Rationality of Belief. Or Why Bayesianism is Neither Necessary Nor Sufficient for Rationality

21 Pages Posted: 29 Mar 2004

See all articles by Itzhak Gilboa

Itzhak Gilboa

Tel Aviv University - Eitan Berglas School of Economics; HEC Paris - Economics & Decision Sciences

Andrew Postlewaite

University of Pennsylvania - Department of Economics

David Schmeidler

Tel Aviv University - Eitan Berglas School of Economics; Ohio State University (OSU)

Date Written: October 2004

Abstract

Economic theory reduces the concept of rationality to internal consistency. The practice of economics, however, distinguishes between rational and irrational beliefs. There is therefore an interest in a theory of rational beliefs, and of the process by which beliefs are generated and justified. We argue that the Bayesian approach is unsatisfactory for this purpose, for several reasons. First, the Bayesian approach begins with a prior, and models only a very limited form of learning, namely, Bayesian updating. Thus, it is inherently incapable of describing the formation of prior beliefs. Second, there are many situations in which there is not sufficient information for an individual to generate a Bayesian prior. Third, this lack of information is even more acute when we address the beliefs that can be attributed to a society. We hold that one needs to explore other approaches to the representation of information and of beliefs, which may be helpful in describing the formation of Bayesian as well as non-Bayesian beliefs.

Keywords: Decision making, Bayesian, Behavioral Economics

JEL Classification: B4, D8

Suggested Citation

Gilboa, Itzhak and Postlewaite, Andrew and Schmeidler, David, Rationality of Belief. Or Why Bayesianism is Neither Necessary Nor Sufficient for Rationality (October 2004). Available at SSRN: https://ssrn.com/abstract=523502

Itzhak Gilboa

Tel Aviv University - Eitan Berglas School of Economics ( email )

P.O. Box 39040
Ramat Aviv, Tel Aviv, 69978
Israel
972-3-640-6423 (Phone)
972-3-640-9908 (Fax)

HEC Paris - Economics & Decision Sciences

Paris
France

Andrew Postlewaite (Contact Author)

University of Pennsylvania - Department of Economics ( email )

Ronald O. Perelman Center for Political Science
133 South 36th Street
Philadelphia, PA 19104-6297
United States
215-898-7350 (Phone)
215-573-2057 (Fax)

HOME PAGE: http://www.econ.upenn.edu/~apostlew

David Schmeidler

Tel Aviv University - Eitan Berglas School of Economics ( email )

P.O. Box 39040
Ramat Aviv, Tel Aviv, 69978
Israel
+972-3-640-9643 (Phone)
+972-3-640-9357 (Fax)

Ohio State University (OSU) ( email )

Blankenship Hall-2010
901 Woody Hayes Drive
Columbus, OH OH 43210
United States

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