No argument about feminism being trans inclusive.
It's just whether you want to include women who identify as trans and also depend on e.g single sex sport and sex specific health care and reproductive rights, or whether you want to exclude them and prioritise men.
I can explain what characteristics women have in common with other women because I can define sex, but I can't explain what women would necessarily have in common with a man who identities as trans that they couldn't have in common with any other man. That's not to say that a woman can't have more in common with a man than she does with another women, but that is a function of their shared humanity. Until 10 years ago this was bog standard feminism.
Im not interested in hearing the stats you will now come at me with relating to crimes committed by transwomen in womens spaces.
This comment just suggests that you haven't been paying attention. It's odd that so many people express confusion, but perhaps the problem is information silos. Anyway, I will try to explain.
If you read the exceptions that allow single sex spaces in the Equality Act, they apply to both sexes equally and don't refer to crimes against women.
The most common exceptions are prompted by the desire for privacy from the opposite sex when in a state of undress and these apply to women and men. You can argue over the situations when this should apply, but you can't argue that a space should be single sex because it is reasonable for a woman to object to the presence of a man and then allow men to use the space if they would prefer. It just doesn't make sense.
It is also undeniable that some single sex provision e.g. prisons, rape crisis centres, exists because MEN are a threat to women. You might wish to argue that only men who identify as men are a threat to women, but gender is not objectively classifiable, (as the police and prison services have demonstrated) so that doesn't really get us anywhere.
The Good Law Project has suggested segregation by 'lived gender', but I have no idea how this makes anyone's life less precarious and I thought I gained the right to stop 'living in a gender' around 1975.
This is quite a long post, and you may not have bothered to read it, but if you have, I hope you are less baffled by the SC decision and the EHRC guidance.