The world is a different place now.
In terms how of complex natural languages etc. are in an abstract sense? I'd expect that to have been more or less the same for the past few tens of millennia... And the argument that catching a baseball (or something like that) is easy for humans but explicitly writing down and solving the differential equations that govern its motion would be much harder is something that IIRC dates back to the mid-20th century.
EDIT: And BTW...
If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is.
-- John von Neumann in 1947. (Actually I was looking for a different quote, but this one will do. EDIT 2: That was “You insist that there is something that a machine can't do. If you will tell me precisely what it is that a machine cannot do, then I can always make a machine which will do just that.”)
The world is a different place now.
In terms how of complex natural languages etc. are in an abstract sense?
I suspect he means that the knowledge base around Moravec's paradox has seeped into many sciences and stories and our implicit understanding of the world.
In a sense, all that we had to know what that after 50 years of trying, there were no marching robots but there were decent chess computer programs... to suspect that something non-intuitive was going on here.
I've just been through the proposal for the Dartmouth AI conference of 1956, and it's a surprising read. All I really knew about it was its absurd optimism, as typified by the quote:
An attempt will be made to find how to make machines use language, form abstractions and concepts, solve kinds of problems now reserved for humans, and improve themselves. We think that a significant advance can be made in one or more of these problems if a carefully selected group of scientists work on it together for a summer.
But then I read the rest of the document, and was... impressed. Go ahead and read it, and give me your thoughts. Given what was known in 1955, they were grappling with the right issues, and seemed to be making progress in the right directions and have plans and models for how to progress further. Seeing the phenomenally smart people who were behind this (McCarthy, Minsky, Rochester, Shannon), and given the impressive progress that computers had been making in what seemed very hard areas of cognition (remember that this was before we discovered Moravec's paradox)... I have to say that had I read this back in 1955, I think the rational belief would have been "AI is probably imminent". Some overconfidence, no doubt, but no good reason to expect these prominent thinkers to be so spectacularly wrong on something they were experts in.