Those in the political center were demonized as out-of-touch elites, as though the people leading the insurgency were ordinary folks — which, in the case of the Brexit campaign, is a laughable proposition. The campaign made the word “expert” virtually a term of abuse, and when experts warned of the economic harm that would follow Brexit, they were castigated as “scaremongers.” Immigrants were described as a bunch of scroungers coming to grab Britons’ jobs and benefits when, in reality, the recent migrants from Eastern Europe contribute far more in taxes than they take in welfare payments. And besides, immigration to Britain from outside the European Union will not be affected by the referendum decision.

The political center has lost its power to persuade and its essential means of connection to the people it seeks to represent. Instead, we are seeing a convergence of the far left and far right. The right attacks immigrants while the left rails at bankers, but the spirit of insurgency, the venting of anger at those in power and the addiction to simple, demagogic answers to complex problems are the same for both extremes. Underlying it all is a shared hostility to globalization.

Britain and Europe now face a protracted period of economic and political uncertainty, as the British government tries to negotiate a future outside the single market where half of Britain’s goods and services are traded. These new arrangements — to be clear about the scale of the challenge — must be negotiated with all the other 27 countries, their individual parliaments and the European Parliament. Some governments may be cooperative; others won’t want to make leaving easy for Britain, in order to discourage similar movements.

Britain is a strong country, with a resilient people and energy and creativity in abundance. I don’t doubt Britons’ capacity to come through, whatever the cost. But the stress on the United Kingdom is already apparent.

Voters in Scotland chose by a large margin to remain in Europe, with the result that there are renewed calls for another referendum on Scottish independence. Northern Ireland has benefited from virtually open borders with the Republic of Ireland. That freedom is at risk because the North’s border with the South now becomes the European Union’s border, a potential threat to the Northern Ireland peace process.

If the people — usually a repository of common sense and practicality — do something that appears neither sensible nor practical, then it forces a period of long and hard reflection. My own politics is waking to this new political landscape. The same dangerous impulses are visible, too, in American politics, but the challenges of globalization cannot be met by isolationism or shutting borders.

The center must regain its political traction, rediscover its capacity to analyze the problems we all face and find solutions that rise above the populist anger. If we do not succeed in beating back the far left and far right before they take the nations of Europe on this reckless experiment, it will end the way such rash action always does in history: at best, in disillusion; at worst, in rancorous division. The center must hold.