World leaders seem to be at a loss about how to approach relations with U.S. President Donald Trump, given his worrying positions and often-bizarre behavior toward politicians and the media, allies and enemies alike. Trump is not just challenging political convention to "shake things up"; he is testing the foundations of U.S. democracy. That test has the potential to transform existing assumptions about the United States and its global role.

Trump was elected largely for one reason: a substantial share of U.S. voters were fed up with the state of the economy and the politicians who had overseen it. Globalization — the proliferation of flows of labor, goods, services, money, information, and technology worldwide — seemed to be benefiting everyone except them.

These voters had a point. While globalization, and the trade openness that underpins it, has the potential to enrich the entire global economy, so far the richest have captured a hugely disproportionate share of the gains. In the U.S., wages for the top 1 percent of earners increased by 138 percent from 1980 to 2013, while wages for the bottom 90 percent grew by just 15 percent.