Hasty generalization is drawing a general rule from too few cases, too few cases to support the conclusion drawn from them. "I met two and they were both like that, therefore they all are" is the exact format of the error.
Why is it disguised as life experience
This fallacy is insidious because it doesn't seem like a logical error, it seems like practical wisdom. Someone observes two or three cases and converts that small sample into a law about an entire group. The difference between observing and generalizing is precisely the size and variety of the sample, and that is where hasty reasoning fails without realizing it.
The silent factory of almost all prejudices
Note that no prejudice needs a lie to be born. Just take a few real, verifiable cases and treat them as if they represented an entire group. That is why this fallacy is called, in the class that gave rise to this article, the silent factory of almost all prejudices: they are not born from invention, they are born from a small sample dressed as a general rule.
How to recognize the error
The question that exposes the hasty generalization is simple: how many cases, exactly, support this conclusion, and are they varied enough to represent the entire group? Two or three observations are rarely enough, even if they seem sufficient to those who have experienced them up close.
How to defend yourself from it
The defense is not to reject all generalizations, generalizing is part of how we learn from experience. The defense is to distinguish between well-founded generalizations, with a broad and varied sample, and hasty ones, taken from a few cases and treated as law. This same caution applies to its cousin fallacy, the appeal to the majority, which trades evidence for quantity in another way.
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What is hasty generalization?
It is the fallacy of drawing a general conclusion from a few cases, insufficient to support it. "I met two and they were both like that, therefore they all are" is the exact error pattern.
Why is hasty generalization dangerous?
Because it disguises itself as life experience and common sense, and is the silent factory of almost all prejudices, which arise from small samples treated as a general rule.
How to avoid hasty generalization?
Asking whether the observed sample is large and varied enough to support the conclusion, and remembering that exceptions alone do not confirm or refute a rule.
The other cluster fallacies: What is ad hominem · What is the strawman fallacy · What is false dilemma
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