It should be clear by now that there are people who can, in fact, be reasonably considered experts; that it is rational to rely, within limits, on ex pert opinion; and that it is possible, by exercising relatively simple criteria, to gain insight into whether a particular expert is reliable or not. It is also true that experts, of course, do make mistakes, and that even the agreement of a large majority of experts in a field does not guarantee that they got it right. That's the nature of scientific truth, as we have seen throughout this book: it is tentative, because it is the result of a human endeavor that is limited both by the type and amount of available evidence and by humans' finite mental powers and emotional reactions. But the examples above show how you can, with a little bit of practice, tell science from bunk!