Kaleberg of Port Angeles, Wash.:

The claim that all we need is higher productivity has been debunked for anyone looking back at the last 30 years. We’ve had plenty of productivity growth, but reduced mobility and greater inequality. Basically, been there, done that. Maybe it’s time to attack the problem instead.

Kyle of Indianapolis defended the claim:

Professor Cowen is writing about total factor productivity (TFP), which accounts for both capital and labor, and it is a better measure of an economy’s production over time. Think of it as a measure of our return on capital. And yes, TFP growth has slowed since 1973. As stated by The Economist, the U.S. TFP growth rate from 1947-1969 was 1.9 percent, slowing to 0.8 percent from 1970-present.

More:

■ Dean Baker of the Center for Economic and Policy Research posted a rebuttal here.

■ In a Q. and A. with Eduardo Porter for The Upshot in July, Mr. Cowen discussed inequality at length, including this passage, which touched on productivity:

“If today we had a rate of technological innovation comparable to say 1890-1930, the middle class and the poor would benefit tremendously from those new goods and services. Income inequality might go up or down but we could stop worrying so much about it.

“That earlier period brought such innovations as electricity, the automobile, radio, the airplane, basic advances in public health, and much better fertilizers, among many others. In more recent times we’ve had a lot of innovations in the manipulation and storage of information, but this just hasn’t benefited ordinary lives as much.”