What it is
Inferring that what is true of the parts must be true of the whole they form.
In the wild
Every player is excellent, so the team is excellent.
How to answer it
Ask whether the property depends on how the parts interact.
Part and whole
Fallacy of composition
Also called Part to whole error
In depth
Origin and naming
The pattern was treated by Aristotle in 'On Sophistical Refutations', and the modern name 'fallacy of composition' was made standard by Richard Whately in his 1826 'Elements of Logic'. It became famous in economics through the observation that what is wise for one saver (a paradox of thrift) can be ruinous when everyone does it at once.
More places it shows up
Every feature on the roadmap scored 'high priority', so the release plan is a high-priority release.
Stand up so you can see; everyone in the crowd stands up; the crowd still cannot see better than before.
Each doc page was written clearly on its own, so the migration guide is clear from start to finish.
We saved on every single itinerary by cutting the buffer day, so the whole trip is cheaper with no added risk.
How to spot it
- Notice when the argument jumps from 'each part' to 'the sum' with no mention of how the parts interact.
- Notice words like 'overall', 'as a whole', 'the team as a unit' riding on a list of part-level facts.
- Notice when scaling up is described as mere repetition, as if everyone can do it at once.