WASHINGTON — He accepts less-than-credible denials from autocratic heads of state about nefarious acts. He disputes the existence of man-made climate change and insists that photographic evidence of the crowd at his inauguration is fake, part of a media plot to harm him.
Over the course of 21 months, President Trump has loudly and repeatedly refused to accept a number of seemingly agreed-upon facts, while insisting on the veracity of a variety of demonstrably false claims that happen to suit his political needs. In the process, he has untethered the White House from the burden of objective proof, creating a rich trove for professional fact-checkers, and raising questions about the basis for many of his decisions.
“If there’s no truth, how do we discuss and make decisions that are rooted in fact?” said Rob Stutzman, a Republican operative based in California. “It’s been abandoned. And it’s something that the Republican base certainly isn’t going to revolt on him on. But it is a huge fundamental problem of how to govern when there are no facts.”
Michael V. Hayden, a former C.I.A. director who served under Presidents George W. Bush and Barack Obama, said that Mr. Trump could be coaxed into believing objective reality, but that it “is not the instinctive departure point for what Donald Trump does.”
“It’s something else — it’s feeling, emotion, preference, loyalty, convenience of the moment,” Mr. Hayden said. He quoted a former speechwriter for Mr. Bush, Michael Gerson, about Mr. Trump: “He lives in the eternal now — no history, no consequences.”
Mr. Trump’s refusal to accept some established facts is hardly new. From his belief in the guilt of five young men of color in connection with a savage attack on a white woman in Central Park in the 1980s, to his conviction that Mr. Obama was born in Kenya, he has carried on what amount to personal crusades in the face of established facts for much of his career.
The most noticeable new variation of that tendency that Mr. Trump has adopted as president is his penchant for giving the benefit of the doubt to authoritarian leaders with whom he has tried to develop personal or political relationships. That was most recently on display this week, when he said that King Salman of Saudi Arabia had assured him that the royal family had no role in the disappearance of the dissident journalist Jamal Khashoggi. The king, he noted, had given a “very strong” denial.
“Here we go again with, you know, you’re guilty until proven innocent,” Mr. Trump told The Associated Press on Tuesday. “I don’t like that. We just went through that with Justice Kavanaugh, and he was innocent all the way as far as I’m concerned.”
By Thursday, as the weight of the evidence of Saudi government complicity became hard to disagree with, Mr. Trump said that he believed that Mr. Khashoggi was dead, and that there could be “severe” consequences for Saudi Arabia.
Still, the initial remarks echoed comments he made last summer about the Russian president, Vladimir V. Putin, who he said had been “extremely strong and powerful in his denial” that Russia had interfered with the 2016 election.
And they were similar to what the president has said about his faith in the widely doubted commitment to denuclearization by the North Korean dictator, Kim Jong-un. “He wrote me beautiful letters,” he said at a rally in Wheeling, W. Va., “and they’re great letters. We fell in love.”
For the president, each of those leaders looms large in his thinking and his plans, and their past behavior does not seem to matter.
“He’s got a personal relationship,” Mr. Hayden said, “and he’s built it himself, with three heads of state who have murdered somebody within another person’s country within the last year.”
Aides to Mr. Trump insisted that his reaction to the disappearance of Mr. Khashoggi and the mounting evidence that he was murdered by a Saudi hit squad had been repeatedly mischaracterized. They pointed out that early on he had said he wanted an investigation.
Mr. Trump has appeared to grow noticeably more comfortable in the role of president, according to advisers, and that comfort level has reinforced his confidence in his own instincts, including what he regards as facts. Mr. Trump often points to a key moment — his election in 2016, which defied the polls — as proof that agreed-upon data can be wrong.
His long career in the New York real estate world convinced Mr. Trump that all people are prone to shading their views according to their own self-interest. Objectivity is not something he expects of people, and he long ago came to believe that “facts” are really arbitrary.
“There are no governing rules — one doesn’t have to be governed by rules or facts,” said David Axelrod, a former senior adviser to Mr. Obama, describing Mr. Trump’s worldview. “Whatever it takes to get what you want or to get to where you want, no matter what you have to justify or what you have to ignore, is O.K.”
In his interview with CBS News’ “60 Minutes” on Sunday night, Mr. Trump repeatedly painted climate science as a matter of political opinion. Scientists who have documented the man-made impact on climate change “have a very big political agenda,” Mr. Trump said, offering no evidence.
Even DNA evidence does not sway Mr. Trump from his beliefs. He maintained that the five young men imprisoned for the Central Park crime were still guilty even after they were exonerated by DNA evidence and a detailed confession from a sixth man.
“They admitted they were guilty,” Mr. Trump said in a statement after the men were cleared of the crime, pointing to their coerced confessions from decades ago.
Mr. Trump has also pushed a number of conspiracy theories over the years. As a citizen and a candidate, Mr. Trump repeatedly tweeted that there was a link between vaccines and autism, a claim scientists have rejected.
“I am being proven right about massive vaccinations — the doctors lied,” Mr. Trump wrote in a 2014 tweet.
And long after Mr. Obama released his long-form birth certificate in 2011, Mr. Trump appeared on Fox News and suggested that the president might not be a citizen.
Mr. Trump’s approach has profound consequences for the credibility of the presidency and the boundaries of acceptable political discourse. It also has serious ramifications for his advisers, as well as people who hear the president’s words outside the United States. And, according to Mr. Hayden, it particularly affects the intelligence officials whose job it is to present Mr. Trump with the information he needs to make critical national security decisions.
“Intelligence is all about context, which is history and consequence,” said Mr. Hayden, and intelligence officials are “trying to pull him into an agreed view of objective reality.”
But in briefings and meetings, Mr. Trump has frequently chosen to adhere to his own beliefs on issues such as the Iran nuclear deal. He has declared that pact to be “a horrible one-sided deal that should have never, ever been made,” based on his belief that Iran was not in compliance with it, despite evidence to the contrary.
For Mr. Trump, personal relationships are more important than institutional ones. That means he “gives weight to data based on who told him, not the evidentiary stack underneath it,” Mr. Hayden said.
The result is that the Russian president or the North Korean leader can seem to have a greater impact with Mr. Trump than his own State Department or C.I.A. His willingness to repeat claims like the notion that Mr. Khashoggi was the victim of “rogue killers” is a function of that, Mr. Stutzman said.
“This rhetoric really matters,” he said, “in that it belies how little he fundamentally understands the institutions of American democracy.”