on. Its aim is to vindicate against 'idealism' the reality
of objects in space, and it is for this reason inserted after the
discussion of the second postulate. The interest which it has excited
is due to Kant's use of language which at least seems to imply that
bodies in space are things in themselves, and therefore that here he
really abandons his main thesis.

[1] B. 274-9, M. 167-9. Cf. B. xxxix (note), M. xl (note).

[2] A. 367-80, Mah. 241-53.

Idealism is the general name which Kant gives to any view which
questions or denies the reality of the physical world; and, as has
been pointed out before,[3] he repeatedly tries to defend himself
against the charge of being an idealist in this general sense. This
passage is the expression of his final attempt. Kant begins by
distinguishing two forms which idealism can take according as it
regards the existence of objects in space as false and _impossible_,
or as doubtful and _indemonstrable_. His own view, which regards their
existence as certain and demonstrable, and which he elsewhere[4]
calls transcendental idealism, constitutes a third form. The first
form is the dogmatic idealism of Berkeley. This view, Kant says,
is unavoidable, if space be regarded as a property of things in
themselves, and the basis of it has been destroyed in the _Aesthetic_.
The second form is the problematic idealism of Descartes, according to
which we are immediately aware only of our own existence, and belief
in the existence of bodies in space can be only an inference, and an
uncertain inference, from the immediate apprehension of our own
existence. This view, according to Kant, is the outcome of a
philosophical attitude of mind, in that it demands that a belief
should be proved, and apparently--to judge from what Kant says of
Berkeley--it does not commit Descartes to the view that bodies in
space, if their reality can be vindicated, are things in themselves.

[3] Cf. p. 76.

[4] A. 369, Mah. 243; cf. B. 44, M. 27.

The assertion that the _Aesthetic_ has destroyed the basis of
Berkeley's view, taken together with the drift of the _Refutation_
as a whole, and especially of Remark I, renders it clear that the
_Refutation_ is directed against Descartes and not Berkeley. Kant
regards himself as having already refuted Berkeley's view, as he
here states it, viz. that the existence of objects in space is
_impossible_, on the ground that it arose from the mistake of
supposing