# fallacy

/ˈfæɫəsi/ (US) · /fˈæləsi/ (UK)

Source: https://englishreference.com/word/fallacy
Updated: 2026-08-27

## Senses

### 1. a mistaken belief

noun · CEFR C1 · Academic

an idea that many people believe is true, but is actually false.

For teachers: a widely held but false belief or misconception.

- It is a common fallacy that eating carrots will give you perfect night vision.
- The documentary aims to expose the fallacy that economic growth can continue indefinitely without environmental consequences.

Usage: Often used with the adjective 'common' or 'popular'.

### 2. faulty reasoning

noun · CEFR C1 · Academic · Technical

a mistake in an argument that makes the conclusion wrong.

For teachers: a failure in reasoning which renders an argument invalid; a specious or deceptive argument.

- The lawyer pointed out the fallacy in the witness's logic.
- His entire thesis rests on a logical fallacy, assuming that because two events happened together, one must have caused the other.

Usage: Frequently appears in the phrase 'logical fallacy'.

## Examples

- It is a fallacy to think that money always brings happiness.
- The politician's argument relied on a logical fallacy that assumed because two events happened together, one caused the other.
- The sunk cost fallacy often compels investors to continue pouring resources into a failing venture simply because they have already committed so much to it.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.