We’ll admit up-front that the title of our forthcoming book,“Over the Cliff: How Obama’s Election Drove the American Right Insane,” indulges in some rhetorical imprecision: conservatives in the United States are of course not really insane in any clinical or legal sense, and we are not suggesting they undergo sanity hearings to determine if their rights should be suspended. We mean “insane” in the common-sense meaning of the word -- having taken leave of their senses. What other word, after all, can properly describe the behavior of people who adamantly insist on believing things that are provably untrue? Einstein facetiously...