Second, criticism provides a new way of proving principles a priori , by showing that they are required for the possibility of experience. In the Refutation of Idealism, Kant argued that inner experience is possible only on the condition of the existence of things in space. The dogmatic procedure in metaphysics, it was noted above, led to the substantive thesis that space is a property of things in themselves, with the consequence that things in space are things in themselves as well. While the transcendental distinction between idealism and realism concerns the way in which we represent space and the things in it, the empirical distinction is concerned with the evidence for their existence. Empirical realism is the view that experience provides proof of the existence of objects in space, while empirical idealism holds that it does not.
Empirical idealism is a skeptical idealism, rather than a dogmatic idealism.
This point is obscured by the fact that at A368, Kant pronounced that the term 'idealist' is always meant skeptically. The other side of Kant's triumphant announcement was the claim that transcendental idealism leads to empirical realism. We do have enough empirical evidence to yield knowledge of the existence of objects in space, though this experience is inner or self-conscious. In the latter, the claim is that the existence of objects in space makes possible the determination of our inner states in time.