Most of the time, we think fast. And most of the time we're really expert at what we're doing, and most of the time, what we do is right.
The psychologist, Paul Rozin, an expert on disgust, observed that a single cockroach will completely wreck the appeal of a bowl of cherries, but a cherry will do nothing at all for a bowl of cockroaches.
We're beautiful devices. The devices work well; we're all experts in what we do. But when the mechanism fails, those failures can tell you a lot about how the mind works.