Earlier quoted context omitted.
> breadth and depth of understanding about psychology have improved dramatically Provide one tiny bit of evidence for this. Do you seriously think that Shakespeare (for e.g.) did not have a profound understanding of human psychology?
not who you are replying to - but: Shakespeare was limited by the number of interactions he had with humans. He did not have the internet. We also have neurology as a science now. So that's one bit of evidence for the claim. Of course Shakespeare had a profound understanding of human nature. And of course he did not have the working vocabulary and knowledge base of modern psychology which has been built up over time…
Humans are great at figuring out how things behave before we have a great model of why they do it. And by Shakespeare’s time, we had a pretty good grasp on practical human psychology, even if we had less understanding of the mechanisms behind it.