There is a common idea in the “critical thinking”/"traditional rationality" community that (roughly) you should, when exposed to an argument, either identify a problem with it or come to believe the argument’s conclusion. From a Bayesian framework, however, this idea seems clearly flawed. When presented with an argument for a certain conclusion, my failure to spot a flaw in the argument might be explained by either the argument’s being sound or by my inability to identify flawed arguments. So the degree to which I should update in either direction depends on my corresponding prior beliefs. In particular, if I have independent evidence that the argument’s conclusion is false and that my skills for detecting flaws in arguments are imperfect, it seems perfectly legitimate to say, “Look, your argument appears sound to me, but given what I know, both about the matter at hand and about my own cognitive abilities, it is much more likely that there’s a flaw in your argument which I cannot detect than that its conclusion is true.” Yet it is extremely rare to see LW folk or other rationalists say things like this. Why is this so?