As we have already noted,[472] Kant in the second edition obscures the
sequence of his argument by offering in the new transcendental
exposition a justification of applied as well as of pure geometry. In so
doing he anticipates the conclusion which is first drawn in this later
paragraph. This would have been avoided had Kant given two separate
transcendental expositions. First, an exposition of pure mathematics,
placed immediately after the metaphysical exposition; for pure
mathematics is exclusively based upon the results of the metaphysical
exposition. And secondly, an exposition of applied mathematics,
introduced after _Conclusion b_. The explanation of applied geometry is
really the more essential and central of the two, as it alone involves
the truly Critical problem, how judgments formed _a priori_ can yet
apply to objects. _Conclusion b_ constitutes, as Vaihinger rightly
insists,[473] the very heart of the _Aesthetic_. The arrangement of
Kant’s argument diverts the reader’s attention from where it ought
properly to centre.
The use which Kant makes of the _Prolegomena_ in his statement of the
new transcendental exposition is one cause of the confusion. The
exposition is a brief summary of the corresponding _Prolegomena_[474]
sections. In introducing this summary into the _Critique_ Kant
overlooked the fact that in referring to applied mathematics he is
anticipating a point first established in _Conclusion b_. The real
cause, however, of the trouble is common to both editions, namely Kant’s
failure clearly to appreciate the fundamental distinction between the
view that space is an _a priori_ intuition and the view that it is the
_a priori_ form of all external intuition, _i.e._ of outer sense. He
does not seem to have fully realised how very different are those two
views. In consequence of this he fails to distinguish between the
transcendental expositions of pure and applied geometry.[475]
=Third paragraph.=--Kant proceeds to develop the subjectivist conclusions
which follow from _a_ and _b_.
“We may say that space contains all things which can appear to us
externally, but not all things in themselves, whether intuited or
not, nor again all things intuited by any and every subject.”[476]
This sentence makes two assertions: (_a_) space does not belong to
things in and by themselves; (_b_) space is not a necessary form of
intuition for all subjects whatsoever.