The first stage in the development of the metaphysical deduction would seem to have consisted in the attempt to view the categories as acquired by reflection upon the activities of the understanding in “comparing, combining, or separating”;[697] and among the notiones rationales, notiones intellectus puri, thus gained, the idea of space is specially noted. The following list is also given:
“The concepts of existence (reality), possibility, necessity, ground, unity and plurality, parts, all, none, composite and simple, space, time, change, motion, substance and accident, power and action, and everything that belongs to ontology proper.”[698]
In Reflexionen, ii. 507 and 509, the fundamental feature of such rational concepts is found in their relational character. They all agree in being concepts of form.[699]
Quite early, however, Kant seems to have developed the view, which has created so many more difficulties than it resolves, that space and time are given to consciousness through outer and inner sense. Though still frequently spoken of as concepts, they are definitely referred to the receptive, non-spontaneous, side of the mind. This is at once a return to the Dissertation standpoint, and a decided modification of its teaching. It holds to the point of view of the Dissertation in so far as it regards them as sensuous, and departs from it in tracing them to receptivity.[700]
The passage quoted from the letter of 1772 to Herz may perhaps be connected with the stage revealed in the Reflexionen already cited. “Comparing, combining, and separating” may be the “some few principles of the understanding” there referred to. That, however, is doubtful, for the next stage in the development likewise resulted in a threefold division. This second stage finds varied expression in Reflexionen, ii. 483, 522, 528, 556-63. These, in so far as they agree, distinguish three classes of categories—of thesis, of analysis, and of synthesis. The first covers the categories of quality and modality, the second those of quantity, the third those of relation.
Reflexionen, ii. 528 is as follows:
This, and the connected Reflexionen enumerated above, are of interest as proving that Kant’s table of categories was in all essentials complete before the idea had occurred to him of further systematising it or of guaranteeing its completeness by reference to the logical classification of the forms of judgment. They also justify us in the belief that when Kant set himself to discover such a unifying principle the above list of categories and the existing logical classifications must have mutually influenced one another, each undergoing such modification as seemed necessary to render the parallelism complete. This, as we shall find, is what actually happened. The logical table, for instance, induced Kant to distinguish the categories of quality from those of modality, while numerous changes were made in the logical table itself in order that it might yield the categories required.
But the most important alteration, the introduction of the threefold division of each sub-heading, is not thus explicable, as exclusively due to one or other of the two factors. The adoption of this threefold arrangement in place of the dichotomous divisions of the logical classification and of the haphazard enumerations of Kant’s own previous lists, seems to be due to the twofold circumstance that he had already distinguished three categories of synthesis or relation (always the most important for Kant), and that this sufficiently harmonised with the logical distinction between categorical, hypothetical, and disjunctive judgments. He then sought to modify the logical divisions by addition in each case of a third, and finding that this helped him to obtain the categories required, the threefold division became for him (as it remained for Hegel) an almost mystical dogma of transcendental philosophy.[701] In so far as it involved recognition that the hard and fast opposites of the traditional logic (such as the universal and the particular, the affirmative and the negative) are really aspects inseparably involved in every judgment and in all existence, it constituted an advance in the direction both of a deeper rationalism and of a more genuine empiricism. But in so far as it was due to the desire to guarantee completeness on a priori grounds, and so was inspired by a persistent overestimate of our a priori powers, it has been decidedly harmful. Much of the useless “architectonic” of the Critique is due to this scholastic prejudice.
This fundamental alteration in the table of logical judgments is introduced with the naive assertion that “varieties of thought in judgments,” unimportant in general logic, “may be of importance in the field of its pure a priori knowledge.” In the Critique of Judgment[702] we find the following passage: