But, let it be granted that we could discover, not in experience, but
in certain firmly-established à priori laws of the use of pure
reason—laws relating to our existence, authority to consider ourselves
as legislating à priori in relation to our own existence and as
determining this existence; we should, on this supposition, find
ourselves possessed of a spontaneity, by which our actual existence
would be determinable, without the aid of the conditions of empirical
intuition. We should also become aware that in the consciousness of our
existence there was an à priori content, which would serve to determine
our own existence—an existence only sensuously determinable—relatively,
however, to a certain internal faculty in relation to an intelligible
world.
But this would not give the least help to the attempts of rational
psychology. For this wonderful faculty, which the consciousness of the
moral law in me reveals, would present me with a principle of the
determination of my own existence which is purely intellectual—but by
what predicates? By none other than those which are given in sensuous
intuition. Thus I should find myself in the same position in rational
psychology which I formerly occupied, that is to say, I should find
myself still in need of sensuous intuitions, in order to give
significance to my conceptions of substance and cause, by means of
which alone I can possess a knowledge of myself: but these intuitions
can never raise me above the sphere of experience. I should be
justified, however, in applying these conceptions, in regard to their
practical use, which is always directed to objects of experience—in
conformity with their analogical significance when employed
theoretically—to freedom and its subject. At the same time, I should
understand by them merely the logical functions of subject and
predicate, of principle and consequence, in conformity with which all
actions are so determined, that they are capable of being explained
along with the laws of nature, conformably to the categories of
substance and cause, although they originate from a very different
principle. We have made these observations for the purpose of guarding
against misunderstanding, to which the doctrine of our intuition of
self as a phenomenon is exposed. We shall have occasion to perceive
their utility in the sequel.
Chapter II. The Antinomy of Pure Reason