@UnlockedXCX “My friend keeps insisting that to say 'women only (born women, not trans)' is basically exactly like 'white people only, not black people' and I'm not sure how to explain that one is discriminatory and the other isn't”
I don’t actually think you can explain in the terms you’d like to, because your premise is wrong. The actual truth of it is – it is discriminatory, but this type of discrimination is okay. And then that would open up all the other arguments about physical strength, vulnerabilities, biology, etc
But sadly you’re unlikely to make any headway with your friend (and one of the biggest reasons we’re in this fix) because we’ve collectively brainwashed ourselves into believing that every kind of discrimination is forever and always bad. Hence the trans movement found itself with an unexpected open goal – people literally could no longer explain to themselves why it was okay to follow their own instincts and act according to the most obvious distinction that had served us fine for the entire history of our species.
So personally I’d just say “no, it’s not the same thing, it’s fine to have women’s groups”, and leave it at that. Then the onus is on her to explain why it’s not. Then you can pick at her arguments in the way you find uncomfortable when it’s done to you. You’ll have disabled her best argument (discrimination is bad) and forced her to argue the specifics.
If it’s too late for that, or she’s woke as a matter of principle, then you can use the “it’s not like white-only groups, it’s like black-only groups” line. This works because, when it’s an outcome they like, the woke don’t actually believe in their principle anymore. Your task then becomes explaining why women are the blacks of this situation, and trans are the Rachel Dolezals.
That could work but I don’t like it because I find it dishonest, and because hell lies further down that road—it’s accepting that it’s okay to discriminate against white people, and how exactly do we think that’s going to play out in the long run?—but against someone who already thinks like this, at least she’ll see your point of view.