We are often proud of our ability to size up a situation and guess what will happen next. But the mental shortcuts that make us fast thinkers also lead us into predictable traps when we try to estimate chances and form beliefs. This chapter looks at those traps—showing you why a basketball player who has made five shots in a row is not "due" to make the sixth, and why adding extra detail to a story can make it feel more likely even though it logically is not.