"What would you think about a law that said that blacks couldn’t get a job without the government’s permission, or women couldn’t get a job without the government’s permission, or gays or Christians or anyone else?" George Mason economist Bryan Caplan asks. It's a pretty easy question. Obviously, such a law is discriminatory on its face, serves no rational purpose, and is unacceptable in a liberal democracy. But Caplan continues: "So why, exactly, is it that people who are born on the wrong side of the border have to get government permission just to get a job?"

This is Caplan's elevator pitch for open borders, an idea that for years was treated as deeply unserious, as an extreme straw man that nativists could beat up in the course of resisting more modest efforts to help immigrants. It had its defenders — philosopher Joseph Carens primary among them — but they were relatively lonely voices.

But in recent years, a small but devoted group of advocates have succeeded in turning open borders from a dirty word to a real movement with strong arguments backing it up. The team at OpenBorders.info — Vipul Naik, John Lee, Nathan Smith, Paul Crider — has led the charge, as Shaun Raviv wrote in an excellent profile of the group in the Atlantic. The University of Colorado's Michael Huemer honed Carens' moral case, while the Center for Global Development's Michael Clemens has been hugely influential in arguing that we're leaving trillions in potential economic growth on the table by enforcing border restrictions.

But few have been as prolific and forceful in their advocacy for the idea as Caplan. "The upside of open borders," he once wrote, "would be the rapid elimination of absolute poverty on earth." He is relentless at rebutting objections. It would take jobs away from native-born workers? It'd hurt growth in poor countries as more and more people leave? It'd leave us vulnerable to crime? No, no, and no.

For more, be sure to toggle over to see the full interview with Caplan. Also be sure to read Caplan's blog , as well as OpenBorders.info , for more on the issue.

But the point is there's no reason to wait that long. "To me," Caplan says, "a big point of open borders is just to fast-forward to the world of the future where everyone can enjoy a First-World standard of living rather than making people wait 100 years."

In the long run, he predicts we'll get open borders once countries are bunched more closely together economically. Hell, we might even get open borders between rich countries in coming years; it's already happened within the EU. The lack of such a setup between the US and Canada is "the one that surprises me the most, actually … Maybe Canadians would have some issue with it, or Canadian nationalists would have some issue, because this plausibly could be the decisive blow to Canadian national identity. That still seems like paranoia to me."

Same goes for the Central American migrant crisis . "I would be against any effort to curtail what’s going on with the child migrant crisis," he says. "This is a loophole, and I believe in pushing loopholes as far as you can possibly can." He also wants Obama to fill the asylum quota — bafflingly, something that hasn't been done in most years. "You’re telling me there aren’t 100,000 people on earth who are going to be horribly persecuted by their governments and who want to come here?" he asks. "Come on."

More incrementally, he wants Obama to take as expansive a view of executive power as possible for the sake of benefiting immigrants. "I think my first step would be, if not legislative amnesty, then presidential fiat amnesty," he says. "Essentially, the kind of things that Republicans accuse Obama of secretly plotting to do are what I think should be done."

Caplan doesn't support any of these policies on their own; if he had his druthers, he'd just open the borders. "I think you should let immigrants become citizens because they’ve been so sorely abused by American citizens for so many years," he says. But any of them is superior to the current system, in which the presumption is that people can't come and work in the United States unless they demonstrate otherwise.

If immigrants hurt American workers, we can charge immigrants higher taxes or admission fees, and use the revenue to compensate the losers. If immigrants burden American taxpayers, we can make immigrants ineligible for benefits. If immigrants hurt American culture, we can impose tests of English fluency and cultural literacy. If immigrants hurt American liberty, we can refuse to give them the right to vote. Whatever your complaint happens to be, immigration restrictions are a needlessly draconian remedy.

So what's an open borders advocate to do? One tack Caplan takes is advocating "keyhole solutions" to common objections raised by open borders opponents — say, responding to claims immigration hurts American workers by charging immigrants admissions fees and redistributing them to US-born workers. As he put it in the paper "Why Should We Restrict Immigration?" :

Today, open borders sounds like a radical position, and you'll never hear a politician of any consequence endorsing it. Most people believe that the United States government should pursue policies that benefit its own residents, even if those policies impose enormous human costs on people from other countries, as border restrictions of any kind do.

"In terms of brain drain, it seems like there has been a lot less than for any other Latin American country, because from Puerto Rico, you can come regardless of your skill level, whereas, for every other country in Latin America, it is much easier for the skilled workers to get in," Caplan notes. "Over half the population has left, but Puerto Rico, by the standards of Caribbean island nations, is a paradise."

Moreover, actual examples we have of open borders suggest that migrants' home countries actually benefit. Take Puerto Rico. Shortly after the US conquered it in the Spanish American War, the Supreme Court established that it was illegal to restrict migration between the island and the rest of the United States. The result was open borders between the US and a much poorer territory, imposed more or less randomly by a court. It made for a good test of the policy's effect: since then, Puerto Rico has far surpassed neighboring countries like the Dominican Republic economically.

In any case, emigration actually helps home countries in a wide variety of ways. Emigrants typically send back money, which can be hugely consequential for their home country's economy. They can create social networks in host countries, and later come home and use those connections to advance their home country's development. Caplan points to the Chinese diaspora as a prime example: "A lot of what’s going on in the development of China is there is this huge, disparate community of ethnic Chinese all over the place, and they have relatives in China. This makes it very easy for them to do business with each other."

The idea here is a little confused ; we should care about making life better for people, whether or not they stay in their home country. But it's wrong even on its own terms. If we're worried about brain drain, we should really be concerned about the current immigration system, in which high-skilled immigrants are privileged over low-skilled ones, ensuring that what migration does occur disproportionately takes the former out of their home countries.

Even if open borders would be economically beneficial for recipient countries, it's worth asking if it benefits the countries people are leaving. A common worry is that open borders would cause a "brain drain," taking talent away from developing countries and hurting them, even as it helps their (former) residents.

Immigration also has a well-documented, positive effect on housing prices. Most Americans own homes at some point in their life, so even if they lose out from immigration in the labor market, they could make up the loss in the housing market. "The Americans who lose from immigration are those who are very low-skilled, who also don’t speak very good English to begin with, and also don’t own real estate," Caplan concludes. "It's a quite small group. If you’re a real nationalist who cares about all Americans, then you should favor immigration, because only like 5 or 10 percent of Americans are losing." And in any case, whatever losses that 5 or 10 percent incurs are swamped by the gains to the rest of the world, and in particular the migrants themselves.

Think about it this way. Low-skilled immigrants increase the supply of people who can do janitorial work or wash dishes or whatnot, which you'd expect to reduce wages for Americans in those jobs. But they also decrease, relatively speaking, the supply of people who can speak English. That raises wages for Americans who can speak English. "When you put that together, it’s at least unclear whether most Americans lose," Caplan surmises. "Furthermore, you can change your occupation. You could move to a job that does less of what is worth less after immigration, and move into a job that does more of what’s valued more."

Not necessarily. "Low-skilled" is actually kind of a misleading term here. Even American high school dropouts have at least one key skill that immigrants generally don't: the ability to speak English. That makes it possible for immigrants to complement the labor of low-skilled, native-born workers, rather than replacing it. "Low-skilled Americans who are fluent in English in a place like New York City wind up supervising the low-skilled immigrants," Caplan says. "They wind up being the bridge, or the people who train immigrants in jobs that they wouldn’t even know about from their home countries."

Opponents of open borders often grant that it would grow the economy. The problem, they say, is that most of those benefits presumably accrue to migrants. What about the workers who are already there? Don't they lose out, in particular low-skilled workers who are already struggling and would face increased competition from low-skilled immigrants?

With numbers that big, the potential gains are enormous. A doubling of world GDP is a reasonable estimate. "This isn’t just trickle-down economics. It’s Niagara Falls economics," he says. "If production in the world were to double, almost everyone is going to get enough of that doubling that they’re going to, in the end, be better off as a result. You can’t double the output of the world and leave a lot of people poor as a result."

If you’re a real nationalist who cares about all Americans, then you should favor immigration because only like 5 or 10 percent of Americans are losing

That's the basic argument for open borders: that you're "moving productive resources" — people — "from places where they’re next to useless to places where they can contribute a lot." The size of the numbers involved makes the case even more compelling. "You might think that moving from Haiti to the United States would cause a 20 percent increase in wages, but no. It’s more like a 2,000 percent increase in wages," Caplan notes. "The difference between the productivity of labor in poor countries and rich countries is so vast, it’s hard to wrap your mind around it."

Alternately, think about what happened in the 1960s and '70s as more and more women joined the workforce in the United States. Was the result mass unemployment for men, as women took all their jobs? Of course not — the economy adjusted, and we're all better off for it. "Would we really be a richer society if we kept half the population stuck at home?" Caplan asks. "Isn’t it better to take people who have useful skills and let them do something with it, than to just keep them locked up someplace where their skills go to waste?"

"Imagine that you’ve got a million people farming in Antarctica. They’re eking out this bare subsistence in agriculture in the snow," he says. "Obviously, if you let those farmers leave Antarctica and go someplace else to farm, the farmers are better off. But isn’t it also better for the world if you let people stop eking out this existence, contributing nothing to the world, and go someplace where they could actually use their skills and not just feed themselves, but produce something for the world economy?"

Here's how Caplan laid out the case for me. For a shorter article summarizing the argument, click the toggle below.

story,interview

Dylan Matthews: What’s your elevator pitch for open borders? What is the first thing you would say to someone who is skeptical about this?

Bryan Caplan: In the elevator pitch I would ask, "What would you think about a law that said that blacks couldn’t get a job without government’s permission, or women couldn’t get a job without the government’s permission, or gays or Christians or anyone else? So why, exactly, is it that people who are born on the wrong side of the border have to get government permission just to get a job?" Would we really be a richer society if we kept half the population stuck at home? Letting someone get a job is not a kind of charity. It’s not a welfare program. It’s just the government leaving people alone to go and make something out of their lives. When most people are on earth are dealt such a bad hand, to try to stop them from bettering their condition seems a very cruel thing to do to someone. My elevator pitch has no economics in it, because the economics is actually too subtle to really explain in an elevator pitch. If I had a little bit more time, I would say, "What do you think the effects for men have been of more women in the workforce?" Are there some men who are worse off? Sure. But would we really be a richer society if we kept half the population stuck at home? Isn’t it better to take people who have useful skills and let them do something with it, than to just keep them locked up someplace where their skills go to waste? Isn’t that not just better for them, but better for people in general, if we allow people to use their skills to contribute to the world instead of keeping them shut up someplace where they just twiddle their thumbs or do subsistence agriculture or whatever?

Dylan Matthews: Let's get into the economics then. Most economists who've tried to model the effects of open borders estimate it would cause a very, very large increase in the size of the global economy — roughly doubling it, in most papers I've seen. Why would that happen? What's the mechanism?

Bryan Caplan: There are some countries where wages are really high and some countries where wages are really low. The question is, "Why is that? Why exactly is the wage so low in Haiti?" You might think that there is something wrong with the Haitians, but the immigration that we already allow shows us that isn’t true. If you move someone from Port Au Prince to Miami, he almost instantly gets an enormous raise. So most of the difference is not due to differences between the workers. It’s a difference in conditions. Open borders allow people to move from the parts of the world where their labor pretty much goes to waste, where it’s hard for anyone to get anything done, and to places where their skills can shine, where they’re able to show what they can do, where they're able to contribute far more. Imagine that you’ve got a million people farming in Antarctica. They’re eking out this bare subsistence in agriculture in the snow. Obviously, if you let those farmers leave Antarctica and go someplace else to farm, the farmers are better off. But isn’t it also better for the world if you let people stop eking out this existence, contributing nothing to the world, and go someplace where they could actually use their skills and not just feed themselves, but produce something for the world economy? This isn’t just trickle-down economics. It’s Niagara Falls economics. The final part is the size of the numbers involved. You might think that moving from Haiti to the United States would cause a 20 percent increase in wages, but no. It’s more like a 2,000 percent increase in wages. The difference between the productivity of labor in poor countries and rich countries is so vast, it’s hard to wrap your mind around it. It comes down to the logic of moving productive resources from places where they’re next to useless to places where they can contribute a lot. Prosperity comes from production, and open borders would massively increase production. As I said in the Intelligence Squared debate, this isn’t just trickle-down economics. It’s Niagara Falls economics. If production in the world were to double, almost everyone is going to get enough of that doubling that they’re going to, in the end, be better off as a result. You can’t double the output of the world and leave a lot of people poor as a result. When you have that massive an outpouring of production, that’s going to raise all or almost all boats.

Dylan Matthews: In rich countries, a lot of people imagine that an influx of foreign workers would reduce wages at a time when median wages have been stagnant for several decades. And because most people are nationalists who privilege the well-being of their countrymen ahead of that of other human beings, that's considered a huge problem with immigration, one that open borders would, on this view, exacerbate. What’s wrong with that mental model of immigration's effects on native workers, apart from the moral problems with treating benefits to foreign-born workers as less important?

Bryan Caplan: The simplest response is to say, "Fine. Let’s accept that way of modeling it, let in immigrants with a entry fee or a surtax, and redistribute the proceeds to low-skilled Americans." That’s the easiest way out, which doesn’t require changing the whole way that people think. But more important is realizing that there are many different kinds of labor. Even Americans we think of as low-skilled actually do very different kinds of labor than, say, low-skilled Bangladeshis. Most low-skilled Americans speak English. They’re familiar with the modern world. When you’re thinking about the kinds of jobs different groups will do, and whether they’ll be competing with each other, you shouldn’t just put everyone into the same "low-skilled" box, but rather realize, "Wow, there are actually a bunch of different low-skilled boxes, and the global poor are in a box that is much lower skilled than even the Americans we think of as being low skilled." Immigrants raise the supply of the non-language skills, but they make language skills more scarce A further key insight is realizing what happens when these different kinds of workers work together. UC Davis' Giovanni Peri and Bocconi University's Gianmarco Ottaviano get at this in their work on the mixing of skills. In places in the US that have a lot of low-skilled immigrants, they do the kinds of things that we think of low-skilled immigrants doing. They wash dishes. They clean hotel rooms. But in places that have very few low-skilled immigrant, you have your native-born, English language speakers cleaning hotel rooms and washing dishes. If you think about that, you realize you are wasting a lot of valuable talent. Low-skilled Americans who are fluent in English in a place like New York City wind up supervising the low-skilled immigrants. They wind up being the bridge, or the people who train immigrants in jobs that they wouldn’t even know about from their home countries. You can think about people’s income as the wage of their language skills multiplied by the amount of hours of language labor they sell, plus the wage of non-language skills multiplied by the amount of hours of non-language labor they sell. Immigrants raise the supply of the non-language skills, but they make language skills more scarce; the ratio of the population that has those skills goes down. In terms of supply and demand, you should think that the wage for the language skills would go up and the wage for the non-language skills goes down, and when you put that together it’s at least unclear whether most Americans lose. Furthermore, you can change your occupation. You could move to a job that does less of what is worth less after immigration, and move into a job that does more of what’s valued more. One other thing that’s worth pointing out: it's a well-documented fact that immigration increases real estate prices. So workers who own some real estate, as most Americans will at some point, benefit. Even if they’re losing in the labor market, they’re gaining in the housing markets. The Americans who lose from immigration are those who are very low-skilled, who also don’t speak very good English to begin with, and also don’t own real estate. It's a quite small group. If you’re a real nationalist who cares about all Americans, then you should favor immigration because only like 5 or 10 percent of Americans are losing.

Dylan Matthews: Another common point of concern is assimilation. People are concerned that large-scale immigration creates populations within countries that are permanently marginalized, that can't be integrated into the rest of society. The evidence for this in the US is very thin but in places like France and Germany, you can see the case a bit more. What’s your reply to that, and why is immigration restriction not the best way of solving that problem?

Bryan Caplan: Immigration restriction is indeed a good way of keeping cultural homogeneity. Japan has got cultural homogeneity, and they have hardly any immigration. If they let in more people, they’d be less homogeneous. In response, I would begin by challenging the goal of cultural homogeneity. Who wants to go and move to a part of the country with almost no immigrants? Places like that are boring. Maybe not just because they lack immigrants, but a conspicuous fact about the low-immigration areas of the country is that they’re just dull places to be. Probably the main kind of cultural assimilation that bothers people is not learning English. This is something where we have very good data, and what the data say is that second generation immigrants have almost total fluency in English. This has been true throughout the entire history of American immigration, and remains true today. Over 90 percent of second generation Mexicans, the group we think of as having the lowest rate of assimilation, are fluent in English. In Germany or Italy it’s easy to understand what would be on a test of cultural literacy. In the United States it’s not. Most complaints about lack of fluency are about first-generation immigrants. There has never been a time when most first generation immigrants learned to speak the language well, for obvious biological reasons. It’s very hard for an adult to learn to speak a new language fluently, but the idea that this is some long-term problem is really just silly. Their kids do learn fluent English. It’s not a problem that is going to change the country in any long-term way. The first generation is going to speak with an accent, or maybe if they come at an old age they’ll never learn to speak English, but it doesn’t mean that they can’t contribute and be useful members of society. The reason why we have this illusion that Spanish-speaking immigrants are not learning English is that there are so many Spanish-speaking immigrants that there is always a new wave of first-generation immigrants. Historically, it was very common to have a wave of German immigrants which then stops, and then, pretty soon, everyone of German ancestry speaks fluent English. It’s not because the first-generation Germans learned to speak fluent English. It’s because they died off and they were not replaced with a new wave of first generation German-speaking immigrants. The same goes for Italians, for Greeks, and so forth. But we’ve had 50 years of wave after wave of Spanish-speaking immigrants. Each time, the first generation doesn’t learn to speak fluent English, and so you look around and you keep seeing these Spanish-speakers who have not assimilated, and you think it’s about the individuals, but it’s really about the cohorts. For Europe, I put a lot of blame on European welfare states, which make it relatively easy for immigrants to never actually try to get jobs. The best way to assimilate and learn how to deal with other people is to get a job where you need to assimilate and deal with other people. As long as you can be more or less permanently on welfare, then it’s very easy to live in an enclave and not deal with other people, but if there is an expectation that you should get a job, then this naturally tends to acculturate people, you increase tolerance, and you build ties between people. This may be a little bit flippant, but, to me, it’s much easier to understand what the Italians or Germans are talking about when they say immigrants don’t assimilate and learn their culture than what Americans are talking about when they say that. In Germany or Italy it’s easy to understand what would be on a test of cultural literacy. In the United States it’s not. Do you name the six lead characters on Friends? Ask how many points a touchdown is worth? You certainly can’t ask people to name three operas. You probably can’t ask them to name three Broadway musicals. There just isn’t nearly as much distinctive American culture that you think people would need to assimilate to. But maybe that's wrong. Maybe it’s extremely important for everyone to be on the same cultural page. So how about this? How about in order to come to this country you have to pass a cultural literacy test? If this were all that it took to get into the US, the world study of English and American culture would blossom as never before, as people tried to learn all the stuff they needed in order to get in. The truth is that there is already a ton of people on earth who are already pre-assimilated, whose entertainment life or their cultural life revolves around American culture. In the 19th Century, you weren’t going to find a lot of people in Germany or Italy who were already reading American books and following American entertainment stars.

Dylan Matthews: You sometimes hear concern from left of center people that more migration would either make the welfare state financially unsupportable, or destroy support for it among people who resent immigrants for getting benefits, or generally undermine the spirit of social solidarity necessary to keep it going. Your redistributive preferences are obviously different from liberals' and leftists', but if you were trying to convince them, what would your argument be?

Bryan Caplan: I would start out by pointing out that there is a whole bunch of rightwing people who think exactly the opposite. They’re worried immigration will make the welfare state explode in size. In general, when there are two groups of people with very different orientations who are both worried about the same thing for opposite reasons, it could be that one is entirely right, but it’s more likely that both are just exaggerating. One of my co-authors, Zac Gochenour, wrote his dissertation on this topic. In Europe there is quite a bit of research that is consistent with the story you’re saying. The researchers in Europe — generally cosmopolitan social democrats, but they’re more social democratic than cosmopolitan — usually reluctantly conclude that immigration undermines support for the welfare state. Now, the magnitude is not that large, but a lot of papers find a moderate effect. For example, in Scandinavia, back when they were entirely blonde up there, a government share of GDP of 60 or 70 percent had broad social support, and it really has fallen since. Now, more like 50 or 60 percent has broad social support. If you talk to people in those countries, it does seem like immigration plays a big role in reducing support, and most of it comes from a sense that a fellow blonde person would never take advantage of the system but an Iraqi or Somali they might. But there is a question of how generalizable these European results are to other countries. Gochenour and his coauthor, Cato's Alexander Nowrasteh, take U.S. state-level data on welfare, education and health spending for programs where states have control. Then they get data on percentage of the population that's foreign born, and related measures like percent of the population that's Hispanic, and then they look to see whether the European results hold up in the United States. There already are eligibility requirements for immigrants for getting on government programs. In general, they don’t. Texas has one of the smallest welfare states in the country, and is very close to California in foreign-born percentage, so it’s clearly possible to have a ton of immigration and a very tiny welfare state or a ton of immigration and a very large welfare state. What Gochenour and Nowrasteh show is when you look the data for all 50 states for the last 40 years you just really see very little pattern. What’s quite shocking about their results is that they not only don't see a pattern in per capita spending, but they don’t even see a pattern in total spending. You might think that letting in a whole lot of immigrants would, at minimum, just increase the total number of people getting benefits, and would increase spending that way, but they don’t even find that. It’s the kind of thing where there are many other forces that are much more important in determining the size of welfare states. Probably the big one is just like the historic ideology of the states, like Texas versus California. To be fair, if you had true open borders, and you had an enormous number of very low-skilled immigrants coming, then I think it’s much more reasonable to think that there would be a decline in per capita spending, and, also, probably reasonable to think that there would be an increase in total spending. If you really had 100 million people show up over the course of a couple of years, then on the one hand, I think people would actually be very interested in cutting per capita benefits, just because the per capita benefits would look so attractive to someone coming from Haiti, but on the other hand there would be so many more people needing benefits that it’s possible the total amount that would be spent would go up, and maybe a percentage of GDP would go up. The fallback is to say they’re not eligible for welfare for a certain amount of time. It could either be a time limit, or it could be they have to actually pay a certain number of dollars in taxes first. When I say this people, often say, "Well, that’s totally unrealistic." I say, "It is realistic because it already exists." There already are eligibility requirements for immigrants for getting on government programs. You have to pay full-time taxes for Social Security for 10 years. There is other government programs where you have to wait five years before you’re eligible. So don’t tell me you can’t do this. We do it already.

Dylan Matthews: How do you imagine, in an open-borders world, migrants engaging politically with the countries that they move to? Should they be able to vote?

Bryan Caplan: My personal view is I think you should let immigrants become citizens because they’ve been so sorely abused by American citizens for so many years. But I would be 95 percent satisfied if they could just come in and work and live normally, which is, I think, what foreigners themselves would be 95 percent satisfied by. Immigrants have much lower rates of voter turnout even when they are eligible to vote, which, again, makes sense because they don’t feel the same attachments to the polity, and they also don’t understand what’s going on in the politics. Incidentally, many people then take this as an additional complaint about immigrants — "not only are they terrible people, but they also don’t vote!" You'd think that if you thought that their political views were so bad, you would thank them for not voting, but the double standard under which immigrants labor is so stark.

Dylan Matthews: What do you make of the brain drain argument? If you have open migration, and 80 percent of Haiti moves to the US, will the remaining 20 percent have an even more miserable existence? Does that negate the benefits?

Bryan Caplan: The first thing to know is that the main reason for selective brain drain is current immigration policy, because right now it is much easier for a skilled worker to get in than an unskilled worker. The reason you have so many skilled workers leaving and so few unskilled workers leaving is because skilled workers can legally leave, and unskilled workers cannot. The main point of open borders is to open up immigration to low-skilled workers as well. But the conventional wisdom among economists who study this is that the net effect even of the smartest people leaving the country is, in general, quite positive, for a few reasons. One is remittances. Your high-skilled workers leave, but they don’t suddenly cut all their emotional ties as soon as they go. Instead, they go and they make a lot more money, and they send a lot of that money home. Remittances exceed foreign aid now. There are a lot of areas in the Third World that are really kept afloat by the people who have left. Within the US we have the much milder idea of people commuting into the city. They work, and then they send the money back home into the suburbs. That way they support their family far better than they could if they had to take the best job they could get within five miles of their house. It’s not such a weird idea. There has also been a lot of work done on the question of whether the possibility of going abroad if you become more skilled actually leads to an increase in the acquisition of skills among people who remain behind. A classic example is the Philippines. The Philippines is a massive exporter of nurses, so you might think this would mean that the Philippines would have almost no nurses left, but, actually, they have an unusually favorable ratio of nurses to population, and a big part of the answer is there are a lot of Filipinos going to nursing school, incentivized by this chance they might be able to go abroad and then become a nurse and make a ton of money abroad. Many don’t actually get that permission, but they still become nurses, and then they wind up being nurses at home. Compared to any of the other islands around there, Puerto Rico is doing fantastically well. On top of this, a lot of immigrants eventually come home. They go abroad, they often acquire business connections while they’re abroad, and they return. They not only bring the skills back, but they also bring back connections, which are a huge deal. A lot of what’s going on in the development of China is there is this huge disparate community of ethnic Chinese all over the place, and they have relatives in China. This makes it very easy for them to do business with each other. A lot of what the so-called brain drain does is create these same kinds of social networks, which wind up being a big help for development. If you want to get an idea about what to really expect under open borders, my favorite social experiment is Puerto Rico. In 1904 there was a Supreme Court case which ruled that Puerto Rican immigration could not be restricted. After the Spanish American War, Puerto Rico became a territory of the US. A Puerto Rican woman went to New York City, and the US Government tried to deport her, she sued, and she won. The Supreme Court didn’t just say that this woman gets to stay. They said any Puerto Rican is free to come and go to the United States. So by judicial fiat, which easily could have the other way, you wind up opening borders between Puerto Rico and the United States. By the way, one funny footnote to the case is the cultural gap was so large that the official Supreme Court docket misspells the woman's name, because they had so little familiarity with Spanish at the time they just got the spelling wrong. There is actually very good data on Puerto Rican migration. In the first 10 years, only a few thousand people come, but then it just becomes like 10,000, and then 30,000, 50,000 and, by now, over half of Puerto Ricans live in the United States. In terms of brain drain, it seems like there has been a lot less than for any other Latin American country, because from Puerto Rico you can come regardless of your skill level, whereas, for every other country in Latin America, it is much easier for the skilled workers to get in. Over half the population has left, but Puerto Rico by the standards of Caribbean island nations is a paradise. It’s poorer than any American state, even worse than Mississippi, but compared to any of the other islands around there, Puerto Rico is doing fantastically well. It does show us what happens not only to Puerto Ricans who moved, but even to the people that stayed behind. They’re still doing very well compared to how they would be if they didn’t have this open borders benefit.

Dylan Matthews: Can we learn anything from the EU's open migration standard, the Schengen Agreement?

Bryan Caplan: It's one of the great political miracles of the 20th Century that this actually happened. I mean, if you told people in 1945 this was going to occur, they would have thought you were insane. Now, a big part of the European integration strategy was to delay labor market integration until very little immigration would happen. They wanted to get the countries into about a 2:1 income band before they did it. Then there is another key barrier, which is having to learn another language. If you open borders, and then nobody comes, what was the point? But, nevertheless, I think most Europeans have been shocked by how much immigration has occurred. Part of me suspects there was sort of a pro-immigration element that knew that there would be more immigration and just pushed it through, and were not totally honest, which ultimately I approve of, when so much good can be done. But I don’t think that was what happened. I think they just miscalculated. In Europe it's considered a sign of what a horrible failure the policy is that so many people left their home countries. To me, it’s a measure of success. If you open borders, and then nobody comes, what was the point? The point of opening borders is for people to actually move and find a better life. My longer-run prediction is the world will have open borders once it doesn’t make much difference anymore. Once development has happened almost everywhere, and there are virtually no desperate backwaters left, that’s when countries will finally relent and say, "Fine. You can come here if you want," and then they’ll open the borders, and then there will be very little migration. To me, a big point of open borders is just to fast forward to the world of the future where everyone can enjoy a First-World standard of living rather than making people wait 100 years.

Dylan Matthews: Yeah. It is interesting to me there isn’t more labor market integration among rich countries. We have tons of free trade deals with various countries, but it would make sense for us and Canada to have open borders too.

Bryan Caplan: That’s the one that surprises me the most, actually. The public is very nativist, they’re very hostile to immigration, but I don’t think they would be hostile to Canadian immigration. It seems like this could get bipartisan support in the US. Maybe Canadians would have some issue with it, or Canadian nationalists would have some issue, because this plausibly could be the decisive blow to Canadian national identity. That still seems like paranoia to me. I’m just puzzled by it. It seems like it’s just the kind of thing that no one wants to spend a lot of political capital pushing, even though there wouldn’t be that much resistance. Cato’s Alexander Nowrasteh asked the Center for Immigration Studies’ Mark Krikorian if he'd support open borders with Canada, and he basically said, "No, because of sovereignty." Why not say, "Yes. We have the right to keep it closed, but we’re not going to anymore"? There didn’t seem to be much of an answer there, but I think Mark’s answer would just be that, too, would undermine the identity of both countries, and would therefore be bad for both countries, because it’s very important for Americans to feel very American, and for Canadians to feel very Canadian. By the way, these estimates of how much open borders would enrich the world, they’re all what I’d called static estimates, where they basically just say, "Everything stays the same except we move some labor from a low-value area to a high-value area." It doesn’t consider the possibility that this could actually lead to greater innovation, or there could be some great synergies when you get two different kinds of people together. It really is an underestimate of all that can be accomplished. Just think about all the talent that right now goes to waste. Take Sendhil Mullainathan, the Harvard economist. When he was kid he rode around in an ox cart. He grew up in some remote village in India riding around in an ox cart, and, now, he’s a professor at Harvard. If he had stayed behind in India, what are the odds that he would be a world-famous professor? Pretty slim. There is so much brain power and talent that is stuck in the Third World, and most of it going to waste. Some people wind up getting to the Indian Institute of Technology, and do great things, but there are so many talented people who just die unknown, unheard of, because they are stuck in a part of the world where being a genius doesn’t really matter.

Dylan Matthews: What do you make of the security argument against open borders, that not having customs or border checks would pose a significant threat to Americans' safety?

Bryan Caplan: If it were totally up to me, I would just open the borders completely, and you don’t even have to show paperwork. People think that’s crazy, but right now within the United States or within the EU, you don’t have to show paperwork. There are axe murderers running around, and they can cross borders just like anybody else unless we’ve figured out who they are. I don’t think it's really that big of a deal. Of course, I’m also someone who has the radical view that terrorism is greatly exaggerated in its quantitative importance, and people put a ton of effort into it just because it makes frightening television. Like, 100 times as many people have died in auto accidents in the United States since 9/11 than died because of terrorism on that day. It’s a huge political problem, but it is way down the list of actual serious social problems or crime problems. When the idea that your group could ever actually gain dominance is absolutely hopeless, you give up. Now, in terms of like how much of an increase in security risk there would be under open borders, this is where I actually turn around a very common anti-immigration argument and say, "Look. Well, you anti-immigration people say that our borders are very porous. It’s very easy to get in." Now, given that, how many horrible terrorists could really be waiting to get into the United States who can’t currently get in? It seems that the ones that want to do this are probably already here, which fortunately appears to be zero. My broader view is that open borders is a great way of diffusing all of these ancient tensions by just giving people who want to get away from the ancient tensions a place where they can go and build a new life for themselves. It’s very striking to me that the US has a whole lot of Israeli immigrants, a whole lot of Arab immigrants, including a lot of Palestinian immigrants, and, yet, the violence between Israelis and Palestinians within the United States is essentially zero. Right now, it would be totally possible for some Israeli immigrants to go and drive to a Palestinians neighborhood in the US or some Palestinians go and drive to a Jewish neighborhood in the US and do something terrible, but it basically never happens. When the idea that your group could ever actually gain dominance is absolutely hopeless, you give up. A lot of what’s going on in Iraq is there are two groups or three groups, each one of which thinks they might be able to win, but if you add in some Iraqi Sunnis and Iraqi Shiites and Iraqi Kurds to the US, they’re not going to kill each other here, because there is no way they’re going to get control of the US. It’s just hopeless. I know immigration critics will say, "There are some British Muslims who are joining ISIS." Like, what percentage? 0.01 percent? It’s not a common path. The idea that that a few bad apples are a reason to ruin the lives of 100,000 people or 1 million people seems pretty crazy to me.

Dylan Matthews: As you said, the political prospects for open borders — before we reach rough income parity between countries — aren’t super bright. In the meantime, how does this influence your thinking on immigration reform? Do we privilege immigrants from desperately poor countries, given that Haiti and the Congo are an order of magnitude poorer than, say, Mexico?