When we buy new clothes not to keep ourselves warm but to look "well-dressed" we are not providing for any important need. We would not be sacrificing anything significant if we were to continue to wear our old clothes, and give the money to famine relief. By doing so, we would be preventing another person from starving. It follows from what I have said earlier that we ought to give money away, rather than spend it on clothes which we do not need to keep us warm. To do so is not charitable, or generous. Nor is it the kind of act which philosophers and theologians have called "supererogatory" - an act which it would be good to do, but not wrong not to do. On the contrary, we ought to give the money away, and it is wrong not to do so.

Famine, Affluence, and Morality, 1972.