On April 8, 1991, when I was a sophomore at Brown University, Supreme Court Justice Antonin Scalia came to campus to speak. Conservatives allegedly existed at Brown, but the school was as true to its left-leaning reputation then as it is now. This was where Amy Carter, the daughter of the former president, got in trouble for protesting apartheid, where a longhaired John F. Kennedy Jr. was also an anti-apartheid activist, where the most popular campus newspaper comic strip featured a character named P.C. Person.

We were right about everything. We knew our enemy and we hated him, whether it was the former segregationist Strom Thurmond or the bigoted Jesse Helms, both somehow in Congress, or the pugnacious Senate minority leader Bob Dole. Students regularly protested in favor of abortion access and need-blind admissions.

That April evening of Scalia’s talk, I lined up with my anti-Helms T-shirt on. I barely made it into a back row of the packed auditorium, where I awaited what would surely be a triumphant Q. and A. session. Once Scalia finished and we the righteous had a chance to speak truth to the evil one, we would rip apart his so-called originalism, his hypocrisies, his imperiousness. We were champing at the bit to have our say.

And then he wiped the floor with us. In answer to our indignant questions, he calmly cited rebutting cases. We fulminated and he reasoned, and when we seethed he lobbed back with charm. Within the hermetic bubble of my liberal upbringing and education, it had never occurred to me that even when finally presented with The Truth, someone from the other side could prevail. I’d been certain we would humiliate him. Instead, I left humbled.

Many valid points have been made about the federal appeals court judge Kyle Duncan’s speaking engagement earlier this month at Stanford Law School, which was repeatedly interrupted by protesters. Advocates of free speech decried the hecklers’ refusal to let Duncan deliver his remarks. Defenders of the students justified their own right to speak. Duncan and others lamented the tenor of the protests and the response from an administrator who failed to quell the vitriol and asked, “Is the juice worth the squeeze?”

The administrator was asking, essentially: Is it worth letting someone speak if some students consider that person’s views objectionable, even abhorrent? But another question to ask is: What gets lost if we don’t let that person speak?

For one thing, the Federalist Society members who invited Duncan, a Trump appointee, missed hearing from a like-minded judge. Duncan, who says he speaks at law schools in part so he can hear from students, lost out as well.

But the protesters themselves suffered the greatest loss. Unleashing on Duncan may have felt good in the way we Brown students felt good asking our “tough” questions of Scalia. But whereas we got to hear the answers, the Stanford Law School students did not. It isn’t enough to challenge someone unless you’re willing to be challenged back. Scalia’s answers may not have made us feel especially good, emotionally or intellectually. They did, however, teach us the value of listening, and motivate us to be smarter.

No matter how charismatic Scalia had been, I still didn’t think him a force for good, which made it easier for me to devalue his arguments. But with time, I realized most people don’t divide neatly into heroes and villains. What happens if you assume your political opponent isn’t evil — if you even know that he’s not?

As some readers of The Times may be aware, nearly 25 years ago I was briefly married to another columnist here, Bret Stephens. When my friends and family members had learned I was dating a conservative — let alone thinking of marrying one — they were stunned. How could an intensely partisan Democrat like me marry someone who described himself — proudly! — as “very conservative”? (“But he’s pro-choice and believes in gay marriage,” I assured them.)

Not surprisingly, Bret and I argued about politics intensely and often. At one point during the Clinton controversies of the 1990s, I remember screaming at him on a Soho sidewalk, my face mottled with tears. How could someone I knew to be a good person possibly believe what he was saying, and why, dammit, must he make his points so cogently? After our divorce and back in my liberal province, I actually missed those intellectual battles. What better way to keep an open and sharp mind? Without someone “in house” to spar with, I found myself seeking political debate elsewhere.

Unfortunately, many Americans — and worryingly, many younger Americans — are looking for it less frequently. In 1958, 33 percent of Democrats said they wanted their daughters to marry a Democrat, and 25 percent of Republicans said they wanted their daughters to marry a Republican. By 2016, 60 percent of Democrats and 63 percent of Republicans felt that way. By 2020, 43 percent of single Democrats said they probably or definitely wouldn’t date someone Republican (compared with 24 percent of single Republicans who wouldn’t date a Democrat). According to one study, only 21 percent of marriages today are politically mixed. Democrats are especially unlikely to have friends from across the political divide. Polls show that partisans on both sides view their opponents as “closed-minded” and “immoral.”

When you don’t know someone personally, it’s easier to assume the worst about him. And if you assume your opponent is immoral, you don’t have to listen to him, that he’s not worthy of charitable interpretation. But if you assume your political opponent is operating in good faith — even if the person isn’t a friend or significant other — you’ll be inclined to hear him out.

Students at Stanford Law School would do well for themselves to hear out their opponents. In the professional world, it won’t be enough to deem their opponents evil and declare the battle won. They will be sitting across tables from their adversaries and trying to make persuasive arguments against them in courtrooms. Their success will depend on a mutual assumption of good faith from both sides — and from the bench, where not only Judge Duncan but 53 percent of active federal appeals judges were appointed by Republican presidents.

According to “Brown University: A Short History,” by Janet M. Phillips, Vartan Gregorian, the school’s president when I attended, “bucked the trend of ‘political correctness’ to keep the Brown community hospitable to a wide range of views.” He invited not only Scalia but also the left-wing academic and activist Angela Davis, to “ensure a steady flow of diverse views and intellectual debate.” Gregorian, who died in 2021, Phillips wrote, “prided himself on the fact that during his tenure no speech, however controversial, was cut short by protest.”

We know universities can do a better job of preventing one form of speech from inhibiting another. The harder task, but perhaps the more important lesson, will be teaching students not to want to do so. They shouldn’t avoid opportunities to hear other perspectives but should actively seek them out, and reckon with the humbling fact that what they already know — or think they already know — may not be all there is to know. Isn’t that, after all, precisely what learning is about?

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