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 Again, the case against de Berk pivoted entirely on the prosecutor’s fallacy, and her conviction was overturned in 2010. David Robert Grimes, Scientific American, 8 Dec. 2023 There has developed a huge fallacy that great risotto is not a dish to be tried at home. Fred Thompson, Charlotte Observer, 31 Jan. 2024 This variant of the base-rate fallacy arises because while multiple cases of SIDS are rare, so too are multiple maternal infanticides. David Robert Grimes, Scientific American, 8 Dec. 2023 That brings us nicely to nuclear testing, also operating on a fallacy that there are no people or animals in the Nevada or Australian deserts. Matt Simon, WIRED, 27 Nov. 2023 Even effective techniques like blood splatter and DNA analysis can be misused in unsound convictions, underpinned by variants of the prosecutor’s fallacy. David Robert Grimes, Scientific American, 8 Dec. 2023 Such a statement is an audacious fallacy, considering that breakdancing, one of the tenets of hip-hop culture, was already in full swing by the time Silberg’s film went into production, capitalizing on themes and communities portrayed in earlier titles like Wild Style (1983). Nicholas Bell, SPIN, 19 Dec. 2023 The retirement fallacy is the idea that everyone should be ready and willing to step out of the workforce by 55+ to make room for younger employees to move up. Sheila Callaham, Forbes, 28 Nov. 2023 And when older people remain, their presence sometimes triggers the retirement fallacy in younger employees. Sheila Callaham, Forbes, 28 Nov. 2023

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 19 Mar. 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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