Seeing all rules and norms as mere facades for a vast conspiracy also legitimizes getting around them to exercise unlimited corruption. The cynicism implicit in conspiratorial thinking frees you up to indulge in anything you want. Mr. Trump was, like many American businessmen, attracted to Russia in the 1990s and early 2000s, a time when rules — both logical and financial — were suspended. Throwing off the constraints of factuality goes together with throwing off political and legal norms, which for Mr. Trump means, among other things, turning his private lawyer, Rudolph Giuliani, into a private diplomat.

There’s a dark joy in being released from the constraints of legality and factuality, something Mr. Putin grasps well. When the Russian president went on international TV during the annexation of Crimea to smirk and say that there were no Russian soldiers on the peninsula, and that the soldiers the world could see were just locals who had bought Russian military uniforms, he wasn’t so much lying as demonstrating that he doesn’t care at all about facts and, by extension, the rules governing his behavior.

Mr. Trump, too, has doubled down since it was revealed he was exerting his own pressure on Ukraine. Despite all the protestations of State Department officials and Ukrainian journalists who painstakingly show that the accusations that Joe Biden helped fire a Ukrainian prosecutor to protect his son are specious, Mr. Trump and his allies have responded by repeating them. The president even suggested that Mr. Biden should be investigated for alleged corruption in China, too.

Mr. Giuliani has gone on cable news to spin an ever-greater web of insinuation, dropping in dark questions about whether Hillary Clinton’s email server might be in Ukraine or why Mr. Trump’s 2016 campaign manager Paul Manafort was jailed because of evidence of his financial impropriety there. Watching clips of Mr. Giuliani, I am reminded of the catchphrase of Russia’s most prominent current affairs TV host as he twirls from one conspiracy to another: “A coincidence? I don’t think so.”

This attitude is what makes Kremlin propaganda today different from its Soviet predecessor. The Soviets tried to make their lies sound factual. Even their disinformation in the West was meant to feel foolproof: For example, the 1980s campaign to show that the C.I.A. had invented AIDS was carefully curated through Soviet-controlled medical conferences. When President Ronald Reagan called out the Soviet leader Mikhail Gorbachev, Mr. Gorbachev feigned horror at the idea that the Soviet Union would stoop to lies. Today, when the Kremlin pushes conspiracies claiming Americans invented Ebola or Zika, these stories are thrown online with no serious attempt to make them sound believable. Their aim as much to confuse as to convince. And there’s no shame in being caught lying.

In my search for how and why the future arrived first in Russia, I’ve interviewed political strategists in Moscow and found their approaches anticipated what we have come to term “populism” in the West today. One spin doctor, Gleb Pavlovsky, who was a senior strategist in Mr. Putin’s 2000 election victory, described how he was faced with a landscape where the ideologies of both communism and democratic capitalism had collapsed; the old social roles and political categories meant nothing. In order to win, he had to collect different interest groups, many of which resented one another, but which all felt they had lost out in the 1990s, and unite them around a vague feeling that they constituted a “majority” and “a people.” Decades later, the Trump campaign likewise united different interest groups, which felt they had been “left behind,” around vague feelings of grievance against “the establishment.”

Mr. Putin skillfully managed to get rid of the old oligarchs by claiming he was cleaning up elite corruption — only to replace it with his own corrupt elite. Mr. Trump and his supporters claim the president is draining the swamp, just as he replaces it with his cronies: Mr. Giuliani, his family, whatever allies and backers are willing to work with him in Washington or Kiev or wherever else.

Mr. Pavlovsky told me last year that the West is reaching a stage of post-ideological development similar to the one Russia reached decades earlier: “The Cold War split global civilization into two alternative forms, both of which promised people a better future,” he said. “The Soviet Union undoubtedly lost. But then there appeared a strange Western utopia with no alternative, ruled over by economic technocrats who could do no wrong. Then that collapsed.”

In Eastern Europe, communism once presented an ideology that claimed to be evidence-based and rational, guiding humanity toward a better future. In the West, the alternative was a vision of capitalism that would inevitably improve the world. Both have now collapsed.

But without an ideology that looks toward the future, there are no goals of progress. Instead of offering a coherent vision for the future, you peddle in nostalgia; you explain the world not through ideas but conspiracies. Instead of being a beacon of hope, you accuse everyone else of being just as corrupt as you are. We are all post-Soviet now.

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Peter Pomerantsev is the author, most recently, of “This Is Not Propaganda: Adventures in the War Against Reality.”

A version of this article appears in print on , Section SR, Page 3 of the New York edition with the headline: Welcome to Eastern Europe, America.