Walter the Banker: The Conjunction Fallacy Reconsidered

17 Pages Posted: 8 Jun 2009 Last revised: 7 Aug 2010

Date Written: June 8, 2009

Abstract

In a famous experiment by Tversky and Kahneman (1983), featuring Linda the bank teller, the participants assign a higher probability to a conjunction of propositions than to one of the conjuncts, thereby seemingly committing a probabilistic fallacy. In this paper, we discuss a slightly different example featuring someone named Walter, who also happens to work at a bank, and argue that, in this example, it is rational to assign a higher probability to the conjunction of suitably chosen propositions than to one of the conjuncts. By pointing out the similarities between Tversky and Kahneman's experiment and our example, we argue that the participants in the experiment may assign probabilities to the propositions in question in such a way that it is also rational for them to give the conjunction a higher probability than one of the conjuncts.

Keywords: Conjunction fallacy, Linda problem, psychology of reasoning, Bayesian epistemology

Suggested Citation

Hartmann, Stephan and Meijs, Wouter, Walter the Banker: The Conjunction Fallacy Reconsidered (June 8, 2009). Available at SSRN: https://ssrn.com/abstract=1415928 or http://dx.doi.org/10.2139/ssrn.1415928

Stephan Hartmann (Contact Author)

LMU Munich ( email )

Munich Center for Mathematical Philosophy
Ludwigstr. 31
Munich, 80539
Germany
+49 89 2180 3320 (Phone)
+49 89 2180 2902 (Fax)

HOME PAGE: http://stephanhartmann.org/

Wouter Meijs

Tilburg University ( email )

PO Box 90153
Tilburg, 5000 LE
Netherlands

HOME PAGE: http://www.uvt.nl/tilps/people/ResearchAssociates/\#meijs

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