I'm a doctor who used to be an engineer. Deriving things from first principles in medicine is a lie we doctors tell ourselves.the truth is this.we have some really good understanding of syne things at molecular levels that we then correlates to things that happen clinically at a macro level, that correlation is very very handwavy. But we teach it as if we know for sure. We don't.
The few things that we think we have a somwhat good correlation for, we often test on our exams, but even for most of those things, it's some handwavy link
I recall being an engineering classes, armed with just calculus and linear algebra and newton laws, I could attack just about every problem from first principles from my entire undergrad. Every. I didn't have to take into consideration real life presentation of the problem. First principles were enough to get me nearly there
Medicine is fundamentally not that way. Yes we learn the biology, but if you reason solely from biology, you will quickly end up in the wrong places. to become a doctor, I had to learn that hard way that yeah a disease doesn't just present this way just because the underlying physics and biology suggests it should. You separately have to learn how the disease presents, then try to tie it back to our extensive but still very very limited understanding of the possible biology.
I have problems with doctors that don't acknowledge how tenous that link is and despite how much we know, we still know so so little. We are far more useful than what we know.
I understand to biology majors, the few things that seem to follow physiologically from moelculqr biology dupes us into thinking medicine currebtly derives from first pricinples. But it doesnt.