Tyler Cowen’s e-book The Great Stagnation offers a novel explanation of the slowdown in U.S. median income growth since the 1970s. Here’s his causal model:
Innovation —> economic growth —> median income growth
In this model there are three potential sources of the reduction in median income growth:
1. Innovation has slowed.
2. The degree to which innovation boosts economic growth has declined.
3. The degree to which economic growth boosts median income growth has declined.
Cowen argues for hypothesis #1. He cites an estimate by Jonathan Huebner, a Pentagon physicist, that the rate of global innovation per capita peaked in the late 1800s, remained high to the mid-1950s, and then steadily declined. And he suggests that whereas “The period from 1880 to 1940 brought numerous major technological advances into our lives…. Today … apart from the seemingly magical internet, life in broad material terms isn’t so different from what it was in 1953.” The high rate of innovation through the mid-1950s enabled rapid economic growth for a few additional decades. But beginning in the 1970s economic growth slowed, and along with it median income growth.
The book is well worth reading. (At four dollars it’s also a good deal — less than a large latte, a Sunday New York Times, or a newsstand copy of The Atlantic.) But I’m skeptical on two counts.
First, I’m not convinced that innovation has in fact slowed significantly. Cowen discusses the internet but not computers more generally. Computers are the engine of the postindustrial economy; they are the modern counterpart to steel, railroads, and the assembly line. Advances in computer hardware and software, their widespread dissemination, and their application to myriad tasks — automation and coordination of supply chains in manufacturing, record keeping and scheduling in services, and much much more — surely represent a massive improvement.
Second, the data point to hypothesis #3. A key difference between the WW2-1973 period and the decades since then is that median income growth has become decoupled from economic growth. (Mark Thoma makes this point too.) The rate of economic growth has been lower in the recent era, but it’s nevertheless been decent. Yet median income growth has been very slow. This contrasts sharply with the prior period.
Here’s one way to see this (others here):
Between 1947 and 1973, GDP per family increased at a rate of 2.6% per year and median family income grew at 2.7% per year. From 1973 to 2007, GDP per family increased at 1.7% per year, but median family income grew at just 0.7% per year.
And note the absolute numbers: GDP per family rose by $52,000 during 1947-73 and then by $82,000 during 1973-2007. Median family income increased by $26,000 during 1947-73 but then by just $13,000 in 1973-2007.
Median family income was $64,000 in 2007. Had it kept pace with GDP per family since the mid-1970s, it instead would have been around $90,000.
I’m all for helping to accelerate the rate of innovation. But the big change in recent decades lies in the degree to which economic growth lifts middle-class incomes. If we want to understand slow income growth, that should be our focus.