How do you deal with them?
The derailer in question is a close friend, who identifies as a feminist. However, of late, I've noticed she has a tendency to derail feminist conversations; one of which was a conversation about rape, in which she insisted it was unfair on men to exclaim that "men shouldn't rape", because, as far as she was concerned, it labelled all men rapists. She's supposed to be an English student, so should have more awareness of how the English language works... But still.
She also went on to explain how this comment was unfair, on the basis that it assumes all rapists are men, and it eliminates the victims of female rapists. We're both in England, so under our law, the presence of a penis is needed for a rape. When she was challenged on this, she carried on to say we didn't know how many male victims of women rapists there are, considering how shaming it must be for a man to admit he's been raped by a woman.
How do I explain to her that forcing women to talk about men in a predominantly woman based experience is derailing, and misogynistic? Because, atm, she won't listen to anyone who tries to explain.