A generalization is a broad statement or conclusion drawn from specific examples or observations. When you notice that every dog you've met likes to play fetch, you might make a generalization that “all dogs like fetch.” When a scientist observes that metals expand when heated in several experiments, she forms a generalization about how metals behave.

Generalizations help us learn from experience and recognize patterns. After trying several mystery novels by the same author, you might generalize that her books always include clever plot twists. That generalization helps you decide whether to read her next book.

The tricky part is knowing when a generalization holds true and when it doesn't. Some generalizations are reliable: “Water freezes at 32 degrees Fahrenheit” works every time at sea level. But other generalizations can be overgeneralizations, meaning they claim too much from too little evidence. Saying “all sixth graders hate vegetables” based on your three friends would be an overgeneralization, since plenty of sixth graders actually enjoy vegetables.

Good thinkers learn to make careful generalizations based on solid evidence while staying open to exceptions. When someone makes a sweeping generalization like “everyone thinks this way” or “that never works,” it's worth asking: is that really true in all cases, or just in some?