1. I keep seeing people making this kind of argument, when discussing trans issues. Intersex people like @mrkhtake2 and scientists like @TriciaFrasman and @FondOfBeetles are becoming justifiably exhausted by having to correct the fundamental misconceptions behind it. 
2. But in addition to being offensive and wrong, this line of argument also seriously derails the conversation we need to be having. What I want to say is, essentially, "So what? Why are you even talking about this?"
3. Is it being suggested that trans people are all intersex? That this is the 'biological basis' of trans identities? I don't think so - the number of trans women who have fathered children prior to transition indicates that plenty of them were unambiguously male.
4. Are they trying to say that because they have 'proved' that sex is 'not a binary', the categories of male and female are entirely meaningless? I think this is the point being made, but (as well as being wrong) it simply doesn't follow.
5. All this bickering about edge cases (intersex people, infertile women, etc etc) is irrelevant to the underlying truth (which everyone learns in infancy) that every person is *perceived* by all other people as being either male or female. Anyone who pretends otherwise is lying.
6. Whether those perceptions align completely with everyone's chromosomes is not the point. Whether a woman is infertile or not does not alter the fact that she is likely to face discrimination on the basis of her membership of the sex that bears children.
7. The categories of male and female are based on the easily observable correlation between external genitalia and secondary sex characteristics and the ability to either bear or father children, noted by all human societies throughout history.
8. The allocation of all kinds of irrelevant characteristics and expectations to male and female people (ie gender) is what causes unhappiness for trans people. It is also (not coincidentally) the means by which women are oppressed.
9. While we are arguing with each other about what words mean, or whether they have any meaning at all, we are doing nothing to challenge that fundamental structure. Sadly, it will not simply melt away in the piercing glare of postmodernism.
10. If we want to change the way society works, we have to organise. Women must be allowed to gather, to name and understand our oppression, and to organise against it. This is not unreasonable, and it is not something we should be having to debate with so-called feminists.
