This chapter starts with Kant's basic rationalist, internalist approach to justification, and then considers its connection to his famous principle of universalizability, his account of the absolute value of the goodwill, and his analysis of the motive duty as the determining ground of goodwill. Kant's argument, if it succeeds, rules out externalist theories of justification and also mere natural inclination, even mere sympathy, as a determining ground of goodwill. It does not, however, rule out a consequentialist account of the normative content of morality.
Keywords: duty, goodwill, internalism, justification, Kant, rationalism, sympathy, universalizability