Foundations of Strategic Equilibrium

The central concept of noncooperative game theory is that of the \emph{strategic equilibrium} (or Nash equilibrium, or noncooperative equilibrium). In this chapter we discuss some of the conceptual issues surrounding this concept and its refinements. Many of these issues have received increasing attention in the last few years. We are not at all comprehensive in covering the approaches that have been taken to the question. In particular, we focus almost exclusively on the ``purely rational'' approach and say almost nothing about other approaches. We do survey some of the issues and approaches that do not fit neatly into the core of our argument in the final section.