Chapter II: System of All Principles of Pure Understanding (3)

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:--

{Logical: equivalent to absence of contradiction.
{Empirical: in the wider sense, equivalent to agreement
{with the formal conditions of experience; in the narrower
Possibility{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.