industrial productivity growth has slowed across the rich world, even if not by as much as in America (see chart 2). The extra bit of American underperformance is trickier to explain. Economists throw out a boatload of hypotheses. America is known to have laxer antitrust enforcement than its peers; perhaps scrutiny was especially needed in the manufacturing sector. Maybe American manufacturing was more advanced when robots arrived on the scene, so had less to gain. Some have even argued that because America’s software and internet sectors have been so lucrative, talent has been diverted away from older industries.