It is striking to me how often a world renowned expert, really top-notch in his field, can turn around and say something spectacularly dumb in an area that isn't his field. You'd be surprised how often people just don't know what they don't know, or get emotionally attached to something foolhardy. You get an expert entertainer talking about statecraft or a hard scientist talking about religion or even just a software guy talking about hardware. It can be gobsmacking.
There is a train of thought that tries to classify people into reliable and unreliable -- worth listening to or not. And I think that's a very bad idea. No one is perfectly reliable. No one has a completely rational and educated worldview. No one. I think just about everyone is going to have an opinion about something that I think is monstrously, provably, stupidly wrong.
I think the best you can do as far as reputation goes is assign it to (person, topic) tuples.
But I still think that's a heuristic at best. Perhaps a necessary one, but I think it's better still to reserve judgement for evaluation of the evidence. Listen to what someone says. Listen to the arguments he makes. Listen to the arguments other people make. Trust your own experience and reason, and go with what makes sense.
What I am saying is that if you ignore people who you think believe stupid things, you'll be ignoring a lot of people who really do know a lot of things worth listening to. And I think more than that, I'm saying that if you classify information, not by empirical value, but by the tribe of who it comes from, you're evaluating the world more like a cultist than like a scientist.
