In nearby Turkey, Recep Tayyip Erdogan, the country’s president and long-dominant political leader, also received a strong democratic mandate from voters in 2014. An attempted coup two years later became an excuse for him to target thousands of civil servants, military officers, journalists and academics whom he suspected of disloyalty.

Mr. Orbán, Mr. Putin and Mr. Erdogan all came to power in countries with an electorate polarized between a more liberal, cosmopolitan urban elite — whether in Budapest, Moscow or Istanbul — and a less-educated rural voter base. This social division is similar to the one that drove the Brexit vote in Britain and Donald Trump’s rise in the United States..

Mr. Trump’s ascent poses a unique challenge to the American system because he fits comfortably into the trend toward illiberal democracy. He validated himself through popular support, but his entire career has been spent trying to bypass inconvenient rules — like the requirement to pay his own subcontractors. Much of his popularity rested heavily on his willingness to break existing customs about political correctness. This seemed politically bracing at first, but quickly became worrisome when Mr. Trump suggested that as president, he would “open up our libel laws” to initiate civil suits against his media critics. His pitch to the American voter was “I alone” can fix the country’s problems through sheer force of personality, and not through a reform of the country’s institutions.

That Mr. Trump expressed admiration for Mr. Putin, and that Mr. Putin returned the favor, should come as no surprise. Like Mr. Putin, Mr. Trump seems to want to use a democratic mandate to undermine the checks and balances that characterize a genuine liberal democracy. He will be an oligarch in the Russian mold: a rich man who used his wealth to gain political power and who would use political power to enrich himself once in office. And like Mr. Putin, Mr. Trump was able to create alternative narratives that often went unchallenged by his supporters.

But the balance between liberalism and democracy has been shifting in other nations as well. The citizens of India and Japan have elected nationalist leaders who many say they believe champion a more closed form of identity than their predecessors. While these leaders have observed the principles of liberalism more scrupulously than the Orbáns or Erdogans of the world, their critics suspect that they are quietly fostering intolerance among their supporters.

How far will this trend toward illiberal democracy go? Are we headed for a period like that of the early 20th century, in which global politics sank into conflict over closed and aggressive nationalism? The outcome will depend on several critical factors, particularly the way global elites respond to the backlash they have engendered. In America and Europe, elites made huge policy blunders in recent years that hurt ordinary people more than themselves. Deregulation of financial markets laid the groundwork for the subprime crisis in the United States, while a badly designed euro contributed to the debt crisis in Greece, and the Schengen system of open borders made it difficult to control the flood of refugees in Europe. Elites must acknowledge their roles in creating these situations.