This important new book takes as its points of departure two questions: What is the nature of valuing? and What morality can be justified in a society that deeply disagrees on what is truly valuable? In Part One, the author develops a theory of value that attempts to reconcile reason with passions. Part Two explores how this theory of value grounds our commitment to moral action. The author argues that rational moral action can neither be seen as a way of simply maximising one's own values, nor derived from reason independent of one's values. Rather, our commitment to the moral point of view is presupposed by our value systems. The book concludes with a defense of liberal political morality.