-We can't talk about group differences, for fear that anyone arguing that differences exist is just trying to shore up oppression. But ... structural oppression and actual group differences can _both exist at the same time_. They're not contradicting each other! Like, the fact that men are physically stronger than women (on average, but the effect size is really big, like _d_ ≈ 2.6 for total muscle mass) is _not unrelated_ to the persistence of patriarchy! That doesn't mean patriarchy is good; to think so would be to commit the naturalistic fallacy of [attempting to derive an _ought_ from an _is_](https://plato.stanford.edu/entries/hume-moral/#io). No one would say that famine and plague are good just because they, too, are subject to scientific explanation. This is pretty obvious, really? But similarly, genetically-mediated differences in cognitive repertoires between ancestral populations are probably going to be _part_ of the explanation for _why_ we see the particular forms of inequality and oppression that we do, just as a brute material fact devoid of any particular moral significance, like how part of the explanation for why European conquest of the Americas went smoother for the invaders than the colonization of Africa had to do with the disease burden going the other way (Native Americans were particularly vulnerable to smallpox, but Europeans were particularly vulnerable to malaria).
+We can't talk about group differences, for fear that anyone arguing that differences exist is just trying to shore up oppression. But ... structural oppression and actual group differences can _both exist at the same time_. They're not contradicting each other! Like, the fact that men are physically stronger than women (on average, but the effect size is enormous, like _d_ ≈ 2.6 for total muscle mass) is _not unrelated_ to the persistence of patriarchy! (The ability to _credibly threaten_ to physically overpower someone, [gives the more powerful party a bargaining advantage](/2020/Jan/book-review-the-origins-of-unfairness/#threatpoints-and-bargaining), even if the threat is typically unrealized.) That doesn't mean patriarchy is good; to think so would be to commit the naturalistic fallacy of [attempting to derive an _ought_ from an _is_](https://plato.stanford.edu/entries/hume-moral/#io). No one would say that famine and plague are good just because they, too, are subject to scientific explanation. This is pretty obvious, really? But similarly, genetically-mediated differences in cognitive repertoires between ancestral populations are probably going to be _part_ of the explanation for _why_ we see the particular forms of inequality and oppression that we do, just as a brute fact of history devoid of any particular moral significance, like how part of the explanation for why European conquest of the Americas happened earlier and went smoother for the invaders than the colonization of Africa had to do with the disease burden going the other way (Native Americans were particularly vulnerable to smallpox, but Europeans were particularly vulnerable to malaria).
+
+Again—obviously—_is_ does not imply _ought_. [TODO: explain that you should imagine yourself in the inferior group]
+
+I don't know how to build a better world, but it seems like there are quite _general_ grounds on which we should expect that it would be helpful to be able to _talk_ about social problems in the language of cause and effect, with the austere objectivity of an engineering discipline. If you want to build a bridge (that will actually stay up), you need to study the ["the careful textbooks \[that\] measure \[...\] the load, the shock, the pressure \[that\] material can bear."](http://www.kiplingsociety.co.uk/poems_strain.htm) If you want to build a just Society (that will actually stay up), you need a discipline of Actual Social Science that can publish textbooks, and to get _that_, you need the ability to _talk_ about basic facts about human existence and make simple logical inferences between them.
+
+And no one can do it! [("Well for us, if even we, even for a moment, can get free our heart, and have our lips unchained—for that which seals them hath been deep-ordained!")](https://www.poetryfoundation.org/poems/43585/the-buried-life) Individual scientists can get results in their respective narrow disciplines; Charles Murray can just _barely_ summarize the science to a semi-popular audience without coming off as _too_ overtly evil to modern egalitarian moral sensibilities. (At least, the smarter egalitarians? Or, maybe I'm just old.) But at least a couple things are even _worse_ (with respect to naïve, non-renormalized egalitarian moral sensibilities) than the ball-hiders like Murray can admit!
+
+Murray approvingly quotes Steven Pinker (a fellow ball-hider, though [Pinker is better at it](https://archive.is/bNo2q)): "Equality is not the empirical claim that all groups of humans are interchangeable; it is the moral principle that individuals should not be judged or constrained by the average properties of their group."
+
+A fine sentiment. I _emphatically_ agree with the _underlying moral intuition_ that makes "Individuals should not be judged by group membership" _sound like_ a correct moral principle—one cries out at the _monstrous injustice_ of the individual being oppressed on the basis of mere stereotypes of what other people who _look_ like them might statistically be like.
+
+But can I take this _literally_ as the _exact_ statement of a moral principle? _Technically?_—no! That's actually not how epistemology works! The proposed principle derives its moral force from the case of complete information: if you _know for a fact_ that I have moral property P, then it would be monstrously injust to treat me differently just because other people who look like me mostly don't have moral property P. But in the real world, we often—usually—don't _have_ complete information about people, [or even about ourselves](/2016/Sep/psychology-is-about-invalidating-peoples-identities/).
+
+Bayes's theorem (just [a few inferential steps away from the definition of conditional probability itself](https://en.wikipedia.org/wiki/Bayes%27_theorem#Derivation), barely worthy of being called a "theorem") states that for hypothesis H and evidence E, P(H|E) = P(E|H)P(H)/P(E). This is [the fundamental equation](http://yudkowsky.net/rational/bayes) [that governs](http://yudkowsky.net/rational/technical/) [all thought](https://www.lesswrong.com/posts/QrhAeKBkm2WsdRYao/searching-for-bayes-structure). When you think you see a tree, that's really just your brain computing a high value for the probability of your sensory experiences given the hypothesis that there is a tree multiplied by the prior probability that there is a tree, as a fraction of all the possible worlds that could be generating your sensory experiences.
+
+What goes for seeing trees, goes the same for "treating individuals as individuals": the _process_ of getting to know someone as an individual, involves exploiting the statistical relationships between what you observe, and what you're trying to learn about. If you see someone wearing an Emacs tee-shirt, you're going to assume that they _probably_ use Emacs, and asking them about their [dot-emacs file](https://www.gnu.org/software/emacs/manual/html_node/emacs/Init-File.html) is going to seem like a better casual conversation-starter compared to the base rate of people wearing non-Emacs shirts. Not _with certainty_—maybe they just found the shirt in a thrift store and thought it looked cool—but the shirt _shifts the probabilities_ implied by your decisionmaking.
+
+The problem that Bayesian reasoning poses for naïve egalitarian moral intuitions, is that there's no _philosophically principled_ reason for "probabilistic update about someone's psychology on the evidence that they're wearing an Emacs shirt" to be treated _fundamentally_ differently from "probabilistic update about someone's psychology on the evidence that she's female".
+
+These are of course different questions, but to a Bayesian reasoner (an inhuman mathematical abstraction for _getting the right answer_), they're the same _kind_ of question: the "correct" update to make is an _empirical_ matter that depends on the actual distribution of psychological traits among Emacs-shirt-wearers and among women. But to a naïve egalitarian, judging someone on their expressed affinity for Emacs is good, but judging someone on their sex is _bad and wrong_.