fallacy

[fal-uh-see]

See more synonyms for fallacy on Thesaurus.com

noun, plural fal·la·cies.

a deceptive, misleading, or false notion, belief, etc.: That the world is flat was at one time a popular fallacy.
a misleading or unsound argument.
deceptive, misleading, or false nature; erroneousness.

Logic. any of various types of erroneous reasoning that render arguments logically unsound.
Obsolete. deception.

Origin of fallacy

1350–1400; < Latin fallācia a trick, deceit, equivalent to fallāc- (stem of fallāx) deceitful, fallacious + -ia -y³; replacing Middle English fallace < Middle French

Synonyms for fallacy

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1. misconception, delusion, misapprehension.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for fallacy

falsehood, deception, misinterpretation, untruth, heresy, paradox, inconsistency, cavil, perversion, delusion, miscalculation, bias, casuistry, artifice, evasion, quirk, ambiguity, speciousness, sophistry, deviation

Examples from the Web for fallacy

Contemporary Examples of fallacy

In fact, what this map really showed was the fallacy of aggregates – and how statistics can mask real cultural shifts.
Beer Countries vs. Wine Countries
Clive Irving
December 7, 2014
Every time the thermometer drops, another anti-science politician mocks climate change as a fallacy.
From Snowy Atlanta to Sunny Sochi, It's All About Global Weirding
Scott Bixby
February 12, 2014
To prove the fallacy of said cargo cult, Olson goes into the numbers.
The GOP's Socially Conservative Minority Voter Cargo Cult
Justin Green
December 15, 2012
The many who believe that human knowledge begins in the academy are guilty of the fallacy of “lecturing birds on how to fly.”
A Manifesto for Disorder: Nassim Nicholas Taleb’s ‘Antifragile’ Reviewed
Robert Herritt
November 26, 2012
Which brings me to the real point here: the entire premise of Mr. Rubin's moral question is built upon a fallacy.
A Sophistic Moral Case For War
Ali Gharib
October 27, 2012

Historical Examples of fallacy

His want of success arose from the insufficiency, not the fallacy, of theory.
Tales And Novels, Volume 8 (of 10)
Maria Edgeworth
Do not commit the fallacy of sitting down for a little rest.
The Forest
Stewart Edward White
There is no need of a long explanation to show the fallacy of this idea.
The Sexual Question
August Forel
Godwin, in all this, reproduces the current fallacy of his generation.
Shelley, Godwin and Their Circle
H. N. Brailsford
A few minutes served to convince her of the fallacy of this expectation.
Chronicles of Border Warfare
Alexander Scott Withers

British Dictionary definitions for fallacy

fallacy

noun plural -cies

an incorrect or misleading notion or opinion based on inaccurate facts or invalid reasoning
unsound or invalid reasoning
the tendency to mislead
logic an error in reasoning that renders an argument logically invalid

Word Origin for fallacy

C15: from Latin fallācia, from fallax deceitful, from fallere to deceive

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for fallacy

late 15c., "deception, false statement," from Latin fallacia "deception," noun of quality from fallax (genitive fallacis) "deceptive," from fallere "deceive" (see fail (v.)). Specific sense in logic dates from 1550s. An earlier form was fallace (c.1300), from Old French fallace.

fallacy in Culture

fallacy

A false or mistaken idea based on faulty knowledge or reasoning. For example, kings who have divorced their wives for failing to produce a son have held to the fallacy that a mother determines the sex of a child, when actually the father does. (See sex chromosomes.)