This thesis examines the theoretical foundations of Kant's moral philosophy. I argue that Kant's moral ideal of a kingdom of ends is to be identified with the theoretical idea of a community, and that this idea can be traced back to the category of community introduced in his table of categories. In particular I argue that, for the mature Kant, the only application of the theoretical idea of community is the moral idea of a kingdom of ends, the only way we can conceive of a kingdom of ends is as a political community governed by juridical laws, and the only way we can conceive of a member of a community is as an autonomous agent. To support my interpretation I show how an understanding of Kant's theoretical work on community and interaction...