Earlier this week I argued, among other things, that it was futile for well-meaning advocates to try to latch onto Donald Trump as a vessel for pointing out policy shibboleths. The problem with Trump is that his brand is so toxic that even his occasional moments of lucidity are tarnished.

Writing in the New York Times, Zeynep Tufekci makes the most explicit case that this is wrong. Relying on the logic of shifting the Overton Window of “acceptable” policy ideas, Tufekci suggests that Trump & the Trumpkins have revealed that the existing gatekeepers are wearing no clothes:

For worse, and sometimes for better, the Overton window is broken. We are in an era of rapidly weakening gatekeepers. …
Mr. Trump doesn’t only speak outrageous falsehoods; he also voices truths outside the Overton window that have been largely ignored, especially by Republican elites. For example, academic research shows that rather than deep cuts, Tea Party voters actually favor government programs, as long as they perceive a benefit for themselves. It’s fairly obvious that the current model of global trade provides a lot more benefits to corporations than to workers, and yet it took Mr. Trump’s rise to have this basic issue widely covered. In Fayetteville, Mr. Trump complained that much of the military’s expensive weaponry had been purchased simply because the large corporations selling it had political clout. As he said this, the people around me, many of them from military families, leapt to their feet in approval. …
The Trump phenomenon is not simply a creation of newspaper columnists or cable news bookers who initially thought his candidacy was a joke to be exploited for ratings. His emergence shows the strength of his supporters, united on social media, who believe that the media is a joke. Mr. Trump and his fans have broken the Overton window, and there is no going back.

As someone writing a book called “The Ideas Industry,” I recognize the precise phenomenon that Tufekci is highlighting here. Indeed, on foreign policy questions in particular — nonproliferation, U.S. alliances, foreign economic policy — Trump is genuinely challenging decades of accepted givens about how the United States should interact with the world. It would seem that Tufekci is also correct that, for the past nine months, the traditional critics and gatekeepers have done a bad job of rebutting these ideas.

Here’s the thing, though, and it goes back to what I said on Monday: What if Tufekci has underestimated the ability of critics to discredit Trump? What if he implodes? What happens to his ideas then?

Donald Trump says he can't wait to take on Hillary Clinton in the fall, but here are three reasons why he could lose a general election. (Sarah Parnass/The Washington Post)

Trump’s political epitaph has been written a lot in the primary season, and to be clear my money is that he still becomes the GOP nominee for president. But for all of Tufekci’s talk about the loyalty of Trump’s supporters, the man remains a spectacularly unpopular presidential candidate. Don’t take my assertion on this point: click here and here and here and here and here and here and so on. It’s not hard to find evidence that Trump is: (a) unpopular and (b) getting way more unpopular.

Within a crowded GOP field, Trump’s jerk persona and heterodox ramblings clearly draw enough support for him to do well. In a general election, he’s such an undisciplined, unmitigated disaster that there’s talk of Democrats retaking the U.S. House of Representatives.

This is happening at the same time that Trump is getting pilloried for his foreign policy statements. Even the foreign policy experts most sympatico with Trump’s worldview are shunning him.

This is clearly correlation and not causation: Remember, most Americans don’t care all that much about foreign policy. But it raises the bigger question: What does the Overton Window look like if Trump craters? Tufekci is looking at the hard-core Trumpkins. What about the rest of the country?

There’s already polling evidence that Americans have shifted their attitudes on Trump’s signature policy idea, and not in the way Trumpkins will like:

In September of 2015, 46 percent of those polled said they favored building a fence along America’s southern border with Mexico. But in its latest poll, Pew found that support had fallen significantly, with only 38 percent favoring a border fence. When the question was reframed to ask about a border wall as opposed to a border fence, only 34 percent said they would favor building a wall along the U.S.-Mexico border.
Support for the legalization of illegal immigration also hit a new high, with 75 percent of poll respondents saying that illegal immigrants should be able to stay in the U.S. rather than being deported. Only 23 percent, a new low, said they favored a national law enforcement effort to deport illegal immigrants. In 2014, 30 percent of respondents said all illegal immigrants should be deported.

To be fair, Pew also shows some public souring on free trade, although even on that issue the evidence is murky.

My point is this: The problem with Trump is that he’s the worst possible messenger for any counterintuitive idea. The more that the mainstream media and actual policy experts pillory Trump for his various transgressions, the more limited his appeal will be to the American electorate — and, concomitantly, the less popular his ideas will be.

It is easy, as Trump seems poised to capture the GOP nomination, to think that his campaign will transform the marketplace of ideas and that he has shifted the Overton Window. Tufekci might very well be right, and goodness knows I’ve been wrong about the ceiling of Trump’s appeal.

Still, I want to suggest that there is an alternative outcome: Trump crashes and burns either as the GOP nominee or as a third-party candidate. Both demographic trends and historical evidence suggest that Trump’s movement is more likely to flame out rather than sustain itself.

Which means that, a year from now, the Overton Window could have indeed shifted — away from Trump’s ideas.