Proof by example
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Proof by example (also known as inappropriate generalisation) is a logical fallacy whereby one or more examples are claimed as "proof" for a more general statement.
This fallacy has the following argument form:
- I know that x
X has the property P. - Therefore, all other elements of X have the property P.
The following example demonstrates why this is a logical fallacy:
- I've seen a person shoot someone.
- Therefore, all people are murderers.
That argument is obviously flawed, but arguments of the same form can sometimes seem superficially convincing, as in the following example:
- I've seen John's brother steal something. John's family must be thieves.
