fallacy

[ fal-uh-see ]

noun

, plural fal·la·cies.

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.

fallacy

/ 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

fallacy

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 .)

Word History and Origins

Origin of fallacy¹

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

Word History and Origins

Origin of fallacy¹

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

Example Sentences

This fallacy was amply disproved by the "cat-eating Haitians" lie.

From Salon

Zero-sum thinking is literally classified as a logical fallacy, and the reason why should be obvious given a moment's thought.

From Salon

Trump's relentless repetition of the zero-sum fallacy, however, has sadly convinced many voters that two groups of people are at odds with each other: men and women.

From Salon

But there’s a disgraceful cynicism working in this “fallacy of the excluded middle.”

From Salon

What he might not have expected was Harris calling out that fallacy.

From Salon

Related Words

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