Granted, Mr. Trump is deeply ignorant about policy. Still, you might have thought that he would try to signal his independence from the Republican establishment by, say, turning to some business economist. Instead, he turned to the usual suspects from the right-wing noise machine. And what choices!

Mr. Kudlow, the conservative columnist, is to economics what Republican commentator William Kristol is to political strategy: If he says something, you know it’s wrong. Years ago, when Mr. Kudlow ridiculed the “bubbleheads” who thought that overvalued real estate could bring down the American economy, you should have rushed for the bomb shelters; when he proclaimed that President George W. Bush was a huge success because a rising stock market is the ultimate verdict on a presidency (unless the president is a Democrat), you should have known that the Bush era would end with epochal collapse.

And then there’s Mr. Moore, the political and economic analyst who has a similarly awesome forecasting record, as well as an impressive lack of even minimal technical competence. Seriously: Read the Columbia Journalism Review’s report on his mess-up over job numbers in 2014.

Of course, Mr. Moore remains the chief economist at the conservative Heritage Foundation. And maybe Mr. Trump believes that this is a certificate of quality - that anyone in that position must be a real expert.

Truly, Mr. Trump, you know nothing.

‘Paul Ryan’ and the Trump Fail
There has been a lot of navel-gazing among news organizations about how everyone in the media - well, almost everyone - wrote off Mr. Trump’s chances of getting the Republican presidential nomination.

The thing is, the polls pointed to Mr. Trump’s strength right from the beginning, and it should have been clear by early last fall at the latest that Mr. Trump wasn’t going to wind up like the various not-Romneys of 2012.

So why did most of the commentariat get it so wrong for so long?

The basic answer, surely - but one a lot of my media colleagues still won’t accept - is that the political scientist Norm Ornstein was right all along: The modern Republican Party was no longer a normal political party; it was an extremist sect that had fed its supporters’ rage, and in so doing had created a Frankenstein’s monster. And most pundits, in refusing to see this, blinded themselves to the way the party had become ripe for Trumpism.

But let me be more specific: I think you can understand this media failure by considering the tale of “Paul Ryan.” Not the actual House Speaker Paul Ryan, but the mythical character created by the media.

The real Paul Ryan has always been a con man - someone playing the part of Serious, Honest Conservative, but never doing a very good job of it. His budgets were always fraudulent in obvious ways, full of trillion-dollar magic asterisks and spectacular evasions. But he has consistently been portrayed in news reports and analyses as an earnest policy wonk.

Why? The answer, certainly, is that in the media’s narrative the two parties must - simply must - be symmetric: If there are serious policy wonks turning out responsible proposals on the Democratic side, there must be comparable people on the Republican side. So someone like “Paul Ryan,” the mythical creature, has to exist - and when Paul Ryan, the real politician, decided to play that character, nobody checked the numbers and pointed out the obvious fakery.

The Ryan phenomenon was part of the same willful blindness that caused most analysts to miss the Trump surge that was staring them in the faces.

And you know what has been really helpful for the few people who didn’t get it all wrong? Numbers. If you did the math on Mr. Ryan’s proposals, you saw that he was engaged in a con, which in turn told you a lot about the real state of the G.O.P. - and that, combined with the polls and demographics, at least left you open to the possibility of a Trump nomination.

Of course, now everyone who got it wrong is busy making up new narratives, equally ungrounded in evidence. Will nobody stop these heads from talking?