We need a new paradigm for a new time. The social trust and social cohesion that characterize an advanced society like the United States are slowly built and vulnerable to erosion. They are eroding. Trump is more the symptom of that erosion than the cause.

Trump’s executive order has unleashed chaos, harmed lawful U.S. residents, and alienated potential friends in the Islamic world. Yet without the dreamy liberal refusal to recognize the reality of nationhood, the meaning of citizenship, and the differences between cultures, Trump would never have gained the power to issue that order.

Liberalism and nationhood grew up together in the 19th century, mutually dependent. In the 21st century, they have grown apart—or more exactly, liberalism has recoiled from nationhood. The result has not been to abolish nationality, but to discredit liberalism.

When liberals insist that only fascists will defend borders, then voters will hire fascists to do the job liberals won’t do. This weekend’s shameful chapter in the history of the United States is a reproach not only to Trump, although it is that too, but to the political culture that enabled him. Angela Merkel and Donald Trump may be temperamental opposites. They are also functional allies.