It's been said that libertarian philosophers love Murray Rothbard as an economist and historian, but not as a philosopher. Libertarian historians love Murray Rothbard as an economist and philosopher, but not as an historian. Libertarian economists love Murray Rothbard as an historian and philosopher, but not as an economist.
I'm not picking on Rothbard at all; this is just an example. I might love what a writer says about areas outside my narrow field of expertise but dismiss what the writer says in an area where I can tell when he or she is making a mistake. This leaves me in an uncomfortable position: if Walter Writer is unreliable on economics (where I'm an expert), why should I think he is reliable on philosophy or theology (where I'm not)? If Walter Writer is an expert on philosophy or theology, then it is appropriate to give him the benefit of the doubt, but when Walter Writer is writing in a field outside his area of expertise and mine, I can't help but wonder where I should be most skeptical. If he gets the economics right, I'm more likely to believe him on philosophy or theology. If he doesn't, I'm less likely to believe him on areas outside his area of specialization.
This makes me lose sleep at night, so I'll turn it over to EconLog readers. When are you most and least willing to give a writer the benefit of the doubt?