though not
beyond it. The systematic development of the Kantian teleology, which is
here indicated in general outlines only, is found in the second part of the
_Critique of Judgment_; while the practical philosophy, which furnishes the
only possible proof, the moral proof, for the reality of the Ideas, erects
on the site left free by the removal of the airy summer-houses of dogmatic
metaphysics the solid mansion of critical metaphysics, that is, the
metaphysics of duties and of hopes. "I was obliged to destroy knowledge
in order to make room for faith." The transition from the impossible
theoretical or speculative knowledge of things in themselves to the
possible "practical knowledge" of them (the belief that there is a God and
a future world) is given in the _Doctrine of Method_, which is divided into
four parts (the Discipline, the Canon, the Architectonic, and the History
of Pure Reason), in its second chapter. There, in the ideal of the _Summum
Bonum_, the proof is brought forward for the validity of the Ideas God,
freedom, and immortality, as postulates inseparable from moral obligation;
and by a cautious investigation of the three stages of assent (opinion,
knowledge, and belief) both doctrinal and moral belief are assigned their
places in the system of the kinds of knowledge.

[Footnote 1: The principle to regard all order in the world (_e.g._, the
shape of the earth, mountains, and seas, the members of animal bodies) as
if it proceeded from the design of a supreme reason leads the investigator
on to various discoveries.]

We may now sum up the results of the three parts of Kant's theoretical
philosophy. The pure intuitions, the categories, and the Ideas are
functions of the spirit, and afford non-empirical _(erfahrungsfreie)_
knowledge concerning the objects of possible experience (and concerning the
possibility of knowledge). The first make universal and necessary knowledge
possible in relation to the forms under which objects can be given to us;
the second make a similarly apodictic knowledge possible in relation to
the forms under which phenomena must be thought; the third make possible a
judgment of phenomena differing from this knowledge, yet not in conflict
with it. The categories and the Ideas, moreover, yield problematical
concepts of objects which are not given to us in intuition, but which may
exist outside of space and time: things in themselves cannot be known, it
is true, but they can be thought, a