RATIONALIZABILITY, STRONG RATIONALITY, AND EXPECTATIONAL STABILITY

We examine the connection between two stability concepts of rational expectations equilibria: expectational stability, based on the convergence of iterations of expectations, and strong rationality, based on uniqueness of the rationalizable solutions of an associated game with restrictions on beliefs. To compare the concepts we embed a standard expectations model in a game-theoretic framework. It is shown that the two stability concepts coincide when agents are homogeneous. For the general case of heterogeneous agents we show that expectational stability is a necessary condition for strong rationality and we provide a sufficient condition for the latter. Journal of Economic Literature Classification Numbers: C72, C62. © 1993 Academic Press. All rights reserved.