Generally defined as the view that one ought to do whatever and only whatever is in one's own maximum interest, benefit, advantage, or good, "ethical egoism" contrasts with (1) psychological egoism, which says that people do in fact, perhaps necessarily, act in that way; and from (2) alternative ethical theories, which claim that we have other fundamental obligations such as to act for the sake of others, even at ultimate cost to ourselves, or in ways having no necessary relation to anyone's benefit.

Egoism strikes many as cutting through pretenses and getting down to fundamentals. This appearance soon dissipates when we make essential distinctions. Foremost is that due to the classic work of Bishop Joseph Butler (1692–1752). Is "self-interest" in that theory to be understood as one's interest in certain states unique to one's own self—as distinct from certain states of other people? Or is it merely interests...