Given the story of his encounter with the psychologist (also in Surely You're Joking, Mr. Feynman!), I'd say he thought so, and ditto with the other fields he mentioned. I believe he was criticizing acceptable social conversation (at the Nobel Prize banquet, I believe!) as being restricted to topics on which nobody sufficiently facile with words could be conclusively shown to be wrong.

The conversation took place in 1965; if Feynman believed that, as is likely, he was very probably correct. On the other hand, a lot of people probably thought they knew something about psychology; it was a popular subject at the time.