As you may have guessed from the last post, I am in the middle of teaching an ethics course in the Summer session. Lately I have been trying to formulate Kant’s response to Hume’s arguments. It seems odd to me that Kant would explicitly respond to Hume’s challenge on causation and yet not respond to his other well known challenges (though, I am in no way entirely up to date on the literature in this area).

The first challenge is Hume’s argument that reason, strictly speaking, never directly causes an action. I have come to believe that Kant basically accepts Hume’s arguments for this conclusion and then introduces a special moral passion which he calls ‘respect for the moral law’. As I see it his answer is that someone with the good will is someone in whom contemplation of the Categorical Imperative causes the feeling of respect. In many ways it seems the same to me as the feeling of rational compulsion one has when contemplating Modus Ponens. I know the standard line is that Kant claims that it is the belief alone that motivates one to act, but what is the argument for this? Does anyone have any thoughts on this, or sources?

The second challenge is the is-ought gap. I am definitely not up on this debate like I should be, but it looks to me that Kant’s endorsement of the ‘ought implies can’ principle commits him to denying that there is an is-ought gap. On the other hand since Kant sees the requirements of morality to be in some sense requirements of rational agency, and since rationality is itself a normative enterprise, you might expect that he would agree with Hume on this point. In fact the emphasis on a priori methodology may in part be explained by wanting to avoid crossing the is-ought divide. I can’t find any discussion of this in Kant or in the secondary literature. Any thoughts?