i don't know if this is a joke or not :-) perhaps i was projecting? in any case, sure, the people you mention (e.g., von neuman) were wrong about a lot of things. so was isaac newton. definitely not stupid. i agree.

in any case, let me elaborate. i recall the higher your IQ, the less likely you are to fall into the traps of cognitive biases and heuristics which lead you to the wrong conclusion (i think bryan caplan reports this data). of course, smart people still tend to fall into these traps (especially when they have ideological blinkers), but my experience is that with smart people you can at least eat away at the intuitive foundations which serve as blocks to rational thinking. i've never had this experience with stupid people because they lack the basic cognitive toolkit to tear down the edifice of irrationality.

and i have socialized with stupid people quite a bit. those less wrong readers who've met me could probably intuit (if they are the subset who have intuition! :-) that i have no great problems with socializing with stupid people. drink beer, talk about sports & sex, and it's all good.

in fact, let me offer a concrete example. i have a friend about 1 std above the mean in IQ. he's an atheist, and open to all sorts of counter-intuitive ideas, and has an interest in intellectual topics. unfortunately, he has great difficulty with basic mathematics and following interlocking & contingent concepts very quickly. given enough time i can get the gist of the sort of ideas across to him, but it is very time & labor intensive (he simply can't think in terms of probability distributions for whatever reason). so over the years we've moved away from intellectual topics because of the frustrations which emerge. we both have an interest in history for example (to give a non-technical domain), but i read books much faster than he does and retain much more. this asymmetry means that it is hard to explore our common interest with any degree of parity.

he would have been a great candidate for the peer group of people who are interested in topics mooted on less wrong, but many of you would find it frustrating and boring talking to him because when he can follow he is in slo-mo, and some concepts and methods are simply not tractable for him. eventually he would become dispirited and withdraw.

so that's why i think stupidity is a problem. i wish it weren't, but i think it is.

i'll link to eliezer on my blog.