Earlier this month, on the eve of a federal trial over Harvard’s use of race in admissions, the university’s president invoked the predominant defense of affirmative action: It enhances education for everybody. “Harvard is deeply committed to bringing together a diverse campus community where students from all walks of life have the opportunity to learn with and from each other,” Larry Bacow wrote.

As a professor, I believe in that ideal as deeply as I believe in anything else. But since the 2016 elections, I’ve come to question whether our elite universities believe it. Despite our rhetoric of diversity, we haven’t made a sustained, explicit effort to learn from a significant but typically ignored minority in our midst: Donald Trump supporters.

Since 2016, I’ve had several pro-Trump students come out to me in my office, with the door closed. One student reported that he had heard a slew of egregiously offensive statements by his peers—including “Trump voters are racists, idiots, or both”—but that he hadn’t said anything in response, for fear of drawing ridicule and hostility. “Please don’t out me in class,” he added.

As Jon Shields and Joshua Dunn wrote in their 2016 book, Passing on the Right, younger conservative professors sometimes describe their plight in the language of gay rights. Like closeted homosexuals, they frequently disguise their identities and play along with the majority—at least until they get tenure, when they’re more likely to express their true selves.

Conservative students don’t have the same freedom. Like the Bryn Mawr student who was flamed on social media after she sought a ride to a 2016 Trump rally—so brutally that she withdrew from school—my Trump-supporting students are understandably afraid that they’ll be vilified by their peers.

Others feel maligned or threatened by their professors, almost all of whom are opposed to the president. So am I. Precisely because I dislike Trump, however, I think it’s my duty to talk with—and learn from—people who disagree with me.

And that’s where I disagree with many of my colleagues, who seem perfectly content to let pro-Trump students stew on the sidelines. Recently, at a faculty meeting at my school, we were asked what we’d do if a Trump supporter said she didn’t feel comfortable expressing her views in class on immigration.

“Why should she feel comfortable?” one professor asked. The people we really need to worry about, another faculty member added, are immigrants and students of color, whose “humanity” is under assault every day.

But insulating our classrooms from pro-Trump sentiment condescends to our minority students, all in the guise of protecting them. They already know that Trump’s election unleashed ugly outbursts of bigotry cross the country. Trump himself has made dozens of highly offensive remarks about racial minorities, women, and the disabled. I understand why our minority students would be skeptical about people who voted for him.

But it’s cynical and prejudicial to assume that every Trump voter is a racist or a misogynist. And, like every prejudice, it’s borne of ignorance: We don’t talk to each other, so we don’t know about each other either. Since the 1970s, as Bill Bishop detailed in his 2009 book The Big Sort, a declining fraction of Americans have reported conversations with people of a different political perspective. And people with more education are even less likely to engage in discussions across the political aisle.

That’s the ultimate indictment of our universities, which should expose us to ideas and people outside of our personal experience. And it underscores the unmet vision of affirmative action, which was designed to help students “learn from their differences” and “stimulate one another to re-examine even their most deeply held assumptions about themselves and their world,” as former Princeton President William G. Bowen wrote decades ago.

Bowen’s comment was cited approvingly by Justice Lewis G. Powell in Regents of the University of California v. Bakke, the landmark 1978 Supreme Court case upholding affirmative action. Drawing again from Bowen, Powell quoted a Princeton graduate who noted that students “do not learn very much when they are surrounded only by the likes of themselves.”

That’s exactly right. And that’s why I hope the federal district court in Boston upholds Harvard’s affirmative action system. But in the same spirit, I also hope we’ll make a concerted effort to insure that all of our students can say what they think once they get here. That means encouraging our Trump supporters to speak up in class (without outing them against their will, of course). And it means insisting that the rest of us grant them a respectful hearing, no matter what we think of Trump.

You can’t support race-conscious admissions, as a way to widen the conversation, then restrict the conversation to people who agree with you. That makes a mockery of affirmative action, and of the university itself. Students need to hear a broad array of voices, so they can learn from their differences. And they won’t learn very much if they are surrounded only by people like themselves.