fallacy

noun
fal·​la·​cy | \ ˈfa-lə-sē How to pronounce fallacy (audio) \
plural fallacies

Definition of fallacy

1a : a false or mistaken idea popular fallacies prone to perpetrate the fallacy of equating threat with capability— C. S. Gray
b : erroneous character : erroneousness The fallacy of their ideas about medicine soon became apparent.
2a : deceptive appearance : deception
b obsolete : guile, trickery
3 : an often plausible argument using false or invalid inference

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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

His fallacy is treating capital as a simple valve that can be used to dial risk up or down, with no unintended consequences. WSJ, "Furman Is Wrong About Bank Capital Buffer," 28 Aug. 2018 As more voices like Bündchen’s join the mental health conversation, dispelling the fallacy of perfection along the way, the old taboos slowly lose their grip. Sara Gaynes Levy, Vogue, "Why Gisele Bündchen’s Honest Conversation About Suicide Is So Important Now," 26 Sep. 2018 The fast-moving planet of communication has been retrograde in Leo since late July, leading to some seriously frustrating financial fallacies. Aliza Kelly Faragher, Allure, "What Your Sign's August 2018 Horoscope Predictions Mean for You," 30 July 2018 Greg Gutfeld: Opioids -- Facts and fallacies. Newt Gingrich: Trump and Macron are two leading reformers trying to drain the swamp. Fox News, "FOX NEWS FIRST: Giuliani sizes up Mueller's 'open mind'; President Trump on 'Fox & Friends' Thursday at 8 a.m. ET," 26 Apr. 2018 My father and others have been speaking about the environment for decades - not basing it on fallacy or new-age hypothesis, but rooted in science and facts, and the sobering awareness of our environmental vulnerability. Caroline Hallemann, Town & Country, "Prince Harry Just Paid Tribute to Prince Charles and His Work in the Fight Against Climate Change," 26 Oct. 2018 The idea the food doesn’t need to be subsidized, that tech workers make so much, is a fallacy. Nellie Bowles, The Seattle Times, "San Francisco officials to tech workers: Leave the office, buy your lunch," 31 July 2018 Sign up for our daily newsletter and never miss our latest and greatest stories Culture A guide to busting through confirmation bias, the cognitive fallacy that's destroying our discourse. Michael Fitzgerald, WIRED, "The Court Case that Enabled Today's Toxic Internet," 8 July 2018 And there is another essential fallacy of these negotiations. NBC News, "North Korea shatters Trump's boastful assurances of an easy path to denuclearization," 7 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'fallacy.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of fallacy

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

History and Etymology for fallacy

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

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Statistics for fallacy

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Time Traveler for fallacy

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

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More Definitions for fallacy

fallacy

noun

English Language Learners Definition of fallacy

: a wrong belief : a false or mistaken idea
: the quality of being false or wrong

fallacy

noun
fal·​la·​cy | \ ˈfa-lə-sē How to pronounce fallacy (audio) \
plural fallacies

Kids Definition of fallacy

1 : a false or mistaken idea
2 : false reasoning

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