Compared to the European average IQ of 100, Ashkenazi Jews are about 1 standard deviation above, at 115, and Northeast Asians are at about 110. If we imagine IQ as a type of "height," and let's say that the average European male was 5'10, it would be as if Jews were on average 6'1 and Asians 6'0. This IQ advantage makes these two groups over-represented in the hard sciences, where braininess makes a big difference in who succeeds vs. who doesn't.
But what about the social sciences? They're not as "hard," but they still require an ability to look at a bunch of stuff and draw patterns out of it, to lock several of these basic patterns into a single more abstract pattern, and so on. So, groups with higher IQ should be over-represented in these fields as well, all else being equal.
And yet there's virtually no major thinker in the social sciences who was insightful, original, broadly visionary and who was also of Northeast Asian background.
Jews are certainly over-represented among major thinkers in the social sciences (see some of the lists of influential Jews in various fields at JINFO). But just about all of the big deals were either nutcases or frauds -- Marx and Freud being the most egregious examples. Slightly lower in overall influence but still joining those two are Boas in anthropology, Derrida in philosophy, and the leaders of neoliberal economic physics-envy.
The only major one who strikes me as insightful, original, and whose vision touched an incredibly broad array of topics was Durkheim in sociology and anthropology. I'm not counting those who did good original work in a limited field, but whose results weren't like a revelation, for example Asch and Milgram in social psychology. Chomsky hits all the marks too, but I don't see that work as part of social science, as he studies properties of an individual's brain or mind without attention to a larger social context. And his linguistics work is more like that of a molecular biologist than a zoologist. I can see how others would include him, though, so that makes one "for-sure" and one "possible" exception to the trend for major Jewish social science thinkers to have come straight from the loony bin.
A major confusion when talking about the disproportionate number of Jews in crazy circles is to think that they're just over-represented everywhere requiring high IQ -- including the sane and brilliant circles. Again I just don't see that when going through the lists at JINFO or thinking off the top of my head. I know there are exceptions at lower levels of accomplishment, but I'm talking really breakthrough figures.
Why do these brainy groups not dominate the social sciences like they do the harder sciences (intellectually, not numerically)? Clearly high IQ is not enough -- you also need a good intuition for how human beings work inside and among each other. I trace the underwhelming performance of these two groups to the ecological niches that they are adapted to, which have relaxed the selection pressures for keen social intelligence and thereby redirected selection to improve other traits.
Asians just seem not to get people at all, not that they have very clear and crazy views about people. For instance, they are poorer than Caucasians at reading faces for basic emotional expressions. They tend to blur "fear" and "disgust," as a result of focusing too much on the eyes and not taking in information from more of the face. This seems like a dialed-down social intelligence, one that sees more noise around the signal, not one that mixes up, say, "fear" and "joy." Since they don't perceive as much about people, they just don't get very interested in social sciences to begin with, or acting, stand-up comedy, rock music, and so on.
What relaxed selection for social intelligence in Asians, and redirected the body's resources into other traits, is the intensive agriculture that they have practiced for nearly 10,000 years. Really intensive agriculture brings hierarchical social structures along with it, to coordinate a highly complex system. For example, you might need to irrigate the land. Small-scale gardeners (horticulturalists), such as those in Sub-Saharan Africa, can just send a woman out with a spade to dig up the ground, plant stuff, and have it grow without needing to divert a river. To thrive in such a top-down society, you shouldn't try to figure out how people work -- you just need to do what you're told so that the whole big machine runs smoothly.
And in your hour-by-hour work, you're engaged mostly with a bunch of stuff that does not have a mind of its own -- your tools, the ground, seeds, plants, and so on. Smaller-scale gardeners, doing less intense work, have plenty of time to socialize. Hunter-gatherers ditto, plus they have to get inside the mind of the animals they're hunting. Pastoralists (animal herders) also have to be able to sympathize with the needs and feelings of their livestock in order to be the best shepherd. As for interactions with people, herders live in far less authoritarian groups, so there's a good deal of buddy-buddy among the in-group members. And even when they encounter someone from the out-group, the interaction takes the form of a showdown in a lawless borderland, where it pays to be able to get inside his head.
All of that is a long way of saying that groups adapted to intensive agriculture will have an impaired social intelligence, such as among Central Americans and East Asians. It's not that their social sense is haywire or biased -- just out-of-focus. Hunter-gatherers would probably make good social scientists if they were smarter, but they tend to have the lowest average IQs, and small-scale gardeners are only somewhat smarter. The key group to have in your population in order to make good social science is pastoralists -- as a rule-of-thumb, you find them wherever at least a good-sized minority can drink milk, from the Northwestern Indian subcontinent through the Middle East and Levant, around the Mediterranean, and into Europe. Although animal herding is a more recent development in East Africa, I'll bet they'd make good social scientists too, compared to other Sub-Saharan Africans.
That's Asians. But what's the deal with Jewish social science? They were restricted to a white-collar occupational niche for close to 1000 years in Europe, serving as tax farmers, money lenders, and other financial and commercial roles. That removes them even further from normal chummy social interaction than does intensive agriculture, but unlike Asians they have produced very clearly articulated, very influential, and very nutty pictures of human nature. Where does this vision that is not fuzzy but clear and almost hallucinatory come from?
Well, if you were a tax farmer or money lender in Medieval Europe, you did not enjoy all the protection of the modern state and market economy. If you made a bad decision, you could have gotten wiped out -- no welfare state to bail you out (in fact, they would have cheered a banker going bankrupt). Some of these bad decisions could be asocial -- like you forget to carry the 1. But a good deal would have been social, for example if you gave the other party the benefit of the doubt and they ended up screwing you. Unlike Asians, then, Jews had fairly frequent interactions with other people, but they were mostly adversarial in nature.
Since even a small miscalculation in that case could prove disastrous, it is more advantageous to set a low threshold for the "nah, that person stinks" detector. In those occupations in those times and places, better to assume that everyone else was stupid, selfish, and treacherous. That way, you'll make sure to do the calculations yourself and to not get taken advantage of by deadbeats.
Imagine if a group of mostly endogamous people were only allowed to work as guards and wardens in the prison system -- would it pay in Darwinian terms for them to have a rosier or darker view of human nature? I would not expect accurate and insightful social science to come from such a group. When your social interactions with your fellow man are mostly adversarial and in the context of a power imbalance that favors you, you aren't going to see human sociality very clearly -- indeed, you will behold a distorted reality, seeing phantom selfishness where there is none, and having a blind spot to the common sense that makes your charges smarter than you think.
Only when you frequently relate to other people on equal terms, experiencing both their good and bad tendencies, will you have a clear basic picture to work with when kicking ideas for social science around your head.