Tyler Cowen says that the predicted future of Robin Hanson’s Age of Em – a world in which most cognitive and much physical labor will be done by emulations of brain-scanned human beings – won’t happen. I agree. I enjoyed the book, and feel a bit guilty about criticizing it, since Hanson asked me for comments on an early draft, which I never got around to giving him (the last eighteen months have been unusually busy for a variety of reasons). So the below are the criticisms which I should have given him, and which might or might not have led him to change the book to respond to them (he might have been convinced by them; he might have thought they were completely wrong; he might have found them plausible but not wanted to respond to them – every good book consists not only of the good counter-arguments it answers, but the good counter-arguments that it brackets off). [click to continue…]