+The point being illustrated here is that if it's socially unacceptable for people who want to talk about sex to say "That's not what I meant by _woman_ in this context _and you know it_", then people who would prefer not to acknowledge sex will always get the last word—not because they have superior arguments, but because the very terms of discourse have been [systematically gamed to conflate dissent with unkindness](/2018/Jan/dont-negotiate-with-terrorist-memeplexes/).
+
+To this it might be objected that trans activists are merely advocating for greater precision, rather than trying to make it socially unacceptable to think about biological sex: after all, you can just say "cis women" (which excludes trans women, trans men, and natal-female nonbinary people) or "assigned female at birth" (which excludes trans women, but includes trans men and natal-female nonbinary people and presumably [David Reimer](https://en.wikipedia.org/wiki/David_Reimer)) or "people with uteruses" (which excludes trans women and natal females who have had a hystorectomy) if that's what you _really mean_. I think this is underestimating the usefulness of having simple, [_short_](https://www.lesserwrong.com/posts/soQX8yXLbKy7cFvy8/entropy-and-short-codes) descriptions for the categories that do the most predictive work on typical cases.
+
+Kind or not, morally justified or not, voluntary or not, sexual dimorphism is _actually a real thing_. Studying the pages of _Gray's Anatomy_—[or _Wikipedia_](https://en.wikipedia.org/wiki/Sex_differences_in_human_physiology) if you're on a budget—you can absorb all sorts of detailed, _specific_ knowledge of the differences between female and male humans, from the obvious (sex organs, vocal pitch, height, muscle mass, body hair) to the less-obvious-but-well-known (chromosomes, hormones, pelvis shape) to the comparatively obscure (blood pressure! lymphocyte concentrations! gray-matter-to-white-matter ratios in the brain!). Nor is this surprising from a theoretical standpoint, where we have theories explaining [mechanisms](https://en.wikipedia.org/wiki/Anisogamy) [by which](https://en.wikipedia.org/wiki/Sexual_selection) sexual dimorphism can evolve and [what kinds of differences](https://en.wikipedia.org/w/index.php?title=Parental_investment&oldid=832276512#Trivers'_parental_investment_theory) it produces in different species.
+
+If—like me—you're the kind of person who is not necessarily _happy_ about sexual dimorphism, you can always deliberately define your categories in order to minimize it: if there's a large sex difference in some observable measurement, just say you _don't care_ about predicting that particular measurement.
+
+But people who have _other_ concerns than minimizing Blue Tribe people's quasi-religious discomfort with sexual dimorphism (it's my former quasi-religion, too, so I'm allowed to make fun of us) might want a common word—or even just a particular _sense_ of a common word—to describe the world they see, in which sex is a real thing worth noticing.
+
+It might be worth noticing even if you don't believe in psychological sex differences! That's why generations of feminists have fought valiantly for women's rights on the grounds that women are every bit the moral and intellectual equals of men, rather than the grounds that it's not clear whether "women" actually exist as a non-arbitrary category.
+
+Being limited to just saying "people with uteruses" when the topic of conversation happens to be childbearing (or whatever the approved socially-just construction turns out to be) is not a suitable replacement (per Alicorn's maxim) when the speaker wants to refer to all the _other_ dimensions along which women statistically have things in common, including things that are hard to articulate or measure.