I believe you've overlooked some important factors. First, Caltech puts a lot more effort into recruiting top women than into recruiting top men.
So if you are a top man but are not considering applying to Caltech Caltech probably won't reach out to try to change your mind. If you are a top women they are much more likely to reach out to you, maybe even sending someone to visit and personally pitch applying to Caltech. This is going to tend to raise the average quality of the set of women who end up applying to Caltech, so we should expect to see a higher acceptance rate for women.
Second, Caltech has been doing this for a long time. It was an all male school until around 1970 then went coed. I don't know when they started actively trying to recruit women, but they were doing it by the late '70s when I was a student there. At that time incoming classes were around 15% women and the percentage was slowly rising. It has been a long slow rise to where they are today.
That gives us at least 45 years of data on the results of these policies and as far as I know no one has ever found any indication that the women of Caltech are any less meritorious than the men. If they had went from 15% women to 50% in a few years then it would probably require lowering standards, but doing it over 45+ years can plausibly be explained just by the recruiting efforts.
Third, wanting to have more women isn't a mere matter of optics. Most undergraduates live on campus. For the first couple of years students are generally required to do so. But Caltech is a very hard school. Most undergraduates have little to no time to have any kind of social life that is not on campus. And they are around the age of peak horniness. When the gender ratio is out of whack in such an environment it causes a lot of stress (at least for the heterosexual students), for both men and women, which can greatly affect academic performance.
Also, as far as imposter syndrome goes, a sizable majority of the men at Caltech probably have it too. Most of them were at the top of the class for their whole life, and without having to put a lot of effort into it. School was always easy. Then they get to Caltech where they have to work their assess off just to reach average. It's hard to avoid getting some imposter syndrome.
So if you are a top man but are not considering applying to Caltech Caltech probably won't reach out to try to change your mind. If you are a top women they are much more likely to reach out to you, maybe even sending someone to visit and personally pitch applying to Caltech. This is going to tend to raise the average quality of the set of women who end up applying to Caltech, so we should expect to see a higher acceptance rate for women.
Second, Caltech has been doing this for a long time. It was an all male school until around 1970 then went coed. I don't know when they started actively trying to recruit women, but they were doing it by the late '70s when I was a student there. At that time incoming classes were around 15% women and the percentage was slowly rising. It has been a long slow rise to where they are today.
That gives us at least 45 years of data on the results of these policies and as far as I know no one has ever found any indication that the women of Caltech are any less meritorious than the men. If they had went from 15% women to 50% in a few years then it would probably require lowering standards, but doing it over 45+ years can plausibly be explained just by the recruiting efforts.
Third, wanting to have more women isn't a mere matter of optics. Most undergraduates live on campus. For the first couple of years students are generally required to do so. But Caltech is a very hard school. Most undergraduates have little to no time to have any kind of social life that is not on campus. And they are around the age of peak horniness. When the gender ratio is out of whack in such an environment it causes a lot of stress (at least for the heterosexual students), for both men and women, which can greatly affect academic performance.
Also, as far as imposter syndrome goes, a sizable majority of the men at Caltech probably have it too. Most of them were at the top of the class for their whole life, and without having to put a lot of effort into it. School was always easy. Then they get to Caltech where they have to work their assess off just to reach average. It's hard to avoid getting some imposter syndrome.