An introduction to Kant's critical philosophy

Preface

This little volume has arisen from a need felt in connection with undergraduate instruction on Kant. Too often Kant has been taught as merely a part in a scheme of philosophy, or as having significance only as a stage in that development of thought which the History of Philosophy presents. The consequence of this treatment has been the warping of his views to suit the general scheme. In opposition to this, we have attempted in this statement of the Critique of Pure Reason to bring out the many-sidedness of his system in itself, and for itself, and to show its significance as more than merely a propaedeutic for further reflections.

We have been painfully conscious of the divergent and even sometimes conflicting tendencies of Kant's thought, and in the opportunities which it thus offers for different interpretations. We have not ignored these conflicting tendencies in his thought for the sake of a unified interpretation, but since we wanted to present what Kant said, rather than what we think Kant ought to have said in order to be consistent, we have thought it better to present them as we found them.

In the observations that we have made from time to time, we have taken those aspects of the diverging tendencies which seemed to us to have been involved in his fundamental position, and upon which he seemed to insist with emphasis.

v

VI PREFACE

The selections from Kant and the observations that have been made, we believe, give a true statement of Kant. We make no pretense of giving a complete interpretation of him. We have tried merely to give a statement of him which would bring out the continuity of the thought, which would emphasize the problems he considered and how they arise, — in short, a statement which ought in some degree to meet the needs of the ordinary student.

In the treatment itself, Kant's own language is very largely taken. The translation used principally is that by Max Mueller, though at times we have made use of the Meiklejohn translation, or have made our own translation.

Glossaries of technical terms as used by Kant are frequently unsatisfactory, and so in the index we mention the principal terms and refer to Kant's own definition of them in the text.

Princeton, N. J. ; 1914.

Contents

PAGE

Historical Development of Kant's Problem i

Metaphysical Exposition of Space 27

Book I. Analytic of Concepts 47 Discovery of the Categories 48

Transcendental Deduction of the Categories 54

Subjective Deduction 56

Of the Synthesis of Apprehension in Intuition 57

Of the Synthesis of Reproduction in Imagination . . 58

Of the Synthesis of Recognition in Concepts 60

Objection Deduction 63

Book II. Analytic of Principles 100 Schematism of the Pure Concepts of the Understanding 100

Principles of the Pure Understanding 101

Axioms of Intuition 103

Anticipations of Perception 104

Analogies of Experience 106

Postulates of Empirical Thought in General 127

Refutation of Idealism 131

Transition to the Transcendental Dialectic 139

The Paralogisms of Pure Reason 150

vii

Vlll CONTENTS

PAGE

Refutation of Mendelssohn's Proof of the Permanence of the Soul 160

Conclusion of the Solution of the Psychological Paralogism 170

General Note on the Transition from Rational Psychology to Cosmology 172

The Antinomy of Pure Reason 177

The Ideal of Pure Reason 196

Criticism of the Ontological Proof for the Existence of God 201

Criticism of the Cosmological Proof for the Existence of God 205

Criticism of the Physi co-Theological Proof for the Existence of God 208

The Regulative Use of the Ideas 212

KANT'S CRITICAL PHILOSOPHY

Modern philosophy may be divided into two great periods: before, and after Kant.

In the Pre-Kantian period there are two opposed lines of development, Englis h^nipirieism and Continental r ationalism. Contine ntal r ati onalism is based on the pri nciple that all true know ledge jgjieri yed from re ason and not from exp erience. More precisely stated, the Continental school maintained that there are in the mind, prior to all experience, inn ate ideas and principle s as self-evident as the axioms of mathematics. From these ideas and principles, they held, it is possible to deduce a se£ureineta^lry^icjust as Euclid deduced his system of geometry.

To understand the reason for this position, one must remember that mathematics was the dominant science

of the time, and that Descartes and Leibniz were m ather maticians of n ote who had made important contributions to the science. Under such conditions it was riatux aJ for_them to look upon the m athematic al mp^^ qg fVlf> o nly method of attaining true knowledg e. Truejjiowledge. is univexsaljjioVjiecessary; and mat hematics furnishes such knowledge. The mathematician does not have to prove in the case of each particular triangle that the three angles are equal to two right angles. He proves its truth from the very nature of the triangle and hence his proof has universal validity. Therefore the rationalist concludes that experience is not the basis of the proofs by means of which we arrive at necessary conclusions; and yet necessary conclusions alone deserve the name of knowledge. The rationalist does not deny that we get valuable information from experience; but he denies that such information is knowledge in the strict sense of the term. It lacks universality and necessity and, in so far, lacks the characteristics of true knowledge.

Rationalism, therefore, implies the application of the mathematical method to philosophy. The scholastic doctrine of essence seems to make this method feasible. The scholastic doctrine of essence holds that in addition to the qualities of a thing, there exists a substance or essence from which the qualities necessarily arise. The existence of a certain essence involves the existence of certain qualities. Therefore a knowledge of the essences of things would make it possible to deduce their properties with strict universality and necessity without any reference to experience. This knowledge the rationalists seek to validate by a general doctrine of innate ideas. On the basis of this doctrine and in this way all true knowledge may be derived.

The truth or falsity of the rationalistic doctrine is a question of fact. Locke insists that we have no knowledge of the essences of real things. We know the essences in the case of mathematics because we are dealing with objects of our own creation. When we are concerned with real objects, we are entirely dependent upon experience. Obviously we have no innate ideas, for were such ideas in the mind from birth, it would be possible for us to deduce everything with certainty and ease without any reference to experience. Knowledge, as a matter of fact, is gained slowly and laboriously by means of experience; whereas it would be apparent almost at once were such ideas a part of our mental equipment. The slow growth, the imperfections, and the limited extent of our knowledge show the falsity of the doctrine of innate ideas.

In the light of his criticism of innate ideas, Locke, in the first book of the Essay, says that knowledge arises when the faculties of mind act on the materials furnished by sense. Unfortunately Locke later interprets this to mean that all knowledge is furnished by sense experience. Sense experience, as given, now becomes everything and synthetic activity is ignored. The empirical doctrine, therefore, makes its appearance not as the logical result of sound criticism of rationalism but as a reaction against it.

The empirical doctrine, in the form now being considered, looks upon the mind as passive. It has no knowledge until something happens to it. It is empty until experience comes, and after experience has made its contribution, mind can add nothing. At most it can only order the sense-given material. Kant points out the fundamental defect in this view when he proves that without some activity, no experience is possible. We may be unconscious of the basal activities underlying consciousness, but the results prove their presence.

Locke compares the mind to a chamber with windows, the windows are the senses and through them knowledge comes into the mind. External objects, as it were, impress themselves on mind as a seal impresses wax. Up to this point mind is passive, but after sensations are aroused, it remembers, compares, desires, and wills. In a word, all knowledge depends upon experience either inner or outer.

All ideas originally given by sensation and reflection are simple and unrelated. From these simple ideas complex ideas are formed. In the second book of the Essay, Locke applies this doctrine to the various facts of experience to see if it will stand the test. On the whole, he seems to be satisfied with the result. We must now ask if he is as successful as he thinks.

In the phenomenal world as known by us, there are objects which we look upon as causing sensations in us and to which we refer those sensations as qualities. We never think in terms of subjective sensations, but in terms of objects and the laws of objects. The senses might give us information concerning the qualities of objects, but there is no sense by which we can perceive the thing that has the qualities. Locke admits that here is an element that does not come from experience. The idea of substance, he says, is the idea of an unknown something which supports the qualities, in which the qualities inhere, and in which they are united. We can not think of qualities as existing by themselves, we are forced to think of them as relating to and supported by some thing. This is what the idea of substance means according to Locke.

The significance of Locke's admission becomes apparent when we consider the part which things play in our

HISTORICAL DEVELOPMENT OE KANT S PROBLEM 5

world. The order of sensations is changed by many accidental circumstances and all would be chaos if we had no objective principles of order. We have an ordered world because we refer sensations to things which are supposed to have objective relations with one another. Without such an objective order no experience would be possible.

Locke assumes the existence of a real material world, and he often takes the position that this world is correctly represented by the primary qualities. It is a world of solid objects, extended in space and capable of motion. At other times he says that the real essences of things are unknown. His reason for asserting the existence of a material world is to be found in the fact that sensations are forced upon us and he assumes that they must be caused by material things.

The preceding argument is based on the assumption that we know causality as an ontological principle. If that principle can not be derived from experience, in his sense of the term, Locke so far as he is an empiricist, has no right to employ it. Now the principle of causality asserts that everything which comes into existence must have a cause. Hume and Kant will show that this principle can not be derived from sense experience.* Fur-

* This statement must not be interpreted to assert that Hume and Kant hold identical positions, nor does it assert that sense experience is in no wise involved in causality. The consideration of this text as a whole will tend to indicate that Kant actually derives knowledge of the existence of causality from a thorough analysis of the world of objective experience, even though experience does not show the real nature of causality as an ontological principle.

thermore, even if we were to grant that the principle could be derived from experience, we could still assert that it gives us no information concerning the nature of a cause outside the field of experience. The cause may be God as Berkeley maintains, and even if it is some physical existence, the theory of representative perception gives us no right to say that some of our ideas are like the cause while others are not.

The empirical doctrine does not warrant the assertion of the existence of God. Locke recognizes that this is so, and proceeds to prove God's existence in a rationalistic manner as follows. From eternity there must have been something; else nothing could now exist. Suppose there is no eternal being, then by hypothesis at one time there would have been nothing, but out of nothing comes nothing. Hence nothing could have existed at any time if at one time there had been nothing. Therefore God exists.

From the preceding discussion it will be apparent that Locke's philosophy contains many diverse elements. He assumes the existence of a material world on the one hand and a number of isolated selves on the other. Then he adopts the physiological method to get some connection between these separate elements. Whenever necessary, rational principles are called in to aid experience. Material things act upon the organs of sense and produce atomic sensations. The self, observing and comparing these sensations furnishes all knowledge of relations including those of space and time.

It is possible to explain the presence of contradictory elements in Locke's philosophy as follows. Locke's ideal of knowledge was rationalistic. Like the rationalists, he takes mathematics as an example of what knowledge should be. But he differs from the rationalists in holding this ideal to be unrealizable except in mathematics and morals. He holds that in mathematics and morals we make our objects, and so have a complete knowledge of them. Hence in respect to them we can deduce the properties with strict necessity. In all other branches of knowledge, on the contrary, we are dealing with objects independent of mind. In the case of real objects, we do not know the essences because our faculties have serious limitations. Therefore, when dealing with matters of fact, it becomes necessary to give up deduction in favor of experience. Experience does not enable us to make universal statements, but it is our only substitute for the more satisfactory rational knowledge. Thus, though Locke is rationalistic in so far as his ideal of knowledge is concerned, he is forced reluctantly to admit that this ideal can be realized only in cases where we make our own objects. As no other course is possible, he takes experience as a last resort.

Before considering Hume, who exerted a profound influence on Kant, we must notice some of Berkeley's conclusions, as they throw considerable light on Hume's general position.

Berkeley reduces matter to simple ideas plus the notion of some cause. This was not very difficult after Locke's discussion of essences. Locke there took the position that all qualities depend upon unknown essences. It was an easy step from this view to Berkeley's position that matter does not exist. Since spirit is the only cause known by us, Berkeley affirms that all ideas not produced by finite spirits are caused by God. These ideas and their order constitute what we call nature.

The general view held by Berkeley is a result of three main assumptions. If one adopts the standpoint of representative perception, ideas coming into mind, by the way of the sense organs, are connected with external reality by a very slender thread. All that we require is some cause capable of producing these sensations. On this point of view, as Descartes admits, the material world might be annihilated and make no difference in our knowledge unless our subjective experience were changed. Berkeley discards matter because it is unknown and its causal activity inconceivable. But although he holds material causality to be inconceivable, Berkeley assumes the principle of causality as a self-evident truth. It becomes one of his most useful instruments. Spirits cause all ideas. God produces our sensations, the atomic material of our world. Spirits are assumed as abstract substances capable of producing and receiving ideas. Finite spirits add external relations to the given atomic and relationless materials of sense. Sensations are neither causes nor effects of other sensations, but they come with a degree of uniformity which we can make use of in our conduct. They are signs or indications of what may be expected to come.*

The main points of the preceding discussion may be summarized as follows. After denying the existence of matter, Berkeley retains the physiological method and

* This view is very much like one phase of Hume's doctrine of causality.

with it all the machinery of representative perception. Causality is accepted as a self-evident principle in spite of our inability to understand how physical things could produce any effect. And finally, Berkeley assumes the existence of selves as abstract substances despite the fact that such substantial spirits are open to all the criticisms which he makes against material substances.

Hume is inclined to take a position contradictorily opposed to the subjective idealism of Berkeley. We venture this assertion in face of the fact that his outcome is unsatisfactory, mainly because he falls back upon the untenable principles of his predecessors. The general tone of Hume's doctrine tends toward phenomenalism. In accordance with this tendency, he attempts to overcome the false duality of ideas and objects. He would take concrete experience for his point of departure. It is apparent that he has no desire to adopt the theory of representative perception. We see this side of Hume in his early statements concerning impressions and ideas. Here we do not seem to start from the assumption that ideas are subjective states of mind. We start from a concrete experience in which subjective and objective are not arbitrarily sundered and set over against each other. This tendency is to the fore in the more valuable portions of Hume's discussions concerning causality, self, and physical substance. Here he emphasizes the fact that we should study concrete experience and not use false abstractions as principles of explanation. We can not get back of experience, all our knowledge is confined to the sphere of possible experience. This point of view is quite in line with the spirit of Kant's philosophy.

IO INTRODUCTION TO KANT S CRITICAL PHILOSOPHY

Unfortunately, however, Hume is never able to free himself from the subjective view of knowledge and the physiological method. If our impressions depend upon the sense organs, they are separate subjective elements and imply an external cause. It now becomes necessary to adopt the doctrine of representative perception. Proceeding in accordance with this general view, Hume bases his analysis of experience on the sense organs, and any idea not derived from sensation is pronounced false. Thus, Hume impelled by this point of view, adopts most of the erroneous assumptions of his predecessors.

Armed with the doctrine that experiences are separate, and though associated are not essentially related, Hume proceeds to examine those principles which imply a real connection. In other words, he proceeds to examine the notion that experiences belong to a self, are related to a world of objects, and are necessarily connected with each other.

In this examination Hume has two ends in view. First, he rules out everything not derived from separate experiences. Secondly, he attempts to show how the false ideas, thus ruled out, come into existence.

Hume holds that all false ideas arise from the association of separate experiences. The physiological point of view led him, as we have seen, to assert the atomic nature of experiences. If he had not, however, in contradiction to the atomic view, held that separate experiences are related and thus associated, he could not have explained why things appear to us as they do. Without the principles of association, his philosophy can give no plausible account of human experience.

HISTORICAL DEVELOPMENT OF KANT S PROBLEM II

Kant, as we shall see, seizes upon this truth and emphasizes both the subjective and the objective principles of synthesis.

If the laws of association are supposed to relate arbitrarily the unrelated atoms of experience, they do not enable Hume to account for our space and time experience. In the end he is forced reluctantly to admit that these ideas refer to the manner in which objects appear to us. He is driven to this conclusion by the following considerations. Each impression is a separate fact resulting from a particular sense and there is no special sense to give space and time.* As all our experiences are in time, and all our impressions of outer sense are referred to space, or to things in space, these ideas can not be explained away. Of the idea of substance it is possible to say that it is an idea produced by a false association of ideas. Obviously, however, space and time resist this method of explanation. No grouping of non-spatial and non-temporal units can produce space and time.f

Hume's final position concerning space and time is an inconsistent compromise. It is, in substance, as follows. Nothing but impressions disposed in a certain manner exist. As the ideas of space and time are not ideas

* Space and time are indivisible wholes and can not come from separate experiences. They are not made up of parts, consequently, if given by separate impressions, each impression would have to give the whole of space or time; but this is impossible.

t The idea of substance may be the idea of something behind the world of perception and gives little trouble, but in space and time, we are dealing with factors involved in the world of perception.

of separate impressions, they must be ideas of the manner or order in which impressions are arranged. But the manner in which impressions are arranged is obviously not a separate impression. Hume's view here is inconsistent with his conception of experience as atomic; it, however, is entirely consistent with the phenomenalistic tendency in his thought. Kant's solution of these problems is more satisfactory.

When we turn to Hume's penetrating examination of the causal principle, several points should be emphasized. Among the most important of these is his insistence that temporal conjunction is a necessary part of the idea. This in itself would make him deny the possibility of reducing causality to logical explanation — a reduction that had been attempted by the rationalists. After an examination of several arguments concerning the nature of causality which the rationalists had put forward, Hume concludes that they are all fallacious. The principle of causality can not be demonstrated by reason; nor is it intuitively certain. It is impossible to prove its necessity either as a general principle or in particular cases. The knowledge of this relation is not, in any instance, attained by reasonings a priori* Let an object be presented to a man of ever so strong natural reason and abilities; if that object be entirely new to him, he will not be able, by the most accurate examination of its sensible qualities, to discover any of its causes or effects. Adam, though his rational faculties be supposed, at the very first, entirely perfect, could not

* Philosophical Works of David Hume. 4 vols. Boston, Little, Brown & Co. Edinburgh, A. & C. Black. 1854, vol. 4, pp. 30-32.

have inferred from the fluidity and transparency of water, that it would suffocate him; or from the light and warmth of fire that it would consume him. Furthermore, every effect is a distinct event from its cause. In vain, therefore, should we pretend to determine any single event, or infer any cause or effect, without the assistance of observation and experience.* Reason, therefore, is unable to discover any causal connection.

Experience, just as little as reason, enables us to discover any necessary connection between events. From experience we never learn anything more than that, as a matter of fact, events follow each other in a certain order. Against the contention that we are at least conscious of an internal power whereby the will is able to produce bodily movements or call up ideas, Hume retorts that these instances of connection are quite as baffling as any others. We do not in the least understand the means whereby the mind exerts an influence on the body, and we are just as little acquainted with any power in the soul which would enable it to produce ideas voluntarily. In this connection Hume asks, Is there not here, either in a spiritual or material substance, or both, some secret mechanism or structure of parts, upon which the effect depends, and which being entirely unknown to us, renders the power or energy of the will equally unknown and incomprehensible? f

As none of our faculties furnish the idea of necessary

connection, how are we to explain the fact of its presence?

Hume answers that it comes from custom or habit. In

single instances of causality we discover only that one event follows another. Such events seem conjoined, but never necessarily connected. If, however, one particular species of events has always been conjoined with another, when one appears we predict the existence of the other. We now assume a connection between them; some power in the one which necessarily produces the other. Thus the idea of necessary connection arises from several instances of conjunction but never from a single case. But as we suppose all instances exactly alike we must conclude that after the repetition of similar instances, the mind is carried by habit, upon the appearance of one event, to expect its usual attendant. We then feel a new impression, to wit, a customary connection in the thought or imagination between one object and its usual attendant; and this sentiment is the original of that idea for which we seek. When we say, therefore, that one object is connected with another, we mean only that these objects have acquired a connection in our thought, by means of which they become proofs of each other's existence.

In light of the preceding discussion, Hume now defines cause to be an object followed by another, and where all the objects, similar to the first, are followed by objects similar to the second. Or, in other words, where, if the first object had not been, the second never had existed. The appearance of a cause always conveys the mind, by a customary transition, to the idea of the effect. We may, therefore, give another definition of cause; and call it, an object followed by another, and whose appearance always conveys the thought to that other. Hume points out that both these definitions are drawn from

HISTORICAL DEVELOPMENT OP KANT 7 S PROBLEM 1 5

circumstances foreign to the cause and that we are unable to indicate anything in the cause which gives it a connection with the effect. We have no idea of this connection; nor even any distinct notion what it is we desire to know, when we endeavor at a conception of it. We say, for instance, that the vibration of this string is the cause of this particular sound. But what do we mean by that affirmation? We either mean, that this vibration is followed by this sound, and that all similar vibrations have been followed by similar sounds: or, that this vibration is followed by this sound, and that, upon the appearance of one, the mind anticipates the senses, and forms immediately an idea of the other. We may consider the relation of cause and effect in either of these two lights; but beyond these we have no idea of it.*

It was Hume's destructive criticism of the causal idea which led Kant to a new and more searching analysis of experience. As an outcome of his investigation, Kant maintains our right to employ causality as an objective principle. It would be a grave error, however, to suppose that Kant either refutes or attempts to refute most of Hume's contentions. Kant agrees with Hume in holding that the principle is not intuitively certain and that it can not be demonstrated by abstract logical reasoning. Furthermore, no analysis of particular events is able to show why they must be connected as they are. Therefore, Hume and Kant are in agreement in the contention that although mind instinctively connects things as causally related, we have no way of knowing the real nature of this connection. The nature of real causal * Loc. cit., pp. 84-89.

activity appears to both to be incomprehensible. Hume, however, just because he adopted the physiological point of view, had to deny that causality is a true constitutive principle in the phenomenal world. Because he looks upon knowledge as a subjective process, Hume is unable to take advantage of the deeper implications of his own critical work. Kant, benefiting by Hume's mistake, gave the causal principle full significance and necessity as a constitutive principle within the world of experience. He saw, as against Hume, that the principle is necessarily involved in all our objective experience.

Hume is commonly supposed to have denied the existence of the self; and indeed such denial would be the necessary outcome of an insistence that ideas and impressions are unrelated. But when Hume's argument is interpreted more sympathetically, we find in it an attempt to refute the substance idea of mind. In opposition to the substance view, Hume justly holds that mind or self is to be found only in the unity of experience, and not as a substance back of such experiences. If we look upon Hume from this point of view, it becomes evident that he marks a great advance over his predecessors, and had it not been for his physiological method, he would have reached a position similar to the one finally worked out by Kant.

Hume's criticism of material substances is similar to his criticism of mental substances. It should have led him to deny the existence of any abstract separation between ideas and things. But instead of appreciating the true outcome of his argument, he is again misled by his physiological method and denies that perceptions have any continuous existence.

On the whole, Hume's conclusions are sceptical. He holds that it is impossible for us to solve the ultimate questions of metaphysics; it is not given us to know essences and ultimate causes. But if Hume's philosophy is called sceptical, one must after all remember that it was the kind of scepticism capable of being developed into the critical philosophy of Kant. Most of Hume's difficulties can be traced back to the position that knowledge is subjective. Furthermore, we must not forget that this position is in direct contradiction with much of his own work. Unfortunately, Hume could not free himself from the dogmatic assumptions of his predecessors. A Kant is necessary to achieve what had been a task too difficult for Hume.