Working with risk science pioneer Paul Slovic, author Dan Gardner sets out to explain in a compulsively readable fashion just what that statement above means as to how we make decisions and run our lives. We learn that the brain has not one but two systems to analyze risk. One is primitive, unconscious, and intuitive. The other is conscious and rational. The two systems often agree, but occasionally they come to very different conclusions. When that happens, we can find ourselves worrying about what the statistics tell us is a trivial threat — terrorism, child abduction, cancer caused by chemical pollution — or shrugging off serious risks like obesity and smoking.