I recently finished a (fairly advanced) draft of “The Global Economic Impact of Open Borders,” posted to SSRN here. Here’s the abstract:
Open borders, in the sense of the abolition of policies restricting migration, would cause billions of people to migrate, and result in almost a doubling of world GDP. Based on a model that stresses human capital as a determinant of the wealth and poverty of nations, but which also has a spatial element and allows total factor productivity to differ across cities, two openborders scenarios are constructed. In the first, “pure market clearing” scenario, world GDP rises 91% as 82% of the world’s population migrates, mostly to the West, and the living standards of unskilled workers worldwide rise to 26% of the US level. In the second scenario, with several adjustments made to favor greater realism at the expense of some arbitrariness, world GDP rises 85% as 58% of the world’s population migrates, and the living standards of unskilled workers worldwide rise to 31% of the US level.
While I plan to do another round of revisions (a sorely needed Acknowledgments section is high on the priority list), I want to bring out some of the main themes of the paper, through blog posts at Open Borders: The Case. One of these is that while the claim that open borders would dramatically raise world GDP (“double world GDP” is the usual, sometimes criticized as over-optimistic but in my view apt, slogan) is robust to many changes in assumptions, it cannot withstand the “hive mind” hypothesis about the determination of GDP.
In technical jargon, the “hive mind” hypothesis is that TFP (total factory productivity) depends on human capital externalities. In non-technical language, the hive mind hypothesis is that people’s productivity and earnings depend, not so much on their own intelligence or skill, as on that of people around them.
(In the academic literature, Jones (2011), “The Hive Mind Across Asia,” seems to be the most prominent paper using the phrase “hive mind” in this sense, but Lucas (1988) is a seminal paper for the idea that human capital externalities are an important determinant of TFP, on which a large literature builds. John Lee comments here on how Docquier, Machado, and Sekkat (2014), the chief outlier among papers estimating the global economic impact of open borders, uses a form of the hive mind hypothesis to arrive at its conclusion that open borders would only raise world GDP by 4%.)
The principal motivation for the hive mind hypothesis is to explain the fact that highly skilled workers do not tend to earn more where skills are scarce. If anything, they earn more where they are abundant. A well-designed study by Michael Clemens uses the randomness of US visa allocations to show clearly that Indian software programmers earn far more in the US than in India, for reasons that seem to indicate higher productivity, since they’re working for the same companies, and the companies would have no reason to sponsor their visas if they didn’t anticipate a productivity increase sufficient to justify the higher salary. Against this, my own experience in Malawi taught me that what Amy Chua (2004) calls “market-dominant minorities” can achieve, in the poorest countries on earth, living standards much superior to those of middle-class Westerners in some respects (land, servants, to some extent leisure) while inferior in others (access to shopping, internet) in such a way that, overall, they might be rated as similar; and Chua (2004) gives very extensive evidence that this is true not just in Malawi but all over the world. My rough assessment is that while Indian software programmers might be far more productive in the US, the living standard earned by human capital is similar all over the world. (More precisely, the additional living standard that a worker with human capital equivalent to that of an average American will enjoy, over and above whatever a local unskilled worker would earn varies by less than an order of magnitude across countries.) Still, even if skills don’t earn less where they are scarce, they ought in theory to earn more, and that they don’t is a mystery demanding explanation.
Normally, a factor of production is most valuable where it is scarcest. Thus, water is intensely valued in California but less so on the rainy East Coast. Land is very expensive in Manhattan, where it is scarce (relative to population), but much less so in Montana, where there’s plenty of it. We should ordinarily expect the same thing with respect to brains, skills, human capital. They should be expensive where they are scarce, cheap where they are abundant. In fact, human capital seems to earn as much or more where it is abundant. To resort to technical language again (sometimes it clarifies) there is a correlation between average human capital and total factor productivity (TFP); and the hive mind hypothesis is essentially that this is causal, with the direction of causation running from average human capital to TFP. There may be a variety of reasons, e.g., smart people vote more like economists (so that democracy => good policy works only as well as the voters are smart), or smart people are better at cooperating, or maybe smart people need stimulation from other smart people to exercise and improve their intelligence. That’s the hive mind hypothesis in a nutshell. If you want more, ParaPundit’s post “Benthamite Libertarian Collectivists Wrong on Open Borders” has a good explanation (though without the term “hive mind”) with further links. Even better are the extensive contributions by anonymous commenter BK at the “Open borders and the economic frontier” posts linked above, and also here and here. Chaper 2 of Collier’s Exodus, which I review here, has what might be called an institutional spin on the hive mind hypothesis.
If the hive hypothesis is true (if average human capital is causally linked to TFP), what does it imply for open borders?
First, if the hive mind hypothesis is true, the impact of open borders on world GDP would probably be far less favorable than most of the existing estimates suggest. In one of the two model extensions that make TFP a function of human capital externalities, I find that world GDP falls by nearly one-quarter under open borders. One critique of open borders is that it would kill the goose that lays the golden eggs. The hive mind hypothesis is probably the form of “killing the goose” argument that has the best support in the literature at the moment.
Second, even in my most pessimistic hive mind scenario, unskilled workers worldwide end up with living standards 15% of the current US level, an order of magnitude above current levels. This is a counter-intuitive result, because in essence, what it shows is that the seemingly most pessimistic open borders scenario, killing the goose, and the seemingly most optimistic open borders scenario, the end of poverty, are actually not inconsistent! Even if the institutional harms/negative externalities/various downsides of open borders were severe enough that world GDP, far from doubling, actually fell substantially, yet billions of the world’s most destitute people would still see their incomes multiplied five-fold, ten-fold, or more, because they could live under institutions that, while much degraded relative to the pre-open borders rich world, were still a good deal better than those they suffer under today; and also because they would benefit from greatly increased opportunities for productive complementarity with skilled workers, which the status quo precludes. Is it worth reducing world GDP by one-quarter to raise the wages of the bottom billion ten-fold? Probably so, if it came to that.
Third– and this is why ParaPundit misses the mark– whatever the normative implications of the hive mind hypothesis may be with respect to immigration, they certainly do not suggest that the status quo is anything like optimal. If one’s goal is to maximize world GDP, the only advantage of the status quo, relative to open borders, is that it involves some human capital stratification, allowing today’s rich countries to be productive “hive minds” of high human capital people. But the migration status quo is a very suboptimal human capital stratification system. First, there should be open borders for smart people– no reason to shut them out– and the admission of people with high IQs and advanced degrees to rich countries could be far more automatic and transparent. We could create schemes to bribe low-IQ, less-educated citizens of rich countries to emigrate and surrender their citizenship, since such emigration should raise average human capital, and TFP, in the source country. We could establish charter cities for low-IQ people to emigrate to, and a bit of ongoing foreign aid might be a fiscal price well worth paying to have them out of the way. Meanwhile, we could establish gated communities for smart people, graduating them into increasing levels of self-government, until eventually they attain full independence as (not philosopher-kings but) philosopher-republics.
Critics of open borders from a hive mind angle, like ParaPundit, can be called on to explain why they don’t advocate a global program of maximal human capital stratification, since that’s what their arguments would really point to.
I’m skeptical of the hive mind hypothesis, and I don’t think open borders would kill the goose that lays the golden eggs; I think it would double world GDP. But I don’t rule the hive mind hypothesis out either, and it’s one of the most respectable reasons to dissent from claims that open borders would raise world GDP dramatically.
More related reading
- Grappling with the Goose by Paul Crider, Open Borders: The Case, February 17, 2014.
- How migration liberalization might eliminate most absolute poverty by Carl Shulman, May 27, 2014, making a very similar point. Here is the summary:
While some estimates that open borders would double gross world product implicitly project the migration of most of the developed country labor force, a much smaller quantity of migration might cut global poverty rates by half or better. The additional income to the poorest required to bring them above extreme poverty lines is in the hundreds of billions of dollars per annum, while doubling world product would approach a hundred trillion dollars of additional annual output. Legal barriers to migration, and blocked desire to migrate, are most extreme for the poorest countries, suggesting extra migrants from those sources. While migrants may receive more income gains than are needed to escape absolute poverty remittances to family, trade, and investment may help to distribute the gains more widely. Overall, the case that migration liberalization for less skilled workers could eliminate most absolute poverty is significantly more robust than the most extreme estimates of global output gains.
- Intelligence, international development, and immigration by Vipul Naik, Open Borders: The Case, August 19, 2012. See also the follow-up Garett Jones responds to my intelligence post.