fallacy

American  

[fal-uh-see] / ˈfæl ə si /

noun

fallacies plural

1. a deceptive, misleading, or false notion, belief, etc..

   That the world is flat was at one time a popular fallacy.

   Synonyms:

   misapprehension, delusion, misconception

2. a misleading or unsound argument.

3. deceptive, misleading, or false nature; erroneousness.

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

5. Obsolete. deception.

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fallacy British  

/ ˈfæləsɪ /

noun

1. an incorrect or misleading notion or opinion based on inaccurate facts or invalid reasoning

2. unsound or invalid reasoning

3. the tendency to mislead

4. logic an error in reasoning that renders an argument logically invalid

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fallacy Cultural  

1. 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.)

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Other Word Forms

Inflected Forms

noun

• fallacies
  plural

Etymology

Origin of fallacy

First recorded in 1350–1400; from Latin fallācia “a trick, deceit,” from fallāc- (stem of fallāx ) “deceitful” + -ia -y ³; replacing Middle English fallace, from Middle French

Explanation

A fallacy is a misleading argument or belief based on a falsehood. If you oppose state testing in schools, you think it is a fallacy that educational quality can be measured by standardized tests. Fallacy comes from the Latin fallacia, for deceit. It technically means a flaw in an argument that makes it deceptive or misleading. In poetry, the "pathetic fallacy" is the false idea that things like rocks or stars have human feelings (pathos). Fallacy can also be used more generally for any false statement or idea. Some synonyms are misconception and error.

Example Sentences

Otherwise we will fall into the Netherlands Fallacy.

From Salon • May 3, 2024

Fallacy 4: Schulz fails to grasp the transformation of college spots.

From Seattle Times • Aug. 18, 2023

It is human nature to not want to give up once we’ve invested time and money because of Sunk Cost Fallacy.

From Slate • Sep. 26, 2022

Fallacy of diversion a general category of informal fallacies in which an arguer presents evidence that functions to divert the attention of the audience from the current subject of argument.

From Textbooks • Jun. 15, 2022

Fallacy of Like Eliminands not asserted to exist.

From Symbolic Logic by Carroll, Lewis

Related Words

• deception
• falsehood
• heresy
• inconsistency
• misinterpretation
• paradox
• untruth