RELEASE THE NEXT BOOM:

The economic case that open borders would dramatically improve the well-being of the world is rock solid.

"Imagine that you've got a million people farming in Antarctica. They're eking out this bare subsistence in agriculture in the snow," [George Mason economist Bryan Caplan] 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?"

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?"

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."

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

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." [...]

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.

Follow @brothersjudd