greater difficulty is involved than that involved in
the corresponding supposition required by Kant's own view. It is
really just as difficult to hold that we can perceive a characteristic
of things as they appear to us _before_ they appear, as to hold that
we can perceive a characteristic of them as they are in themselves
_before_ we perceive them.
[45] Cf. _Prol._, Section 8.
[46] _Prol._, § 9 (cf. p. 55).
The fact is that the real difficulty with which Kant is grappling in
the _Prolegomena_ arises, not from the supposition that spatial bodies
are things in themselves, but from the supposed presupposition of
geometry that we must be able to perceive empty space before we
perceive bodies in it. It is, of course, impossible to defend the
perception of empty space, but _if_ it be maintained, the space
perceived must be conceded to be not, as Kant thinks, something mental
or subjective, but a real characteristic of things. For, as has been
pointed out, the paradox of pure perception is reached solely through
the consideration that, while in empirical perception we perceive
objects, in pure perception we do not, and since the objects of
empirical perception are spatial, space must be a real characteristic
of them.
The general result of the preceding criticism is that Kant's
conclusion does not follow from the premises by which he supports it.
It should therefore be asked whether it is not possible to take
advantage of this hiatus by presenting the argument for the merely
phenomenal character of space without any appeal to the possibility of
perceiving empty space. For it is clear that what was primarily before
Kant, in writing the _Critique_, was the _a priori_ character of
geometrical judgements themselves, and not the existence of a
perception of empty space which they were held to presuppose.[47]
[47] The difficulty with which Kant is struggling in the
_Prolegomena_, §§ 6-11, can be stated from a rather different
point of view by saying that the thought that geometrical
judgements imply a perception of empty space led him to apply
the term '_a priori_' to perception as well as to judgement.
The term, _a priori_, applied to judgements has a valid
meaning; it means, not that the judgement is made prior to
all experience, but that it is not based upon experience,
being originated by the mind in virtue of its own powers of
thinking. Applied to perception, however, '_a priori_' must
mean prior to all experience, and, since the object of
perception is essentially individual (cf. B. 741, M. 435),
this use of the term gives rise to the impossible task of
explaining how a perception can take place prior to the
actual experience of an individual in perception (cf.
_Prol._, § 8).
If, then, the conclusion that space is only the form of sensibility
can be connected with the _a priori_ character of geometrical
judgements without presupposing the existence of a perception of empty
space, his position will be rendered more plausible.
This can be done as follows. The essential characteristic of a
geometrical judgement is not that it takes place prior to experience,
but that it is not based upon experience. Thus a judgement, arrived at
by an activity of the mind in which it remains within itself and does
not appeal to actual experience of the objects to which the judgement
relates, is implied to hold good of those objects. If the objects were
things as they are in themselves, the validity of the judgement could
not be justified, for it would involve the gratuitous assumption that
a necessity of thought is binding on things which _ex hypothesi_ are
independent of the nature of the mind. If, however, the objects in
question are things as perceived, they will be through and through
conditioned by the mind's perceiving nature; and, consequently, if a
geometrical rule, e. g. that a three-sided figure must have three
angles, is really a law of the mind's perceiving nature, all
individual perceptions, i. e. all objects as perceived by us, will
necessarily conform to the law. Therefore, in the latter case, and in
that only, will the universal validity of geometrical judgements be
justified. Since, then, geometrical judgements are universally valid,
space, which is that of which geometrical laws are the laws, must be
merely a form of perception or a characteristic of objects as
perceived by us.
This appears to be the best form in which the substance of Kant's
argument, stripped of unessentials, can be stated. It will be
necessary to consider both the argument and its conclusion.
The argument, so stated, is undeniably plausible. Nevertheless,
examination of it reveals two fatal defects. In the first place, its
starting-point is false. To Kant the paradox of geometrical judgements
lies in the fact that they are not based upon an appeal to experience
of the things to which they relate. It is implied, therefore, that
judgements which are based on experience involve no paradox, and for
the reason that in experience we apprehend things as they are.[48] In
contrast with this, it is implied that in geometrical judgements the
connexion which we apprehend is not real, i. e. does not relate to
things as they are. Otherwise, there would be no difficulty; if in
geometry we apprehended rules of connexion relating to things as they
are, we could allow without difficulty that the things must conform to
them. No such distinction, however, can be drawn between _a priori_
and empirical judgements. For the necessity of connexion, e. g.
between being a three-sided figure and being a three-angled figure, is
as much a characteristic of things as the empirically-observed shape
of an individual body, e. g. a table. Geometrical judgements,
therefore, cannot be distinguished from empirical judgements on the
ground that in the former the mind remains within itself, and does not
immediately apprehend fact or a real characteristic of reality.[49]
Moreover, since in a geometrical judgement we do in fact think that we
are apprehending a real connexion, i. e. a connexion which applies to
things and to things as they are in themselves, to question the
reality of the connexion is to question the validity of thinking
altogether, and to do this is implicitly to question the validity of
our thought about the nature of our own mind, as well as the validity
of our thought about things independent of the mind. Yet Kant's
argument, in the form in which it has just been stated, presupposes
that our thought is valid at any rate when it is concerned with our
perceptions of things, even if it is not valid when concerned with the
things as they are in themselves.
[48] Cf. p. 17.
[49] For the reasons which led Kant to draw this distinction
between empirical and _a priori_ judgements, cf. pp. 21-2.
This consideration leads to the second criticism. The supposition that
space is only a form of perception, even if it be true, _in no way
assists_ the explanation of the universal validity of geometrical
judgements. Kant's argument really confuses a _necessity_ of relation
with the _consciousness of a necessity_ of relation. No doubt, if it
be a law of our perceiving nature that, whenever we perceive an object
as a three-sided figure, the object as perceived contains three
angles, it follows that any object as perceived will conform to this
law; just as if it be a law of things as they are in themselves that
three-sided figures contain three angles, all three-sided figures will
in themselves have three angles. But what has to be explained is the
universal applicability, not of a law, but of a judgement about a law.
For Kant's real problem is to explain why _our judgement_ that a
three-sided figure must contain three angles must apply to all
three-sided figures. Of course, if it be granted that in the judgement
we apprehend the true law, the problem may be regarded as solved. But
how are we to know that what we judge _is_ the true law? The answer is
in no way facilitated by the supposition that the judgement relates to
our perceiving nature. It can just as well be urged that what we think
to be a necessity of our perceiving nature is not a necessity of it,
as that what we think to be a necessity of things as they are in
themselves is not a necessity of them. The best, or rather the only
possible, answer is simply that that of which we apprehend the
necessity must be true, or, in other words, that we _must_ accept the
validity of thought. Hence nothing is gained by the supposition that
space is a form of sensibility. If what we judge to be necessary is,
as such, valid, a judgement relating to things in themselves will be
as valid as a judgement relating to our perceiving nature.[50]
[50] The same criticism can be urged against Kant's appeal to
the necessity of _constructing_ geometrical figures. The
conclusion drawn from the necessity of construction is stated
thus: "If the object (the triangle) were something in itself
without relation to you the subject, how could you say that
that which lies necessarily in your subjective conditions of
constructing a triangle must also necessarily belong to the
triangle in itself?" (B. 65, M. 39). Kant's thought is that
the laws of the mind's constructing nature must apply to
objects, if, and only if, the objects are the mind's own
construction. Hence it is open to the above criticism if, in
the criticism, 'construct' be substituted for 'perceive'.
This difficulty is concealed from Kant by his insistence on the
_perception_ of space involved in geometrical judgements. This leads
him at times to identify the judgement and the perception, and,
therefore, to speak of the judgement as a perception. Thus we find him
saying that mathematical judgements are always _perceptive_,[51] and
that "It is only possible for my perception to precede the actuality
of the object and take place as _a priori_ knowledge, if &c."[52]
Hence, if, in addition, a geometrical judgement, as being a judgement
about a necessity, be identified with a necessity of judging, the
conformity of things to these universal judgements will become the
conformity of things to rules or necessities of our judging, i. e. of
our perceiving nature, and Kant's conclusion will at once follow.[53]
Unfortunately for Kant, a geometrical judgement, however closely
related to a perception, must itself, as the apprehension of what is
necessary and universal, be an act of thought rather than of
perception, and therefore the original problem of the conformity of
things to our mind can be forced upon him again, even after he thinks
that he has solved it, in the new form of that of the conformity
within the mind of perceiving to thinking.
[51] _Prol._, § 7.
[52] _Prol._, § 9.
[53] Cf. (_Introduction_, B. xvii, M. xxix): "But if the
object (as object of the senses) conforms to the nature of
our faculty of perception, I can quite well represent to
myself the possibility of _a priori_ knowledge of it [i. e.
mathematical knowledge]."
The fact is simply that the universal validity of geometrical
judgements can in no way be 'explained'. It is not in the least
explained or made easier to accept by the supposition that objects
are 'phenomena'. These judgements must be accepted as being what we
presuppose them to be in making them, viz. the direct apprehension of
necessities of relation between real characteristics of real things.
To explain them by reference to the phenomenal character of what is
known is really--though contrary to Kant's intention--to throw doubt
upon their validity; otherwise, they would not need explanation. As a
matter of fact, it is _impossible_ to question their validity. In the
act of judging, doubt is impossible. Doubt can arise only when
we subsequently reflect and temporarily lose our hold upon the
consciousness of necessity in judging.[54] The doubt, however, since
it is non-existent in our geometrical consciousness, is really
groundless,[55] and, therefore, the problem to which it gives rise is
unreal. Moreover if, _per impossibile_, doubt could be raised, it
could not be set at rest. No vindication of a judgement in which we
are conscious of a necessity could do more than take the problem a
stage further back, by basing it upon some other consciousness of a
necessity; and since this latter judgement could be questioned for
precisely the same reason, we should only be embarking upon an
infinite process.
[54] Cf. Descartes, _Princ. Phil._ i. § 13, and _Medit._ v
sub fin.
[55] The view that kinds of space other than that with which
we are acquainted are possible, though usually held and
discussed by mathematicians, belongs to them _qua_
metaphysicians, and not _qua_ mathematicians.
We may now consider Kant's conclusion in abstraction from the
arguments by which he reaches it. It raises three main difficulties.
In the first place, it is not the conclusion to be expected from
Kant's own standpoint. The phenomenal character of space is inferred,
not from the fact that we make judgements at all, but from the fact
that we make judgements of a particular kind, viz. _a priori_
judgements. From this point of view empirical judgements present no
difficulty. It should, therefore, be expected that the qualities which
we attribute to things in empirical judgements are not phenomenal, but
belong to things as they are. Kant himself implies this in drawing his
conclusion concerning the nature of space. "Space does not represent
any quality of things in themselves or things in relation to one
another; that is, it does not represent any determination of things
which would attach to the objects themselves and would remain, even
though we abstracted from all subjective conditions of perception. For
neither absolute nor relative[56] determinations of objects can be
perceived prior to the existence of the things to which they belong,
and therefore not _a priori_."[57] It is, of course, implied that in
experience, where we do not discover determinations of objects prior
to the existence of the objects, we do apprehend determinations of
things as they are in themselves, and not as they are in relation to
us. Thus we should expect the conclusion to be, not that all that we
know is phenomenal--which is Kant's real position--but that spatial
(and temporal) relations alone are phenomenal, i. e. that they alone
are the result of a transmutation due to the nature of our perceiving
faculties.[58] This conclusion would, of course, be absurd, for what
Kant considers to be the empirically known qualities of objects
disappear, if the spatial character of objects is removed. Moreover,
Kant is prevented by his theory of perception from seeing that this is
the real solution of his problem, absurd though it may be. Since
perception is held to arise through the origination of sensations by
things in themselves, empirical knowledge is naturally thought of as
knowledge about sensations, and since sensations are palpably within
the mind, and are held to be due to things in themselves, knowledge
about sensations can be regarded as phenomenal.
[56] The first sentence shows that 'relative determinations'
means, not 'determinations of objects in relation to us', but
'determinations of objects in relation to one another.' Cf.
B. 37, M. 23; and B. 66 fin., 67 init., M. 40 (where these
meanings are confused).
[57] B. 42, M. 26.
[58] This conclusion is also to be expected because,
inconsistently with his real view, Kant is here (B. 41-2, M.
25-6) under the influence of the presupposition of our
ordinary consciousness that in perception we are confronted
by things in themselves, known to be spatial, and not by
appearances produced by unknown things in themselves. Cf. (B.
41, M. 25) "and thereby of obtaining immediate representation
of them [i. e. objects];" and (B. 42, M. 26) "the receptivity
of the subject to be affected by objects necessarily precedes
all perceptions of these objects." These sentences identify
things in themselves and bodies in space, and thereby imply
that in empirical perception we perceive things in themselves
and as they _are_.
On the other hand, if we consider Kant's conclusion from the point of
view, not of the problem which originates it, but of the distinction
in terms of which he states it, viz. that between things as they are
in themselves and things as perceived by us, we are led to expect the
contrary result. Since perception is the being affected by things, and
since the nature of the affection depends upon the nature of our
capacity of being affected, in _all_ perception the object will become
distorted or transformed, as it were, by our capacity of being
affected. The conclusion, therefore, should be that in all judgements,
empirical as well as _a priori_, we apprehend things only as
perceived. The reason why Kant does not draw this conclusion is
probably that given above, viz. that by the time Kant reaches the
solution of his problem empirical knowledge has come to relate to
sensation only; consequently, it has ceased to occur to him that
empirical judgements could possibly give us knowledge of things as
they are. Nevertheless, Kant should not have retained in his
formulation of the problem a distinction irreconcilable with his
solution of it; and if he had realized that he was doing so he might
have been compelled to modify his whole view.
The second difficulty is more serious. If the truth of geometrical
judgements presupposes that space is only a property of objects as
perceived by us, it is a paradox that geometricians should be
convinced, as they are, of the truth of their judgements. They
undoubtedly think that their judgements apply to things as they are in
themselves, and not merely as they appear to us. They certainly do not
think that the relations which they discover apply to objects only as
perceived. Not only, therefore, do they not think that bodies in space
are phenomena, but they do not even leave it an open question whether
bodies are phenomena or not. Hence, if Kant be right, they are really
in a state of illusion, for on his view the true geometrical judgement
should include in itself the phenomenal character of spatial
relations; it should be illustrated by expressing Euclid I. 5 in
the form that the equality of the angles at the base of an isosceles
triangle belongs to objects as perceived. Kant himself lays this down.
"The proposition 'all objects are beside one another in space'
is valid under[59] the limitation that these things are taken as
objects of our sensuous perception. If I join the condition to the
perception, and say 'all things, as external phenomena, are beside
one another in space', the rule is valid universally, and without
limitation."[60] Kant, then, is in effect allowing that it is possible
for geometricians to make judgements, of the necessity of which
they are convinced, and yet to be wrong; and that, therefore, the
apprehension of the necessity of a judgement is no ground of its
truth. It follows that the truth of geometrical judgements can no
longer be accepted as a starting-point of discussion, and, therefore,
as a ground for inferring the phenomenal character of space.
[59] A. reads 'only under'
[60] B. 43, M. 27.
There seems, indeed, one way of avoiding this consequence, viz. to
suppose that for Kant it was an absolute starting-point, which nothing
would have caused him to abandon, that only those judgements of which
we apprehend the necessity are true. It would, of course, follow that
geometricians would be unable to apprehend the necessity of
geometrical judgements, and therefore to make such judgements, until
they had discovered that things as spatial were only phenomena. It
would not be enough that they should think that the phenomenal or
non-phenomenal character of things as spatial must be left an open
question for the theory of knowledge to decide. In this way the
necessity of admitting the illusory character of geometry would be
avoided. The remedy, however, is at least as bad as the disease.
For it would imply that geometry must be preceded by a theory of
knowledge, which is palpably contrary to fact. Nor could Kant accept
it; for he avowedly bases his theory of knowledge, i. e. his view
that objects as spatial are phenomena, upon the truth of geometry;
this procedure would be circular if the making of true geometrical
judgements was allowed to require the prior adoption of his theory of
knowledge.
The third difficulty is the most fundamental. Kant's conclusion (and
also, of course, his argument) presupposes the validity of the
distinction between phenomena and things in themselves. If, then, this
distinction should prove untenable in principle, Kant's conclusion
with regard to space must fail on general grounds, and it will even
have been unnecessary to consider his arguments for it. The importance
of the issue, however, requires that it should be considered in a
separate chapter.
NOTE to page 47.
The argument is not affected by the contention that, while
the totality of spaces is infinite, the totality of colours
or, at any rate, the totality of instances of some other
characteristic of objects is finite; for this difference
will involve no difference in respect of perception and
conception. In both cases the apprehension that there is a
totality will be reached in the same way, i. e. through the
_conception_ of the characteristic in general, and the
apprehension in the one case that the totality is infinite
and in the other that it is finite will depend on the
apprehension of the special nature of the characteristic in
question.
CHAPTER IV
PHENOMENA AND THINGS IN THEMSELVES
The distinction between phenomena and things in themselves can be best
approached by considering Kant's formulation of the alternative views
of the nature of space and time. "What are space and time? Are they
real existences? Or are they merely determinations or relations of
things, such, however, as would also belong to them in themselves,
even if they were not perceived, or are they attached to the form of
perception only, and consequently to the subjective nature of our
mind, without which these predicates can never be attributed to any
thing?"[1]
[1] B. 37, M. 23.
Of these three alternatives, the first can be ignored. It is opposed
to the second, and is the view that space and time are things rather
than relations between things. This opposition falls within the first
member of the wider opposition between things as they are in
themselves and things as they are as perceived, and Kant, and indeed
any one, would allow that if space and time belong to things as they
are in themselves and not to things only as perceived, they are
relations between things rather than things. The real issue,
therefore, lies between the second and third alternatives. Are space
and time relations between things which belong to them both in
themselves and also as perceived by us, or are they relations which
belong to things only as perceived?
To this question we may at once reply that, inasmuch as it involves an
impossible antithesis, it is wholly unreal. The thought of a property
or a relation which belongs to things as perceived involves a
contradiction. To take Plato's example, suppose that we are looking at
a straight stick, partially immersed in water. If we have not
previously seen the stick, and are ignorant of the laws of refraction,
we say that the stick is bent. If, however, we learn the effect of
refraction, and observe the stick from several positions, we alter our
assertion. We say that the stick is not really bent, but only looks or
appears bent to us. But, if we reflect at all, we do not express our
meaning by saying that the stick _is_ bent to us as perceiving, though
not in reality.[2] The word 'is' essentially relates to what really
is. If, therefore, the phrase 'to us as perceiving' involves an
opposition to the phrase 'in reality', as it must if it is to be a
real qualification of 'is', it cannot rightly be added to the word
'is'. To put the matter more explicitly, the assertion that something
_is_ so and so implies that it is so and so in itself, whether it be
perceived or not, and therefore the assertion that something is so and
so to us as perceiving, though not in itself, is a contradiction in
terms. The phrase 'to us as perceiving', as a restriction upon the
word 'is', merely takes back the precise meaning of the word 'is'.
That to which the phrase can be added is not the word 'is', but the
word 'looks' or 'appears'. We can rightly say that the stick looks or
appears bent to us as perceiving. But even then the addition only
helps to make explicit the essential meaning of 'appears', for
'appears' really means 'appears to us', and 'as perceiving' only
repeats the meaning of 'appears' from the side of the perceiving
subject as opposed to that of the object perceived. The essential
point, however, is thereby brought out that the phrase 'to us as
perceiving' essentially relates not to what a thing is, but to what it
looks or appears to us.
[2] Similarly, we do not say--if we mean what we say--of a
man who is colour blind that an object which others call blue
_is_ pink to him or to his perception, but that it _looks_
pink to him.
What, then, is the proper statement of Kant's view that space is a
determination of things only as they appear to us, and not as they are
in themselves? It should be said that things are not in reality
spatial, but only look or appear spatial to us. It should not be said
that they _are_ spatial for our perception, though not in themselves.
Thus the view properly stated implies that space is an illusion,
inasmuch as it is not a real property of things at all. This
implication, however, is precisely the conclusion which Kant wishes to
avoid. He takes infinite trouble to explain that he does not hold
space and time to be illusions.[3] Though _transcendentally ideal_
(i. e. though they do not belong to things in themselves), they are
_empirically real_. In other words, space and time are real relations
of _something_, though not of things in themselves.
[3] B. 44, 52, 53-4, 62-3, 69-70; M. 27, 31-2, 37-8, 41-2;
_Prol._, § 13, Remark iii.
How, then, does Kant obtain something of which space and time can be
regarded as really relations? He reaches it by a transition which at
first sight seems harmless. In stating the fact of perception he
substitutes for the assertion that things appear so and so to us the
assertion that things produce appearances in us. In this way, instead
of an assertion which relates to the thing and states what it is not
but only appears, he obtains an assertion which introduces a second
reality distinct from the thing, viz. an appearance or phenomenon, and
thereby he gains something other than the thing to which space can be
attached as a real predicate. He thus gains something in respect of
which, with regard to spatial relations we can be said to have
_knowledge_ and not illusion. For the position now is that space,
though not a property of things in themselves, _is_ a property of
phenomena or appearances; in other words, that while things in
themselves are not spatial, phenomena and appearances _are_ spatial.
As evidence of this transition, it is enough to point out that, while
he states the _problem_ in the form 'Are things in themselves spatial
or are they only spatial as appearing to us?'[4] he usually states the
_conclusion_ in the form 'Space is the form of phenomena', i. e.
phenomena are spatial. A transition is thereby implied from 'things as
appearing' to 'appearances'. At the same time, it is clear that Kant
is not aware of the transition, but considers the expressions
equivalent, or, in other words, fails to distinguish them. For both
modes of stating the conclusion are to be found even in the same
sentence. "This predicate [space] is applied to things only in so far
as they appear to us, i. e. are objects of sensibility [i. e.
phenomena]."[5] Again, the common phrase 'things as phenomena' implies
the same confusion. Moreover, if Kant had realized that the transition
was more than one of phraseology he must have seen that it was
necessary to recast his argument.
[4] This is Kant's way of putting the question which should
be expressed by asking, 'Are things spatial, or do they only
look spatial?'
[5] B. 43, M. 26. Cf. _Prol._, § 9 fin. with § 10 init.
It may be said, then, that Kant is compelled to end with a different
distinction from that with which he begins. He begins with the
distinction between things as they are in themselves and things as
they appear to us, the distinction relating to one and the same
reality regarded from two different points of view. He ends with the
distinction between two different realities, things-in-themselves,[6]
external to, in the sense of independent of, the mind, and phenomena
or appearances within it. Yet if his _argument_ is to be valid, the
two distinctions should be identical, for it is the first distinction
to which the argument appeals.[7] In fact, we find him expressing what
is to him the same distinction now in the one way and now in the other
as the context requires.
[6] It should be noticed that 'things-in-themselves' and
'things as they are in themselves' have a different meaning.
[7] Cf. p. 55 and ff.
The final form of Kant's conclusion, then, is that while things in
themselves are not, or, at least, cannot be known to be spatial,
'phenomena,' or the appearances produced in us by things in
themselves, are spatial. Unfortunately, the conclusion in this form is
no more successful than it is in the former form, that things are
spatial only as perceived. Expressed by the formula 'phenomena are
spatial', it has, no doubt, a certain plausibility; for the word
'phenomena' to some extent conceals the essentially mental character
of what is asserted to be spatial. But the plausibility disappears on
the substitution of 'appearances'--the true equivalent of Kant's
_Erscheinungen_--for 'phenomena'. Just as it is absurd to describe the
fact that the stick only looks bent by saying that, while the stick is
not bent, the appearance which it produces is bent, so it is, even on
the face of it, nonsense to say that while things are not spatial, the
appearances which they produce in us are spatial. For an 'appearance',
being necessarily something mental, cannot possibly be said to be
extended. Moreover, it is really an abuse of the term 'appearance' to
speak of appearances _produced by_ things, for this phrase implies a
false severance of the appearance from the things which appear. If
there are 'appearances' at all, they are appearances _of_ things and
not appearances _produced by_ them. The importance of the distinction
lies in the difference of implication. To speak of appearances
produced by things is to imply that the object of perception is merely
something mental, viz. an appearance. Consequently, access to a
non-mental reality is excluded; for a perception of which the object
is something belonging to the mind's own being cannot justify an
inference to something beyond the mind, and the result is inevitably
solipsism. On the other hand, the phrase 'appearances of things',
whatever defects it may have, at least implies that it is a non-mental
reality which appears, and therefore that in perception we are in
direct relation to it; the phrase, therefore, does not imply from the
very beginning that the apprehension of a non-mental reality is
impossible.
The objection will probably be raised that this criticism is much too
summary. We do, it will be said, distinguish in ordinary consciousness
between appearance and reality. Consequently there must be some form
in which Kant's distinction between things in themselves and phenomena
and the conclusion based upon it are justified. Moreover, Kant's
reiterated assertion that his view does not imply that space is an
illusion, and that the distinction between the real and the illusory
is possible _within_ phenomena, requires us to consider more closely
whether Kant may not after all be entitled to hold that space is not
an illusion.[8]
[8] Cf. p. 93 and ff.
This objection is, of course, reasonable. No one can satisfy himself
of the justice of the above criticisms until he has considered the
real nature of the distinction between appearance and reality. This
distinction must, therefore, be analysed. But before this is done it
is necessary, in order to discover the real issue, to formulate the
lines on which Kant may be defended. 'The reality,' it may be urged,
'which ideally we wish to know must be admitted to exist _in itself_,
in the sense of independently of the perception, and consequently its
nature must be admitted to be independent of perception. Ideally,
then, our desire is to know things[9] as they are in themselves, a
desire sufficiently expressed by the assertion that we desire to know
things, for to know them is to know them as they are, i. e. as they
are independently of perception. Again, since the reality which we
desire to know consists of individuals, and since the apprehension of
an individual implies perception, knowledge of reality requires
perception. If in perception we apprehended reality as it is, no
difficulty would arise. But we do not, for we are compelled to
distinguish what things are, and what they look or appear; and what
they appear essentially relates to perception. We perceive them as
they look or appear and, therefore, not as they are, for what they
look and what they are are _ex hypothesi_ distinguished. And this fact
constitutes a fatal obstacle to knowledge in general. We cannot know
anything as it _is_. At least the negative side of Kant's position
must be justified. We never can know things as they are in themselves.
What then do we know? Two alternative answers may be given. It may be
held that the positive side of Kant's position, though indefensible in
the form that we know things as they appear to us, is valid in the
form that we know what things look or appear. This, no doubt, implies
that our ordinary beliefs about reality are illusory, for what things
look is _ex hypothesi_ different from what they are. But the
implication does not constitute an important departure from Kant's
view. For in any case only that is knowledge proper which relates to
things as they are, and therefore the supposed knowledge of things as
they appear may be discarded without serious loss. On the other hand,
it may be held that the positive side of Kant's position can be
vindicated in the form that, while we do not know things in
themselves,[10] we do know the appearances which they produce in us.
It is true that this view involves the difficulty of maintaining that
appearances are spatial, but the difficulty is not insuperable.
Moreover, in this form the doctrine has the advantage that, unlike the
former, it does not imply that the knowledge which we have is only of
illusions, for instead of implying that our knowledge is merely
knowledge of what things look but really are not, it implies that we
know the real nature of realities of another kind, viz. of
appearances. Again, in this form of the view, it may be possible to
vindicate Kant's doctrine that the distinction between the real and
the illusory is tenable within what we know, for it may be possible to
distinguish within appearances between a 'real' appearance[11] and an
'illusory' appearance.[12]'
[9] 'Things' is substituted for 'the reality which we believe
to exist independently of perception' in order to conform
to Kant's language. The substitution, of course, has the
implication--which Kant took for granted--that the reality
consists of a plurality of individuals.
[10] 'Things in themselves' has here to be substituted for
'things as they are in themselves' in the statement of the
negative side of the position, in order to express the proper
antithesis, which is now that between two things, the one
known and the other unknown, and not that between two points
of view from which one and the same thing is known and not
known respectively.
[11] _Erscheinung._
[12] _Schein._
An implication of this defence should be noticed. The issue relates
to the nature of space[13], and may be stated in terms of it. For,
since space is a presupposition of all other properties which the
non-philosophical consciousness attributes to physical things, it
makes no difference whether we say that things _only appear_ heavy,
hard, in motion, &c., or whether we say that things _only appear_
spatial. In the same way it is a matter of indifference whether we say
that, though things are not heavy, hard, &c., their appearances are
so, or whether we say that, though things are not spatial, their
appearances are so. The issue, then, concerns the possibility of
maintaining either that things only appear spatial, or that the
appearances which they produce are spatial, while the things
themselves are not, or, at least cannot be known to be, spatial.
[13] We might add time also; but, for a reason which will
appear later (p. 139), it can be neglected.
The tenability of these alternative positions has to be considered
apart from the argument of the _Aesthetic_, for this, as we have seen,
breaks down. At the outset it is important to realize that these
positions are the product of philosophical reflection, and constitute
general theories of knowledge. As has been pointed out, the
distinction between appearance and reality first arises in our
ordinary or scientific consciousness.[14] In this consciousness we are
compelled to distinguish between appearance and reality with respect
to the details of a reality which, as a whole, or, in principle, we
suppose ourselves to know. Afterwards in our philosophical
consciousness we come to reflect upon this distinction and to raise
the question whether it is not applicable to reality as a whole. We
ask with respect to knowledge in general, and not merely with respect
to certain particular items of knowledge, whether we know or can know
reality, and not merely appearance. The two positions just stated are
alternative ways of answering the question in the negative. They are,
then, philosophical views based upon a distinction found in our
ordinary consciousness. Consequently, in order to decide whether the
distinction will bear the superstructure placed upon it by the
philosophical consciousness, it is necessary to examine the
distinction as it exists in our ordinary consciousness.
[14] I. e. the consciousness for which the problems are those
of science as opposed to philosophy.
The distinction is applied in our ordinary consciousness both to the
primary and to the secondary qualities of matter, i. e. to the size,
shape, position and motion of physical bodies, and to their colour,
warmth, &c. We say, for instance, that the moon looks[15] or appears
as large as the sun, though really it is much smaller. We say that
railway lines, though parallel, look convergent, just as we say that
the straight stick in water looks bent. We say that at sunset the sun,
though really below the horizon, looks above it. Again, we say that to
a person who is colour blind the colour of an object looks different
to what it really is, and that the water into which we put our hand
may be warmer than it appears to our touch.
[15] 'Looks' means 'appears to sight', and 'looks' is
throughout used as synonymous with 'appear', where the
instance under discussion relates to visual perception.
The case of the primary qualities may be considered first. Since the
instances are identical in principle, and only differ in complexity,
it will be sufficient to analyse the simplest, that of the apparent
convergence of the railway lines.
Two points at once force themselves upon our notice. In the first
place, we certainly suppose that we perceive the reality which we wish
to know, i. e. the reality which, as we suppose, exists independently
of our perception, and not an 'appearance' of it. It is, as we say,
the real lines which we see. Even the term 'convergent', in the
assertion that the lines look convergent, conveys this implication.
For 'convergent' is essentially a characteristic not of an appearance
but of a reality, in the sense in which something independent of
perception may be opposed as a reality to an 'appearance', which, as
such, presupposes perception. We can say neither that an appearance is
convergent, nor that the appearance of the lines is convergent. Only a
reality similar to the lines, e. g. two roads, can be said to be
convergent. Our ordinary thought, therefore, furnishes no ground for
the view that the object of perception is not the thing, but merely an
appearance of or produced by it. In the second place, the assertion
that the lines _look_ convergent implies considerable knowledge of the
real nature of the reality to which the assertion relates. Both the
terms 'lines' and 'convergent' imply that the reality _is_ spatial.
Further, if the context is such that we mean that, while the lines
look convergent, we do not know their real relation, we imply that
the lines really possess some characteristic which falls within the
genus to which convergence belongs, i. e. we imply that they are
convergent, divergent, or parallel. If, on the other hand, the context
is such that we mean that the lines only look convergent, we imply
that the lines are parallel, and therefore presuppose complete
knowledge in respect of the very characteristic in regard to which we
state what is only appearance. The assertion, then, in respect of a
primary quality, that a thing looks so and so implies knowledge of its
general character as spatial, and ignorance only of a detail; and the
assertion that a thing only looks or appears so and so implies
knowledge of the detail in question.
Attention may now be drawn to a general difficulty which may be raised
with respect to the use of the terms 'looks' and 'appears'. It may be
stated thus: 'If the lines are not convergent, how is it possible even
to say that they _look_ convergent? Must it not be implied that at
least under _certain_ circumstances we should perceive the lines as
they are? Otherwise, why should we use the words 'look' or 'appear' at
all? Moreover, this implication can be pushed further; for if we
maintain that we perceive the real lines, we may reasonably be asked
whether we must not under _all_ circumstances perceive them as they
are. It seems as though a reality cannot be perceived except as it
is.' It is the view to which this difficulty gives rise which is
mainly responsible for the doctrine that the object of perception is
not the reality, but an appearance. Since we do distinguish between
what things look and what they are, it would seem that the object of
perception cannot be the thing, but only an appearance produced by
it. Moreover, the doctrine gains in plausibility from the existence of
certain illusions in the case of which the reality to which the
illusion relates seems non-existent. For instance, if we look steadily
at the flame of a candle, and then press one eyeball with a finger, we
see, as we say, two candles;[16] but since _ex hypothesi_ there is
only one candle, it seems that what we see must be, not the candle,
but two images or appearances produced by it.
[16] Cf. Dr. Stout, on 'Things and Sensations' (_Proceedings
of the British Academy_, vol. ii).
This difficulty is raised in order to draw attention to the fact that,
in the case of the railway lines, where it can be met on its own
ground[17], this is because, and only because, we believe space to be
'real', i. e. to be a characteristic of reality, and because we
understand its nature. The distinction between the actual and the
apparent angle made by two straight lines presupposes a limiting case
in which they coincide. If the line of sight along which we observe
the point of intersection of two lines is known to be at right angles
to both lines, we expect, and rightly expect, to see the angle of
intersection as it is. Again, if we look at a short portion of two
railway lines from a point known to be directly above them, and so
distant that the effects of perspective are imperceptible, we can say
that the lines look what they are, viz. parallel. Thus, from the point
of view of the difficulty which has been raised, there is this
justification in general for saying that two lines _look_ parallel or
_look_ at right angles, that we know that in certain cases what they
look is identical with what they are. In the same way, assertions of
the type that the moon _looks_ as large as the sun receive
justification from our knowledge that two bodies of equal size and
equally distant from the observer _are_ what they look, viz. of the
same size. And in both cases the justification presupposes knowledge
of the reality of space and also such insight into its nature as
enables us to see that in certain cases there must be an identity
between what things look and what they are in respect of certain
spatial relations. Again, in such cases we see that so far is it from
being necessary to think that a thing must be perceived as it is, that
it is not only possible but necessary to distinguish what a thing
looks from what it is, and precisely in consequence of the nature of
space. The visual perception of spatial relations from its very nature
presupposes a particular point of view. Though the perception itself
cannot be spatial, it presupposes a particular point in space as a
standpoint or point of view,[18] and is therefore subject to
conditions of perspective. This is best realized by considering the
supposition that perfect visual powers would enable us to see the
whole of a body at once, and that this perception would be possible if
we had eyes situated all round the body. The supposition obviously
breaks down through the impossibility of combining two or more points
of view in one perception. But if visual perception is necessarily
subject to conditions of perspective, the spatial relations of bodies
can never look what they are except in the limiting case referred to.
Moreover, this distinction is perfectly intelligible, as we should
expect from the necessity which we are under of drawing it. We
understand perfectly why it is that bodies must, in respect of their
spatial relations, look different to what they are, and we do so
solely because we understand the nature of space, and therefore also
the conditions of perspective involved in the perception of what is
spatial. It is, therefore, needless to make the assertion 'Two lines
appear convergent' intelligible by converting the verb 'appears' into
a substantive, viz. an 'appearance', and then making the assertion
relate to an 'appearance'. For--apart from the fact that this would
not achieve the desired end, since no suitable predicate could be
found for the appearance--the assertion that the lines _look_ or
_appear_ convergent is perfectly intelligible in itself, though not
capable of being stated in terms of anything else.[19] If we
generalize this result, we may say that the distinction between
appearance and reality, drawn with regard to the primary qualities of
bodies, throughout presupposes the reality of space, and is made
possible, and indeed necessary, by the nature of space itself.
[17] Cf., however, p. 87 and pp. 89-91.
[18] This is, of course, not refuted by the reminder that we
see with two eyes, and that these are in different places.
[19] It is important to notice that the proper formula to
express what is loosely called 'an appearance' is 'A looks or
appears B', and that this cannot be analysed into anything
more simple and, in particular, into a statement about
'appearances'. Even in the case of looking at the candle,
there is no need to speak of two 'appearances' or 'images'.
Before we discover the truth, the proper assertion is 'The
body which we perceive looks as if it were two candles', and,
after we discover the truth, the proper assertion is 'The
candle looks as if it were in two places'.
We may now turn to the way in which we draw the distinction with
respect to the secondary qualities of physical things. It must, it
seems, be admitted that in our ordinary consciousness we treat these
qualities as real qualities of bodies. We say that a bell is noisy;
that sugar is sweet; that roses smell; that a mustard plaster is hot;
that the sky is blue. It must also be admitted that in our ordinary
consciousness we draw a distinction between appearance and reality
_within_ these qualities, just as we do _within_ the primary
qualities. Just as we speak of the right or real shape of a body, so
we speak of its right or real colour, taste, &c., and distinguish
these from its apparent colours, taste, &c., to some individual. We
thereby imply that these qualities are real qualities of bodies, and
that the only difficulty is to determine the particular character of
the quality in a given case. Yet, as the history of philosophy shows,
it takes but little reflection to throw doubt on the reality of these
qualities. The doubt arises not merely from the apparent impossibility
of finding a principle by which to determine the right or real quality
in a given case, but also and mainly from misgivings as to the
possible reality of heat, smell, taste, noise, and colour apart from a
percipient. It must also be admitted that this misgiving is well
founded; in other words, that these supposed real qualities do
presuppose a percipient, and therefore cannot be qualities of things,
since the qualities of a thing must exist independently of the
perception of the thing.[20] This will readily be allowed in the case
of all the secondary qualities except colour. No one, it may
reasonably be said, who is familiar with and really faces the issue,
will maintain that sounds, smells, tastes, and sensations of touch
exist apart from a sensitive subject. So much is this the case, that
when once the issue is raised, it is difficult and, in the end,
impossible to use the word 'appear' in connexion with these qualities.
Thus it is difficult and, in the end, impossible to say that a bell
_appears_ noisy, or that sugar _appears_ sweet. We say, rather, that
the bell and the sugar produce certain sensations[21] in us.
[20] Cf. pp. 72-3, and 91.
[21] _Not_ 'appearances'.
The case of colour, however, is more difficult. From the closeness of
its relation to the shape of bodies, it seems to be a real quality of
bodies, and not something relative to a sensitive subject like the
other secondary qualities. In fact, so intimate seems the relation of
colour to the shape of bodies, that it would seem--as has, of course,
often been argued--that if colour be relative to a sensitive subject,
the primary qualities of bodies must also be relative to a sensitive
subject, on the ground that shape is inseparable from colour.[22] Yet
whether this be so or not, it must, in the end, be allowed that colour
does presuppose a sensitive subject in virtue of its own nature, and
quite apart from the difficulty--which is in itself insuperable--of
determining the right colour of individual bodies. It must, therefore,
be conceded that colour is not a quality of bodies. But if this be
true, the use of the term 'look' or 'appear' in connexion with colour
involves a difficulty which does not arise when it is used in
connexion with the primary qualities. Bodies undoubtedly look or
appear coloured. Now, as has already been suggested,[23] the term
'look' seems to presuppose some identity between what a thing is and
what it looks, and at least the possibility of cases in which they are
what they look--a possibility which, as we have seen, is realized in
the case of the primary qualities. Yet, if colour is not a quality of
bodies, then, with respect to colour, things look what they never are,
or, in other words, are wholly different from what they look;[24] and
since it seems impossible to hold that colour is really a property of
bodies, this conclusion must, in spite of its difficulty, be admitted
to be true.
[22] Cf. p. 91 note.
[23] Cf. p. 82.
[24] It is assumed that there is not even plausibility in the
supposition of continuity or identity between colour proper
and its physical conditions in the way of light vibrations.
There remain, however, to be noticed two respects in which assertions
concerning what things look in respect of colour agree with
corresponding assertions in respect of the primary qualities. They
imply that what we perceive is a reality, in the sense already
explained.[25] Thus the assertion that the grass looks green implies
that it is a reality which looks green, or, in other words, that the
object of perception is a reality, and not an 'appearance'. Again,
such assertions imply that the reality about which the assertion is
made is spatial. The term 'grass' implies extension, and only what is
extended can be said to look coloured. If it be urged that what looks
coloured need only _look_ extended, it may be replied that the two
considerations which lead us to think that things only _look_ coloured
presuppose that they _are_ spatial. For the two questions, the
consideration of which leads to this conclusion, are, 'What is the
right or real colour of an individual thing?' and 'Has it really any
colour at all, or does it only look coloured?' and neither question is
significant unless the thing to which it refers is understood to be
spatial.
[25] I. e. in the sense of something which exists
independently of perception.
We may now return to the main issue. Is it possible to maintain either
(1) the position that only appearances are spatial and possess all the
qualities which imply space, or (2) the position that things only
appear spatial and only appear or look as if they possessed the
qualities which imply space? It may be urged that these questions have
already been implicitly answered in the negative. For the division of
the qualities of things into primary and secondary is exhaustive, and,
as has been shown, the distinction between 'appearance' and 'reality',
when drawn with respect to the primary qualities and to colour--the
only secondary quality with respect to which the term 'appears' can
properly be used[26]--presupposes the reality of space. Consequently,
since we do draw the distinction, we must accept the reality of that
which is the condition of drawing it at all. But even though this be
conceded--and the concession is inevitable--the problem cannot be
regarded as solved until we have discovered what it is in the nature
of space which makes both positions untenable. Moreover, the admission
that in the case of colour there is no identity between what things
look and what they are removes at a stroke much of the difficulty of
one position, viz. that we only know what things look or appear, and
not what they are. For the admission makes it impossible to maintain
as a general principle that there must be some identity between what
they look and what they are. Consequently, it seems _possible_ that
things should be wholly different from what they appear, and, if so,
the issue cannot be decided on general grounds. What is in substance
the same point may be expressed differently by saying that just as
things only _look_ coloured, so things may only _look_ spatial. We are
thus again[27] led to see that the issue really turns on the nature of
space and of spatial characteristics in particular.
[26] Cf. pp. 86-7.
[27] Cf. p. 79.
In discussing the distinction between the real and the apparent shape
of bodies, it was argued that while the nature of space makes it
necessary to distinguish in general between what a body looks and what
it is, yet the use of the term _look_ receives justification from the
existence of limiting cases in which what a thing looks and what it is
are identical. The instances considered, however, related to qualities
involving only two dimensions, e. g. convergence and bentness, and it
will be found that the existence of these limiting cases is due solely
to this restriction. If the assertion under consideration involves a
term implying three dimensions, e. g. 'cubical' or 'cylindrical',
there are no such limiting cases. Since our visual perception is
necessarily subject to conditions of perspective, it follows that
although we can and do see a cube, we can never see it as it _is_.
It _is_, so to say, in the way in which a child draws the side of a
house, i. e. with the effect of perspective eliminated; but it never
can be seen in this way. No doubt, our unreflective knowledge of the
nature of perspective enables us to allow for the effect of
perspective, and to ascertain the real shape of a solid object from
what it looks when seen from different points. In fact, the habit of
allowing for the effect of perspective is so thoroughly ingrained in
human beings that the child is not aware that he is making this
allowance, but thinks that he draws the side of the house as he sees
it. Nevertheless, it is true that we never see a cube as it is, and if
we say that a thing looks cubical, we ought only to mean that it looks
precisely what a thing looks which is a cube.
It is obvious, however, that two dimensions are only an abstraction
from three, and that the spatial relations of bodies, considered
fully, involve three dimensions; in other words, spatial
characteristics are, properly speaking, three-dimensional. It follows
that terms which fully state spatial characteristics can never
express what things look, but only what they are. A body may be
cylindrical, and we may see a cylindrical body; but such a body can
never, strictly speaking, _look_ cylindrical. The opposition, however,
between what a thing _is_ and what it _looks_ implies that what it
_is_ is independent of a percipient, for it is precisely correlation
to a percipient which is implied by 'looking' or 'appearing'. In fact,
it is the view that what a thing really is it is, independently of
a percipient, that forms the real starting-point of Kant's thought.
It follows, then, that the spatial characteristics of things, and
therefore space itself, must belong to what they are in themselves
apart from a percipient, and not to what they look.[28] Consequently,
it is so far from being true that we only know what things look and
not what they are, that in the case of spatial relations we actually
know what things are, even though they never look what they are.
[28] This consideration disposes of the view that, if colour
is relative to perception, the primary qualities, as being
inseparable from colour, must also be relative to perception;
for it implies that the primary qualities cannot from their
very nature be relative to perception. Moreover, if the
possibility of the separation of the primary qualities from
colour is still doubted, it is only necessary to appeal to
the blind man's ability to apprehend the primary qualities,
though he may not even know what the word 'colour' means. Of
course, it must be admitted that some sensuous elements are
involved in the apprehension of the primary qualities, but
the case of the blind man shows that these may relate to
sight instead of to touch. Moreover, it, of course, does not
follow from the fact that sensuous elements are inseparable
from our perception of bodies that they belong to, and are
therefore inseparable from, the bodies perceived.
This conclusion, however, seems to present a double difficulty. It is
admitted that we perceive things as they look, and not as they are.
How, then, is it possible for the belief that things _are_ spatial to
arise? For how can we advance from knowledge of what they look to
knowledge of what they are but do not look? Again, given that the
belief has arisen, may it not after all be illusion? No vindication
seems possible. For how can it be possible to base the knowledge of
what things are, independently of perception, upon the knowledge of
what they look? Nevertheless, the answer is simple. In the case of the
perception of what is spatial there is no transition _in principle_
from knowledge of what things look to knowledge of what things are,
though there is continually such a transition _in respect of details_.
It is, of course, often necessary, and often difficult, to determine
the precise position, shape, &c., of a thing, and if we are to come to
a decision, we must appeal to what the thing looks or appears under
various conditions. But, from the very beginning, our consciousness of
what a thing appears in respect of spatial characteristics implies the
consciousness of it as spatial and therefore also as, in particular,
three-dimensional. If we suppose the latter consciousness absent, any
assertion as to what a thing appears in respect of spatial
characteristics loses significance. Thus, although there is a process
by which we come to learn that railway lines are really parallel,
there is no process by which we come to learn that they are really
spatial. Similarly, although there is a process by which we become
aware that a body is a cube, there is no process by which we become
aware that it has a solid shape of some kind; the process is only
concerned with the determination of the precise shape of the body.
The second difficulty is, therefore, also removed. For if assertions
concerning the apparent shape, &c. of things presuppose the
consciousness that the things _are_ spatial, to say that this
consciousness may be illusory is to say that all statements concerning
what things _appear_, in respect of spatial relations, are equally
illusory. But, since it is wholly impossible to deny that we can and
do state what things appear in this respect, the difficulty must fall
to the ground.
There remains to be answered the question whether Kant's position is
tenable in its other form, viz. that while we cannot say that reality
is spatial, we can and must say that the appearances which it produces
are spatial. This question, in view of the foregoing, can be answered
as soon as it is stated. We must allow that reality is spatial, since,
as has been pointed out, assertions concerning the apparent shape of
things presuppose that they are spatial. We must equally allow that an
appearance cannot be spatial. For on the one hand, as has just been
shown, space and spatial relations can only qualify something the
existence of which is not relative to perception, since it is
impossible to perceive what is spatial as it is; and on the other hand
an appearance, as being _ex hypothesi_ an appearance to some one,
i. e. to a percipient, must be relative to perception.
We may say, then, generally, that analysis of the distinction between
appearance and reality, as it is actually drawn in our ordinary
consciousness, shows the falsity of both forms of the philosophical
agnosticism which appeals to the distinction. We know things; not
appearances. We know what things are; and not merely what they appear
but are not. We may also say that Kant cannot possibly be successful
in meeting, at least in respect of space, what he calls 'the easily
foreseen but worthless objection that the ideality of space and of
time would turn the whole sensible world into pure illusion'.[29] For
space, according to him, is not a property of things in themselves; it
cannot, as has been shown, be a property of appearances; to say that
it is a property of things as they appear to us is self-contradictory;
and there is nothing else of which it can be said to be a property.
[29] _Prol_., § 13, Remark iii. (Cf. p. 100 note.) Cf. the
confused note B. 70, M. 42. (See Dr. Vaihinger's Commentary
on the _Critique_, ii, 488 ff.)
In conclusion, it may be pointed out that the impossibility that
space[30] and spatial characteristics should qualify appearances
renders untenable Kant's attempt to draw a distinction between reality
and appearance _within_ 'phenomena' or 'appearances'. The passage in
which he tries to do so runs as follows:
[30] The case of time can be ignored, since, as will be seen
later (pp. 112-14), the contention that space is 'ideal'
really involves the admission that time is real.
"We generally indeed distinguish in appearances that which essentially
belongs to the perception of them, and is valid for every human
sense in general, from that which belongs to the same perception
accidentally, as valid not for the sensibility in general, but for a
particular state or organization of this or that sense. Accordingly,
we are accustomed to say that the former is knowledge which represents
the object itself, whilst the latter represents only the appearance
of the same. This distinction, however, is only empirical. If we stop
here (as is usual) and do not again regard that empirical perception
as itself a mere phenomenon (as we ought to do), in which nothing
which concerns a thing in itself is to be found, our transcendental
distinction is lost; and in that case we are after all believing that
we know things in themselves, although in the world of sense,
investigate its objects as profoundly as we may, we have to do with
nothing but appearances. Thus we call the rainbow a mere appearance
during a sunny shower, but the rain the thing in itself; and this is
right, if we understand the latter conception only physically as that
which in universal experience and under all different positions with
regard to the senses is in perception so and so determined and not
otherwise. But if we consider this empirical element[31] in general,
and inquire, without considering its agreement with every human sense,
whether it represents an object in itself (not the raindrops, for
their being phenomena by itself makes them empirical objects), the
question of the relation of the representation to the object is
transcendental; and not only are the raindrops mere appearances, but
even their circular form, nay, even the space in which they fall,
are nothing in themselves but mere modifications or fundamental
dispositions of our sensuous perception; the transcendental object,
however, remains unknown to us."[32]
[31] _Dieses Empirische._
[32] B. 62-3, M. 37-8. _Erscheinung_ is here translated
'appearance'.
Kant's meaning is plain. He is anxious to justify the physical
distinction made in our ordinary or non-philosophical consciousness
between a thing in itself and a mere appearance,[33] but at the same
time to show that it falls within appearances, in respect of the
philosophical distinction between things in themselves and appearances
or phenomena. The physical distinction is the first of which we become
aware, and it arises through problems connected with our senses.
Owing, presumably, to the contradictions which would otherwise ensue,
the mind is forced to distinguish between things and the 'appearances'
which they produce, and to recognize that they do not correspond. The
discrepancy is due to the fact that our perceptions are conditioned by
the special positions of our physical organs with regard to the object
of perception, and we discover its real nature by making allowance for
these special positions. We thereby advance in knowledge to the extent
of overcoming an obstacle due to the nature of our senses. But, this
obstacle overcome, philosophical reflection forces upon us another.
The thing which we distinguish in our ordinary consciousness from its
appearances is, after all, only another appearance; and although the
physical problem is solved concerning its accordance with our special
senses, there remains the philosophical problem as to whether this
appearance need correspond to what in the end is the real thing, viz.
that which exists in itself and apart from all perception. The only
possible answer is that it need not. We therefore can only know
appearances and not reality; in other words, we cannot have knowledge
proper. At the same time, our knowledge of appearances is objective to
the extent that the appearances in question are the same for every
one, and for us on various occasions; for the effects due to special
positions of our senses have been removed. If, therefore, we return to
the physical distinction, we see that the 'things' to which it refers
are only a special kind of appearance, viz. that which is the same for
every one, and for us at all times. The physical distinction, then,
being a distinction between one kind of appearance and another, falls
within 'phenomena' or 'appearances'.
[33] It should be noticed that the passage is, in the main,
expressed in terms of the distinction between 'things' and
'appearances', and not, as it should be, in terms of the
distinction between what things are and what things appear
or look.
Now the obvious objection to this line of thought is that the result
of the second or metaphysical application of the distinction between
reality and appearance is to destroy or annul the first or physical
application of it. To oppose the rain, i. e. the raindrops as the
thing in itself to the rainbow as a mere appearance is to imply that
the rain is not an appearance. For though what is opposed to a _mere_
appearance may still be an appearance, it cannot be called an
appearance at all if it be described as the thing in itself. If it be
only another appearance, it is the same in principle as that to which
it is opposed, and consequently cannot be opposed to it. Thus, if Kant
means by the rain, in distinction from the rainbow, the appearance
when, as we say, we see the circular raindrops, the title of this
appearance to the term thing in itself is no better than that of the
rainbow; it is, in fact, if anything, worse, for the appearance is
actual only under exceptional circumstances. We may never see the
raindrops thus, or in Kant's language, have this 'appearance'; and
therefore, in general, an appearance of this kind is not actual but
only possible. The truth is that we can only distinguish something as
the thing in itself from an appearance, so long as we mean by the
thing in itself what Kant normally means by it, viz. something which
exists independently of perception and is not an appearance at
all.[34] That of which Kant is really thinking, and which he _calls_
the appearance which is the thing, in distinction from a mere
appearance, is not an appearance; on the contrary, it is the raindrops
themselves, which he describes as circular and as falling through
space, and which, as circular and falling, must exist and have these
characteristics in themselves apart from a percipient. Kant's formula
for an empirical thing, i. e. a thing which is an appearance, viz.
'that which in universal experience and under all different positions
with regard to the senses is in perception so and so determined', is
merely an attempt to achieve the impossible, viz. to combine in one
the characteristics of a thing and an appearance. While the reference
to _perception_ and to _position with regard to the senses_ implies
that what is being defined is an appearance, the reference to
_universal_ experience, to _all_ positions with regard to the senses,
and to that which _is so and so determined_ implies that it is a
thing. But, plainly, mention of position with regard to the senses, if
introduced at all, should refer to the _differences_ in perception due
to the different position of the object in particular cases. There is
nothing of which it can be said that we perceive it in the same way or
that it looks the same from _all_ positions. When Kant speaks of that
which under _all_ different positions with regard to the senses is so
and so determined, he is really referring to something in the
consideration of which all reference to the senses has been discarded;
it is what should be described as that which _in reality and apart
from_ all positions with regard to the senses is so and so determined;
and this, as such, cannot be an appearance. Again, the qualification
of 'is so and so determined' by 'in perception' is merely an attempt
to treat as relative to perception, and so as an appearance, what is
essentially independent of perception.[35] Kant, no doubt, is thinking
of a real presupposition of the process by which we distinguish
between the real and the apparent qualities of bodies, i. e. between
what they are and what they appear. We presuppose that that quality is
really, and not only apparently, a quality of a body, which we and
every one, judging from what it looks under various conditions (i. e.
'in universal experience'), must believe it to possess in itself and
independently of all perception. His mistake is that in formulating
this presupposition he treats as an appearance, and so as relative to
perception, just that which is being distinguished from what, as an
appearance, is relative to perception.
[34] Hence Kant's protest (B. 45, M. 27), against
illustrating the ideality of space by the 'inadequate'
examples of colour, taste, &c., must be unavailing. For his
contention is that, while the assertion that space is not a
property of things means that it is not a property of things
in themselves, the assertion that colour, for example, is not
a property of a rose only means that it is not a property of
a thing in itself in an empirical sense, i. e. of an
appearance of a special kind.
[35] Cf. pp. 72-3.
Underlying the mistake is the identification of perception with
judgement. Our apprehension of what things _are_ is essentially a
matter of thought or judgement, and not of perception. We do not
_perceive_[36] but _think_ a thing as it is. It is true that we can
follow Kant's language so far as to say that our judgement that the
portion of the great circle joining two points on the surface of a
sphere is the shortest way between them _via_ the surface belongs
essentially to the thinking faculty of every intelligent being, and
also that it is valid for all intelligences, in the sense that they
must all hold it to be true; and we can contrast this judgement with a
perception of the portion of the great circle as something which,
though it cannot be said to be invalid, still differs for different
beings according to the position from which they perceive it. Kant,
however, treats the judgement as a _perception_; for if we apply his
general assertion to this instance, we find him saying that what we
judge the portion of the great circle to be essentially belongs to the
_perception_ of it, and is valid for the _sensuous_ faculty of every
human being, and that thereby it can be distinguished from what
belongs to the same perception of a great circle accidentally, e. g.
its apparent colour, which is valid only for a particular organization
of this or that sense.[37] In this way he correlates what the great
circle really is, as well as what it looks, with perception, and so is
able to speak of what it is for perception. But, in fact, what the
great circle is, is correlated with thought, and not with perception;
and if we raise Kant's transcendental problem in reference not to
perception but to thought, it cannot be solved in Kant's agnostic
manner. For it is a presupposition of thinking that things are in
themselves what we think them to be; and from the nature of the case a
presupposition of thinking not only cannot be rightly questioned, but
cannot be questioned at all.
[36] Cf. pp. 72-3.
[37] In the _Prol._, § 13, Remark iii, Kant carefully
distinguishes judgement from perception, but destroys the
effect of the distinction by regarding judgement as referring
to what is relative to perception, viz. appearances.
NOTE ON THE FIRST ANTINOMY
Kant holds that the antinomy or contradiction which arises when we
consider the character of the world as spatial and temporal, viz. that
we are equally bound to hold that the world is infinite in space and
time, and that it is finite in space and time, is due to regarding the
world as a thing in itself. He holds that the contradiction
disappears, as soon as it is recognized that the world is only a
phenomenon, for then we find that we need only say that the world is
_capable_ of being extended infinitely in respect of time and
space.[1] Objects in space and time are only phenomena, and, as such,
are actual only in perception. When we say that a past event, or that
a body which we do not perceive, is real, we merely assert the
possibility of a 'perception'. "All events from time immemorial prior
to my existence mean nothing else than the possibility of prolonging
the chain of experience from the present perception upwards to the
conditions which determine this perception according to time."[2]
"That there may be inhabitants of the moon, although no one has ever
seen them, must certainly be admitted, but this assertion only means
that we could come upon them in the possible progress of
experience."[3] The contradictions, therefore, can be avoided by
substituting for the actual infinity of space and time, as relating to
things in themselves, the possible infinity of a series of
'perceptions'.
[1] B. 532-3, M. 315.
[2] B. 523, M. 309.
[3] B. 521, M. 308.
This contention, if successful, is clearly important. If it could be
shown that the treatment of the world as a thing in itself is the
source of a contradiction, we should have what at least would seem a
strong, if not conclusive, ground for holding that the world is a
phenomenon, and, consequently, that the distinction between phenomena
and things in themselves is valid.
Professor Cook Wilson has, however, pointed out that Kant's own
doctrine does not avoid the difficulty. For, though, according to
Kant, the infinity of actual representations of spaces and times is
only possible, yet the possibilities of these representations will be
themselves infinite, and, as such, will give rise to contradictions
similar to those involved in the infinity of space and time. Moreover,
as Professor Cook Wilson has also pointed out, there is no
contradiction involved in the thought of the world as spatial and
temporal; for, as we see when we reflect, we always presuppose that
space and time are infinite, and we are only tempted to think that
they must be finite, because, when maintaining that the world must be
a whole, we are apt to make the false assumption, without in any way
questioning it, that any whole must be finite.
CHAPTER V
TIME AND INNER SENSE
The arguments by which Kant seeks to show that time is not a
determination of things in themselves but only a form of perception
are, _mutatis mutandis_, identical with those used in his treatment of
space.[1] They are, therefore, open to the same criticisms, and need
no separate consideration.
[1] Cf. B. 46-9, §§ 4, 5 and 6 (a), M. 28-30, §§ 5, 6 and 7
(a) with B. 38-42, § 2 (1-4), and § (3) to (a) inclusive, M.
23-6, §§ 2, 3, and 4 (a). The only qualification needed is
that, since the parts of time cannot, like those of space,
be said to exist simultaneously, B. § 4 (5), M. § 5, 5 is
compelled to appeal to a different consideration from that
adduced in the parallel passage on space (B. § 2 (4), M. § 2,
4). Since, however, B. § 4 (5), M. § 5, 5 introduces no new
matter, but only appeals to the consideration already urged
(B. § 4, 4, M. § 5, 4), this difference can be neglected. B.
§ 5, M. § 6 adds a remark about change which does not affect
the main argument.
Time, however, according to Kant, differs from space in one important
respect. It is the form not of outer but of inner sense; in other
words, while space is the form under which we perceive things, time is
the form under which we perceive ourselves. It is upon this difference
that attention must be concentrated. The existence of the difference
at all is upon general grounds surprising. For since the arguments by
which Kant establishes the character of time as a form of perception
run _pari passu_ with those used in the case of space, we should
expect time, like space, to be a form under which we perceive things;
and, as a matter of fact, it will be found that the only _argument_
used to show that time is the form of inner, as opposed to outer,
sense is not only independent of Kant's general theory of forms of
sense, but is actually inconsistent with it.[2] Before, however, we
attempt to decide Kant's right to distinguish between inner and outer
sense, we must consider the facts which were before Kant's mind in
making the distinction.
[2] B. 49 (b), M. 30 (b). See pp. 109-12.
These facts and, to a large extent, the frame of mind in which Kant
approached them, find expression in the passage in Locke's _Essay_,
which explains the distinction between 'ideas of sensation' and 'ideas
of reflection'.
"Whence has it [i. e. the mind] all the materials of reason and
knowledge? To this I answer, in one word, from experience.... Our
observation, employed either about external, sensible objects, or
about the internal operations of our minds, perceived and reflected
on, by ourselves, is that which supplies our understandings with all
the materials of thinking. These two are the fountains of
knowledge...."
"First, Our senses, conversant about particular sensible objects, do
convey into the mind several distinct perceptions of things, according
to those various ways, wherein those objects do affect them: and thus
we come by those ideas we have of Yellow, White, Heat, Cold, Soft,
Hard, Bitter, Sweet, and all those, which we call sensible qualities;
which, when I say the senses convey into the mind, I mean, they, from
external objects, convey into the mind what produces there those
perceptions. This great source of most of the ideas we have, depending
wholly upon our senses, and derived by them to the understanding, I
call _sensation_."
"Secondly, The other fountain, from which experience furnisheth the
understanding with ideas, is the perception of the operations of our
own mind within us, as it is employed about the ideas it has got;
which operations, when the soul comes to reflect on, and consider, do
furnish the understanding with another set of ideas, which could not
be had from things without; and such are Perception, Thinking,
Doubting, Believing, Reasoning, Knowing, Willing, and all the
different actings of our own minds; which we being conscious of, and
observing in ourselves, do, from these, receive into our
understandings as distinct ideas, as we do from bodies affecting our
senses. This source of ideas every man has wholly in himself; and
though it be not sense as having nothing to do with external objects,
yet it is very like it, and might properly enough be called internal
sense. But, as I call the other sensation, so I call this
_reflection_; the ideas it affords being such only as the mind gets,
by reflecting on its own operations within itself."[3]
[3] Locke, _Essay_, ii, 1, §§ 2-4.
Here Locke is thinking of the distinction between two attitudes of
mind, which, however difficult it may be to state satisfactorily, must
in some sense be recognized. The mind, undoubtedly, in virtue of its
powers of perceiving and thinking--or whatever they may be--becomes
through a temporal process aware of a spatial world in its varied
detail. In the first instance, its attention is absorbed in the world
of which it thus becomes aware; subsequently, however, it is in some
way able to direct its attention away from this world to the
activities in virtue of which it has become aware of this world, and
in some sense to make itself its own object. From being conscious it
becomes self-conscious. This process by which the mind turns its
attention back upon itself is said to be a process of 'reflection'.
While we should say that it is by perception that we become aware of
things in the physical world, we should say that it is by reflection
that we become aware of our activities of perceiving, thinking,
willing, &c. Whatever difficulties the thought of self-consciousness
may involve, and however inseparable, and perhaps even temporally
inseparable, the attitudes of consciousness and self-consciousness may
turn out to be, the distinction between these attitudes must be
recognized. The object of the former is the world, and the object of
the latter is in some sense the mind itself; and the attitudes may be
described as that of our ordinary, scientific, or unreflecting
consciousness and that of reflection.
The significance of Locke's account of this distinction lies for our
purposes in its anticipation of Kant. He states the second attitude,
as well as the first, in terms of sense. Just as in our apprehension
of the world things external to, in the sense of existing
independently of, the mind are said to act on our physical organs or
'senses', and thereby to produce 'perceptions' in the mind, so the
mind is said to become conscious of its own operations by 'sense'. We
should notice, however, that Locke hesitates to use the word 'sense'
in the latter case, on the ground that it involves no operation of
external things (presumably upon our physical organs), though he
thinks that the difficulty is removed by calling the sense in question
'internal'.
Kant is thinking of the same facts, and also states them in terms of
sense, though allowance must be made for the difference of standpoint,
since for him 'sense', in the case of the external sense, refers not
to the affection of our physical organs by physical bodies, but to the
affection of the mind by things in themselves. Things in themselves
act on our minds and produce in them appearances, or rather
sensations, and outer sense is the mind's capacity for being so
affected by outer things, i. e. things independent of the mind. This
is, in essentials, Kant's statement of the attitude of consciousness,
i. e. of our apprehension of the world which exists independently of
the mind, and which, for him, is the world of things in themselves. He
also follows Locke in giving a parallel account of the attitude of
self-consciousness. He asks, 'How can the subject perceive itself?'
Perception _in man_ is essentially passive; the mind must be
_affected_ by that which it perceives. Consequently, if the mind is to
perceive itself, it must be affected by its own activity; in other
words, there must be an inner sense, i. e. a capacity in virtue of
which the mind is affected by itself.[4] Hence Kant is compelled to
extend his agnosticism to the knowledge of ourselves. Just as we do
not know things, but only the appearances which they produce in
us,[5] so we do not know ourselves, but only the appearances which we
produce in ourselves; and since time is a mode of relation of these
appearances, it is a determination not of ourselves, but only of the
appearances due to ourselves.
[4] Cf. B. 67 fin., M. 41 init.
[5] It is here assumed that this is Kant's normal view of the
phenomenal character of our knowledge. Cf. p. 75.
The above may be said to represent the train of thought by which Kant
arrived at his doctrine of time and the inner sense. It was reached by
combining recognition of the fact that we come to be aware not only of
the details of the physical world, but also of the successive process
on our part by which we have attained this knowledge, with the view
that our apprehension of this successive process is based on 'sense',
just as is our apprehension of the world. But the question remains
whether Kant is, on his own principles, entitled to speak of an inner
sense at all. According to him, knowledge begin
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