  For example, presumably it was morally wrong for Hitler to order a program of genocide, even if it served some of his desires and wasn’t detrimental to any of them. (The characteristic of morality that Moral Absolutism expresses is sometimes described, following Immanuel Kant, as its consisting of ‘categorical’ rather than ‘hypothetical’ imperatives; see the entry on  Kant’s moral philosophy.)   If (as Moral Rationalism claims) an action (like ordering genocide) is morally wrong for an agent (like Hitler) only if there is a reason for him not to do it, and if (as HTR claims) there is a reason for him not to do it only if he has some desire that would be served by his not doing it, then it follows that whether an action is morally wrong for an agent depends upon what he or she desires. But that seems incompatible with Moral Absolutism. So it seems we must reject at least one of HTR, Moral Rationalism, and Moral Absolutism.