 This is a tricky matter. There are many possible reasons why so many people in a field might agree, and such agreement doesn’t always signal that they are all correct. One possibility is that all the foregoing putative experts were trained by one and the same “guru”, who was a very persuasive and compelling figure. (Using a Bayesian analysis, it becomes clear that identifying an extra concurring believer need not strengthen one’s evidence as compared with a single believer. See Goldman (2001: 99–102).)