Washington • Even by President Trump’s standards, this Memorial Day weekend was memorable for the sheer volume of balderdash, bunk, poppycock and patent nonsense flowing from the White House.

Balderdash: Trump went after the “failing and corrupt” New York Times for citing a senior White House official “who doesn’t exist” and admonished the newspaper to “use real people, not phony sources.” It turned out the senior official in question had spoken at a White House briefing arranged by Trump’s aides and attended by dozens of reporters.

Bunk: Trump attacked “the 13 Angry Democrats” working for Robert S. Mueller III, apparently referring to prior party registration. But Mueller himself is a Republican, appointed by a Republican who was himself appointed by Trump.

Poppycock: He called for “pressure on the Democrats to end the horrible law that separates children from there [sic] parents once they cross the Border into the U.S.” There is no such law, and Attorney General Jeff Sessions has acknowledged that family separation “inevitably” results from Trump’s “zero-tolerance” enforcement policy.

Patent nonsense: “Who’s going to give back the young and beautiful lives (and others) that have been devastated and destroyed by the phony Russia Collusion Witch Hunt?” Trump asked. I can picture the GoFundMe campaign: “Paul Manafort, a young and beautiful 69-year-old, had a promising career ahead of him selling access to the White House before he was cruelly indicted. …”

Early in this weekend’s monsoon of malarkey, New York Times White House reporter Maggie Haberman tweeted that Trump told “demonstrable falsehoods” — and she was roundly ridiculed on Twitter for failing to say Trump was lying. She defended herself by saying Trump’s pronouncements “can be hard to label” because “he often thinks whatever he says is what’s real.”

Haberman is right, but there’s another reason not to label Trump’s untruths “lies”: Calling him a liar lets him off easy. A liar, by definition, knows he’s not telling the truth. Trump’s behavior is worse: With each day it becomes more obvious he can’t distinguish between fact and fantasy. It’s an illness, and it’s spreading.

I’ve been writing for two years about his seeming inability to separate truth from falsehood: from his claim that he opposed the Iraq War to his belief that his rainy inauguration was “really sunny.” The man who ghostwrote Trump’s “Art of the Deal” marveled at Trump’s “ability to convince himself that whatever he is saying at any given moment is true.”

Trump has acknowledged as much himself. In a 2007 deposition — he was suing author Timothy O’Brien for asserting that Trump’s net worth wasn’t in the billions but in the range of $150 million to $250 million — Trump was asked how he calculates his net worth.

“My net worth fluctuates,” Trump said, “and it goes up and down with markets and with attitudes and with feelings, even my own feelings. … I would say it’s my general attitude at the time that the question may be asked.”

Of course, Trump’s “feelings” don’t change his net worth any more than they change the weather. That he thinks they do is his problem — and ours.

Writing last week for NBCNews.com, a professor of cognitive neuroscience at University College London, along with a researcher, offered an explanation for Trump’s mendacity.

Noting that the daily average number of Trump falsehoods has been rising since he took office (as measured by The Washington Post’s Fact Checker), the professor, Tali Sharot, pointed to the biological process of “emotional adaptation.” People tend to feel uncomfortable when they tell lies, but research has found that the discomfort is reduced each time a person lies — thereby increasing the frequency of lies.

Trump’s fictions are so pain-free that they may not feel like lies to him — honestly. And, ominously, they may seem less glaring to others over time. Sharot noted that people “may desensitize to the president’s falsehoods in the same way that they do to overused perfume, making them less likely to act to correct this pattern of behavior.”

You can see this in the repeated failure of congressional Republicans to call out Trump’s untruths, when they obviously know better. Trump may not be able to separate fact from fiction, but those who knowingly back up his falsehoods are liars.

So what should we call the twaddle and claptrap Trump spouts? I propose “Trumpery.” Defined as “worthless nonsense,” it also has a felicitous echo of “Trumped up.”

Go ahead and say he’s lying, if you think so. To me, his facility with fallacy and his pain-free fibbery aren’t symptomatic of a liar but of a madman.

Dana Milbank | The Washington Post