Published in Topics in Theoretical Economics, Volume 4, Issue 1, November 10, 2004.
NOTE: At the time of publication, the author Eduardo Zambrano was not yet affiliated with Cal Poly.
When evaluating the rationality of a player in a game one has to examine counterfactuals such as "what would happen if the player were to do what he does not do?" In this paper I develop a model of a normal form game where counterfactuals of this sort are evaluated as in the philosophical literature (cf. Lewis, 1973; Stalnaker, 1968). According to this method one evaluates a statement like ``what would the player believe if he were to do what he does not do'' at the world that is closest to the actual world where the hypothetical deviation occurs. I show that in this model common knowledge of rationality need not lead to rationalizability. I also present assumptions that allow rationalizability to follow from common knowledge of rationality. These assumptions suggest that rationalizability may not rely on weaker assumptions about belief consistency than Nash equilibrium.
2004 by the author.
Number of Pages
This article is also available at http://www.bepress.com/bejte/topics/vol4/iss1/art8.