fallacy

From Middle English, from Old French fallace, from Latin fallacia (“deception, deceit”), from fallax (“deceptive, deceitful”), from fallere (“to deceive”).

• (Received Pronunciation) IPA^(key): /ˈfæləsi/

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fallacy (plural fallacies)

1. Deceptive or false appearance; that which misleads the eye or the mind.
   • 1749, Henry Fielding, The History of Tom Jones, a Foundling. In Six Volumes, volume (please specify |volume=I to VI), London: Printed by A[ndrew] Millar, […], OCLC 928184292:

     Mr Jones expressed great gratitude to the lady for the kind intentions towards him which she had expressed, and indeed testified, by this proposal; but, besides intimating some diffidence of success from the lady’s knowledge of his love to her niece, which had not been her case in regard to Mr Fitzpatrick, he said, he was afraid Miss Western would never agree to an imposition of this kind, as well from her utter detestation of all fallacy as from her avowed duty to her aunt.

   Synonyms: deception, deceitfulness

2. (logic) An argument, or apparent argument, which professes to be decisive of the matter at issue, while in reality it is not. A specious argument.
   • 1983, Richard Ellis, The Book of Sharks, Knopf, →ISBN, page 163:

     Baldridge also showed the "one molecule of blood," usually held to be the stimulus for attracting sharks, to be another common fallacy, since a molecule of blood does not exist.

• logical fallacy
• formal fallacy
• informal fallacy

• fail
• fallacious
• fallibilist
• fallibilism
• fallibility
• fallible

• sophism
• Appendix:Glossary of fallacies

• fallacy in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913.
• fallacy in The Century Dictionary, New York, N.Y.: The Century Co., 1911.
• fallacy at OneLook Dictionary Search