Composition and division
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The logical fallacies of composition and division are a pair of fallacies which are based on a confusion between what is true of the part and what is true of the whole. The fallacy of composition is an incorrect inference from what is known of the parts to asserting the same of the whole; and the fallacy of division is the reverse, from the whole to the part. Comparing the fallacy to the figures of speech called synecdoche (as when one says "wheels" to refer to an auto), one might say that the fallacy consists of taking the figure of speech literally.
[edit] Examples
Textbook examples of the fallacy:
- Because large objects are made of atoms, large objects have the properties of atoms, and atoms have the properties of large objects.
- Because the head of state represents the nation, to say something bad about him/her is to insult the nation.
Some examples of the fallacy as used by creationists:
- Because no living thing is older than a few hundred, or at most a few thousand, years old, life itself is no older than a few thousands of years.
- Because entropy does not decrease in an isolated and closed system, it does not decrease in the universe as a whole (which is made up of isolated and closed systems); and it does not decrease in any part of the universe.
A favorite of climate change deniers:
- Because no individual human being is powerful enough to affect the climate of Earth, anthropogenic climate change is impossible.
[edit] Spotlight fallacy
Composition and division is related to, but distinct from the spotlight fallacy. The latter is committed when unrepresentative information about parts is being used to make statements about the whole, even though the inference is correct, while the latter applies when the inference itself is incorrect, even if the information about parts is complete or at least representative.