Abstract: This book is about ideas at the centre of our thought about our individual lives and about society—‘well-being’, ‘welfare’, ‘utility’, and ‘quality of life’. It aims to answer three questions: What is the best way to understand well-being? to what extent can it be measured? what role should it play in moral and political thought? The book argues that the sharp contrast between reason and desire found in our modern intellectual tradition has hampered answers to those questions. The book first tries to describe the place of both reason and desire in our thought about well-being. It then uses the notion of well-being, so explained, in discussions of whether values are commensurable, of what measurement of one person's well-being is demanded by ethics and whether it can be supplied by us, and whether we can effectively compare one person's well-being with another's. It ends with discussions of the relation of individual well-being to morality in general, to equality, fair constitution, rights, punishment and rewards, and distribution.

Keywords: commensurability, distribution, equality, ethics, interpersonal comparisons, punishment, quality of life, rights, utility, welfare, well-being