Cognition and Chance: The Psychology of Probabilistic Reasoning

W hat constitutes a paradox is, to some degree, a matter of semantics. One dictionary definition is “a statement that is seemingly contradictory or opposed to common sense and yet is perhaps true” (Webster's New Collegiate Dictionary); there are others. Paradoxes that proved to be so important to the history of mathematics, especially during the early part of the 20th century, often involved self-contradictory statements, or what appeared to be different but equally valid mathematical proofs leading to contradictory conclusions.

Many problems involving probability theory have been described and discussed in the literature as paradoxes. Some of them can be resolved readily by carefully analyzing the situations involved; others are less easily dispatched. Sometimes the same problem is referred to by some authors as a paradox and by others as something else. The problem of the inquisitive prisoner is a case in point (for a description, see Nickerson, 1996); it has been called a paradox

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