Part 2 / Book 2 — CHAPTER II SYSTEM OF ALL PRINCIPLES OF PURE UNDERSTANDING (continued 2)

It is significant that in the new argument[1238] of the second edition the space factor, emphasised in the second proof of the first edition, is again made prominent.[1239] The principle is, indeed, reformulated in such manner as to suggest its limitation to spatial existences. “All substances, so far as they can be perceived to coexist in space, are in thoroughgoing reciprocity.” Now it is decidedly doubtful whether Kant means to limit the category of reciprocity to spatial existences. As we have already noted,[1240] he would seem to hold that though the category of causality can acquire meaning only in its application to events in space, it may in its subsequent employment be extended to the states of inner sense. The latter are effects dynamically caused, and among their causal conditions are mechanical processes in space. The extension of the category of reciprocity to include sensations and desires undoubtedly gives rise to much greater difficulties than those involved in the universal application of the causal principle. On the other hand, its limitation to material bodies must render the co-ordination of mental states and mechanical processes highly doubtful, and would carry with it all the difficulties of an epiphenomenal view of psychical existences. The truth probably is that in this matter Kant had not thought out his position in any quite definite manner; and that owing to the influence, on the one hand of the dualistic teaching of the traditional Cartesian physics, and on the other of his increasing appreciation of the part which space must play in the definition and proof of the principles of understanding, he limited the category of reciprocity to spatial existences, without considering how far such procedure is capable of being reconciled with his determinist view of the empirical self. His procedure is also open to a second objection, namely, that while thus reformulating the principle, he fails to remodel his proof in a sufficiently thoroughgoing fashion. The chief stress is still laid upon the temporal element; and in order to obtain a proof of the principle that will harmonise with the prominence given to the space-factor, we are thrown back upon such supplementary suggestions as we can extract from the second argument of the first edition. It is there stated that “without dynamical communion even spatial community (communio spatii) could never be known empirically.”[1241] That is an assertion which, if true, will yield a proof of the principle of reciprocity analogous to that which has been given of the principle of causality; for it will show that just as the conception of causality is involved in, and makes possible, the awareness of time, so the conception of reciprocity is involved in, and makes possible, the awareness of space.

The proof will be as follows. The parts of space have to be conceived as spatially interrelated. Space is not a collection of independent spaces; particular spaces exist only in and through the spaces which enclose them. In other words, the parts of space mutually condition one another. Each part exists only in and through its relations, direct or indirect, to all the others; the awareness of their coexistence involves the awareness of this reciprocal determination. But space cannot, any more than time, be known in and by itself;[1242] and what is true of space must therefore hold of the contents, in terms of the interrelations of which space can alone be experienced. How, then, can the reciprocal determination of substances in space be apprehended by a consciousness which is subject in all its experiences to the conditions of time? As Kant has pointed out in A 211 = B 258,[1243] objective coexistence is distinguished from objective sequence by reversibility of the perceptions through which it is apprehended. When A and B coexist, our perceptions can begin with A and pass to B, or start from B and proceed to A. There is also, as Kant observes in the second proof, a further condition, namely, that the transition is in each case made through a continuous series of changing perceptions.

“Only the continuous influences in all parts of space can lead our senses from one object to another. The light, which plays between our eye and the celestial bodies, produces a mediate communion between us and them, and thereby establishes the coexistence of the latter. We cannot empirically change our position (perceive such a change), unless matter in all parts of space makes the perception of our position possible to us. Only by means of its reciprocal influence can matter establish the simultaneous existence of its parts, and thereby, though only mediately, their coexistence with even the most remote objects. Without communion, every perception of an appearance in space is broken off from every other, and the chain of empirical representations, i.e. experience, would have to begin entirely anew with every new object, without the least connection with preceding representations, and without standing to them in any relation of time.”[1244]

But even such reversibility of continuous series does not by itself establish coexistence. For in the imagination[1245] we can represent such series, without thereby acquiring the right to assert that they exist not as series but as simultaneous wholes. And as Kant might also have pointed out, even in sense-perception we can experience reversible continuous series that do not in any way justify the inference to coexistence. We may, for instance, produce on a musical instrument a series of continuously changing sounds, and then in immediate succession produce the same series in reverse order. An additional factor is therefore required, namely, the interpretation of the reversibility of our perceptions as being grounded in objects which, because spatially extended, and spatially continuous with one another, can yield continuous series of perceptions, and which, because of their thoroughgoing reciprocity, make possible the reversing of these series. To summarise the argument in a sentence: as the objectively coexistent, if it is to be known at all, can only be known through sequent representations, the condition of its apprehension is the possibility of interpreting reversible continuous series as due to the reciprocal interaction of spatially ordered substances.

This argument has a twofold bearing. Its most obvious consequence is that all things apprehended as coexistent must be conceived as standing in relations of reciprocal interaction; but by implication this involves the further consequence that the conceptual principle of reciprocity is an integral factor in all apprehension of space. Space, though intuitive in character, has a meaning that demands this concept for its articulation. Just as consciousness of temporal sequence is only possible in terms of causation, so consciousness of spatial coexistence is only possible through application of the category of reciprocity. And since, on Kant’s view, awareness of space conditions awareness of time, these conclusions carry the Critical analysis of our consciousness of time a stage further. In confirmation of the more general argument of the objective deduction, reciprocity is added to the already large sum-total of the indispensable conditions of our time-consciousness; while in regard to time itself it is shown that, owing to its space-reference, coexistence may be counted among its possible modes.

I have made occasional reference to the positions adopted by Stout in his Manual of Psychology, and may here indicate their relation to the present argument. Stout cites four “categories” or ultimate principles of unity which “belong even to rudimentary perceptual consciousness as a condition of its further development,”[1246] namely, spatial unity, temporal unity, causal unity, and the unity of different attributes as belonging to the same thing. The criticism which, from the standpoint of the Analogies, has to be passed upon this list,[1247] is that it ignores the category of reciprocity, i.e. of systematic interconnection, and that it fails to recognise the close relation in which the various principles stand to one another. The temporal unity must not be isolated from causal unity, nor either of them from the spatial unity, with which the category of reciprocity is inseparably bound up. Further, Kant maintains that these principles are demanded, not merely for the development of perceptual consciousness, but for its very existence.

But Kant’s argument suggests many difficulties which we have not yet considered, and we may again employ Schopenhauer’s criticisms to define the issues involved.

“The conception of reciprocity ought to be banished from metaphysics. For I now intend, quite seriously, to prove that there is no reciprocity in the strict sense, and this conception, which people are so fond of using, just on account of the indefiniteness of the thought, is seen, if more closely considered, to be empty, false, and invalid.... It implies that both the states A and B are cause and that both are effect of each other; but this really amounts to saying that each of the two is the earlier and also the later; thus it is an absurdity.”[1248]

This criticism proceeds on the assumption that the category of reciprocity reduces to a dual application of the category of causality. If that were the case, there would, of course, be no separate category of reciprocity,[1249] and further it would, as Schopenhauer maintains, be impossible to regard A and B as being at one and the same time both cause and effect of one another. Causality determines the order of the states of substances in the time series; reciprocity must be distinct from causality if it is to be capable of defining the order of their coexistent states in space. A deduction from the dual application of the conception of causality has, therefore, no bearing upon the question of the possibility of this further category. Kant has laid himself open to this criticism by a passage which occurs in the first proof, and which shows that he was not quite clear in his own mind as to how reciprocity ought to be conceived.

“That alone can determine the position of anything else in time, which is its cause or the cause of its determinations. Every substance (inasmuch as only in its determinations can it be an effect) must therefore contain in itself the causality of certain determinations in the other substance, and at the same time the effects of the causality of that other, i.e. they must stand in dynamical communion (immediately or mediately), if their coexistence is to be known in any possible experience.”[1250]

It should be noted that in the new proof[1251] in the second edition Kant is careful to employ the terms ground and influence in place of the terms cause and causality.

Secondly, Schopenhauer argues that if the two states necessarily belong to each other and exist at one and the same time, they will not be simultaneous, but will constitute only one state.[1252] Schopenhauer is again refusing to recognise the conditions under which alone a special category of reciprocity is called for. We can speak of simultaneity only if a multiplicity be given; and if it be given, its nature as simultaneous plurality cannot be comprehended through a causal law, which, as such, applies only to sequent order.

Lastly, Schopenhauer endeavours to confirm his position by examination of the supposed instances of reciprocity.

”[In the continuous burning of a fire] the combination of oxygen with the combustible body is the cause of heat, and heat, again, is the cause of the renewed occurrence of the chemical combination. But this is nothing more than a chain of causes and effects, the links of which have alternately the same name.... We see before us only an application of the single and simple law of causality which gives the rule to the sequence of states, but never anything which must be comprehended by means of a new and special function of the understanding.”[1253]

Schopenhauer is again misled by his equating of reciprocity with causal action. Combustion is quite obviously a case of sequent processes. Instead of proving that coexistence does not involve reciprocity, Schopenhauer is only showing that cause and effect may sometimes, as Kant himself observes,[1254] seem to be simultaneous.[1255] Action followed by reaction is not equivalent to what Kant means by reciprocal determination. Schopenhauer also cites the instance of a pair of scales brought to rest by equal weights.

“Here there is no effect produced, for there is no change; it is a state of rest; gravity acts, equally divided, as in every body which is supported at its centre of gravity, but it cannot show its force by any effect.”[1256]

This example is more in line with what Kant would seem to have in view, but is still defined in reference to the problem of causation, and not in reference to that of coexistence. Kant is not enquiring whether coexistent bodies are related as causes and effects, though, as we have already observed, his language betrays considerable lack of clearness on this very point. He is endeavouring to define the conditions under which we are enabled to recognise that bodies, external to one another in space and apprehensible only through sequent perceptions, are none the less coexistent. And the answer which he gives is that coexistence can only be determined by reference of each existence to the totality of systematic relations within which it is found, its particular spatial location being one of the factors which condition this reference. Causal explanation in the most usual meaning of that highly ambiguous phrase, namely, as explanation of an artificially isolated event by reference to antecedents similarly isolated from their context, may partially account for this event being of one kind rather than another, but will not explain why it is to be found at this particular time in this particular place. That is to say, it will not answer the question which is asked when we are enquiring as to what events are coexistent with it.

But the considerations which thus enable us to dispose of Schopenhauer’s criticisms have the effect of involving us in new, and much more formidable, difficulties. Indeed they disclose the incomplete, and quite inadequate, character of Kant’s proof of the third Analogy. For must not spatial co-existence be independently known if it is to serve as one of the factors determinant of reciprocity? Can the apprehension of extended bodies wait upon a prior knowledge of the system of nature to which they belong?

The mere propounding of these questions does not, however, suffice to overthrow Kant’s contention. For he is prepared—that is indeed the reason why the Critique came to be written—to answer them in a manner that had never before been suggested, save perhaps in the philosophies of Plato and Aristotle. This answer first emerges in the Dialectic, in the course of its treatment of the wider problem, of which the above difficulties are only special instances, how if conditioned parts can only be known in terms of an unconditioned whole, any knowledge whatsoever can be acquired by us. But though Kant in the Dialectic gives due prominence to this fundamental problem, the hard and fast divisions of his architectonic—and doubtless other influences which would be difficult to define—intervene to prevent him from recognising its full implications. For the problem is viewed in the Dialectic as involving considerations altogether different from those dwelt upon in the Analogies, and as being without application to the matters of which they treat.

The situation thus created is very similar to that which is occasioned by Kant’s unfortunate separation of the problems of space and time in the Aesthetic from the treatment of the categories in the Analytic. In the Aesthetic space and time are asserted to be intuitive, not conceptual, in nature; and yet in the Analytic we find Kant demonstrating that the principles of causality and reciprocity are indispensably involved in their apprehension. But even more misleading is the separation of the problems of the Aesthetic and Analytic from those of the Dialectic. Kant’s primary and prevailing interest is in the metaphysics, not in the mere methodology, of experience; and it is in the Dialectic that the metaphysical principles which underlie and inspire all his other tenets first find adequate statement. Since the third Analogy defines the criterion of coexistence in entire independence of all reference to the Ideas of Reason, Kant is thereby precluded from even so much as indicating the true grounds upon which his position, if it is to be really tenable, must be made to rest. For as he ultimately came to recognise, the intuition of space not only involves the conceptual category of reciprocal determination, but likewise demands for its possibility an Idea of Reason. In space the wider whole is always prior in thought to the parts which go to constitute it. But though Kant states[1257] that this characteristic of space justifies its being entitled an Idea of Reason, he nowhere takes notice of the obvious and very important bearing which this must have upon the problem, how we are to formulate the criterion of coexistence.

The general character of time is analogous to that of space, and our formulation of the criterion of causal sequence is therefore similarly affected. The system of nature is not the outcome of natural laws which are independently valid; natural laws are the expression of what this system prescribes; they are the modes in which it defines and embodies its inherent necessities.

The situation which these considerations would seem to disclose may, therefore, be stated as follows. If the empirical criteria of truth are independent of the Ideas of Reason, the Analytic may be adequate to their discussion, but will be unable to justify the assertion that there is a category of reciprocal or systematic connection distinct from that of causality. If, however, it should be found that these criteria are merely special applications of standards metaphysical in character—and that would seem to be Kant’s final conclusion,—only in the light of the wider considerations first broached in the Dialectic, can we hope to define their nature and implications with any approach to completeness.

4. THE POSTULATES OF EMPIRICAL THOUGHT IN GENERAL

First Postulate.—That which agrees, in intuition and in concepts, with the formal conditions of experience is possible.

Second Postulate.—That which is connected with the material conditions of experience (that is, with sensation) is actual.

Third Postulate.—That which is determined, in its connection with the actual, according to universal conditions of experience is (that is, exists as) necessary.

In this section Kant maintains that when the Critical standpoint is accepted, possibility, actuality and necessity can only be defined in terms of the conditions which render sense-experience possible. In other words, the Critical position, that all truth, even that of a priori principles, is merely de facto, involves acceptance of the view that the actual reduces to the experienced, and that only by reference to the actual as thus given can possibility and necessity be defined. The Leibnizian view that possibility is capable of being defined independently of the actual, and antecedently to all knowledge of it, must be rejected.

An analysis of the text can be profitably made only after a detailed examination of Kant’s general argument; and to that task we may at once apply ourselves. The section affords further illustration of the perverting influence of Kant’s architectonic, as well as of the insidious manner in which the older rationalism continued to pervert his thinking in his less watchful moments.

First Postulate.—In the opening paragraphs Kant uses (as it would seem without consciousness of so doing) the term possibility in two very different senses.[1258] When the possible is distinguished from the actual and the necessary, it acquires the meaning defined in this first Postulate; it is “that which agrees with the formal conditions of experience.” But it is also employed in a much narrower sense to signify that which can have “objective reality, i.e. transcendental truth.”[1259] The possibility of the objectively real rests upon fulfilment of a threefold condition: (1) that it agree with the formal conditions of experience; (2) that it stand in connection with the material of the sensuous conditions of experience; and (3) that it follow with necessity upon some preceding state in accordance with the principle of causality, and so form part of a necessitated order of nature. In other words, it must be causally necessitated in order to be empirically actual; and only the empirically actual is genuinely possible. Such is also the meaning that usually attaches to the term possible in the other sections of the Critique. A ‘possible experience’ is one that can become actual when the specific conditions, all of which must themselves be possible, are fulfilled. An experience which is not capable of being actual has no right to be described even as possible. As a term applicable to the objectively real, the possible is not wider than the actual, but coextensive with it. As Kant himself remarks, those terms refer exclusively to differences in the subjective attitude of the apprehending mind.

This ambiguity in the term ‘possibility’ has caused a corresponding ambiguity in Kant’s employment of the term ‘actuality.’ It leads him to endeavour to define the actual, not in its connection with the conditions of possibility, but in distinction from them. The possible having been defined (in the first Postulate) solely in terms of the formal factors of experience, he proceeds to characterise the actual in a similarly one-sided fashion, exclusively in terms of the material element of given sensation. Doubtless the element of sensation must play a prominent part in enabling us to decide what is or is not actually existent, but no definition which omits to take account of relational factors can be an adequate expression of Critical teaching. Indeed, we only require to substitute the words ‘sensuously given’ for ‘actual’ in Kant’s definition of the third Postulate (i.e. of the necessary) in order to obtain a correct statement of the true Critical view of actual existence: it is “that which is determined in its connection with the sensuously given according to universal conditions of experience.” For Kant the actual and the necessary, objectively viewed, coincide. Necessity is for the human mind always merely de facto; and nothing can be objectively actual that is not causally determined. As the empirically possible cannot, in its objective reference, be wider than the empirically necessary, one and the same definition adequately covers all three terms alike. While the distinctions between them will, of course, remain, they will be applicable, not to objects, but only to the subjective conditions of experience in so far as these may vary from one individual to another. Experiences capable of being actual for one individual may be merely possible for another. And what is merely actual to one observer may by others be comprehended in its necessitating connections. The terms will not denote differences in the real, but only variations in the cognitive attitude of the individual.

Thus in professing to show that the three Postulates are transcendental principles, Kant does less than justice to his own teaching. For though both here and in the opening sections of the chapter[1260] he speaks of them in this manner, i.e. as being conditions alike of ordinary and of scientific experience, he has himself admitted in so many words the inappropriateness of such a description.

“The principles of modality are nothing more than explanations [not, it may be noted, proofs] of the concepts of possibility, actuality and necessity, in their empirical use, and are therefore at the same time restrictions of all the categories to this merely empirical use, ruling out and forbidding their transcendental [= transcendent] employment.”[1261]

That is to say, these so-called principles are not really principles; they merely embody explanatory statements designed to render the preceding results more definite, and especially to guard against the illegitimate meanings which the Leibnizian metaphysics had attached to certain of the terms involved.

These considerations bring us to the real source of Kant’s perverse argumentation, namely, the artificial (but none the less imperious) demands of his architectonic. He is constrained to provide a set of principles corresponding to the categories of modality. The definitions of the modal categories have therefore to be called by that inappropriate name. But that is not the end of the matter. In order to meet the needs of his logical framework, Kant proceeds even further than he had ventured to do in the sections on the Axioms of Intuition and Anticipations of Perception. There he fell so far short as to provide only a single principle in each case. In dealing, however, with the categories of relation he has been able to define each of the three categories separately, and to derive from each a separate principle. Many of the defects in his argument are, indeed, traceable to this source. The close interrelations of the three principles are, as we have had occasion to note, seriously obscured. But still, in the main, separate treatment of each has proved feasible. Kant, encouraged, as we may believe, by this successful fulfilment of architectonic requirements, now sets himself to develop, in similar fashion, a separate principle for each modal category. But for any such enterprise the conditions are less favourable than in the case of the categories of relation. For, as just indicated, no one of the three can, on Critical principles, possess any genuine meaning save in its relation to the others. Before following out this line of criticism, we must however note some further points in Kant’s argument.

In A 219 = B 266, and again in A 225 = B 272, Kant makes the statement that a concept can be complete prior to any decision as to its possibility, actuality, or necessity. This contention is capable of being interpreted in two quite independent ways, and in only one of those ways is it tenable. He may mean that the distinction between the possible, the actual, and the necessary, does not concern the objectively real, which as such is always both actual and necessary, but only the subjective attitude of the individual towards the objects of his thought and experience. From the Critical standpoint, as we have been arguing, such a contention is entirely just. But Kant would seem in the above statement to be chiefly concerned to maintain that a conception may be complete and determinate, even while we remain in doubt whether the existence for which it stands is even possible.[1262] Such a view is merely a relic of the Leibnizian rationalism from which he is striving to break away. All existences have their place in a systematic order of experience, and no conception of them can be either complete or determinate which fails to specify the causal context to which they belong. The process of specifying the detail of a concept is the only process whereby we can define its possibility, actuality, or necessity.[1263] Were it capable of complete statement without determination of its modal character, it could never form part of a unified experience. The examples of “fictitious” concepts, which Kant cites, are either so determinate as to be demonstrably inconsistent with experience, and therefore empirically impossible, or so indeterminate as to afford no sufficient means of deciding even as to their possibility.

There is a further objection to the definition given of possibility in the first Postulate. After stating that the possible is what agrees with the formal conditions of experience, Kant proceeds, on the one hand, to argue that the forms of intuition and the categories of understanding may, in accordance with this criterion, be viewed as possible, and, on the other hand, to maintain that no other concepts can be so regarded.[1264] That is to say, the possible, as thus interpreted, does not consist in something additional to, and in harmony with, the conditions of experience, but reduces without remainder to those very forms. Now Kant is not betrayed merely by inadvertence into thus narrowing the sphere of the possible; such limitation is an almost inevitable consequence of the one-sided manner in which he has treated the concept of the possible in this first Postulate. He professes to be proceeding in the light of the results obtained in the transcendental deduction, and to be defining the possible in terms of the conditions which make sense-experience possible. But the deduction has shown that experience is possible only in so far as the material factors co-operate with the formal. And when this is recognised, it becomes obvious that a definition of the possible in terms of sensation,—namely, as that which is capable of being presented in sense-perception,—is equally legitimate, and is indeed required in order to correct the deficiencies of the definition which Kant has himself given. As both factors are indispensable in all possible experience, both must be reckoned with in defining the possible.

Kant’s argument in the fifth paragraph is somewhat obscured by its context. He is contending that fictitious (gedichtete) concepts, elaborated from the contents presented in perception, cannot be determined as possible. As they involve sensuous contents, the formal elements of experience do not suffice for proof of their possibility; and since the contents are supposed to have been recombined in ways not supported by experience, an empirical criterion is equally inapplicable. Obviously Kant is here using the term ‘possible’ not in the meaning of the first Postulate, but in its narrower connotation as signifying that which is capable of objective reality. Such fictitious concepts may completely fulfil all the demands prescribed by space, time, and the categories, and yet, as he here insists, be none the less incapable of objective existence.

The argument is still further obscured by the character of the concrete examples which Kant cites. They involve modes of action or of intuition which contradict the very conditions of human experience, and so for that reason alone fall outside the realm of the empirically possible. That would not, however, seem to be Kant’s meaning in employing them. Assumed powers of anticipating the future or of telepathic communication with other minds are, he says, concepts

“...the possibility of which is altogether groundless, as they cannot be based on experience and its known laws, and without such confirmation are arbitrary combinations of thoughts, which, although indeed free from contradiction, can make no claim to objective reality and so to the possibility of an object such as we here profess to think.”[1265]

The mathematical examples which Kant gives in A 223 = B 271[1266] are no less misleading. The concept of a triangle can, it is implied, be determined as possible in terms of the first Postulate, since it harmonises with a formal condition of experience, namely, space. This is true only if it be granted that construction in space can be executed absolutely a priori, in independence of all sense-experience. Such is, of course, Kant’s most usual view; and to that extent the argument is consistent. Mathematical concepts will from this point of view represent the only possible exception to the general statement that the formal conditions of experience constitute a criterion of possibility for no concepts save themselves. Kant’s final conclusion is clearly and explicitly stated in the following terms:

“I leave aside everything the possibility of which can be derived only from its reality in experience, and have here in view only the possibility of things through a priori concepts; and I maintain the thesis that the possibility of such things can never be established from such concepts taken in and by themselves, but only when they are viewed as formal and objective conditions of experience in general.”[1267]

We are now in a position to appreciate the reasons which have induced Adickes to regard the text as of composite origin.[1268] Adickes argues that Kant’s original intention was to treat the three concepts together, showing that they can be defined only in empirical terms, and that their significance is consequently limited to the world of appearance. Such is the content of the first, second, fourth (excepting the first sentence), and fifth paragraphs. No attempt is made to separate the three Postulates, and the term possibility is throughout employed exclusively as referring to objective reality. (In the third paragraph it is used in both senses.) The other paragraphs were, according to Adickes’ theory, added later, when Kant unfortunately resolved to fulfil more exactly the requirements of his architectonic. That involved the formulation of three separate Postulates, with all the many evil consequences which that attempt carried in its train. He must then have interpolated the third paragraph, added the first sentence to the fourth paragraph, corrected the too extensive sweep of the older paragraphs through the introduction of the sixth paragraph, further supplemented the exposition of the first Postulate by the seventh paragraph, and added independent treatments of the postulates of actuality and necessity. This may seem a very complicated and hazardous hypothesis; but careful examination of the text, with due recognition of the confused character of the argument as it stands, will probably convince the reader that Adickes is in the right.

Second Postulate.[1269]—Perception is necessary to all determination of actuality. The actual is either itself given in perception or can be shown, in accordance with the Analogies, to stand within the unity of objective experience, in connection with what is thus given. So long as Kant expresses himself in these terms his statements are entirely valid. Nothing which cannot be shown to be bound up with the contingent material of sense-experience can be admitted as actual. He proceeds, however, to give a definition of actuality which entirely omits all reference to the Analogies, and which is open to the same fundamental criticism as his characterisation of possibility in the first Postulate. Though the earlier statements give due recognition both to the material content and to the relational forms constitutive of complete experience, Kant now contrasts the mere or bare (blosser) concept and the given perception in a manner which suggests the unfortunate distinction drawn in the Prolegomena, and repeated in the second edition of the Critique, between judgments of perception and judgments of experience.[1270] Kant’s reference to “the mere concept of a thing”[1271] is on the same lines as the opening paragraph of the section. However complete the concept may be, it yields not the least ground for deciding as to the existence of its object.

Kant’s thinking, as I have already pointed out, is here perverted by the continuing influence of the Leibnizian rationalism. He is forgetting that, on Critical principles, even the categories are meaningless except in their reference to the contingently given. If that be true of the strictly a priori, it must hold with even greater force of empirical concepts with sensuous content. As the sole legitimate function of concepts, whether a priori or empirical, is to organise and unify the material of sense, there can be no such thing as the mere or bare concept. Such a combination of words is without Critical significance. A concept as such must refer to, and embody insight into, the real. Only in proportion to its incompleteness, that is, to its indefiniteness, can it remain without specific and quite determinate location within the context of unified experience. It may, indeed, be found convenient to retain the phrase “mere concept” notwithstanding its misleading character and rationalistic origin. It must, however, be used only to mark the indefiniteness, indeterminateness, or incompleteness which prevents it from adequately revealing the denotation to which through the nature of its content it necessarily refers. Meaning and existence, connotation and denotation, are complementary the one to the other, and though not, perhaps, coextensive (if that term has itself meaning in this connection), are none the less inseparably conjoined. When Kant’s utterances, as frequently happens, imply the contrary, they may be taken as revealing the strength and insidious tenacity of the influences from which he was sufficiently courageous, but not always sufficiently watchful, to break away.

The doctrine of the “mere concept” finds its natural supplement in the equally un-Critical assertion that

“...perception [evidently employed in the less pregnant sense, as signifying ‘sensation accompanied by consciousness’], which supplies the material to the concept, is the sole character of actuality.”[1272]

This same position is expressed equally strongly by Kant in his Reflexionen (ii. 1095).

“Possibility is thought without being given; actuality is given without being thought; necessity is given through being thought.”

Such statements are entirely out of harmony with Kant’s central teaching. There is no lack of passages in the Critique which inculcate the direct contrary. Though the element of sensation is a sine qua non of all experience of the actual, the formal elements are no less indispensable. In their absence the merely given would reduce to less than a dream; for even in dreams images are interpreted and are referred to some connected context. The given, merely as such, cannot enter the field of consciousness, and is therefore “for us as good as nothing.” As Caird has pointed out, we find in Kant

“...two apparently contradictory forms of expression—(1) that the understanding by means of its conceptions refers our preceptions to objects, and (2) that conceptions are referred to objects only indirectly through perceptions. The former mode of expression is preferred whenever Kant has to show that ‘perceptions without conceptions are blind’; the latter when he has to show that ‘conceptions without perceptions are empty.’”[1273] “We can understand the possibility of Kant’s looking at the subject in these two opposite ways, only if we remember the reciprocal presupposition of perception and conception in the judgment of knowledge, and the way in which Kant tries to explain it, now from the point of view of perception, and now from the point of view of conception. The effect of this is, no doubt, a formal contradiction which Kant himself never disentangles, but which we must endeavour to disentangle, if we would do justice to him.”[1274]

The one-sidedness of Kant’s definition of actuality is certainly due to the cause suggested by Caird. The definition, notwithstanding its misleading character, serves to enforce against the older rationalism, with which Kant throughout this section is almost exclusively concerned, the central tenet through which the Critical teaching is distinguished from that of Leibniz, namely, that neither existence, possibility, nor necessity, can be established save by reference to the contingent nature of the sensuously given. Proof by reference to the possibility of experience can establish only those conditions which can be shown to be de facto necessary in order that consciousness of time may be accounted for. The formal conditions of experience, which in and by themselves are determinable neither as actual nor as possible, are established as actual, and so as necessary, by reference to the merely given; they are necessary only in this merely relative fashion, as being indispensable to what can never itself be viewed as other than contingent.

“Our knowledge of the existence of things reaches, then, only so far as perception and its continuation according to laws of nature can extend. If we do not start from experience, or do not proceed according to laws of the empirical connection of appearances, our guessing or enquiring into the existence of anything will only be an idle pretence.”[1275]

Polemically, therefore, Kant’s formulation of the second Postulate is not without its advantages, though from the inner standpoint of Critical teaching it is altogether inadequate.

For comment upon A 226 = B 273, and upon the general teaching of this Postulate in its important bearing upon Kant’s phenomenalism, cf. above, pp. 318-19.

B 274-9.—Refutation of Idealism, cf. above, p. 308 ff.

Third Postulate.[1276]—In the opening sentence Kant draws the distinction which was lacking in his treatment of the first Postulate between ‘material’ and ‘formal’ modality. (No distinction, however, is drawn between the ‘formal’ possibility of the first Postulate and logical possibility, which consists in absence of contradiction.) It is with the former alone that we have to deal. As existence cannot be determined completely a priori, necessity can never be known from concepts, but only by reference to the actually given, in accordance with the universal principles that condition experience. Further, since such empirical necessity does not concern the existence of substances, but only the existence of their states, viewed as dynamically caused, the criterion of empirical necessity reduces to the second Analogy, viz. that everything which happens is determined by an antecedent empirical cause. This criterion does not extend beyond the field of possible experience, and even within that field applies only to those existences which can be viewed as effects, i.e. as events which come into existence in time, and of which therefore the causes are of the same temporal and conditioned character. The necessity is a hypothetical necessity; given an empirical event, it can always be legitimately viewed as necessitated by an antecedent empirical cause.

Kant introduces, reinterprets, and in this altered form professes to justify, four of the central principles of the Leibnizian metaphysics. In mundo non datur casus gives expression to the above empirical principle. Non datur fatum may be taken as meaning that natural (i.e. empirical) necessity is a conditioned and therefore comprehensible necessity, and is consequently not rightly described as blind. The other two principles, non datur saltus, and non datur hiatus connect with the principle of continuity already established in the Anticipations of Perception and in the second Analogy.

Kant’s further remarks reveal an uneasy feeling that he is neglecting to assign these principles to the pigeon-holes provided in his architectonic. The reader, he states, may easily do so for himself. That may be so, but only if the reader be permitted the same high-handed methods of adjustment that are here illustrated in Kant’s location of non datur fatum with the principles of modality.[1277]

In the next paragraph (A 230 = B 282) Kant suddenly, without warning or explanation, attaches to the term possibility a meaning altogether different from any yet assigned to it. He now takes it as equivalent to the absolutely or metaphysically possible. Combining this with the meanings previously given to it by Kant we obtain the following table:—

Possibility– Logical: equivalent to absence of contradiction.

Empirical: in the wider sense, equivalent to agreement with the formal conditions of experience; in the narrower or stricter sense, involving in addition the capacity of being presented in sense-experience.

Metaphysical: equivalent to absolute possibility, a conception not of understanding but of Reason.

When this last meaning is given to the term, an entirely new set of problems arises, to the confusion of the reader who very properly continues to employ the term possibility in the empirical sense which, as Kant has been insisting, is alone legitimate. Kant has temporarily changed over to the standpoint of the metaphysical view which he has been criticising, and accordingly uses the term ‘possibility’ in the Leibnizian sense. Is Leibniz, he asks, justified in maintaining that the field of the possible is wider than the realm of the actual, and the latter in turn wider in extent than the necessary? In reply Kant accepts the metaphysical meaning assigned to the term ‘possibility,’ but restates the problem in Critical fashion. Do all things belong as appearances to the context of a single experience, or are other types of experience possible? Do other forms of intuition besides space and time, other forms of understanding besides the discursive through concepts, come within the range of the possible? These are questions which fall to be answered, not by the mere understanding, the sole function of which is empirical, but by Reason, which transcends the world of appearance.

Kant introduces these questions, as he is careful to state,[1278] only because they are currently believed to be within the competence of the understanding; and he now for the first time points out that possibility, in this sense, means absolute possibility, that which is independent of all limiting conditions, a meaning ruled out by the preceding treatment of the modal categories. Like all other absolute conceptions, it belongs to Reason, and must therefore await treatment in the Dialectic. These admissions come, however, only after the discussion has been completed. Had Kant reversed the order of the two paragraphs which constitute this digression, and marked them off as being a digression, he would have greatly assisted the reader in following the argument.

Kant adds a refutation of the merely logical arguments by which Leibniz had professed to establish the priority and greater scope of the possible. From the proposition, everything actual is possible, we can infer by immediate inference that some possible things are actual. That, however, would seem to imply that part of the possible is not actual, and that something must be added to the possible in order to constitute the actual. But this, Kant replies, is obviously an untenable view. The something additional to the possible, not being itself possible, we should be constrained to regard as impossible. For our understanding,[1279] the possible is that which connects with some perception in agreement with the formal conditions of experience. (Kant here gives the correct Critical definition of the possible, by combining the two first postulates.) Whether, and how far, other existences beyond the field of sense experience are possible, we have no means of deciding.

B 288-294.—This second edition section emphasises the fact that possibility cannot be determined through the categories alone, but only through the categories in their relation to intuition, and indeed to outer intuition. Possibility is throughout taken as referring to objective reality. The section is chiefly important in connection with the problems bearing on the relation of inner and outer sense and on the nature of our consciousness of time.[1280]

In B 289-91 Kant criticises those rationalistic arguments which rest upon the equating of necessity of thought with necessity of existence. When it is sought by mere analysis of concepts to prove that all accidental existence has a cause, the most that can be shown is that the existence of the accidental cannot be comprehended by us, unless the existence of a cause be assumed. But we may not argue that a condition of possible understanding is likewise a condition of possible existence.[1281] What is or is not possible for thought is, without special proof, no sufficient criterion of what is or is not possible in the real. If, again, the term accidental be taken as meaning that which can exist only as a consequence of some other existence, the general principle becomes merely analytic, and must not be taken as establishing the synthetic principle of causality. The latter demands transcendental proof by reference to the possibility of contingent experience.