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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 Mueller, 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, Secs. 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, Secs.
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. Sec. 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.