Abstract: Existing equilibrium concepts for games make use of the subjective expected utility model axiomatized by Savage (1954) to represent players' preferences. Accordingly, each player's beliefs about the strategies played by opponents are represented by a probability measure. Motivated by the Ellsberg Paradox and relevant experimental findings demonstrating that the beliefs of a decision maker may not be representable by a probability measure, this paper generalizes Nash Equilibrium in finite extensive form games to allow for preferences conforming to the multiple priors model developed in Gilboa and Schmeidler (1989). The implications of this generalization for strategy choices and welfare are studied.
JEL Classification: C72;D81