The theory of social choice is very rich in topics and issues that have been discussed since Kenneth Arrow’s seminal contribution in 1951. This keynote chapter is only able to deal with only a few of them. The start is Arrow’s impossibility theorem, two routes that escape from this negative result and the issue of whether there are some properties that should be satisfied by every aggregation rule in order to qualify as desirable. Next, the literature on individual liberty and rights is related to the notion of freedom in the sense of control over one’s functioning bundle. Then the procedural aspect of individual and collective choice, often mentioned but not worked out in detail, is discussed. Finally, a particular approach to measure and compare capability sets is proposed.

There are two versions of the capability approach, one associated with the work of Amartya Sen and the other with that of Martha C. Nussbaum. The two versions differ substantially in their use of the central concepts and it is not exactly clear how they are related to each other. Drawing on game theory, this chapter presents a framework that synthesizes the two versions of the capability approach. It allows us to give a precise rendition of the contents and scope of capability and also enables us to make a careful distinction between different types of capabilities.