ether, and to do this is implicitly to question the validity of
our thought about the nature of our own mind, as well as the validity
of our thought about things independent of the mind. Yet Kant's
argument, in the form in which it has just been stated, presupposes
that our thought is valid at any rate when it is concerned with our
perceptions of things, even if it is not valid when concerned with the
things as they are in themselves.

[48] Cf. p. 17.

[49] For the reasons which led Kant to draw this distinction
between empirical and _a priori_ judgements, cf. pp. 21-2.

This consideration leads to the second criticism. The supposition that
space is only a form of perception, even if it be true, _in no way
assists_ the explanation of the universal validity of geometrical
judgements. Kant's argument really confuses a _necessity_ of relation
with the _consciousness of a necessity_ of relation. No doubt, if it
be a law of our perceiving nature that, whenever we perceive an object
as a three-sided figure, the object as perceived contains three
angles, it follows that any object as perceived will conform to this
law; just as if it be a law of things as they are in themselves that
three-sided figures contain three angles, all three-sided figures will
in themselves have three angles. But what has to be explained is the
universal applicability, not of a law, but of a judgement about a law.
For Kant's real problem is to explain why _our judgement_ that a
three-sided figure must contain three angles must apply to all
three-sided figures. Of course, if it be granted that in the judgement
we apprehend the true law, the problem may be regarded as solved. But
how are we to know that what we judge _is_ the true law? The answer is
in no way facilitated by the supposition that the judgement relates to
our perceiving nature. It can just as well be urged that what we think
to be a necessity of our perceiving nature is not a necessity of it,
as that what we think to be a necessity of things as they are in
themselves is not a necessity of them. The best, or rather the only
possible, answer is simply that that of which we apprehend the
necessity must be true, or, in other words, that we _must_ accept the
validity of thought. Hence nothing is gained by the supposition that
space is a form of sensibility. If what we judge to be necessary is,
as such, valid, a judgement relating to things in themselves will be
as valid as a judge