Scott Alexander uses an analogy between race and culture to argue that mathematical clustering arguments don't determine whether race 'exists' any more than they determine whether culture 'exists'.
Longer summary
Scott Alexander discusses the concept of 'Eulering,' using complex math to debunk common sense ideas, and proposes 'Feynmaning' as a counter-technique. He applies this to the debate about race, comparing arguments against race as a biological concept to similar arguments that could be made about culture. He concludes that mathematical arguments about clustering don't determine whether race 'exists' any more than they determine whether culture 'exists,' and suggests that race doesn't have any extra reality beyond culture. The post uses an analogy between race and culture to challenge both those who claim race isn't real and those who claim it's more 'scientific' than culture.
Shorter summary