SECTION IV. Of the Transcendental Problems of Pure Reason, in So Far As They

OF THE TRANSCENDENTAL PROBLEMS OF PURE REASON, IN SO FAR AS THEY ABSOLUTELY MUST BE CAPABLE OF SOLUTION

There are sciences the very nature of which requires that every question which can occur in them must be completely answerable from what can be presumed to be known. This is true of the science of ethics. When I ask to what course of action I am committed in moral duty, the question must be answerable in terms of the considerations which have led to its being propounded. For there can be no moral obligation in regard to that of which we cannot have knowledge. We must not plead that the problem is unanswerable; a solution must be found. Kant proceeds to argue that this is no less true of transcendental philosophy.

“...it is unique among speculative sciences in that no question which concerns an object given to pure Reason is insoluble for this same human Reason, and that no excuse of an unavoidable ignorance, or of the unfathomable depth of the problem, can release us from the obligation to answer it thoroughly and completely. That very concept which enables us to ask the question must also qualify us to answer it, since, as in the case of right and wrong, the object is not to be met with outside the concept.”

The third and fourth paragraphs would seem to be later interpolations. The section, like Section III., must have been written at the time when Kant still regarded the doctrine of antinomy as covering the entire field of metaphysics. Transcendental philosophy is identified with cosmology, as dealt with in the antinomies. But in the third paragraph the former is taken as a wider term. Also, in the first two paragraphs the problems of pure Reason are regarded as soluble because their objects are not to be met with outside the concepts of them; whereas in the third paragraph they are viewed as soluble because their object is given empirically. Again, in the second paragraph transcendental philosophy has been taken as unique among speculative [i.e. theoretical] sciences; in the fourth paragraph mathematics is placed alongside it.

Examination of this section as a whole (and the same is true of the immediately following section) justifies the conclusion that at the time when it was written Kant regarded the Ideas of Reason as having a purely and exclusively regulative function, and consequently as exhausting their inherent meaning in their empirical reference. He regards them as entirely lacking in metaphysical significance. They are invented by Reason for Reason’s own satisfaction, and must therefore yield in their internal content the explanation of their existence, and must also supply a complete and thorough answer to all problems which are traceable to them. A dogmatic (i.e. ontological) solution of the antinomies is, as we have already found, impossible; the Critical solution considers the question subjectively,

“...in accordance with the foundation of the knowledge upon which it is based.” “For your object is only in your brain, and cannot be given outside it; so that you have only to take care to be at one with yourself, and to avoid the amphiboly which transforms your Idea into a supposed representation of an object which is empirically given and therefore to be known according to the laws of experience.”

Kant’s argument in proof of this purely subjective interpretation of the Ideas consists in showing that they are not presented in any given appearances, and are not even necessary to explain appearances. The unconditioned, whether of quantity, of division, or of origination, has nothing to do with any experience, whether actual or possible.

“You would not, for instance, in any wise be able to explain the appearances of a body better, or even differently, if you assumed that it consists either of simple or of inexhaustibly composite parts; for neither a simple appearance nor an infinite composition can ever come before you. Appearances demand explanation only in so far as the conditions of their explanation are given in perception, [and the unconditioned can never be so given].”

This standpoint, at once sceptical and empirical, is further developed in the next section.