On the reality of the conjunction fallacy

Ashley Sides, Daniel Osherson, Nicolao Bonini, Riccardo Viale

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Attributing higher "probability" to a sentence of form p-and-q, relative to p, is a reasoning fallacy only if (1) the word probability carries its modern, technical meaning and (2) the sentence p is interpreted as a conjunct of the conjunction p-and-q. Legitimate doubts arise about both conditions in classic demonstrations of the conjunction fallacy. We used betting paradigms and unambiguously conjunctive statements to reduce these sources of ambiguity about conjunctive reasoning. Despite the precautions, conjunction fallacies were as frequent under betting instructions as under standard probability instructions.

Original languageEnglish (US)
Pages (from-to)191-198
Number of pages8
JournalMemory and Cognition
Issue number2
StatePublished - 2002

All Science Journal Classification (ASJC) codes

  • Experimental and Cognitive Psychology
  • Neuropsychology and Physiological Psychology
  • Arts and Humanities (miscellaneous)


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