A burned out portable light system is seen at UC Berkeley after a student protest turned violent during a demonstration over right-wing speaker Milo Yiannopoulos.Stephen Lam / Reuters

Among the many terrifying questions that Donald Trump’s presidency poses is this: How do you oppose an indecent leader while still behaving decently yourself?

When it comes to the habits of deference extended to previous presidents, I’m fine with breaking the rules. If Democrats want to oppose all of Trump’s nominees on the basis that he himself is dangerous and illegitimate, that strikes me as fine. If performers who have traditionally performed at governmental functions want to boycott his, I’m fine with that, too. Trump practices demagoguery, bigotry, and cruelty. He does not deserve the deference granted a normal president.

But when Trump’s opponents use the danger he and his supporters pose to restrict basic freedoms, there’s a problem. Which is what happened earlier this week at the University of California, Berkeley, when a violent protest prevented Milo Yiannopoulos, a Breitbart News writer who has made his name by viciously mocking women, trans people, and African Americans, from speaking on campus.

Judging from my Twitter feed, not many progressives defend the violence, which appears to have been carried out by masked hoodlums who arrived from off-campus. But vast numbers said Berkeley should have peacefully denied Yiannopoulos an opportunity to speak on campus. In the words of one Twitter user, “Free speech ≠ every college has an obligation to give you an official platform for your speech.”

The problem with this argument is that it was not Berkeley itself that invited Yiannopoulos. It was the Berkeley College Republicans, who are legally a separate entity. And as Berkeley Chancellor Nicholas Dirks explained, “long-standing campus policy permits registered student organizations to invite speakers to campus and to make free use of meeting space in the Student Union for that purpose.” So the issue is not whether Berkeley should have given Yiannopoulos a platform. It is whether Berkeley should have denied some of its students the ability to give him a platform. And “consistent with the dictates of the First Amendment as uniformly and decisively interpreted by the courts,” Dirks argued, “the university cannot censor or prohibit events, or charge differential fees.”

That strikes me as a strong argument. Universities should establish rules for how they treat speakers that student organizations invite. And they should not alter those rules depending on the ideas those speakers espouse, even if their ideas are hateful.  (And yes, I’d apply that not merely to Milo but to a neo-Nazi like Richard Spencer). At Berkeley, the rules say that student organizations get to host their speakers at the Student Union for free. If Berkeley changes that because Yiannopoulos is a misogynist, what happens if a Palestinian group invites a speaker that conservatives call anti-Semitic?

Of course, Berkeley students also have the right to protest Yiannopoulos. But the university has an obligation to ensure that their right to protest does not prevent the College Republicans from hearing their invited guest. Is the university obligated to spend extra money, which it would not expend for a normal speaker, because Yiannopoulos’s speech requires extra security? I’m not sure. But in any case, Berkeley did not spend extra money. It required the College Republicans to come up with funds for additional security themselves; an anonymous patron contributed $6,000 to help them.

The second argument for preventing Yiannopoulos from speaking is that his ideas are more than merely offensive. His conduct at public events has constituted harassment. As a group of Berkeley professors detailed in a letter, Yiannopoulos, projected a picture of a trans student onto a screen during his speech at the University of Wisconsin, Milwaukee, last December—an event that was also live-streamed on Breitbart News. He “continued to ridicule and vilify her in front of the live campus audience and the online audience. The student was so disturbed by this experience that she withdrew from the university.”

But this argument is weak, too. Yiannopoulos’s behavior at the Milwaukee campus sounds disgusting. But as Dirks wrote in response, “critical statements and even the demeaning ridicule of individuals are largely protected by the Constitution.” If they were not, a lot of comedians would have trouble performing live. And even if the targeted UWM student has grounds to sue, Berkeley cannot prevent the College Republicans from hosting Yiannopoulos because of the possibility that he might do something like that again.

Politically, the problem with shutting Yiannopoulos down is obvious. The reason the College Republicans invited him in the first place was “because we believe there exists a dearth of intellectual diversity on this campus,” and “conservative thought is actively repressed.” Not letting him speak on campus just makes their point. It lets Yiannopoulos depict himself as a victim of “political correctness.” Which is the grievance that fuels his ugly persona in the first place.

But the argument for letting Yiannopoulos speak is more than tactical. It’s a matter of principle. Conservative students have the right to bring obnoxious bigots to speak on campus and other students have a right to protest. But universities should not let the protesters shut them down. That was hard for many leftists to accept even before Trump’s election. Now that an obnoxious bigot occupies the White House, it’s even harder. But Trump’s presidency is, in part, a test of whether ordinary Americans can avoid sinking to his level, whether a citizenry can respect the principles that its leaders do not. What happened to Milo Yiannopoulos this week is part of that test. It’s important that progressives at Berkeley, and around the country, do not fail.