# Fallacy of division

*Also called: Whole to part error*

- **Cluster:** Part and whole — Traits smuggled between members and groups
- **Page:** https://fallacy.wiki/fallacy/division/
- **In Arabic:** https://fallacy.wiki/ar/fallacy/division.md
- **Licence:** CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/

## What it is

Inferring that what is true of the whole must be true of each of its parts.

## In the wild

> The company is profitable, so every department is.

## How to answer it

Ask for the breakdown. Aggregates hide their own variation.

## Origin and naming

The mirror image of the fallacy of composition, and treated with the same lineage: Aristotle sketched it in 'On Sophistical Refutations', and both were formalised under their current names in nineteenth-century logic textbooks. The atomist move — a whole is coloured, so its tiniest pieces must be — is the classic textbook target.

## More places it shows up

- The dataset contains a billion rows, so each row must be huge.
- The choir performed superbly tonight, so our new tenor probably covered himself in glory.
- The department is described as flat and agile, so every team inside it must run that way.
- The podcast won a national award, so my favourite episode must be among the best.

## How to spot it

- Notice when a whole-level label ('world-class hospital', 'well-run system') is handed down to a member with no member-level check.
- Notice when an aggregate figure (average, total, general reputation) does all the talking and no breakdown is ever asked for.
- Notice when the part is described with confidence even though it was never inspected on its own.

## Nearby

- [Fallacy of composition](https://fallacy.wiki/fallacy/composition.md)
- [Ecological fallacy](https://fallacy.wiki/fallacy/ecological.md)
- [Fallacy of accident](https://fallacy.wiki/fallacy/accident.md)

## Read more

- [Wikipedia](https://en.wikipedia.org/wiki/Fallacy_of_division)
- [The Fallacy Files](https://www.fallacyfiles.org/division.html)

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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.