Hi, not the parent poster here. I believe the argument being made is that diagnostic criteria, and diagnoses themselves, can be shaped by cultural norms. As the Overton window shifts, so do the thoughts and behaviors that we deem pathological.

> Surely you’re not trying to draw some conclusion between an entire countries modern day medical field and a theory a person proposed in the 1800s, right?

That would depend on whether anything has changed since the 1800s. But that's very clearly not so -- consider that recovered memory therapy (https://en.wikipedia.org/wiki/Recovered-memory_therapy), based on as much science as drapetomania, was practiced in the 1990s, and still has adherents today.

Also, for human psychology to be regarded as a medical field, it would have to be based in science. But human psychology studies the mind, therefore by definition it's not based in science.