The 1960s and 1970s did turn out to reveal a country sharply divided along generational, racial, religious, gender and political lines. White and black, gay and straight, men and women, religious and secular, antiwar protesters and hard-hatted patriots all faced off. For a time, the founding principles of American society — the “unalienable rights” of “life, liberty and the pursuit of happiness” — seemed like they would be unable to adjudicate between the competing, often clashing, interests.

But the American creed, originally formulated by 18th-century slave-owners and zealously upheld by white males across the ideological spectrum, still managed to command broad enough loyalty. This was largely because no alternative seemed as effective at generating prosperity and advancing personal freedoms. Gradual improvements, such as the Civil Rights Act of 1964, the war on poverty and the gains of feminism, maintained faith in the American Dream — that most seductive ideology and substitute religion of the modern world.

By the 1980s, Reagan or Reaganites would brush aside any suggestion that there was a “national malaise.” The collapse of Communism seemed to vindicate the American model. The disappearance of an antagonist that had defined America’s self-image for much of the 20th century unleashed the solipsistic idealism that Niebuhr, among many midcentury intellectuals, had warned against. Postcommunist Russia received an army of American economists, technocrats and journalists determined to usher the country into American-style democracy and free markets.

It has been too easily forgotten that the calamitous failure of these “market Bolsheviks,” as the economist Joseph Stiglitz called them, helped spawn the first major demagogue of our time: Vladimir V. Putin. Mr. Putin came to power in Russia in the late 1990s on the back of his promise to sort things out after the country’s experiment in privatization and deregulation led to a collapse in incomes and standards of health, and a rise in unemployment and mortality rates. This American-assisted debacle in Russia long preceded the unraveling of Iraq and the great unwinding in America itself.

It already revealed how a networked elite, consisting of neoliberal globalizers and liberal internationalists as well as neoconservative intellectuals, had amassed unaccountable influence while becoming a service class for politicians. Subsequent fiascos — the rise of Al Qaeda and then the Islamic State, the crisis of unregulated financial capitalism followed by the bailout of culpable bankers — confirmed that this elite was too entrenched to be displaced by its failures and too arrogant to learn from them.

Mr. Putin’s success in stoking a bitter Russian nationalism had signaled early our age of anger, one in which demagogues would be best placed to exploit the rage of those left behind, cheated, disoriented and scorned by global regimes of privatization. And yet this record is barely discussed today, even as centrist and liberal intellectuals routinely accuse Mr. Putin of trying to influence political outcomes in America. In another self-protective move, these intellectuals have taken to blaming identity politics for Mr. Trump’s support among white male voters.

Some continue to offer a limited variety of can-doism, in which the march of progress — lately landmarked by bathroom access for transgenders — will surely resume at the next available opportunity, in 2020. The acclaim with which both liberal internationalists like Zakaria and neocons like Bill Kristol greeted the Trump administration’s recent missile strikes in Syria revealed a largely unimpaired fantasy of righteous omnipotence.