Justin’s Notes

Small Differences Can Still Draw Sharp Lines

2026-08-29 · AI-generated insight

Gould and the Winegard–Carl review are arguing about the same statistical fact and reaching opposite conclusions — which reveals that the fact itself doesn't settle the question.

Gould's move is to take the smallness of measured genetic differences between human groups and conclude that race is superficial: visible traits like skin color fool us into inferring deep divergence that isn't there. Winegard and Carl, channeling the standard critique of Lewontin, accept the premise entirely — variation at any single locus is mostly within-group — but show that the conclusion doesn't follow. Correlated small differences across many loci can produce highly reliable classification. Their face analogy is the crux: no single feature distinguishes male from female faces well, yet the ensemble does so 95 percent of the time.

The interesting synthesis is that both can be right, because they're answering different questions. Gould is talking about magnitude: how much do groups differ? Winegard and Carl are talking about structure: can groups be distinguished? These come apart. A signal can be faint at every frequency and still be unmistakable in aggregate. "Skin deep" and "statistically legible" are not opposites.

This suggests the real dispute is downstream of the statistics: what follows from legible-but-small structure? Gould's implicit worry is that classifiability gets mistaken for deep essential difference — precisely the inference he says visible traits invite. The Lewontin critique shows classification is possible; it doesn't show the differences matter for anything Gould cared about. The trap on both sides is letting one statistic — either the small per-locus variance or the high classification accuracy — stand in for the whole question of what race is.

Woven from these notes

obvious: As long as most scientists accepted the ancient division of races, they expected important genetic differences. But the recent origin of races… squares well with the minor genetic differences now measured. Human groups do vary strikingly in a few highly visible characters (skin color, hair form)—and this may fool us into thinking that overall differences must be great. But we now know that our usual metaphor of superficiality—skin deep—is literally
— Gould

In brief, Lewontin ignored the fact that differences among human populations are correlated. Although population variation at any one genetic locus tends to be small, global population structure becomes clear if one examines correlated differences across loci. For a simple analogy, consider men and women’s faces. If one takes any particular characteristic, say nose size, there is likely to be more variation within a sex than between the sexes (and it would be nearly impossible to classify faces by sex with any accuracy using only nose size). However, if one considers all facial characteristics together (which is, after all, how we actually experience human faces), then sex differences become sufficiently clear that an observer can guess the correct sex more than 95 percent of the time.

— Bo Winegard, Noah Carl Superior: The Return of Race Science—A Review