Walter the banker: the conjunction fallacy reconsidered,Stephan Hartmann · Wouter Meijs

Abstract

In a famous experiment by Tversky and Kahneman (Psychol Rev 90:293–

315, 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 namedWalter, 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.