This book presented a theory of fairness and social welfare. By fairness, we mean that economic justice is a question of fair resource allocation. To be precise about what a fair resource allocation can be, we need to define the economic ingredients of the situation – that is, the available goods to allocate, the nature of the goods (whether they are private of public, divisible or not, in known or uncertain quantities, and so on), the available technology to produce new goods, and the internal and external resources owned by the agents.

What is fair, then, depends on the context; any analysis begins by identifying fairness requirements that capture basic ethical principles in that context. We have surveyed a variety of contexts in this book. Even if they all turned out to have specificities, a general picture emerges. First, fairness involves the equalization of something. Second, that thing must be related to the way agents value being given access to a given quantity of resources. To sum up, our undertaking is consistent with the notion that a society is just if and only if it equalizes the subjective value that agents give to the entire bundle of internal and external resources to which they are given access.

Our theory refers to social welfare. Defining social welfare requires aggregating the well-being of the members of a society.