Scanlon offers a sharp challenge to much contemporary moral philosophy. Most philosophers think that agreements between people play only a subsidiary role in moral theory. What is right or wrong is independent of what people accept. Agreements rest on morality; they do not underlie it. Scanlon dissents. In his conception, morality depends on principles it would not be reasonable for people to reject. These agreements do not derive from further moral facts. Scanlon also challenges the view that desires give reasons for action, leveling heavy artillery at the contrary position of Bernard Williams. The originality, scope, and careful argument of this work mark it as an indispensable book.