Abstract
This paper discusses an apparent contrast between Kant’s accounts of the mathematical antinomies in the first Critique and in the Prolegomena. The Critique claims that the antitheses are infinite judgements. The Prolegomena seem to claim that they are negative judgements. For the Critique, theses and antitheses are false because they presuppose that the world has a determinate magnitude, and this is not the case. For the Prolegomena, theses and antitheses are false because they presuppose an inconsistent notion of world. The paper argues that the contrast between the two works is only apparent, and provides an interpretation which removes it.