> completely and entirely objectively wrong about everything.

You mean things like:

* people not being fully rational, but also having unconscious thought processes

* human mind consisting of multiple sub-agents that sometimes have different goals

* hypnosis not being necessary to cure problems, mere talking can achieve the same effect

* sex being an important force in human psychology

...or something else specifically?

When talking about people in the past, you may want to consider that everything they were right about sounds to us now as obvious (sometimes, thanks to them), so yeah it seems like everyone in the past only had two kinds of opinions: obvious, and wrong.