From Sally Haslanger’s Changing the Ideology and Culture of Philosophy: Not by Reason (Alone):

Why there aren’t more women of my cohort in philosophy? Because there were very few of us
and there was a lot of outright discrimination. I think a lot of philosophers aren’t aware of what women in the profession deal with, so let me give some examples. In my year at Berkeley and in the two years ahead of me and two years behind me, there was only one woman each year in a class of 8-10. The women in the two years ahead of me and the two years behind me dropped out, so I was the only woman left in five consecutive classes. In graduate school I was told by one of my teachers that he had “never seen a first rate woman philosophy and never expected to because women were incapable of having seminal ideas.” I was the butt of jokes when I received a distinction on my prelims, since it seemed funny to everyone to suggest I should get a blood test to determine if I was really a woman. In a seminar in philosophical logic, I was asked to give a presentation on a historical figure when none of the other (male) students were, later to learn that this was because the professor assumed I’d be writing a thesis on the history of philosophy. When I was at Penn as a junior faculty member and told a senior colleague that I was going to be married (to another philosopher, Stephen Yablo, then at UM), his response was, “Oh, I’m so sorry we’ll be losing you.” This was in 1989.

I mention these anecdotes (and there are many more) not in order to gain sympathy, or because they are especially egregious, but because this sort of thing still happens all the time. When I was at the University of Michigan in the mid-90’s there were three consecutive graduate student classes with no women. When this was raised as an issue, the majority of faculty hadn’t even noticed it. In many departments women find themselves solos on faculties or in graduate school cohorts. Virtually all minorities in philosophy find themselves solos. Surviving as a solo is a painful and difficult process I’ll discuss more below.

Moreover, blatant discrimination has not disappeared. I’ve witnessed plenty of occasions when a woman’s status in graduate school was questioned because she was married, or had a child (or took time off to have a child so was returning to philosophy as a “mature” student), or was in a long-distance relationship. For some reason, this never seems to be an issue for men. I know many women who have interests and talents in M&E who have been encouraged to do ethics or history of philosophy. I’ve been contacted as recently as this year by graduate student women’s groups and individual women to help them strategize about problems they are facing as women in their programs, problems that include alleged sexual harassment, hostile or chilly climate, and various sorts of unfairness. I am contacted by Deans who are reevaluating tenure decisions of women (and minorities) to comment on norms and practices in philosophy that seem to have disadvantaged the tenure candidate in question. And I never cease to be amazed.

My point here is that I don’t think we need to scratch our heads and wonder what on earth is
going on that keeps women out of philosophy. In my experience it is very hard to find a place in philosophy that isn’t actively hostile towards women and minorities, or at least assumes that a successful philosopher should look and act like a (traditional, white) man. And most women and minorities who are sufficiently qualified to get into grad school in philosophy have choices. They don’t have to put up with this mistreatment. Many who recognize that something about choices is relevant have explained to me that women choose not to go into philosophy because they have other options that pay better or have more prestige. This may be true for some, but this doesn’t sound like the women I know who have quit philosophy (and it sounds a lot more like the men I know who have quit). Women, I believe, want a good working environment with mutual respect. And philosophy, mostly, doesn’t offer that.

Editing to add:

And this, via Bernard Hurley: