Who says that persistent unemployment is supposed to result from that?
The hypothetical situation we're discussing, unless I'm desperately confused, is one in which machines are better than humans at all the things humans need or want doing. Not one where various particular human capabilities have been exceeded by precisely focused technology (which is what we've had time and time again in the past) but one where machines are simply better than we are at everything. This is not at all the same.
That is indeed the ultimate hypothetical situation we're discussing, but we're also discussing other situations in the present or very near future where only some human job-skills have been obsoleted. From the Mechanical Engineering article, I got the impression the Race Against the Machine authors thought that jobs were being obsoleted faster than people could re-train for the new ones. Thus, increased unemployment.
I doubt that a major chunk of current unemployment is thus explained, but I like the fact that this might get people thinking. They can connect the dots to the possible future situation you've named, and perhaps start thinking more seriously about AI.
Mechanical Engineering magazine (paywalled until next month) and Financial Times, among others, recently reviewed the book Race Against the Machine by economists Erik Brynjolfsson and Andrew McAfee. The FT reviewer writes:
And ME magazine quotes McAfee in an interview:
Both reviewers also hint that McAfee and Brynjolfsson offer a partial explanation of the "jobless recovery", but either the book's argument is weak or the reviewers do a poor job summarizing it. Such a purported explanation might be the main attraction for most readers, but I'm more interested in the longer-term picture. Be it the "nightmarish vision" of the future mentioned in FT, or the simpler point about wages offered by McAfee, this might be a good hook to get the general public thinking about the long-term consequences of AI.
Is that a good idea? Should sleeping general publics be left to lie? There seems to be significant reluctance among many LessWrongers to stir the public, but have we ever hashed out the reasons for and against? Please describe any non-obvious reasons on either side.