1). There is a lot of, for want of a better term, "mental masturbation" around here: arguing for the sake of arguing, debating insignificant points, flashy but ultimately useless displays of intellect etc. Men tend to enjoy this sort of thing much more than women. Perhaps the female equivalent would be "social masturbation" -- endless gossiping about other people's trivia.

2). There's a major bias toward discussing math and science topics on here, and objective rather than subjective experience. Rationality, as a meta-construct, arguably isn't necessarily limited to these domains. I don't see why it can't be applied to equally good effect to literature and the humanities, art, interpersonal relationships, etc. Broaden your conversations to include some more of these topics (but, of course, with the same characteristic rational approach) and you may win over more female participants.