Years ago our teacher told us the story of the man who made canned tuna more popular than canned salmon. As I recall, this advertising guy had the account for some brand of canned tuna, which at the time was mostly being used as pet food. Most customers preferred canned salmon. What could he do to increase the public’s preference for this brand of tuna and thereby increase its sales? He came up with a simple slogan – “Guaranteed not to turn pink in the can.” Sales of canned tuna soon outpaced those of canned salmon. Was the man lying? No, his brand of tuna didn’t turn pink in the can. Neither did salmon, of course (or any other brand of tuna), but that’s beside the point. This story makes two important points. First, it’s most likely a myth (see Snopes ), but that hasn’t stopped it from being repeated endlessly as if it were true. The sincere repetition of false information as if it were true is common. Much of what we call “Conventional Wisdom” consists of just this sort of “knowledge