In a recent paper, Eckart Förster challenges interpreters to explain why in the first Critique practical reason has a canon but no dialectic, whereas in the second Critique, there is not only a dialectic, but an antinomy of practical reason. In the Groundwork, Kant claims that there is a natural dialectic with respect to morality (4:405), a different claim from those advanced in the first and second Critiques. Förster's challenge may therefore be reformulated as the problem of explaining why practical reason has a canon in the first Critique, a dialectic in the Groundwork, and an antinomy in the second Critique. In this paper, I answer this challenge. I argue that these differences are due to the different aims and scope of the works, and in particular, the different place of the inclinations in their arguments.