Hasty generalization

What Is a Hasty Generalization Fallacy?

Also called the fallacy of insufficient statistics or sample, the hasty generalization fallacy occurs when someone assumes something is true about a large group based on an extremely small sample size. Fallacies, as flaws in logical reasoning in an argument, are seen in both speech and writing. The hasty generalization fallacy, however, is frequently — and often unintentionally — used in everything from formal arguments to casual conversation. Often, it occurs as a result of prejudice or lazy reasoning.

In a hasty generalization fallacy, the writer or speaker makes a claim that because something is true about a sample of a larger group, it is true about the group as a whole. For example, some might say "I have dated three redheads, and they all had tempers. Therefore, all redheads have tempers." This is a hasty generalization because three is not a large enough sample size to accurately determine the temper of all redheads.