As the Cold War wound down almost four decades ago, a top adviser to the reformist Soviet leader, Mikhail S. Gorbachev, warned the West that “we are going to do the most terrible thing to you. We are going to deprive you of an enemy.”

In the celebrations of the triumph of Western liberal democracy, of free trade and open societies, few considered how disorienting the end of a binary world of good and evil would be.

But when the spread of democracy in newly freed societies looked more like the spread of divisive global capitalism, when social fracture grew and shared truth died, when hope collapsed in the communities technology left behind, a yearning for the certainties of the providential authoritarian leader set in.

“In the absence of a shared reality, or shared facts, or a shared threat, reason had no weight beside emotion,” said Nicole Bacharan, a French political scientist. “And so a dislocated world of danger has produced a hunger for the strongman.”

A different Russia, briefly imagined as a partner of the West, eventually became an enemy once more. But by the time it invaded Ukraine in 2022, disillusionment with Western liberalism had gone so far that President Vladimir V. Putin’s tirades against the supposed decadence of the West enjoyed wide support among far-right nationalist movements across Europe, in the United States and elsewhere. Western allies stood firm in defense of Ukrainian democracy, but even that commitment is wobbling.

The curious resurrection and resounding victory of Donald J. Trump amounted to the apotheosis of a long-gathering revolt against the established order. No warning of the fragility of democracy or freedom, no allusion to 20th-century cataclysm or Mr. Trump’s attraction to dictators, could hold back the tide.