Certainly, I agree that almost no one interacts with sex chromosomes on a day-to-day basis; no one even knew that sex chromosomes _existed_ before 1905. [(Co-discovered by a woman!)](https://en.wikipedia.org/wiki/Nettie_Stevens) But the function of [intensional definitions](https://www.lesswrong.com/posts/HsznWM9A7NiuGsp28/extensions-and-intensions) in human natural language isn't to exhaustively [pinpoint](https://www.lesswrong.com/posts/3FoMuCLqZggTxoC3S/logical-pinpointing) a concept in the detail it would be implemented in an AI's executing code, but rather to provide a "treasure map" sufficient for a listener to pick out the corresponding concept in their own world-model: that's why [Diogenes exhibiting a plucked chicken in response to Plato's definition of a human as a "featherless biped"](https://www.lesswrong.com/posts/jMTbQj9XB5ah2maup/similarity-clusters) seems like a cheap "gotcha"—we all instantly know that's not what Plato meant. ["The challenge is figuring out which things are similar to each other—which things are clustered together—and sometimes, which things have a common cause."](https://www.lesswrong.com/posts/d5NyJ2Lf6N22AD9PB/where-to-draw-the-boundary) But sex chromosomes, and to a large extent specifically the [SRY gene](https://en.wikipedia.org/wiki/Testis-determining_factor) located on the Y chromosome, _are_ such a common cause—the root of the [causal graph](https://www.lesswrong.com/posts/hzuSDMx7pd2uxFc5w/causal-diagrams-and-causal-models) underlying all _other_ sex differences. A smart natural philosopher living _before_ 1905, knowing about all the various observed differences between women and men, might have guessed at the existence of some molecular mechanism of sex determination, and been _right_. By the "treasure map" standard, "XX is female; XY is male" is a pretty _well-performing_ definition—if you're looking for a [_simple_ membership test](https://www.lesswrong.com/posts/edEXi4SpkXfvaX42j/schelling-categories-and-simple-membership-tests) that's entangled with a lot of information about the many intricate ways in which females and males statistically differ.
Certainly, I agree that almost no one interacts with sex chromosomes on a day-to-day basis; no one even knew that sex chromosomes _existed_ before 1905. [(Co-discovered by a woman!)](https://en.wikipedia.org/wiki/Nettie_Stevens) But the function of [intensional definitions](https://www.lesswrong.com/posts/HsznWM9A7NiuGsp28/extensions-and-intensions) in human natural language isn't to exhaustively [pinpoint](https://www.lesswrong.com/posts/3FoMuCLqZggTxoC3S/logical-pinpointing) a concept in the detail it would be implemented in an AI's executing code, but rather to provide a "treasure map" sufficient for a listener to pick out the corresponding concept in their own world-model: that's why [Diogenes exhibiting a plucked chicken in response to Plato's definition of a human as a "featherless biped"](https://www.lesswrong.com/posts/jMTbQj9XB5ah2maup/similarity-clusters) seems like a cheap "gotcha"—we all instantly know that's not what Plato meant. ["The challenge is figuring out which things are similar to each other—which things are clustered together—and sometimes, which things have a common cause."](https://www.lesswrong.com/posts/d5NyJ2Lf6N22AD9PB/where-to-draw-the-boundary) But sex chromosomes, and to a large extent specifically the [SRY gene](https://en.wikipedia.org/wiki/Testis-determining_factor) located on the Y chromosome, _are_ such a common cause—the root of the [causal graph](https://www.lesswrong.com/posts/hzuSDMx7pd2uxFc5w/causal-diagrams-and-causal-models) underlying all _other_ sex differences. A smart natural philosopher living _before_ 1905, knowing about all the various observed differences between women and men, might have guessed at the existence of some molecular mechanism of sex determination, and been _right_. By the "treasure map" standard, "XX is female; XY is male" is a pretty _well-performing_ definition—if you're looking for a [_simple_ membership test](https://www.lesswrong.com/posts/edEXi4SpkXfvaX42j/schelling-categories-and-simple-membership-tests) that's entangled with a lot of information about the many intricate ways in which females and males statistically differ.