+Certainly _most_ men are nice, civilized people who don't harrass women—and occasional Hemsworthlike, lumberjack-bearded androphilic trans men with a feminine personalities, present even less of a threat. But when designing the social norms for a safe space for the modal cis woman, false positives (including someone who shouldn't be included) are probably going to be worse than false negatives (excluding someone who shouldn't be). If "Does this person look male?" is _easier to assess_ than "Does this person-of-whatever-sex look like a potential threat to my safety, comfort, and privacy?"—and possibly more importantly, is easier for third parties to _agree on_ when third parties are called in to enforce the rules—then the rule ends up being "no men" (or more precisely, "no male-looking people", with corresponding consequences for trans men and non-passing trans women), because "no suspicious-looking people" is nearly impossible to enforce in a non-arbitrary way.
+
+Depending on your values, this may not be the best rule! This is (despite everything) not a politics blog. I should hope to help clearly identify the trade-offs inherent in the objective reality of a situation, rather than champion one trade or the other; it's not for me to decide what kind of spaces people should demand, or what false-positive and false-negative rates they should accept.
+
+[TODO: transition sentence (no pun intended)]
+
+[TODO (somewhere): self-identity is itself a Schelling point]
+
+When the _Times_ of London filed some freedom-of-information act requests, they found that [almost 90% of harrassment/assault/voyeurism incidents in changing rooms took place in the minority of unisex facilities](https://www.thetimes.co.uk/edition/news/unisex-changing-rooms-put-women-in-danger-8lwbp8kgk).
+
+[TODO: explicitly acknowledge that I'm not trying to shift goalposts; locker rooms are different from bathrooms, everyone deserves to pee]
+
+Ozy continues—
+
+> Similarly, early-transition trans women can be placed into the former category. In our culture, it is generally very stigmatized for men to wear dresses, skirts, makeup, and other signifiers of womanhood. In particular, catcallers and sexist harassers essentially never do: if you're a catcaller or a sexist harasser, it is probably because you are invested in a particular style of masculinity that is completely incompatible with wearing a skirt. Therefore, allowing all dress-wearing people to use the women's bathroom has minimal risk of allowing catcallers in. In the event that men wearing dresses and makeup is completely destigmatized to the point that even sexist assholes do so, I am happy to reexamine this statement.
+
+Although I lack relevant lived experience, I suspect this is _wildly_ overestimating the _ideological_ component of women's discomfort around men. I agree that certain very overt kinds of harrassment (the kind that involves yelling slurs or obcenities) can be attributed to sexist subcultures of _machismo_ and toxic masculinity. Unfortunately, I fear the [threat model](https://en.wikipedia.org/wiki/Threat_model) is a little bit subtler and more expansive than that.
+
+[TODO: expand on the expanded threat model, marginalism]
+
+Maybe you want to bite that bullet. But you should at least _acknowledge_ the existence of the bullet, once someone points it out. And if you want to call yourself a rationalist, maybe try to proactively look for the bullet
+
+-----
+
+I think there's a more general lesson underlying these kinds of discussions. If you want to get through life without _verbally_ acknowledging the concept of biological sex, then you _can_ get away with it.
+
+If the object of discussion is a large, undeniable, binary sex difference, you can always say, "Oh, that's a mere policy question that can be handled on the basis of more specific details of that particular use-case." So, for example, we can agree with people with prostates should get prostate cancer screenings as they get older, without necessarily reifying that category of people as 'men' or 'males'.
+
+And if the object of discussion is a small, statistical sex difference, you can always point out (correctly! importantly!), "Some cis people of that gender are like that, too!"
+
+Does the fact that it's possible to scrupulously rephrase any individual sentence to elide sex imply that the corresponding mental _representation_ of the concept of 'sex' is of little practical use? I don't think so, and I've tried, within the limits of my time and my writing ability, to explain why. But if some readers still aren't convinced—well, maybe I can live with that.
+
+[...]