The Supreme Court has struck down affirmative action. That might help campus diversity.

When Donald Trump won the 2016 presidential election, I was despondent. As a liberal Democrat, I was appalled by his positions on abortion, taxes, and much else.

But as a professor, I was worried for a different reason: Almost everyone I encountered on campus agreed with me. That’s a poor formula for effective education, which requires us to grapple with diverse ideas and perspectives.

I’ve been thinking about 2016 more than usual lately, as I read about Thursday’s U.S. Supreme Court decision curtailing race-based affirmative action. That also makes me worried, because I believe affirmative action has helped all my students — whatever their race — learn more from each other. Diversity is always a good thing.

But the diversity generated by affirmative action was incomplete. At our elite universities, especially, we admitted classes that were diverse racially but not economically. By 2017, students from families in the top 1% of the income bracket were 77 times more likely to be admitted to an Ivy League school than people whose families earned less than $30,000 a year.

The diversity generated by affirmative action was incomplete.

At Penn, where I teach, a survey of 1,113 undergraduates in 2016 found that 70% came from some of the wealthiest neighborhoods in the country. Only 5% came from zip codes in the second-lowest quintile of median household income, and not a single student — yes, you read that right — was from the country’s poorest neighborhoods.

College costs had a lot to do with that, of course. But so did affirmative action, which incentivized our elite schools to enlist nonwhite students regardless of economic background. And most of these students came from — you guessed it — the wealthier precincts. At Harvard, 71% of Black and Latino students in 2018 were considered “economically advantaged.”

So we ended up with classes where people look different from each other, but mostly live in the same fancy places. And the small number of students who aren’t rich are disproportionately nonwhite. They check the right diversity box. White working-class students don’t.

At a school like Penn, you’ll find wealthy students of every race and less affluent students who are Black and Latino. You’re a lot less likely to meet a white kid whose parents work in factories and didn’t go to college.

And guess who voted for Donald Trump? In 2016, 67% of noncollege-educated whites supported Trump, whereas just 28% backed Hillary Clinton.

That helps explain the enormous political skew at schools like Harvard, where students favored Clinton over Trump by 80% to 6%. And it also helps account for our inability to understand the Trump phenomenon, or even to discuss it.

I’ve sat in classrooms where faculty and students claimed that anyone who voted for Trump was a racist or a misogynist. Never mind that four out of 10 female voters supported Trump in 2016 and 2020, or that he drew more nonwhite votes during his second presidential campaign than in his first one. We have our Trump story, and we’re sticking to it.

But if there were more actual Trump voters in our midst, we couldn’t dismiss them so easily. They would challenge our assumptions, which we would be forced to defend. And everyone would learn from the debate, which was the goal of affirmative action in the first place.

» READ MORE: Want to save our democracy? Talk — and listen — to someone you don’t agree with. | Jonathan Zimmerman

“The Nation’s future depends on leaders trained through exposure to that robust exchange of ideas which discovers truth ‘out of a multitude of tongues,’” the Supreme Court declared in Regents of the University of California v. Bakke, its landmark 1978 ruling allowing colleges to consider race when deciding whom to admit. (The decision quoted from an earlier case.)

Now that affirmative action has been struck down, some colleges may adopt a class-based form of affirmative action, giving extra consideration to applicants from low-income families. Some critics warn that will reduce the number of nonwhite students; others argue that racial diversity could hold steady if colleges also do away with preferences for the children of alumni. It’s too early to know.

But here’s what we do know: Admitting students based on income instead of race could bring in more white working-class students, which will make our campuses more ideologically diverse places. And that’s a good thing.

News flash: Americans are deeply polarized along political lines. We don’t understand, tolerate, or trust each other. The only way to change that is to bring different people together, to talk and to learn. Let’s do it.

Jonathan Zimmerman teaches education and history at the University of Pennsylvania. He is the author of “Whose America?: Culture Wars in the Public Schools,” which was published last year in a revised 20th-anniversary edition by the University of Chicago Press.