I think the point GP was trying to make is that this isn't necessarily a case of male professors being nice to women just because they are attracted to them (or assume that they might be attractive) and that there is a possibility of sex. (or something to that effect)
It's still 'sexism' if a professor responds better to female students than male students because he perceives female students as being more receptive and grateful for the help. But not necessarily in a negative "I'm hoping to get laid" sort of way.
Sexism != reacting to the sexes differently. Men and women are not the same, and therefore they evoke different responses and reactions. This is not sexism.
No, it is not. Sexism, like racism, never has a positive or neutral connotation in any context in which I have ever heard it used. A black man is not intrinsically different than a white man. Therefore, to treat him such is racist, period. A woman is, however, intrinsically different than a man. To denigrate her because she is a women is sexism. To treat her as if she were a man and refuse to acknowledge her as a woman is, arguably, also sexism. On the contrary, merely to react differently to her, but not negatively, is not sexism.
I find that separating connotations from the core meanings of words leads to clearer arguments. In your position, if someone calls you sexist and you deny that, it's not clear if you're denying treating someone differently based on their sex or if you just don't think you're mistreating the person. My stance is more likely to lead to a response of, "Yes, I'm being sexist, but not in a wrong way."
I'm not saying anything of the sort. The implication that professors are being nice to female students to get sex implies that they are trying to abuse the power of their authority. If they are being nice because they perceive female students as more receptive to/grateful for help, it's a little more benign, no?
