Now the American question:

By uncanny coincidence, EU referendum day in the U.K. coincided with the U.S. Supreme Court decision that halts President Obama’s program of executive amnesty for young illegal immigrants and their parents, an estimated 5 million people. American policymakers—like their U.K. and EU counterparts—have taken for granted that an open global economy implies (and even requires) the mass migration of people. Yet this same mass migration is generating populist, nativist reactions that threaten that same open economy: The anti-EU vote in the U.K., the Donald Trump campaign for president in the United States.

Is it possible that leaders and elites had it all wrong? If they’re to save the open global economy, maybe they need to protect their populations better against globalization’s most unwelcome consequences—of which mass migration is the very least welcome of them all?

If any one person drove the United Kingdom out of the European Union, it was Angela Merkel, and her impulsive solo decision in the summer of 2015 to throw open Germany—and then all Europe—to 1.1 million Middle Eastern and North African migrants, with uncountable millions more to come. Merkel’s catastrophically negative example is one that perhaps should be avoided by U.S. politicians who seek to avert Trump-style populism in the United States. Instead, the politician who most directly opposes Donald Trump—presumptive Democratic nominee Hillary Clinton—is doubling down on Merkelism.