The U.S. Senate waded into the debate about free speech on college campuses Thursday, as a panel of experts offered their views on what has emerged as an increasingly controversial issue on college campuses.

The Senate Committee on Health, Education, Labor, and Pensions convened the hearing amid a national debate on how to protect free speech on campuses, including by protecting the rights of those who may harbor hateful views. Chaos ensued at the University of Florida last week when white nationalist Richard Spencer spoke on campus, and protests against former Breitbart editor Milo Yiannopolous at the University of California, Berkeley earlier this year turned violent. In August, activist Heather Heyer was killed at a march protesting a white supremacist rally at the University of Virginia.

Attorney General Jeff Sessions last month pledged to “protect students’ free expression” regardless of their political views. But Democrats don’t think the Trump administration is doing enough to tackle hate speech, a concern eight of the 11 Democrats on the committee expressed Wednesday in a letter to Secretary of Education Betsy DeVos.

Toward the end of the committee hearing, Sen. Elizabeth Warren, one of the signatories on that letter, said colleges should not prohibit speakers no matter how extreme their views are. She also condemned extremists on the right and the left who use violence against people they disagree with.

Warren, D-Mass., gave the example of right-wing intellectual Charles Murray, who she called an extremist who wears a “fancy suit and peddles racist junk science about how white men are biologically speaking intellectually superior to everyone else.” She encouraged people to challenge his views.

“As someone who worked as an academic researcher for decades, I think that spouting fake science is extremely corrosive to public policy and should be called out in public at every possible opportunity,” said Warren, who spent most of her life in academia, including many years teaching law at Harvard University.

Still, she rejected censorship.

“I think it’s dangerous to suppress speech. First, suppression can backfire. Instead of shutting up individuals with disgusting views it becomes a launching pad to national attention,” Warren said. “Bigots and white supremacists can make themselves out to be First Amendment martyrs and grow their audiences. And second, suppression suggests weakness, It makes us sound afraid, that we’re afraid we can’t defeat evil ideas with good ideas.”

The senator then turned to panelist Allison Stanger, a Middlebury College professor who says she disagrees with Murray but moderated a talk with him on campus earlier this year. Protesters interrupted the event before it started and forced a change of venue, and Murray was later violently assaulted by a mob of students. Warren used this example to condemn violence and to encourage people to engage in debates rather than silo themselves off.

“The notion that I just want to underline here is that the people who attacked you get no special protection, neither does the Charlottesville white supremacist who murdered a woman there or the three white supremacists who tried to shoot people at the University of Florida last week,” Warren said to Murray. “They will go to jail. Free speech is not about violence, it is not about silence. What I’m concerned about is that right now it is all too easy for all of us to avoid hearing anything that we don’t already agree with. And that is an enormous threat to our democracy.”