-This _should_ just be more social-science nerd stuff, the sort of thing that would only draw your attention if, like me, you feel bad about not being smart enough to do algebraic topology and want to console yourself by at least knowing about the Science of not being smart enough to do algebraic topology. The reason everyone _and her dog_ is still mad at Charles Murray a quarter century later is Chapter 13, "Ethnic Differences in Cognitive Ability", and Chapter 14, "Ethnic Inequalities in Relation to IQ". So, _apparently_, different ethnic/"racial" groups have different average scores on IQ tests. [Ashkenazi Jews do the best](https://slatestarcodex.com/2017/05/26/the-atomic-bomb-considered-as-hungarian-high-school-science-fair-project/). (I sometimes privately joke that the fact that I'm [only 85% Ashkenazi (according to 23andMe)](/images/ancestry_report.png) explains my low IQ.) East Asians do a little better than Europeans/"whites". And—this is the part that no one is happy about—the difference between U.S. whites and U.S. blacks is about Cohen's _d_ ≈ 1. (If two groups differ by _d_ = 1 on some measurement that's normally distributed within each group, that means that the mean of the group with the lower average measurement is at the 16th percentile of the group with the higher average measurement, or that a uniformly-randomly selected member of the group with the higher average measurement has a probability of about 0.76 have having a higher measurement than a uniformly-randomly selected member of the group with the lower average measurement.)
+This _should_ just be more social-science nerd stuff, the sort of thing that would only draw your attention if, like me, you feel bad about not being smart enough to do algebraic topology and want to console yourself by at least knowing about the Science of not being smart enough to do algebraic topology. The reason everyone _and her dog_ is still mad at Charles Murray a quarter century later is Chapter 13, "Ethnic Differences in Cognitive Ability", and Chapter 14, "Ethnic Inequalities in Relation to IQ". So, _apparently_, different ethnic/"racial" groups have different average scores on IQ tests. [Ashkenazi Jews do the best](https://slatestarcodex.com/2017/05/26/the-atomic-bomb-considered-as-hungarian-high-school-science-fair-project/), which is why I sometimes privately joke that the fact that I'm [only 85% Ashkenazi (according to 23andMe)](/images/ancestry_report.png) explains my low IQ. (I'm pretty dumb compared to some of my [robot-cult](/tag/my-robot-cult/) friends.) East Asians do a little better than Europeans/"whites". And—this is the part that no one is happy about—the difference between U.S. whites and U.S. blacks is about Cohen's _d_ ≈ 1. (If two groups differ by _d_ = 1 on some measurement that's normally distributed within each group, that means that the mean of the group with the lower average measurement is at the 16th percentile of the group with the higher average measurement, or that a uniformly-randomly selected member of the group with the higher average measurement has a probability of about 0.76 have having a higher measurement than a uniformly-randomly selected member of the group with the lower average measurement.)
+
+It's important not to overinterpret the IQ-scores-by-race results; there are a bunch of standard caveats that go here that everyone's treatment of the topic needs to include. Again, just because variance in a trait is statistically associated with variance in genes _within_ a population, does _not_ mean that differences in that trait _between_ populations are _caused_ by genes: [remember the illustrations about](#heritability-caveats) sun-deprived plants and internet-deprived red-haired children. Group differences in observed tested IQs are entirely compatible with a world in which those differences are entirely due to the environment imposed by an overtly or structurally racist society. Maybe the tests are culturally biased. Maybe people with higher socioeconomic status get more opportunities to develop their intellect, and racism impedes socio-economic mobility. And so on.
+
+The problem is, a lot of the blank-slatey environmentally-caused-differences-only hypotheses for group IQ differences become less compelling when you look into the details. "Maybe the tests are biased", for example, isn't an insurmountable defeater to the entire endeavor of IQ testing—it is _itself_ a falsifiable hypothesis, or can become one if you specify what you mean by "bias" in detail. One idea of what it would mean for a test to be _biased_ is if it's partially measuring something other than what it purports to be measuring: if your test measures a _combination_ of "intelligence" and "submission to the hegemonic cultural dictates of the test-maker", then individuals and groups that submit less to your cultural hegemony are going to score worse, and if you _market_ your test as unbiasedly measuring intelligence, then people who believe your marketing copy will be misled into thinking that those who don't submit are dumber than they really are. But if so, and if not all of your individual test questions are _equally_ loaded on intelligence and cultural-hegemony, then the cultural bias should _show up in the statistics_. If some questions are more "fair" and others are relatively more culture-biased, then you would expect the _order of item difficulties_ to differ by culture: the ["item characteristic curve"](/papers/baker-kim-the_item_characteristic_curve.pdf) plotting the probability of getting the biased question "right" as a function of _overall_ test score should differ by culture, with the hegemonic group finding it "easier" and others (answering honestly) finding it "harder". Conversely, if the questions that discriminate most between differently-scoring cultural/ethnic/"racial" groups were the same as the questions that discriminate between (say) younger and older children _within_ each group, that would be the kind of statistical clue you would expect to see if the test was unbiased and the group difference was real. Hypotheses that accept IQ test results as unbiased, but attribute group differences to the environment, also make statistical predictions. Controlling for parental socioeconomic status only cuts the black–white gap by a third.
+
+[TODO: sentence about sources of variation within/between groups based on Jensen]
+
+[TODO: sentence about colorism based on https://www.mdpi.com/2624-8611/1/1/17/htm "Skin color is actually only controlled by a small number of alleles, so if you think societal discrimination on skin color causes IQ differences"]
+
+And so on.
+
+In mentioning these arguments in passing, I'm _not_ trying to provide a comprehensive lit review on the causality of group IQ differences. (That's [someone else's blog](https://humanvarieties.org/2019/12/22/the-persistence-of-cognitive-inequality-reflections-on-arthur-jensens-not-unreasonable-hypothesis-after-fifty-years/).) I'm not (that) interested in this particular topic. I am ... doing some context-setting for the problem I am interested in, of fixing public discourse. The reason we can't have an intellectually-honest public discussion about human biodiversity is because good people want to respect the anti-oppression Schelling point and are afraid of giving ammunition to racists and sexists in the war over the shared map. "Black people are genetically less intelligent than white people, on average" is the kind of sentence that pretty much only racists would feel _good_ about saying out loud, independently of its actual truth value. In a world where most speech is about manipulating shared maps for political advantage rather than _getting the right answer for the right reasons_, it is _rational_ to infer that anyone who entertains such hypotheses is either motivated by racial malice, or is at least complicit with it—and that rational expectation isn't easily cancelled with a _pro forma_ "But civil discourse" or "But the true meaning of Equality is unfalsifiable" disclaimer.
+
+To speak to those who aren't _already_ oblivious science nerds—or are committed to emulating such, as it is scientifically dubious whether anyone is really that oblivious—you need to put _more effort_ into your excuse for why you're interested in these topics. Here's mine, and it's from the heart, though it's up to the reader to judge for herself how credible I am when I say this—
+
+I don't want to be complicit with hatred or oppression. I want to stay loyal to the underlying egalitarian–individualist axiology that makes the blank slate doctrine _sound like a good idea_. But I also want to understand reality, to make sense of things. I want a world that's not lying to me. Having to believe false things—or even just not being able _say_ certain true things when they would otherwise be relevant—extracts a _dire_ cost on our ability to make sense of the world, because you can't just censor a few forbidden hypotheses—[you have to censor everything that _implies_ them](https://www.lesswrong.com/posts/wyyfFfaRar2jEdeQK/entangled-truths-contagious-lies), and everything that implies _them_: the more adept you are at making logical connections, [the more of your mind you need to excise to stay in compliance](https://www.lesswrong.com/posts/XTWkjCJScy2GFAgDt/dark-side-epistemology).
+
+We can't talk about group differences, for fear that belief in differences will be abused 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_ ≈ [TODO: size] for [TODO: operationalization]) is _not unrelated_ to the persistence of patriarchy! That doesn't mean patriarchy is good! [(You can't derive an _ought_ from an _is_.)](https://plato.stanford.edu/entries/hume-moral/#io) This is pretty obvious, really?