Definition of fallacy in English:

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Pronunciation: /ˈfaləsi/

noun (plural fallacies)

1A mistaken belief, especially one based on unsound arguments: the notion that the camera never lies is a fallacy
More example sentences
  • What binds all these things together is a recurring human mistake: the fallacy of total belief in the present and its technology.
  • I can't summon the necessary faith to believe in magic if I suspect it's inconsistent nonsense, or a mess of superstitions based on fallacies.
  • It is based on myths and fallacies which provide legitimacy for gross social inequalities.
misconception, mistaken belief, misbelief, delusion, false notion, mistaken impression, misapprehension, misjudgement, miscalculation, misinterpretation, misconstruction, error, mistake, untruth, inconsistency, illusion, myth, fantasy, deceit, deception, sophism;
sophistry, casuistry, faulty reasoning, unsound argument
1.1 Logic A failure in reasoning which renders an argument invalid: Kraft exposes three fallacies in this approach
More example sentences
  • Finally, yet another theory of fallacy says a fallacy is a failure to provide adequate proof for a belief, the failure being disguised to make the proof look adequate.
  • So the knowledge argument is invalid because it involves a fallacy of equivocation: ‘know’ means something different in the two premises.
  • Dretske has denied that knowledge is closed under implication; further, he has diagnosed closure as the fallacy that drives arguments for scepticism.
1.2 [mass noun] Faulty reasoning: the potential for fallacy which lies behind the notion of self-esteem
More example sentences
  • I was under the impression that this was a forum where political issues could be discussed rationally: if you want me to be pedantic and point out every logical fallacy in every reply I've received then I'll do that.
  • Predictably, the appeal to personal experience is another well-known logical fallacy.
  • The little logical fallacy that bugged me the most was the scene where the earthquake followed the Amtrak train.


Late 15th century (in the sense 'deception, guile'; gradually superseding Middle English fallace): from Latin fallacia, from fallax, fallac- 'deceiving', from fallere 'deceive'.

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Line breaks: fal|lacy

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