“We are all Keynesians now,” Richard Nixon famously remarked, but only Donald Trump could have convinced himself that he is Keynes. Consider this exchange from an interview with The Economist published Thursday:

You understand the expression “prime the pump”?

Yes.
We have to prime the pump.

It’s very Keynesian.
We’re the highest-taxed nation in the world. Have you heard that expression before, for this particular type of an event?

Priming the pump?
Yeah, have you heard it?

Yes.
Have you heard that expression used before? Because I haven’t heard it. I mean, I just…I came up with it a couple of days ago and I thought it was good. It’s what you have to do.

It’s…
Yeah, what you have to do is you have to put something in before you can get something out.

As a million Twitter wags immediately pointed out, Trump hadn’t invented the phrase. It is, as The Economist’s editors suggested, usually associated with John Maynard Keynes’s theories. (In fact, the phrase seems to have been popularized by Herbert Hoover.) And not only did Trump not invent it, he’s been using it since at least March, when he spoke of priming the pump in an interview with Robert Draper.

Trump’s blithe confidence that he invented one of the most common phrases in popular economic discourse is stunning on several counts. It not only suggests a self-confidence bordering on delusion, it illuminates a worrisome fact: The president both knows very little about the things he talks about, and has little interest in learning more.

Throughout his talk with The Economist, Trump alternates between statements, mostly about trade and economics, that are plainly untrue and those that are meaninglessly empty.

Trump says, “I was going to terminate NAFTA last week, I was all set, meaning the six-month termination,” but then says he received calls from the leaders of Canada and Mexico. “And they both asked almost identical questions. ‘We would like to know if it would be possible to negotiate as opposed to a termination.’ And I said, ‘Yes, it is. Absolutely.’ So, so we did that and we’ll start.” Trump continues to suggest in interviews that his decision to renegotiate rather than pull out was a novel idea, but in fact he had been saying since the campaign that he would first try to renegotiate, and failing that would withdraw.

Asked what would constitute a more fair NAFTA, Trump cannot say. He tries to dodge the question, saying how big it would be and recounting again his decision to renegotiate rather than withdraw. Finally, he settles for a tautological answer. What would be a fair NAFTA? “We have to be able to make fair deals.” Oh.

Trump, and Treasury Secretary Steven Mnuchin, continue to claim falsely that China ceased devaluing its currency recently. “As soon as the president got elected they went the other way,” Mnuchin says. In fact, China stopped devaluing in 2014.

In describing his decision not to take a hard line with China, the president continues to treat the idea that the U.S. cannot provoke Beijing and also expect its cooperation on North Korea as a revelation, rather than a banal truism of international diplomacy.

Trump admits that he might need Democratic support to pass a tax plan: “Um. Little bit,” he says. But when The Economist presses him on how he would obtain it, he changes the subject: “I think the Democrats are going to like it. We may align it with infrastructure, which they like. They like it as much as the Republicans like it. We need infrastructure in our country. This country has wasted $6 trillion in the Middle East. Wasted. Like taking it and throwing it right out that window. Right in to the Rose Garden. See that beautiful Rose Garden? Look at those very nicely dressed people.” That doesn’t come remotely close to answering the question.

Discussing his tax proposal, Trump simply rejects the universal consensus that the wealthy would benefit most from cuts. “Well, I don’t believe that. Because they’re losing all of their deductions, I can tell you,” he says. Once again, when pressed on details, Trump heads off in a different direction. “I get more deductions, I mean I can tell you this, I get more deductions, they have deductions for birds flying across America, they have deductions for everything,” he said. Soon he’s reverted to talking about how short his tax plan really is: “You know when we put out that one page, I said, we should really put out a, you know, a big thing, and then I looked at the one page, honestly it’s pretty well covered. Hard to believe.” Indeed.

The interviewers tried to pin Trump down on his view on the interest deduction, but the president bounced the question to Mnuchin, who said the administration was “contemplating” keeping it. Trump’s answer strongly implies he has no view at all:

So what would your preference be, Mr. President? You know about that very well.
No, I would say probably … I think we’re contemplating is the word. And it hasn’t been determined yet, but we’re contemplating.

Contemplating…
We’re contemplating various … I have to say, we’re contemplating various things, but one of the things that’s very important is simplicity. We want to keep it as simple as possible. Because even if you do, it’s complicated. I mean even if you keep it simple with taxes it gets complicated.

Trump praises a value-added tax (VAT), though the reason appears to be that when he leaves Britain it is refunded. It’s unclear whether he recognizes that EU citizens don’t receive a refund. Some members of Congress have suggested a border-adjustment tax, similar to a VAT, as a method of protectionism. But when asked about a BAT, Trump once again changes the subject: “We are dealing with Congress … because it’s not really what I’m considering. I mean look, on health care, I think we have a great bill and there’s still a little bit further to go because we’re also dealing with the Senate, but the Senate I believe really wants to get something done because Obamacare is dead, just so we understand.”

No one expects the president to be able to speak in great depth about every detail of economic policy, but Trump is particularly clumsy in his discussions. Most often, he cannot speak in any kind of detail, and changes the subject to obscure that; where he does speak in specifics, he is wrong.

“You know the hardest thing about being the president of the United States, it is unique in its isolation,” Trump’s predecessor Barack Obama said in an interview this week. “The burdens of leadership are true in any country, but in part because of the security apparatus around a U.S. president, you live in what’s called ‘the bubble.”

Every modern president struggles with “the bubble.” Obama seemed acutely aware of it, George W. Bush perhaps less so. But Trump is unusual in actively courting it. When he goes out, he goes out to his own restaurants. He has spent most weekends at Mar-a-Lago, though he recently went to Bedminster, New Jersey, instead—once again, to a club he owns.

Trump has demonstrated his ignorance of policy at various points in recent weeks, but now he seems proud of it. He boasted to Time in another interview published Thursday that he is cutting off any news source with which he disagrees. “I’ve been able to do something that I never thought I had the ability to do. I’ve been able not to watch or read things that aren’t pleasant,” he said. “In terms of your own self, it’s a very, very good thing. The equilibrium is much better.”

Surely, it is true that one feels better if one is not watching, hearing, and reading things that are harshly critical of one’s self. But it doesn’t make for good governance, because when the president is hearing only one side of the story, and only the one that he already agrees with, he will be less informed and make worse decisions.

For example, one problem with Trump’s trade obsession is that he continues to view international trade as identical to the business deals he conducted in the real-estate business. That’s no great surprise: As Kate Kelly recently reported, of the few people who do penetrate the White House bubble, many of them are business titans who view the world the same way. Trump told Time, “It’s never different. I think it’s never different. It’s always the same.” These deals are zero-sum, and there must be a loser. Yet more than any numbers, Trump is obsessed with respect. NAFTA “really has to do with self-respect as a nation,” he said.

Trump has surrounded himself with people who think similarly to him—or, at the very least, will not correct him when he claims authorship of a 100-year-old cliche like “priming the pump.” The consequences of this isolation are visible in the firing of FBI Director James Comey, the greatest political crisis so far in an administration whose brand is political crisis. Although some members of the White House staff reportedly hesitated, spokeswoman Sarah Huckabee Sanders said on Wednesday that the president did not expect the backlash. “How could he have, considering the fact that most of the people declaring war today were the very ones that were begging for Director Comey to be fired?” she asked.

He might have known if he were more interested in alternate views—and perhaps if he had been reading a wider range of news sources. Can Trump begin to bone up on the issues and seek a wider range of views? The president is 70 years old and seems set in these bad habits. As the editors of The Atlantic wrote last fall, “He is an enemy of fact-based discourse; he is ignorant of, and indifferent to, the Constitution; he appears not to read.” Perhaps the best hope is that some of his advisers will convince him that seeking out contrary views, like “priming the pump,” is his own idea.