Moral scepticism and agency: Kant and Korsgaard

One argument put forward by Christine Korsgaard in favour of her constructivist appeal to the nature of agency, is that it does better than moral realism in answering moral scepticism. However, realists have replied by pressing on her the worry raised by H. A. Prichard, that any attempt to answer the moral sceptic only succeeds in basing moral actions in non-moral ends, and so it self-defeating. I spell out these issues in more detail, and suggest that both sides can learn something by seeing how the sceptical problematic arises in Kant. Doing so, I argue, shows how Korsgaard might raise the issue of scepticism against the realist whilst avoiding the Prichardian response.