Why social mobility is important

By Felix Salmon
July 30, 2012
Tim Harford is a fan of the clear way in which Alex Tabarrok has couched the debate -- which started with a Tyler Cowen post back in January -- about the desirability of intergenerational economic mobility.

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Tim Harford is a fan of the clear way in which Alex Tabarrok has couched the debate — which started with a Tyler Cowen post back in January — about the desirability of intergenerational economic mobility. Or, in English, is it a good thing if quite a lot of poor people become rich?

The Marginal Revolution guys say that looking at economic mobility is overrated; Cowen, also in January, linked to a bunch of critics of that position, including John Quiggin, Brad DeLong, and Paul Krugman. Recently, DeLong resuscitated the discussion, and Krugman came back for a second go-round as well, all of which resulted in Cowen being rude about Krugman, and Tabarrok trying to clear things up.

Tabarrok’s post is indeed clear, but it’s clear in an invidious way. He basically starts with his conclusion, saying that if a high-mobility society has no better outcome, in general, than low-mobility society, then there’s not very much to choose between them. And similarly, he says, if both a high-mobility society and a low-mobility society have the same very good outcome, then again there’s not much to choose between them.

But this obtusely misses the fundamental reason why high mobility is a good thing: that it improves outcomes. A sclerotic society where no rich people become poor and where no poor people become rich is never going to be a hive of creative destruction. Cowen even comes close to admitting this, when he says that “if the general standard of living is rising, mobility takes care of itself over time” — except he has the causality largely backwards. If you have lots of social mobility, then the general standard of living is going to go up: you’ll have lots of poor people becoming richer, and you’ll also have the rich protecting their downside, in the likely event that they become poorer, by doing their best to improve the lot of the poor.

So when Cowen talks about economic mobility not mattering much “for a given level of income”, or when Tabarrok talks about “some simple societies” with fixed levels of income, they’re taking the variable in the equation and they’re turning it into a constant. What they should be doing is looking at two societies, equal in all respects except that one is high-stasis and the other is high-churn, then fast-forwarding to see which one turns out better. The answer, of course, is the high-churn society — which means, working backwards, that if you want growth, you also want social mobility.

As a result, it’s reasonable to conclude that anything which impedes social mobility — like rising inequality, say — also impedes growth. The effect might not be huge, but it’s there. And the only way not to see it is to effectively assume your conclusions.

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