The central claim of this book is that morality provides a set of heuristics that, when followed, serves to produce the best expected outcome, for each of us, over the course of our lives, given the constraints placed by other people. That's quite a mouthful, but the basic idea is straightforward. Each of us has goals we would like to attain and ends we wish to achieve. However, your ability to attain your goals and achieve your ends is constrained by the fact that you are a social being. You live in a society where other people are trying to attain their goals and achieve their ends and, on some occasions, their goals and ends are incompatible with yours. The heuristics embedded within moral theories prescribe ways of acting so that the majority of people wind up sufficiently satisfied with their lot in life the majority of the time.

That description, while accurate as it stands, still leaves out one key aspect of the account developed in this book: societies have structure. The structure of society is composed of social relations, friendship networks, kinship networks, professional networks, and so on. The structure of society constrains how people interact, how people learn, and what people do in order to attain their goals. Social structure proves to be a powerful influence and is, I shall argue, the main reason why our moral theories have the form that they have.