Kant and the Fact of Reason

It is often thought that Kant abandoned his argument for the justification of morality in the Groundwork of the Metaphysics of Morals for a radically different argument in the Critique of Practical Reason. In the Groundwork, Kant appears to try to justify our commitment to the moral law on the basis of our freedom, but in the Critique, he tries to justify that commitment on the basis of what he calls the fact of reason. I assess and reject influential interpretations of both arguments as being philosophically unsound, and I propose, what I take to be, a novel and promising account of the fact of reason.