The primacy of practical reason and the idea of a practical postulate

Abstract

This chapter deals with the content of Immanuel Kant's three postulates, namely, existence of God, own transcendental freedom and immortality, and explains his arguments in their favour. It begins by commenting on Kant's argument, 'On the Primacy of Practical Reason', with a special emphasis on the logical structure of that argument. Kant argument is difficult to follow, and even more difficult to assess, among other things because it is framed in terms of the respective 'interests' of two cognitive faculties. That a practically necessary belief can be rational without evidence is taken to be equivalent to the claim that pure practical reason has primacy over pure speculative reason. The chapter looks at the idea of a postulate of pure practical reason and at the epistemological status Kant assigns to it. It concludes that the main idea behind Kant's argument does not depend on Kant's own, demanding conception of morality.