You recognize when you know something for certain, right? You know the sky is blue, or that the traffic light had turned green, or where you were on the morning of September 11, 2001--you know these things, well, because you just do. In On Being Certain, neurologist Robert Burton challenges the notions of how we think about what we know. He shows that the feeling of certainty we have when we know something comes from sources beyond our control and...