Aristotle claims in the Nicomachean Ethics that it is the virtuous person "more than any other sort of person who seems to be a self-lover. … he awards himself what is finest and best of all" (1168b28–30). Aristotle's thought is that if one pursues things such as pleasure and wealth, one pursues what is base, injuring oneself. Contrast this with the implication of the recommendation "Look out for number one." This advice is not taken to mean that one should pursue virtue. Rather, the idea is that the interests of others should take second place to one's own. Virtue is not usually seen as the path of self-interest, especially because it can often involve self-sacrifice. This conflict suggests that effective pursuit of self-interest, or the interests of others, requires an account of the nature of well-being. (Henceforth, I will often use the term well-being rather than self-interest since that...