+I just spent a few paragraphs picking on the "sports segregated around an Aristotelian binary" remark, because sports is a case where the relevant effect sizes are _so_ large as to make the point [hard for all but the most ardent gender-identity partisans to deny](/2017/Jun/questions-such-as-wtf-is-wrong-with-you-people/).
+
+But the point is general. If _any_ concrete negative consequence of gender self-identity categories is going to be waved away with, "Oh, but that's a mere _policy_ decision that can be dealt with on some basis other than gender, and therefore doesn't count as an objection to the new definition of gender words", then it's not clear what the new definition is _for_. The policymaking categories we use to make decisions are _closely related_ to the epistemic categories we use to make predictions.
+
+An illustrative example: like many gender-dysphoric males, I [cosplay](/2016/Dec/joined/) [female](/2017/Oct/a-leaf-in-the-crosswind/) [characters](/2019/Aug/a-love-that-is-out-of-anyones-control/) at fandom conventions sometimes. And, unfortunately, like many gender-dysphoric males, I'm _not very good at it_. I think someone looking at some of my cosplay photos and trying to describe their content in clear language—not trying to be nice to anyone or make a point, but just trying to use language as a map that reflects the territory—would say something like, "This is a photo of a man and he's wearing a dress." The word _man_ in that sentence is expressing _cognitive work_: it's a summary of the [lawful cause-and-effect evidential entanglement](https://www.lesswrong.com/posts/6s3xABaXKPdFwA3FS/what-is-evidence) whereby the photons reflecting off the photograph are correlated with photons reflecting off my body at the time the photo was taken, which are correlated with my externally-observable secondary sex characteristics (facial structure, beard shadow, _&c._), from which evidence an agent using an [efficient naïve-Bayes-like model](http://lesswrong.com/lw/o8/conditional_independence_and_naive_bayes/) can assign me to its "man" category and thereby make probabilistic predictions about some of my traits that aren't directly observable from the photo, and achieve a better [score on those predictions](http://yudkowsky.net/rational/technical/) than if the agent had assigned me to its "woman" category, where by "traits" I mean not (just) particularly sex chromosomes ([as Yudkowsky suggested on Twitter](https://twitter.com/ESYudkowsky/status/1067291243728650243)), but the _conjunction_ of dozens or hundreds of observable measurements that are [_causally downstream_ of sex chromosomes](/2021/Sep/link-blood-is-thicker-than-water/): reproductive organs _and_ muscle mass (sex difference effect size of [Cohen's _d_](https://en.wikipedia.org/wiki/Effect_size#Cohen's_d)≈2.6) _and_ Big Five Agreeableness (_d_≈0.5) _and_ Big Five Neuroticism (_d_≈0.4) _and_ short-term memory (_d_≈0.2, favoring women) _and_ white-to-gray-matter ratios in the brain _and_ probable socialization history _and_ [any number of other things](https://en.wikipedia.org/wiki/Sex_differences_in_human_physiology)—including differences we might not necessarily currently know about, but have prior reasons to suspect exist: no one _knew_ about sex chromosomes before 1905, but given all the other systematic differences between women and men, it would have been a reasonable guess (that turned out to be correct!) to suspect the existence of some sort of molecular mechanism of sex determination.
+
+Making someone say "trans woman" instead of "man" in that sentence depending on my verbally self-reported self-identity may not be forcing them to _lie_, exactly.
+
+(Because it's understood, "openly and explicitly and with public focus on the language and its meaning", what _trans women_ are:
+
+
+But it _is_ forcing them to obfuscate the probabilistic inference they were trying to communicate with the original sentence (about modeling the person in the photograph as being sampled from the "men" [cluster in configuration space](https://www.lesswrong.com/posts/WBw8dDkAWohFjWQSk/the-cluster-structure-of-thingspace)), and instead use language that suggests a different cluster-structure ("trans women", two words, are presumably a subcluster within the "women" cluster).