<a id="ace-model"></a>The third part of the book is about genetic influences on class structure! Untangling the true causes of human variation is a really hard technical philosophy problem, but behavioral geneticists have at least gotten started with their simple _ACE_ model. It works like this: first, assume (that is, "pretend") that the genetic variation for a trait is _additive_ (if you have the appropriate SNP, you get more of the trait), rather than exhibiting _epistasis_ (where the effects of different loci interfere with each other) or Mendelian _dominance_ (where the presence of just one copy of an allele (of two) determines the phenotype, and it doesn't matter whether you heterozygously have a different allele as your second version of that gene). Then we pretend that we can partition the variance in phenotypes as the sum of the "additive" genetic variance _A_, plus the environmental variance "common" within a family _C_, plus "everything else" (including measurement "error" and the not-shared-within-families "environment") _E_. Briefly (albeit at the risk of being _cliché_): nature, nurture, and _noise_.
-Then we can estimate the sizes of the _A_, _C_, and _E_ components by studying fraternal and identical twins. (If you hear people talking about "twin studies", this is what they mean—_not_ case studies of identical twins raised apart, which _are_ really cool but don't happen very often.) Both kinds of twins have the same family environment _C_ at the same time (parents, socioeconomic status, schools, _&c._), but identical twins are twice as genetically related to each other as fraternal twins, so the extent to which the identical twins are more similar is going to pretty much be because of their genes. "Pretty much" in the sense that while there are ways in which the assumptions of the model aren't quite true (assortative mating makes fraternal twins more similar in the ways their parents were _already_ similar before mating, identical twins might get treated more similarly by "the environment" on account of their appearance), Murray assures us that the experts assure us that the _quantitative_ effect of these deviations are probably pretty small!
+<a id="twin-studies"></a>Then we can estimate the sizes of the _A_, _C_, and _E_ components by studying fraternal and identical twins. (If you hear people talking about "twin studies", this is what they mean—_not_ case studies of identical twins raised apart, which _are_ really cool but don't happen very often.) Both kinds of twins have the same family environment _C_ at the same time (parents, socioeconomic status, schools, _&c._), but identical twins are twice as genetically related to each other as fraternal twins, so the extent to which the identical twins are more similar is going to pretty much be because of their genes. "Pretty much" in the sense that while there are ways in which the assumptions of the model aren't quite true (assortative mating makes fraternal twins more similar in the ways their parents were _already_ similar before mating, identical twins might get treated more similarly by "the environment" on account of their appearance), Murray assures us that the experts assure us that the _quantitative_ effect of these deviations are probably pretty small!
Anyway, it turns out that the effect of the shared environment _C_ for most outcomes is smaller than most people intuitively expect—actually close to zero for personality and adult intelligence specifically! Sometimes sloppy popularizers summarize this as "parenting doesn't matter" in full generality, but it depends on the trait or outcome you're measuring: for example, the shared environment component gets up to 25% for years-of-schooling ("educational attainment") and 36% for "basic interpersonal interactions." _Culture_ obviously exists, but for underlying psychological traits, the part of the environment that matters is mostly not shared by siblings in the same family—not the part of the environment we know how to control. Thus, a lot of economic and class stratification actually ends up being along genetic lines: the nepotism of family wealth can buy opportunities and second chances, but it doesn't actually live your life for you.
Anyway, so Murray and Herrnstein talk about this "intelligence" construct, and how it's heritable, and how it predicts income, school success, not being a criminal, _&c._, and how Society is becoming increasingly stratified by cognitive abilities, as school credentials become the ticket to the new upper class.
-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 of a 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](http://web.archive.org/web/20200620184942/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 got a 131](/images/wisc-iii_result.jpg) on the [WISC-III](https://en.wikipedia.org/wiki/Wechsler_Intelligence_Scale_for_Children) at age 10, but that's pretty dumb [compared to](http://zackmdavis.net/blog/2016/06/the-view-from-below/) 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 of having a higher measurement than a uniformly-randomly selected member of the group with the lower average measurement.)
+<a id="the-reason-everyone-and-her-dog-is-still-mad"></a>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 of a 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](http://web.archive.org/web/20200620184942/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 got a 131](/images/wisc-iii_result.jpg) on the [WISC-III](https://en.wikipedia.org/wiki/Wechsler_Intelligence_Scale_for_Children) at age 10, but that's pretty dumb [compared to](http://zackmdavis.net/blog/2016/06/the-view-from-below/) 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 of having a higher measurement than a uniformly-randomly selected member of the group with the lower average measurement.)
Given the tendency for people to distort shared maps for political reasons, you can see why this is a hotly contentious line of research. Even if you take the test numbers at face value, racists trying to secure unjust privileges for groups that score well, have an incentive to "play up" group IQ differences in bad faith even when they shouldn't be [relevant](https://www.lesswrong.com/posts/GSz8SrKFfW7fJK2wN/relevance-norms-or-gricean-implicature-queers-the-decoupling). As economist Glenn C. Loury points out in _The Anatomy of Racial Inequality_, cognitive abilities decline with _age_, and yet we don't see a moral panic about the consequences of an aging workforce, because older people are construed by the white majority as an "us"—our mothers and fathers—rather than an outgroup. _Individual_ differences in intelligence are also presumably less politically threatening because "smart people" as a group aren't construed as a natural political coalition—although Murray's work on cognitive class stratification would seem to suggest this intuition is mistaken.
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 aspects of reality are even _worse_ (with respect to naïve, non-renormalized egalitarian moral sensibilities) than the ball-hiders like Murray can admit, having already blown their entire [Overton budget](https://www.lesswrong.com/posts/DoPo4PDjgSySquHX8/heads-i-win-tails-never-heard-of-her-or-selective-reporting) explaining the relevant empirical findings.
-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 id="individuals-should-not-be-judged-by-the-average"></a>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.
projects / Ultimately_Untrue_Thought.git / blobdiff