Aristotle and the Origins of Evil

Why do human beings, on Aristotle's view, have an innate tendency to badness, that is, to developing desires that go beyond and against their natural needs? Given Aristotle's teleological assumptions (including the thesis that nature does nothing in vain), such tendency should not be present. I argue that the culprit is to be found in the workings of rationality, in particular in the (necessary) presence of theoretical reason. As theoretical reason requires that human beings have unlimited non-rational desires for the fine (to kalon), it also gives rise to a tendency to form unlimited non-rational desires for other things.