Evidence, at the level of a single argument in any field that isn't subject to unambiguous experimental tests, is "what seems convincing". That's almost tautological. Careers in these fields -- which make up the vast majority of talky fields out there, incidentally, and thus include the vast majority of arguments that a randomly selected member of the public will ever get into -- aren't made by being right in an abstract sense, but by convincing bosses, investors, and/or members of the public that you're right. Avoiding being manipulated by your opponents is also important, but that has a lot less to do with formal logic and a lot more to do with social dynamics. Out in the wild, I don't see a whole lot of passion for the mathematical rules of logic and evidence in the practice of people whose job it is to argue with other strong debaters, i.e. lawyers and politicians. Same goes -- in an admittedly more sophisticated way -- for many branches of academia, which is theoretically a reference class made up entirely of people who're well-informed about the rules of logic and evidence, so we're not just dealing with a need to pander here. What I do see is a lot of complex signaling behavior, a lot of sophistication around the selection and presentation of evidence that favors your side, and a lot of techniques for seeming, or for actually being, sincere in the presentation of your argument. Which is exactly what I'd expect. We're not dealing with predator/prey dynamics here, where the criteria for fit and unfit are unambiguous and large chunks of fitness ultimately come down to physics; we're dealing with a nasty incestuous free-for-all, where fitness is usually socially determined, using brains that're built not for formal logic but for managing personal alliances. What do you think the cheapest route to winning an argument is going to be, most of the time?