Paul Krugman has some words for job creators and other high skilled people: we don’t need you.

…textbook economics says that in a competitive economy, the contribution any individual (or for that matter any factor of production) makes to the economy at the margin is what that individual earns — period. What a worker contributes to GDP with an additional hour of work is that worker’s hourly wage, whether that hourly wage is $6 or $60,000 an hour. This in turn means that the effect on everyone else’s income if a worker chooses to work one hour less is precisely zero. If a hedge fund manager gets $60,000 an hour, and he works one hour less, he reduces GDP by $60,000 — but he also reduces his pay by $60,000, so the net effect on other peoples’ incomes is zip.

First let me just say that the extent to which what people earn is equal to their marginal product is greatly unappreciated, so before I disagree with Krugman I just want to pause and point out that this is truer than most people think. But it’s not true everywhere and always. Note that Krugman does not go so far to say that marginal product *does* in fact equal income, but that “textbook economics says that in a competitive economy…”, and that job creator praise is not “something that comes out of the free-market economic principles these people claim to believe in”, and that “Even if you believe that the top 1% or better yet the top 0.1% are actually earning the money they make…”.

He doesn’t actually say “people earn what they make”, nor does he say how good of an approximation to reality marginal product theory is. But in his economics textbook with Robin Wells, they are a bit more explicit, and do call the marginal product theory a pretty good approximation:

The main conclusion you should raw from this discussion is that marginal productivity theory is not a perfect description of how factor incomes are determined, but that it works pretty well. The deviations are important. But, by and large, in a modern economy with well-functioning labor markets, factors of production are paid the equilibrium value of the marginal product -the value of the marginal product of the last unit employed in the market as a whole.

This is a really important point, and I don’t disagree. But I think that many high skilled, high paid workers, and job creators in the U.S. can be an important deviation from this general rule. Many of these people work at moving the productivity frontier forward, and thus increasing the marginal productivity of other workers. After all, one of the important things that entrepreneurs do is find ways to increase the productivity of other workers so they can underprice their competitors. The process of creative destruction is not manna from heaven. I won’t pretend to know have all the answers about what drives this process, but entrepreneurs, job creators, and high skilled people are an important part of it.

Consider, for instance, that if we suddenly kicked out the top 10% of high IQ people (or 10% most productive people, or 10% most creative people, or whatever) in the U.S.. It strikes me as fairly likely that the total output of the remaining 90% would go down. Krugman seems to argue that this would not be the case. But even if you disagree with me in the short run, in the long-run the productivity increasing innovations these people would have made won’t show up, and the rest of us would have lower productivity as a result.

Now, instead of kicking out the top 10% of workers, just make them work less as a result of high income taxes.  See my concern?

Lowered incentives of job creators and other innovators should be considered as one of the likely downsides to higher taxes.

Note that if you don’t think this is true, then what business do we have subsidizing higher education? If workers capture the entirety of their higher productivity, then I don’t see who gains by giving young people money to go to college rather than just cash.