Economists should listen more to techies on what techs will be feasible at what costs, but techies should also listen more to economists on the social implications of tech costs. Alas, just as economists prefer to rely on their intuitive folk tech forecasts, techies prefer to rely instead on their intuitive folk economics.
His point is that I should back off from my claims that artificial intelligence will be very difficult. For Hanson, I am not enough of an authority on technology. I should defer to authorities.
I try to stay away from arguing from authority. When I cite economic theory as an authority, it is not with a view toward saying "Shut up and listen to economists." It is instead with a view of trying to explain why the economic theory is convincing.
My views on artificial intelligence have been shaped by reading books on it. Here I wrote after reading Jeff Hawkins' On Intelligence in 2004. Later, in 2005 I looked at Ray Kurzweil's predictions, and I found a pattern of errors.
There are some engineers who say, "Of course someday we can reverse-engineer the human brain." That is a non-falsifiable statement. We could go 1000 years without reverse-engineering the brain, and somebody could still be saying that we can do it. If engineers are willing to set milestones for the reverse engineering problem and put money on when we reach those milestones, I probably will be willing to bet against them. Even though I do not qualify as an authority.