But conservatives don’t see the rejection of their orthodoxies by people who know what they’re talking about as a sign that they might need to rethink. Instead, they’ve soured on scholarship and education in general. Remarkably, a clear majority of Republicans now say that colleges and universities have a negative effect on America.

So the party that currently controls all three branches of the federal government is increasingly for bigotry and against education. That should disturb you for multiple reasons, one of which is that the G.O.P. has rejected the very values that made America great.

Think of where we’d be as a nation if we hadn’t experienced those great waves of immigrants driven by the dream of a better life. Think of where we’d be if we hadn’t led the world, first in universal basic education, then in the creation of great institutions of higher education. Surely we’d be a shrunken, stagnant, second-rate society.

And that’s what we’ll become if modern know-nothingism prevails.

I’ve been rereading an important 2012 book, Enrico Moretti’s “The New Geography of Jobs,” about the growing divergence of regional fortunes within the United States. Until around 1980, America seemed on the path toward broadly spread prosperity, with poor regions like the Deep South rapidly catching up with the rest. Since then, however, the gaps have widened again, with incomes in some parts of the nation surging while other parts fall behind.

Moretti argues, rightly in the view of many economists, that this new divergence reflects the growing importance of clusters of highly skilled workers — many of them immigrants — often centered on great universities, that create virtuous circles of growth and innovation. And as it happens, the 2016 election largely pitted these rising regions against those left behind, which is why counties carried by Hillary Clinton, who won only a narrow majority of the popular vote, account for a remarkable 64 percent of U.S. G.D.P., almost twice as much as Trump counties.

Clearly, we need policies to spread the benefits of growth and innovation more widely. But one way to think of Trumpism is as an attempt to narrow regional disparities, not by bringing the lagging regions up, but by cutting the growing regions down. For that’s what attacks on education and immigration, key drivers of the new economy’s success stories, would do.

So will our modern know-nothings prevail? I have no idea. What’s clear, however, is that if they do, they won’t make America great again — they’ll kill the very things that made it great.