# Fallacy of four terms

*Also called: Quaternio terminorum*

- **Cluster:** Broken structure — The form itself does not carry the conclusion
- **Page:** https://fallacy.wiki/fallacy/four-terms/
- **In Arabic:** https://fallacy.wiki/ar/fallacy/four-terms.md
- **Licence:** CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/

## What it is

A syllogism that looks valid but uses four terms because one word shifted meaning.

## In the wild

> Nothing is better than wisdom; a sandwich is better than nothing; so a sandwich beats wisdom.

## How to answer it

Count the distinct concepts, not the distinct words. A valid syllogism has exactly three.

## Origin and naming

Quaternio terminorum — 'four terms' — names a syllogism that carries one term too many. A valid categorical syllogism needs exactly three: the two in the conclusion plus the middle that links them. In practice the fourth term is usually smuggled in by one word doing double duty, which makes this fallacy a close cousin of equivocation.

## More places it shows up

- Banks deal with money; the river has banks; so the river deals with money.
- Justice requires blind judgment; a referee is blind to the replay; so referees are just.
- Stars light up the sky; celebrities are stars; so celebrities light up the sky.
- Iron is an element; you iron a shirt; so pressing shirts involves chemistry homework.

## How to spot it

- Notice when the middle word appears twice but no paraphrase can give it one consistent meaning both times.
- Notice when a joke-style riddle is doing the job of an argument — surprise at the wordplay is often the tell.
- Notice when the premises are each trivially true and the conclusion absurd; the leak is usually a fourth term.

## Nearby

- [Equivocation](https://fallacy.wiki/fallacy/equivocation.md)
- [Undistributed middle](https://fallacy.wiki/fallacy/undistributed-middle.md)

## Read more

- [Wikipedia](https://en.wikipedia.org/wiki/Fallacy_of_four_terms)
- [Internet Encyclopedia of Philosophy](https://iep.utm.edu/fallacy/)

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From fallacy.wiki — a bilingual field guide to 91 logical fallacies, published by phi holdings. Licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/): reuse freely with attribution to fallacy.wiki.