This critical survey of recent work on Kant's doctrine of the fact of reason and his doctrine of the practical postulates (of freedom, God, and immortality) assesses the implications of these doctrines for the debate about realism and antirealism in Kant's moral philosophy. Section 1 briefly surveys some salient considerations from the first Critique and Groundwork. In section 2, I argue that recent work on the role, content, "factual" nature, and epistemic status of the fact of reason does not support (...) an anti-realist interpretation of Kant's ethics. In section 3, I argue that recent work on the derivation and epistemic and ontological status of the practical postulates does not support an anti-realist interpretation of Kant's ethics. (shrink)

Several interpretive disagreements about Kant's theory of divine commands (esp. in the work of Allen Wood and John E. Hare) can be resolved with further attention to Kant's works. It is argued that Kant's moral theism included (at least until 1797) the claim that practical reason, reflecting upon the absolute authority of the moral law, should lead finite rational beings like us to believe that there exists an omnipotent, omniscient and holy being who commands our obedience to the moral law (...) and proportions happiness to virtue. Kant's apparently contradictory claims about the relationship between morality and religion reflect his view that our acceptance of the authority of the moral law is incomplete or rationally unstable absent such a theological postulate. (shrink)

Immanuel Kant (1724–1804) argued that moral requirements are based on a standard of rationality he dubbed the “Categorical Imperative” (CI). Immorality thus involves a violation of the CI and is thereby irrational. Other philosophers, such as Locke and Hobbes, had also argued that moral requirements are based on standards of rationality. However, these standards were either desirebased instrumental principles of rationality or based on sui generis rational intuitions. Kant agreed with many of his predecessors that an analysis of practical reason (...) will reveal only the requirement that rational agents must conform to instrumental principles. Yet he argued that conformity to the CI (a non-instrumental principle) and hence to moral requirements themselves, can nevertheless be shown to be essential to rational agency. This argument was based on his striking doctrine that a rational will must be regarded as autonomous, or free in the sense of being the author of the law that binds it. The fundamental principle of morality — the CI — is none other than the law of an autonomous will. Thus, at the heart of Kant's moral philosophy is a conception of reason whose reach in practical affairs goes well beyond that of a Humean ‘slave’ to the passions. Moreover, it is the presence of this self-governing reason in each person that Kant thought offered decisive grounds for viewing each as possessed of equal worth and deserving of equal respect. (shrink)