The New York Times’ Wednesday story revealing Donald Trump was fully and meticulously briefed before his inauguration about direct Russian interference in the 2016 election solves the mystery once and for all: Trump simply cannot permit his own brain to accept any evidence that he didn’t win the presidency by millions of votes. That’s it. No matter how many Russian emails and texts the nation’s intelligence apparatus show him, no matter how many times he is reminded of what is incontrovertibly true, Trump’s mind cannot reconcile reality with his own truth: that he is the most beloved and cherished leader in American history. Even when he was forced to walk back his Helsinki comments about trusting Russia more than his own intelligence agencies, in a performance arguably more horrifying than the original press conference with Vladimir Putin, Trump couldn’t manage to stay on message. Within hours of his clarification, he had reverted back to “no” when asked whether Russia was still targeting the United States.

This isn’t an intelligence problem or even a political problem. It’s an epistemological problem. This president is never going to allow himself to believe something that is abhorrent to him, and he will therefore dismiss, deflect, and contradict any information that doesn’t confirm his pre-existing beliefs. Whether or not he’s ever directly conspired with Russia, whether or not the Russians have something on him, Trump’s mental health requires him to reject even flawlessly sourced facts that he cannot integrate into his worldview. The most important conclusion we can draw from the past week’s events is that even his own aides have given up on trying to persuade him of the truth. Or as Sen. John Thune glumly conceded, regarding Trump’s walk-back, “I guess it’s probably the best we’re going to be able to get.” His reality is a fixed point. We either work around him, like Thune, or devote useless energy to trying to dissuade him.

Donald Trump believes only what he wants to believe. Although Washington Republicans will surely continue to craft their workarounds, nobody can deny any longer that Trump is willing to destabilize decades-old geopolitical alliances and undermine American national security, doing so chiefly in service of his own delusions. History books will someday have to note that American democracy died largely as a result of one man’s terminal case of confirmation bias.

But here’s the catch. Trump’s refusal to countenance any reality that doesn’t map on to the movie kicking around inside his brain isn’t an affliction that’s limited to Trump. It’s perfectly mirrored in the devotion of the Trump loyalists who suffer from precisely the same disorder. The president’s inability to differentiate between reality and what he wants to be true is the reason his staunchest supporters see him as the patron saint of choose-your-own-ending geopolitics. The bulk of unyielding Trump fans don’t want or need a coherent narrative. Trump’s performance in Helsinki on Monday was heroic because Russia is not the enemy, the “deep state” is. Trump’s walk-back in Washington the next day was heroic because he was man enough to concede that he misspoke and Russia is again the enemy and we trust our national intelligence apparatus. And Trump’s walk-back of his walk-back is also heroic because … Russia is not the enemy, the “deep state” is. Yeah, that’s the ticket. It’s like Build-A-Bear, but for truth.

The sad fact is that if you challenge the truth long enough, reality will shift to confirm to your delusion.

Given that so many Trump supporters can no longer be swayed by objective provable facts, the next logical step after conceding that for every fact there is an “alternative fact” would be to concede that nobody can really know anything for certain anymore, so just believe in what you want. Or better yet, believe in whatever truth Trump believes, even if those beliefs seem to shift by the hour. This is the famous Hannah Arendt formulation about authoritarian government leading people to give up altogether on the pursuit of truth. It’s also a fantastically powerful form of double-decker narcissism: I believe the guy who believes only what he wants to believe. And that double-decker narcissism is working. As Karen Tumulty notes, “regardless of how many ‘double negatives’ he spins, his base stands by him.” Tumulty cites polling that shows his approval rating within his party—87 percent in June, per Gallup—is “a near-record among modern presidents, second only to George W. Bush’s 92 percent in the wake of 9/11.”

Trump used to at least make a show of hewing to some coherent narrative, even if it wasn’t accurate. But this week, he’s barely trying to square his Helsinki statements with his correction of his Helsinki statements. And he won’t try to square his correction with what he says in tweets and press conferences. He doesn’t have to. He knows what he believes and that is that his voters revere him, and they revere him for demanding that what he believes be accepted as true, regardless of accepted reality. If the denialists can believe in nothing else, they can still put their faith in the denialist in chief.

The sad fact is that if you challenge the truth long enough, reality will shift to conform to your delusion. Trump critics who were rightly horrified by the week’s unravelling could be dismissed as hysterics. Intelligence sources wounded and affronted by Trump’s insistence that they are working against him ramped up the kinds of leaks that became the spine of Wednesday’s New York Times piece about Russian briefings. The more the reality-based community pushes back against Trump’s imaginary worldview, the more readily and provably he dismisses them as “deep state” traitors.

For the longest time, the debate we’ve been having in this country has centered on whether we want to live in red-state America or blue-state America, whether to cocoon ourselves in the Fox News bubble or bathe in the airwaves of MSNBC. But by sheer force of his own temperament, moral character, and mental habit, Donald Trump has launched us into another, far scarier era. We will now have to choose between living in reality as expressed in objective reporting and shared fact, or whether we’re willing to accept that from now on, for many, many people, truth will be defined and constrained only by what the president wants to believe, in the moment he wants to believe it.