They also raise an idea that might remind you of the big free-trade debates: that workers, and politicians, should make peace with the idea that some good jobs will go away, when technology renders them obsolete.

“What I hope doesn’t happen,” McAfee said, “is that this turns into a conversation about, who can bash technology and try to maintain the middle class and preserve the economy in amber.”

The problem with that is, a lot of workers who lost jobs from automation (or outsourcing, for that matter) in the last decade are still waiting for better jobs to come along. What to do with those workers, particularly older ones, is one of the most vexing questions policymakers face. Improved skill training could be part of the solution, Brynjolfsson and McAfee say.

But they also suggest, longer term, that as countries get richer, their safety nets grow. The implication is, maybe America will eventually need a bigger one.