There are plenty of things you could say about Labour’s All-Women Shortlists (AWS). Tony Blair called them 'not ideal at all' in 1995. In 1996, Peter Jepson and Roger Dyas-Elliott – two men who’d been rejected as Labour candidates – called them sex discrimination. An industrial tribunal agreed with them, and Labour was forced to suspend the policy until 2002, when it was able to bring in the Sex Discrimination (Election Candidates) Act, permitting positive discrimination in candidate selection. In 2002, Owen Jones called them 'most successful at expanding the career options of a tiny elite of professional, university-educated women', Blair’s hesitancy forgotten and AWS rewritten as a tool of centrist hegemony.

This, though, is the most important thing to be said about them: they work, and they’re the only thing in our first-past-the-post system that has worked when it comes to getting more women into parliament. Before Labour used AWS, the party had 37 female MPS out of 271 total; after, it had 101 out of 418. And Labour has been the party driving women’s overall representation in parliament: in 1997, there were only 19 female MPs from all the other parties combined. Labour has made women in parliament normal, and AWS have been the means of doing that.

So when there’s a proposal that has the potential to drastically change the purpose and function of AWS, it matters. The work of achieving equal representation is not done. Women are still less than a third of MPs, and not yet quite half of the PLP. Now, Labour has declared that AWS are open to all 'self-defining women' – not restricted to women plus transwomen with a gender recognition certificate, but free to include anyone who says 'I am a woman'. There’s no requirement to have medically transitioned here, or even to be living 'in-role'. Self-identity means, simply, that you declare your gender, and it’s incumbent on other people to treat you accordingly, regardless of how you present.

One of the perversities of this decision is that it’s not clear how, exactly, selection panels are supposed to screen for sincerity in those who announce their womanhood. A repeated nostrum of trans politics is (as Lily Madigan said on LBC this week) 'if someone says to me they’re a transwoman then I’m inclined to believe them'. There’s no way in that scheme to filter out the wreckers and the spoilers who still have it in for AWS, the men’s rights activists treading the path of Jepson and Dyas-Elliott. Legal challenges to AWS might have been ruled out, but who needs to go to the trouble when you can just self-identify in and render them meaningless?

Weirder still, though, is the philosophical chasm it opens up under feminism. If AWS are open to 'self-defining women' rather than female people, does that mean Labour thinks that women have been excluded from politics because of their self-definition rather than for being female? What does it even mean to 'define yourself as a woman'? When a woman was defined as someone who had no right to take up a place in parliament, did that make the first female MPs by definition 'non-women'? Trying to catch hold of something solid in the slippy circularity of 'a woman is anyone who identifies as a woman' becomes endlessly confounding: what, after all, is a woman?

Talk to women about the obstacles to launching political careers and the stories they tell are all about the difficulty of juggling caring responsibilities with campaigning, and the struggle of competing against men with bigger war chests (thank you wage gap) and wives to pick up the domestic slack – plus, of course, the outright sexism of selection panels who would be happy to pick a woman but somehow never have the good fortune to meet the right one. More grimly, there are the cases of harassment and sexual assault collected by the LabourToo campaign: raping a woman is an effective way of limiting her political ambitions. These are things that happen to women because they’re female, not because of a mysterious inner sense of gender.

To add to the general confusion, the same week that Labour was declaring AWS open to self-identified women, RuPaul was taking a pasting because he’d said he would 'probably not' accept a medically transitioning transwoman as a contestant on Drag Race. ('You can take performance enhancing drugs and still be an athlete, just not in the Olympics,' he tweeted – because where’s the thrilling artifice in someone conjuring up a cleavage when they already have breasts, whether hormonally induced or implants?) So while it would be transphobic for Labour not to treat transwomen as women when it comes to AWS, RuPaul is transphobic for treating transwomen as women and (tentatively) ruling them out of a contest for men who perform en femme. Right.

There aren’t any trans people in parliament, so there may well be a case for parties to work on expanding representation. But it’s not clear why that should happen at the expense of women rather than of over-represented men. It’s also not clear why these measures should only benefit transwomen and not transmen. After all, think of a trans political figure, and you’re probably thinking of a transwoman. Heather Peto. Emily Brothers. Sophie Cook. Lily Madigan. Munroe Bergdorf. Transmen are simply not in the picture. There’s probably a reason why the normal patterns of our sexist society become reversed when you mix in the word 'trans'. But it would be very hard for anyone in the Labour Party now to articulate it.