In logic, equivocation ('calling two different things by the same name') is an informal fallacy resulting from the use of a particular word/expression in multiple senses throughout an argument leading to a false conclusion.[1][2] Abbott and Costello's "Who's on first?" routine is a well known example of equivocation.[3][4]

It is a type of ambiguity that stems from a phrase having two distinct meanings, not from the grammar or structure of the sentence.[1]

Below is an example of equivocation in a syllogism (a logical chain of reasoning).

  • Since only man [human] is rational,
and no woman is a man [male],
therefore, no woman is rational.[1]

The first instance of "man" implies the human species, while the second implies just the males.

See alsoEdit


  1. ^ a b c Damer, T. Edward (21 February 2008). Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments. Cengage Learning. pp. 121–123. ISBN 0-495-09506-0.
  2. ^ Fischer, D. H. (June 1970), Historians' fallacies: toward a logic of historical thought, Harper torchbooks (first ed.), New York: HarperCollins, p. 274, ISBN 978-0-06-131545-9, OCLC 185446787
  3. ^ Curtis, Gary (n.d.). "Logical Fallacy: Equivocation". The Fallacy Files. Retrieved 17 July 2017.
  4. ^ Abbott & Costello Who's On First on YouTube