In the last three recoveries, however, America’s economic engine has emitted sounds we’d never heard before. The 1990 recovery took 15 months, not the typical six, to reach the prerecession peaks of economic performance. After the 2001 recession, it took 39 months to get out of the valley. And now our machine has been grinding for 60 months, trying to hit its prerecession levels — and it’s not clear whether, when or how we’re going to get there. The economic machine is out of balance and losing its horsepower. But why?

The answer is that efficiency innovations are liberating capital, and in the United States this capital is being reinvested into still more efficiency innovations. In contrast, America is generating many fewer empowering innovations than in the past. We need to reset the balance between empowering and efficiency innovations.