I am not assuming this, but the point is that it is perfectly valid to keep doing studies on the fundamental and pretty well-understood phenomenon of birth-sex and whether it is a significant causal factor on the biology of homo sapiens.
It is a simple variable, we can start from it and then try to see whether gender self-identity has any effect.
We can be pretty sure of the sex-at-birth of any human being given some simple tests. It is a simple variable that we can trust have been correctly recorded the vast majority of time. Gender identity? not so simple.
And given a correct understanding of the differences, if any, between sex-at-birth individuals, we will have a good framework from which we can investigate if those differences follow gender identity, and if so, what is their causal relationship with gender, etc. etc. etc...
What I am questioning, is that if every time a scientist do a sex-at-birth based study we question implicitly if they are not being bigots, we will end up censoring scientific inquiry for no good reason at all. (yeah, I do believe that not all scientific inquiry is allowable, for example, I oppose research on chemical and biological weapons)
Gender identity is a fairly recent cultural invention too, it just started out as a euphemism for the desire to be the opposite sex, or, more commonly, some stereotyped idea of the opposite sex.
In a culture without such polarized ideals of how males and females should behave and present themselves, the concept probably wouldn't exist at all.
“Fundamental” is carrying too much weight in your argument
You’re supposing that the binary classifier is the most accurate starting point.
I’m suggesting that you should assume that this is a biased starting point and shouldn’t have any power as a benchmark or reference frame in any dimension
The same way we don’t use ideas like humors anymore because they are based on bad assumptions
A long time ago I wanted to be a medical doctor, but humanity somehow dodged this bullet (luckily, may I say) and I quit medical school just before the third year (the fact that programming computers paid my bills, while medical school did not at the time may have been partially responsible for this).
So, I am no medical doctor, but I was a pretty diligent student, and given the few things I studied about human physiology, I can assure you that biological sex is a pretty much fundamental fact for species that propagate via sexual reproduction, something that I can provide some anedoctal evidence being an homo sapiens, and being one of the parents of a certain number of other homo sapiens.
Maybe it is not as fundamental as the measurement of whether someone have a pulse or not at the present moment, or if their core temperature is around 36C, but it is still really consequential. Indeed, sex is far more consequential than something like race, which basically is mostly irrelevant for medicine.
You see, the problem with your analogy, is that humours was not a theory really based on the systematic observation of reality. Once we could measure more and more things empirically, it was pretty clear that it was a crackpot theory.
And while in a sense, you may be right and someday we could come up with new scientific facts that showed that the whole edifice of sexual reproduction would be superceded by new, better scientific concepts, the fact is that this has not happened, and frankly, it doesn't look even remotely likely to happen.
Until the day we have an alternative scientific theory, with predictions that can be reliably reproduced on experiments, and that explain such foundational biological issues such as human reproduction and secondary sexual characteristics, sex continues to be a very useful category of study.
Indeed, even the medical field of gender reassignment treatment relies heavily on the corpus of knowledge based on the concept of sex in things like hormonal treatment and puberty blockers.
It is a simple variable, we can start from it and then try to see whether gender self-identity has any effect.
We can be pretty sure of the sex-at-birth of any human being given some simple tests. It is a simple variable that we can trust have been correctly recorded the vast majority of time. Gender identity? not so simple.
And given a correct understanding of the differences, if any, between sex-at-birth individuals, we will have a good framework from which we can investigate if those differences follow gender identity, and if so, what is their causal relationship with gender, etc. etc. etc...
What I am questioning, is that if every time a scientist do a sex-at-birth based study we question implicitly if they are not being bigots, we will end up censoring scientific inquiry for no good reason at all. (yeah, I do believe that not all scientific inquiry is allowable, for example, I oppose research on chemical and biological weapons)