President Trump is a showman and always has been. Even as a real estate developer with no designs on politics, he understood that exaggeration, hyperbole, or — let's not mince words — outright lying were tools he could use to sell his buildings and himself. Every project was the biggest, the best, the most luxurious, the most sought-after, whether it really was or not. It even extended to things like claiming Trump Tower is 68 stories tall when the real number is 58. If it moves units, that's all that matters.

But when we say that someone is lying, we presume that they know they're lying. That's what distinguishes the "lie" from the "falsehood" or the "untruth." You can unwittingly tell a falsehood, but if you lie it means you knew what you were doing. Or to quote the philosopher George Costanza, "It's not a lie if you believe it."

This has always been a tricky issue with Trump, because there are some false claims he keeps making long after it's been repeatedly pointed out to him that they're false, and others where it's hard to tell whether he knows they're false or not. Beneath it all is the unavoidable conclusion that he just doesn't care, in part because his experience has taught him that there's no cost to him for being caught in a lie. After all, he got elected president, didn't he?

But as he sits brooding in the Oval Office, beset on all sides by critics and haters and a world that refuses to bend to his will, Trump seems to be coming unglued. I refer you to two reports that emerged this Wednesday; here's the first, from The Washington Post:

Trump has occasionally told senior advisers that the Access Hollywood tape could be fabricated or may not be real, according to two people who have heard him make the comments. At various moments — including during huddles with his aides at Trump Tower after he won the election and before taking office — Trump has sought to distance himself from the tape.

Trump has asked others whether they think the voice sounds like him, suggesting that it does not, and has wondered aloud whether perhaps the tape was doctored or edited in an unfair way to villainize him.

"He would just assert it, and people would kind of say, 'Okay, let's move along,' " said one person who had heard the comments. "There's no point in sitting there and litigating it with him."

A second person who has discussed the tape with Trump recalled, "He says: 'It's really not me. I don't talk like that.' " [The Washington Post]

And then there's this, from The New York Times:

In recent days, he has continued to seed doubt about his appearance on the Access Hollywood tape, stunning his advisers ...

Mr. Trump's falsehoods about the Access Hollywood tape are part of his lifelong habit of attempting to create and sell his own version of reality. Advisers say he continues to privately harbor a handful of conspiracy theories that have no grounding in fact.

In recent months, they say, Mr. Trump has used closed-door conversations to question the authenticity of President Barack Obama's birth certificate. He has also repeatedly claimed that he lost the popular vote last year because of widespread voter fraud, according to advisers and lawmakers. [The New York Times]

You might say while it's deeply troubling to see the president embracing conspiracy theories or believing that millions of people voted illegally for his opponent, it doesn't necessarily mean that he has lost his mind. But the fact that he thinks that it wasn't him on the Access Hollywood tape suggests that Trump has had a profound break with reality.

My Washington Post colleague Greg Sargent argues that this is just the latest phase of Trump's assault on truth, which is meant to render the very notion of facts meaningless and thus delegitimize any source (i.e. the entire news media) that claims to present facts to the public, particularly those facts that don't reflect well on Donald Trump. If he can make you question what you hear with your own ears — even after he publicly apologized for it — then it will be simple to persuade you not to believe it when people say that his tax bill raises taxes on millions, or that America's image around the world has plunged since he became president, or that his campaign colluded with various Russians trying to manipulate our electoral system for their own ends.

That is true in a broader sense, but on the narrow point of the Access Hollywood tape, this isn't something he has said publicly. It isn't part of a strategy to deflect the stories of the more than a dozen women who have accused him of various forms of sexual harassment and misconduct (he says they're all liars, which apparently is good enough for his supporters). This is what Trump says in private, to those he trusts. It sounds like it's what he really believes. Which is utterly, completely insane.

It's not surprising to learn that Trump's aides tiptoe gingerly around him when he leaps down these rabbit holes, trying to divert him to another topic like parents waving a toy in front of a crying baby. After all, he's their boss, and anyone who did the reasonable thing — which would be smacking him across the face and crying "Snap out of it!" like Cher in Moonstruck — wouldn't have a job anymore. But one can't help but wonder what they say to each other or themselves after they walk out of the Oval Office, "stunned" as they are. Do they contemplate quitting? Fantasize about warning the public that the country's leader is off his rocker? A couple of them saw fit to tell the story to reporters, but most are keeping their heads down and pushing forward.

Only a few of Trump's aides are called upon to defend his behavior to the public, and those who do have long ago given up any pretense that truth matters. For instance, when Trump retweeted bogus anti-Muslim videos from a far-right fringe figure in Great Britain on Wednesday, Press Secretary Sarah Huckabee Sanders said that the veracity of the videos was irrelevant. "Whether it's a real video, the threat is real, and that is what the president is talking about," she said. What matters isn't whether Trump is lying to you, it's whether he sent the message he wanted to send.

And that gets to the heart of the problem. It isn't just that no one around the president can stand up to him and call him out on his more lunatic beliefs, it's that they actively enable him. They encourage him not to care what's true and what isn't, because he knows they'll defend him. The apparatus he has built around himself serves to reinforce his most horrifying tendencies.

Which is why — in addition to the increasingly bizarre contents of Trump's mind — this isn't going to change.