Book II, Chapter 1: ‘On a dialectic of pure practical reason in general’

The very first paragraph of Book II of the Critique of Practical Reason presents serious difficulties of interpretation for any reader who is already familiar with the first Critique. For the claim that pure reason ‘always has its dialectic,’ not only in its theoretical use but also in its practical use (CPrR:107, 6), directly contradicts the Critique of Pure Reason of 1781. The earlier text had defined dialectic explicitly as a ‘logic of illusion’ that created the mere ‘semblance’ of objective assertions (CPR A 61). It is quite true that Kant there understood the antinomies, just as he would in the second Critique, as a kind of fortunate confusion insofar as they compel human reason to reflect upon its own limits and to distinguish clearly between phenomena and noumena, between appearances and things in themselves. But at the same time this distinction was also intended to secure the fundamental possibility of genuine morality precisely because the moral law relates directly to freedom, and thus to the noumenal realm, rather than to the sensible world of appearances. And in the first Critique, Kant had expressly denied that practical reason also possessed a comparable dialectic.