Last April, an economist named Branko Milanovic published a proposal to reduce global economic inequality in the Financial Times. The best way to help the world’s poor, he wrote, is to encourage movement of labor and get countries to open up their borders. But of course, that’s easier said than done: many citizens of rich host countries balk at the idea of increased migration. When they imagine foreigners settling down within their borders, they fear that their jobs, their benefits, and their idea of national (and, let’s face it, ethnic) unity will be threatened.