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TRANSCRIBER'S NOTE

1. The original text includes Greek characters. For this text version these letters have been replaced with transliterations represented within square brackets [Greek: ].

2. Footnotes have been moved to the end of the chapter.

3. Apart from that, no other changes have been made in the text.

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

REFERENCES

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.

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'.

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]

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]

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'.

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.

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.

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.

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.

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]

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.

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.

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]

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.

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.

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.

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.

FOOTNOTES

[1] Locke's Essay, i, 1, §§ 2, 4.

[2] Caird, i, 10.

[3] B. 19, M. 12.

[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.)

[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.

[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.

[7] B. 5, M. 4.

[8] Ibid.

[9] B. 10, M. 7.

[10] Straightness means identity of direction.

[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.

[12] B. x-xii, M. xxvi.

[13] Cf. pp. 101-2.

[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.

[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.

[18] i. e. as not having a place in the reality which, as we think, exists independently of the mind.

[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.

[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.

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.

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]

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]

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'.

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.

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.

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.

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.

FOOTNOTES

[1] Cf. B. 1, 29, 33, 74-5, 75, 92-4; M. 1, 18, 21, 45-46, 57.

[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.

[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.

[7] This distinction within perception is of course compatible with the view that the elements so distinguished are inseparable.

[8] See p. 29, note 1.

[9] Cf. B. 1, M. 1.

[10] Cf. B. 1 init., M. 1 init.; B. 34, M. 21 sub fin.

[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).

[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.

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]

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.

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]

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.

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]

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.

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.

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]

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.

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]

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.

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]

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]

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]

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.

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]

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.'

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.

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.

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.

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.

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.

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]

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.

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]

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.

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.

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.

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.

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.

FOOTNOTES

[1] B. 58, M. 35.

[2] Cf. B. 43 init., M. 26 med.

[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.

[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).

[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.

[17] B. 38, M. 24.

[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.

[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).

[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.

[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.

[25] For a possible objection and the answer thereto, see note, p. 70.

[26] viz. that it is a priori and a pure perception.

[27] §§ 6-11.

[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.

[31] Cf. B. 42, M. 26 (a) fin., (b) second sentence.

[32] Cf. B. 43, M. 26-7.

[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.

[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."

[36] This becomes more explicit in § 8 and ff.

[37] This is also, and more obviously, implied in §§ 8-11.

[38] Pure perception only means that the space perceived is empty.

[39] Prol. § 8.

[40] The and not a, because, for the moment, time is ignored.

[41] Prol., § 9.

[42] Prol., § 11.

[43] Prol., § 10.

[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.

[45] Cf. Prol., Section 8.

[46] Prol., § 9 (cf. p. 55).

[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).

[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.

[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'.

[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]."

[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.

[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.

[59] A. reads 'only under'

[60] B. 43, M. 27.

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]

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.

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.

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.

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.

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]

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]'

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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:

"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]

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'.

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.

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.

FOOTNOTES

[1] B. 37, M. 23.

[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.

[3] B. 44, 52, 53-4, 62-3, 69-70; M. 27, 31-2, 37-8, 41-2; Prol., § 13, Remark iii.

[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.

[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.

[8] Cf. p. 93 and ff.

[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.

[13] We might add time also; but, for a reason which will appear later (p. 139), it can be neglected.

[14] I. e. the consciousness for which the problems are those of science as opposed to philosophy.

[15] 'Looks' means 'appears to sight', and 'looks' is throughout used as synonymous with 'appear', where the instance under discussion relates to visual perception.

[16] Cf. Dr. Stout, on 'Things and Sensations' (Proceedings of the British Academy, vol. ii).

[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'.

[20] Cf. pp. 72-3, and 91.

[21] Not 'appearances'.

[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.

[25] I. e. in the sense of something which exists independently of perception.

[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.

[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.)

[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.

[31] Dieses Empirische.

[32] B. 62-3, M. 37-8. Erscheinung is here translated 'appearance'.

[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.

[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.

[36] Cf. pp. 72-3.