g them, removes the contradiction[13].
Further, though the assumption leads to the denial of speculative
knowledge in the sphere of metaphysics, it is still possible that
reason in its practical aspect may step in to fill the gap. And the
negative result of the assumption may even have a positive value. For
if, as is the case, the moral reason, or reason in its practical
aspect, involves certain postulates concerning God, freedom, and
immortality, which are rejected by the speculative reason, it is
important to be able to show that these objects fall beyond the scope
of the speculative reason. And if we call reliance on these
postulates, as being presuppositions of morality, faith, we may say
that knowledge must be abolished to make room for faith.

[13] Cf. pp. 101-2.

This answer to the main problem, given in outline in the Preface, is
undeniably plausible. Yet examination of it suggests two criticisms
which affect Kant's general position.

In the first place, the parallel of mathematics which suggests the
'Copernican' revolution does not really lead to the results which Kant
supposes. Advance in mathematics is due to the adoption not of any
conscious assumption but of a certain procedure, viz. that by which we
draw a figure and thereby see the necessity of certain relations
within it. To preserve the parallel, the revolution in metaphysics
should have consisted in the adoption of a similar procedure, and
advance should have been made dependent on the application of an at
least quasi-mathematical method to the objects of metaphysics.
Moreover, since these objects are God, freedom, and immortality, the
conclusion should have been that we ought to study God, freedom, and
immortality by somehow constructing them in perception and thereby
gaining insight into the necessity of certain relations. Success or
failure in metaphysics would therefore consist simply in success or
failure to see the necessity of the relations involved. Kant, however,
makes the condition of advance in metaphysics consist in the adoption
not of a method of procedure but of an assumption, viz. that objects
conform to the mind. And it is impossible to see how this assumption
can assist what, on Kant's theory, it ought to have assisted, viz. the
study of God, freedom, and immortality, or indeed the study of
anything. In geometry we presuppose that individual objects conform to
the universal rules of relation which we discover. Now suppose we
de