Writers and thinkers generalize all the time:

When we draw a conclusion from an array of facts, we engage in inductive reasoning. Such reasoning deals in probability, not certainty. For a conclusion to be highly probable, it must be based on evidence that is sufficient, representative, and relevant.

Hasty generalization fallacy

The fallacy known as hasty generalization is a conclusion based on insufficient or unrepresentative evidence.

HASTY GENERALIZATION

The rate of cancer is higher in Dover than in the rest of the state. Don’t move to Dover if you don’t want to get cancer.

The causes for the rate of cancer in a population are complex. Living in a particular city does not necessarily cause cancer.

In a single year, scores on standardized tests in California’s public schools rose by ten points. Therefore, more children than ever are succeeding in America’s public school systems.

Data from one state do not justify a conclusion about the whole United States.

Many people rely inappropriately on single experiences to make broad generalizations.

First, the dietitians said eggs were bad for you, but now they say eggs are OK. You can’t trust anyone’s advice on foods to eat or avoid.

Scientists will change their positions, but that does not mean that all scientific opinion should be distrusted.

NOTE: Many hasty generalizations contain words like all, ever, always, and never, when qualifiers such as most, many, usually, and seldom would be more accurate.

Stereotype fallacy

A stereotype is a hasty generalization about a group. Here are a few examples.

STEREOTYPES

Stereotyping is common because of our human tendency to perceive selectively. We tend to see what we want to see; that is, we notice evidence confirming our already formed opinions and fail to notice evidence to the contrary. For example, if you have concluded that politicians are corrupt, your stereotype will be confirmed by news reports of legislators being indicted—even though every day the media describe conscientious officials serving the public honestly and well.