Paper #1470

Title:

Uncertain rationality and robustness in games with incomplete information

Authors:

Fabrizio Germano and Peio Zuazo-Garin

Date:

February 2015

Abstract:

Economic predictions are highly sensitive to model and informational specifications. Weinstein and Yildiz (2007) show that, in static games with incomplete information, only very weak predictions, namely, the interim correlated rationalizable (ICR) actions, are robust to higher-order belief misspecifications. This paper extends their robustness analysis to allow for higher-order uncertainty about rationality. We introduce interim correlated p-rationalizability (ICRp) as a solution concept for games with incomplete information. We first confirm the robustness of the ICR predictions to small departures from common belief in rationality by showing the continuity of ICRp actions at p = 1, where they coincide with ICR. At the same time, we show that Weinstein and Yildiz's (2007) deeper results on the structure of rationalizability, most notably, their discontinuity and generic local uniqueness properties, fail as soon as any arbitrarily small amount of higher-order uncertainty about rationality is introduced. Thus, we find that common belief in rationality is a necessary condition for Weinstein and Yildiz's (2007) discontinuity property to hold. Among other things, this reveals the diminishing strategic impact of higher-order belief constraints.

Keywords:

Robustness, rationalizability, uncertain rationality, incomplete information, belief hierarchies.

JEL codes:

C72, D82, D83

Area of Research:

Microeconomics

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