This chapter is a very compressed review of the neoclassical orthodoxy on the nature of rationality on economic theory. It defends the orthodoxy both against the behavioral criticism that it assumes too much and the revisionist view that it assumes too little. In places, especially on the...

This chapter surveys a sizable and growing literature on coalition formation. We refer to theories in which one or more groups of agents (“coalitionsâ€) deliberately get together to jointly determine within-group actions, while interacting noncooperatively across groups. The chapter...

In one of the most influential existence theorems in mathematics, John F. Nash proved in 1950 that any normal form game has an equilibrium. More than five decades later, it was shown that the computational task of finding such an equilibrium is intractable, that is, unlikely to be carried out...