Journal of Economic Perspectives: Vol. 6 No. 4 (Fall 1992)


Quick Tools:

Print Article Summary
Export Citation
Sign up for Email Alerts Follow us on Twitter


JEP - All Issues

Common Knowledge

Article Citation

Geanakoplos, John. 1992. "Common Knowledge." Journal of Economic Perspectives, 6(4): 53-82.

DOI: 10.1257/jep.6.4.53


An event is common knowledge among a group of agents if each one knows it, if each one knows that the others know it, if each one knows that each one knows that the others know it, and so on. Thus, common knowledge is the limit of a potentially infinite chain of reasoning about knowledge. The purpose of this paper is to survey some of the implications for economic behavior of the hypotheses that events are common knowledge, that actions are common knowledge, that optimization is common knowledge, and that rationality is common knowledge. It will begin with several puzzles that illustrate the strength of the common knowledge hypothesis. It will then study how common knowledge can illuminate many problems in economics. In general, the discussion will show that a talent for interactive thinking is advantageous, but if everyone can think interactively and deeply all the way to common knowledge, then sometimes puzzling consequences may result.

Article Full-Text Access

Full-text Article (Complimentary)


Geanakoplos, John (Yale U)

JEL Classifications

D80: Information, Knowledge, and Uncertainty: General
C72: Noncooperative Games


View Comments on This Article (0) | Login to post a comment

Journal of Economic Perspectives

Quick Tools:

Sign up for Email Alerts

Follow us on Twitter

Subscription Information
(Institutional Administrator Access)


JEP - All Issues

Virtual Field Journals

AEA Member Login:

AEAweb | AEA Journals | Contact Us