fallacy

noun

fal·​la·​cy ˈfa-lə-sē How to pronounce fallacy (audio)
plural fallacies
1
a
: a false or mistaken idea
popular fallacies
prone to perpetrate the fallacy of equating threat with capabilityC. S. Gray
b
: erroneous character : erroneousness
The fallacy of their ideas about medicine soon became apparent.
2
a
: deceptive appearance : deception
b
obsolete : guile, trickery
3
: an often plausible argument using false or invalid inference

Did you know?

Philosophers are constantly using the word fallacy. For them, a fallacy is reasoning that comes to a conclusion without the evidence to support it. This may have to do with pure logic, with the assumptions that the argument is based on, or with the way words are used, especially if they don't keep exactly the same meaning throughout the argument. There are many classic fallacies that occur again and again through the centuries and everywhere in the world. You may have heard of such fallacies as the "ad hominem" fallacy, the "question-begging" fallacy, the "straw man" fallacy, the "slippery slope" fallacy, the "gambler's" fallacy, or the "red herring" fallacy. Look them up and see if you've ever been guilty of any of them.

Examples of fallacy in a Sentence

The fallacy of their ideas about medicine soon became apparent. the once-common fallacy that girls just weren't any good at math
Recent Examples on the Web To scrutinize where everyone else went wrong is to fall, willingly, into what might be thought of as the fans’ fallacy: the assumption that only one team has agency, that its fate is defined by its own strengths and weaknesses and nothing else, that no external factors are at play. Rory Smith, New York Times, 29 Mar. 2024 Harlene introduced me to a concept of her own invention: the Robinson fallacy. Joseph O’Neill, The New Yorker, 11 Mar. 2024 See all Example Sentences for fallacy 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'fallacy.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Latin fallacia, from fallac-, fallax deceitful, from fallere to deceive

First Known Use

15th century, in the meaning defined at sense 2b

Time Traveler
The first known use of fallacy was in the 15th century

Dictionary Entries Near fallacy

Cite this Entry

“Fallacy.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fallacy. Accessed 25 Apr. 2024.

Kids Definition

fallacy

noun
fal·​la·​cy ˈfal-ə-sē How to pronounce fallacy (audio)
plural fallacies
1
: a false or mistaken idea
2
: the quality or state of being false

More from Merriam-Webster on fallacy

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