The theory of value or of the good is one of the two main branches of ethical theory, alongside the theory of the right. Whereas the theory of the right specifies which actions are right and which are wrong, the theory of value says which states of affairs are intrinsically good and which intrinsically evil. The theory of the right may say that keeping promises is right and lying wrong; the theory of value can say that pleasure is good and pain evil, or that knowledge and virtue are good and vice evil. Since these states are not actions they cannot be right or wrong, but they can have positive or negative value. The theory of value is important, first, because it gives content to some important claims about the right. Consequentialists about the right hold that one ought always to do what will result in the best outcome; to know what this implies we must know in particular what makes outcomes good. Even non-consequentialists usually recognize some moral duty to produce good outcomes, and that duty, too, needs content.1 There is no point telling people to promote the good without telling them what the good is. Second, on some non-consequentialist views the duties that compete with promoting the good likewise presuppose claims about the good. These duties can make it wrong to do what will have the best overall outcome, for example, wrong intentionally to kill one innocent person even if this will save five innocent people’s lives. But some say this is because, given an initial intrinsic value of life, there is not only a duty to promote and preserve it but also a separate and stronger duty not to destroy it; there can also be 1 separate and stronger duties not to destroy other goods such as knowledge and virtue.2 On this view even the duties that constrain pursuit of the good concern the good, though as something to be respected rather than simply brought about. Finally, the theory of value is important in itself. Often things happen that do not result from anyone’s choice and could not have been prevented by choice...