“There is an awkward public-relations challenge for any champion of hard-nosed science. When scientists confront the deniers of evolution, or the devotees of homeopathic medicine, or people who believe that childhood vaccinations cause autism—all of whom are as demonstrably mistaken as anyone can be—they understandably fight shy of revealing just how riddled with error and misleading information the everyday business of science actually is. When you paint yourself as a defender of the truth, it helps to keep quiet about how often you are wrong.”