No simple analysis could possibly settle that question, but here's one thought. If sexism is still prevalent in philosophy, we should expect women, on average, to move less quickly than men through the academic ranks -- from graduate student to non-tenure-track faculty to tenure-track Assistant Professor to tenured Associate or full Professor. It would then follow that women would be on average older than men at the lower ranks.
As it happens, the data Joshua Rust and I collected for our study of the voting rates of philosophers can be re-analyzed with this issue in mind.
For the voting study, we collected (among other things) academic rank data for most professors of philosophy in five states: California, Florida, Minnesota, North Carolina, and Washington State. Examining voter registration records, we found unambiguous name matches for 60.4% of those professors. Since four states (all but North Carolina) provided age data for registered voters, we were able to compare rank and age.
Overall 23.1% of the philosophy professors in our study were female. The average birth year of men and women at each rank are:
Non-Tenure-Track: women 1958.1, men 1960.4That the average male tenured professor is older than the average female tenured professor fits with the idea that the gender ratio is philosophy has improved over time; but that the average female untenured professor is older than the average male suggests that women are still slower to progress to tenure.
Assistant Profesor: women 1965.3, men 1970.0
Tenured Professor: women 1955.3, men 1948.7
If you can bear with lists of numbers, the facts become clearer if we break down the data by birthyear first, then gender and rank:
1900-1939 (54 profs.):
96% male (90% full, 10% assoc.)1940-1949 (100 profs.):
4% female (50% full, 50% assoc.)
77% male (78% full, 13% assoc., 3% asst., 6% non-TT)1950-1959 (104 profs.):
23% female (70% full, 9% assoc., 4% asst., 17% non-TT)
71% male (55% full, 28% assoc., 4% asst., 12% non-TT)1960-1969 (99 profs.):
29% female (43% full, 27% assoc., 7% asst., 23% non-TT)
65% male (29% full, 39% assoc., 20% asst., 19% non-TT)1970-1979 (57 profs.):
35% female (22% full, 39% assoc., 29% asst., 14% non-TT)
81% male (2% full, 11% assoc., 74% asst., 13% non-TT)There's a general increase of representation of women in philosophy in the younger generations, but for almost all age groups women are underrepresented among full professors and overrepresented in the lower ranks. It seems to me that the natural interpretation is that although women are coming into philosophy at higher rates than they used to, they either progress more slowly through the ranks or enter philosophy later in their lives (which is perhaps just another way of progressing more slowly). Even the reversal of the gender ratio trend for women born in 1970 or later fits with this: Men may be more overrepresented in this group than in slightly older groups not because that generation has fewer women pursuing philosophy but rather because the men are completing their Ph.D.'s and moving into teaching more quickly.
19% female (0% full, 18% assoc., 45% asst., 36% non-TT)
It doesn't follow straightaway that the cause of women's slower progression is sexism, of course. Childbearing and other factors may play a role. It's also encouraging, I think, to see the rank differences diminishing in the younger groups.
Update, July 30: Brian Leiter looks at the assistant professors from top departments twelve years ago, and Rob Wilson breaks it down by gender in the comments to this post.