Also, sorry, I have to rant about this part:
"Biological essentialism (the idea that only chromosomes matter) fails at every practical hurdle. How many readers have had their chromosomes tested? Do you have to have your genitals checked before using the supermarket toilets?"
For the thousandth time...biological essentialism is NOT the idea that 'only chromosomes matter'. Biological essentialism is the view that females are inferior by virtue of their biology, that women's XX chromosomes causes and explains female inferiority. Feminists say that women's bodies and reproductive capacity does NOT inevitably relegate them to a lower social order. Women are not less capable than men because of their bodies. Feminists reject biological essentialism.
There's a lazy idea going around that biological essentialism means categorising people by virtue of biological features, which means that it is essentialist to group together disabled people, black people, children and the old. Obviously, there is nothing 'essentialist' at all about saying that disabled people are disabled because their bodies do not function properly. Similarly, saying that women are female is not essentialist!
And let's get to the second stupid argument - you haven't had your chromosomes checked so you don't know what they are, therefore chromosomes can't matter for classification into sex. As any first year philosophy student knows, some properties are deep and hidden and cannot be tracked or detected on the surface level. It took advanced scientific research to discover the true nature of water, that it is H20. It would be utterly absurd to say ' you don't know that water is h20 because you haven't tested its chemical makeup." The reason that is absurd is because we don't have to test the chemical makeup of every clear liquid we encounter to know it's water. Instead, what we do, is we track 'water (h20)' by following reliable surface properties such as 'clear' 'liquid' 'not viscous' 'comes out of a tap.' We are able to reliably know that something is h20 because other properties are attached to its deeper nature. So if we see a clear liquid in a lake, we can be 99.9% sure it is water as opposed to poison simply because those features track h20 so well.
It's the same with sex. There are surface features which track the biological chromosomal makeup of a person with almost 100% accuracy. If a person has given birth, if they have periods, if they have breasts, vaginas, if they have a certain appearance (secondary sexual characteristics) that is an almost certain indication that they have XX chromosomes, especially when the features are combined. So you don't have to test someone to find out their genetics because you can reliably track the underlying sex of people by virtue of these surface features. We are remarkably good at it. I know this is long and tedious, but I am just so fed up of these glib, superficial responses coming from the genderist side. They are such weak, fallacious responses and they never seem to stop coming. I wonder sometimes if they are trying to change the meaning of biological essentialism by fiat .