other hand, there now appears an unexpected and very satisfactory
proof of the consistency of the speculative critical philosophy. For
whereas it insisted that the objects of experience as such,
including our own subject, have only the value of phenomena, while
at the same time things in themselves must be supposed as their basis,
so that not everything supersensible was to be regarded as a fiction
and its concept as empty; so now practical reason itself, without
any concert with the speculative, assures reality to a supersensible
object of the category of causality, viz., freedom, although (as
becomes a practical concept) only for practical use; and this
establishes on the evidence of a fact that which in the former case
could only be conceived. By this the strange but certain doctrine of
the speculative critical philosophy, that the thinking subject is to
itself in internal intuition only a phenomenon, obtains in the
critical examination of the practical reason its full confirmation,
and that so thoroughly that we should be compelled to adopt this
doctrine, even if the former had never proved it at all. *



{PREFACE ^paragraph 10}

* The union of causality as freedom with causality as rational
mechanism, the former established by the moral law, the latter by
the law of nature in the same subject, namely, man, is impossible,
unless we conceive him with reference to the former as a being in
himself, and with reference to the latter as a phenomenon- the
former in pure consciousness, the latter in empirical consciousness.
Otherwise reason inevitably contradicts itself.