therefore explains the possibility of as much synthetic a priori cognition as is presented by the general theory of motion, which is no less fruitful.” (KrV B49)69
Without succession no change would be possible: the passage from A to non A would be only a contradiction and the variety and multiplicity of experience could not be explained. For instance, a chrysalis turns into a butterfly only through time. Butterflies have a life cycle consisting of four stages: from egg to larva, through a chrysalis and finally to become a butterfly. Without the succession in time the progress from one stage to another could not be possible.←60 | 61→
Now, a question arises from these considerations:
“Now how can an outer intuition inhabit in the mind that precedes the objects themselves, and in which the concept of the latter can be determined a priori? Obviously not otherwise than insofar as it has its seat merely in the subject, as its formal constitution for being affected by objects and thereby acquiring immediate representation, i.e. intuition, of them; thus only as the form of outer sense in general.” (KrV B41)70
Understanding what Kant means by ‘subject’ is undoubtedly problematic. Does he refer to a psychological subject? A theoretical one? In which sense?
Kant’s inquiry concerns the conditions of possibility of knowledge and not the psychological process. For this reason, the term ‘subjective’ might here be interpreted as not objective. Forms are not objects of experience but rather belong to the subject who has experiences: they do not belong to a subject absolutely regarded as autonomous and isolated, nor to an absolute object. As Cohen interprets the notion of the form (Cohen 1918, p. 205), on the one hand it is the form of the phaenomenon, that is, the object of experience; on the other hand it belongs to the subject transcendentally intended, as the field of the object’s possible manifestation. From this perspective form is a condition that can justify the regularity of human experience, in which the contents vary, but this variation is reduced to rules. These considerations explain why space and time are endowed with empirical reality as well as transcendental ideality: they are not conditions of the possibility of things in themselves, but of things given in the experience with respect to its limits and conditions. In other words: it makes sense to apply space and time to phenomena, to objects of experience (empirical reality); but there is no sense in applying them to things in themselves, which are not and cannot be given in experience (transcendental ideality71 of pure intuitions).
If one were to claim that space and time have transcendental reality, this would imply that intuition has the capacity to bring the contingent content of experience to the existence, consequently making the contingent side of the process of knowledge (the empirical content) necessary. On the other hand, it is possible to think of an intuition that is characterised by a transcendental reality: the intuition ←61 | 62→of an understanding that is a-human, an intellectus archetypus, in which thought and being are identified. But we cannot investigate whether this intuition can be real since it cannot be given in our experience, it is beyond the limits of our possible knowledge. Its possibility is only a logical one: given human intuition, it is possible to think of an intuition that is its opposite; it is possible to think the negation of human intuition (as A leads to the thought of not-A). In this sense the Transcendental Aesthetic is a negative doctrine of the noumenon, which is the thought of an object that is not and cannot be given in our experience:
“Now the doctrine of sensibility is at the same time the doctrine of the noumenon in the negative sense, i.e. of things that the understanding must think without this relation to our kind of intuition, thus not merely as appearances but as things in themselves, but about which, however, it also understands that in this abstraction it cannot consider making any sense of its categories, since they have significance only in relation to the unity of intuitions in space and time, and can even determine this unity a priori, through general concepts of combination only on account of the mere ideality of space and time.” (KrV B307–308)72
So far, sensibility can only provide a necessary, although insufficient, indication of the constitution of the unity of the object: the forms of intuitions are not those in which the synthesis is completely constituted; it requires an additional contribution of the understanding for the possibility of the representation of objective unities (and not only of relations of successions or coexistence among impressions) to be justified. Without the act of thinking, objective cognition cannot be possible because there would be only a flow of separate impressions in which nothing could be distinguished as permanent, objective or unitary. The possibility of distinguishing between undetermined objects of intuition and determined objects of cognition lies in the activity of the understanding, which is responsible to provide the objectivity of the representations (Holzhey 1970, p. 219).←62 | 63→
3.2 The doctrine of the understanding
The purpose of the Transcendental Analytic is the development of a “logic of truth”, focusing on the faculty of the understanding in order to look for the principles of objectivity:
“The part of transcendental logic, therefore, that expounds the elements of the pure cognition of the understanding, and the principles without which no object can be thought at all, is transcendental analytic, and at the same time a logic of truth.” (KrV A62/B87)73
The general logic deals with the formal criteria of truth, which are universal and necessary insofar as it abstracts from its content and deals only with the form of our thought (KrV A54/B78). A criterion which is not only universal and necessary but also sufficient is not possible: a criterion, in order to be universal and necessary has to be abstract to the particular content of experience (otherwise, it would not be universal), while to be sufficient, it would have to refer to the particular content of experience (the truth or falsity of any epistemic judgement is determined by its relation to its particular content and object). Therefore, no criteria can be at the same time both universal and sufficient (KrV A59/B83–84). Still, it is possible to have universal and necessary criteria of truth in a transcendental sense: the Transcendental Analytic can be regarded as a “logic of truth” (KrV A62/B87) insofar as it provides the conditions of the possibility of judgements to be either objectively true or false. The a priori principles of the understanding are these conditions of the possibility of objects of experience, and thus, any epistemic judgement has to respect the universal and necessary rules of transcendental logic.
In order to identify the principles of the understanding it is necessary to refer to a guiding thread (Leitfaden) which is found by Kant in the forms of thinking intended as formal modalities as the basis of the judgement, deprived of all content. Kant is proceeding in this way: if thinking means judging, i.e. the process through which a predicate is attributed to a subject, then there are as many modalities of thinking as there are of the judgement. Since Kant asserts that the Aristotelian general logic is complete and conclusive, it suffices to consider it for individuating the forms of thought. The same function of the understanding is the source of the analytic unity of the judgement as well as of the synthesis of ←63 | 64→representations, thus providing a sort of universal range of the limits in which an object can be given in the experience. In the “metaphysical deduction” of the categories (KrV B159), Kant derives twelve categories from the Aristotelian table of the twelve forms of judgements, namely: unity, plurality, totality (quantity); reality, negation, limitation (quality); of inherence and subsistence, causality and dependence, community (relation), possibility-impossibility, existence-nonexistence, necessity-contingency (modality)74.
After exposing the categories Kant has
