Malcolm Gladwell writes:
When we say that pit bulls are dangerous, we are making a generalization, just as insurance companies use generalizations when they charge young men more for car insurance than the rest of us (even though many young men are perfectly good drivers), and doctors use generalizations when they tell overweight middle-aged men to get their cholesterol checked (even though many overweight middle-aged men wont experience heart trouble). Because we dont know which dog will bite someone or who will have a heart attack or which drivers will get in an accident, we can make predictions only by generalizing. As the legal scholar Frederick Schauer has observed, painting with a broad brush is an often inevitable and frequently desirable dimension of our decision-making lives.
Another word for generalization, though, is stereotype, and stereotypes are usually not considered desirable dimensions of our decision-making lives. The process of moving from the specific to the general is both necessary and perilous.