Yesterday, the United States entered a new and chilling stage of what I have called the “age of rage.” After two attempted assassinations of President Donald Trump, leading conservative leader Charlie Kirk, father of two, was gunned down at a campus event at Utah Valley University. I learned the news while I was in Prague to speak on my book,“The Indispensable Right: Free Speech in an Age of Rage” and the growing attacks on free speech around the world. I never imagined that I would be speaking about Charlie’s murder and what it represents for free speech.

I cannot claim to have been a close friend of Charlie Kirk, but I knew him and respected him. In his relatively short life, Charlie energized a generation of conservative college students at a time of intense liberal orthodoxy and intolerance.

Kirk came up with the brilliant idea of challenging liberals to simply debate issues from abortion to immigration.  His group would go to campuses and invite debate with signs reading “prove me wrong” and encourage liberals to engage in dialogue rather than violence.

The left had particular reason to hate Kirk.  Campuses have long been the bastions of the left, reinforced by faculties which now have few, if any, conservatives or Republicans. Higher education has long been an incubator for intolerance; shaping a generation of speech phobics who shout down or attack those with opposing views.

Kirk struck at the heart of that power base. Polls show that most students do not feel comfortable speaking about their values in our universities and many conservatives hide their views to avoid retaliation from faculty and students.

Kirk was changing that but showing students that they could be open and bold about their views. He told them that they did not have to yield to orthodoxy and the groupthink. Now he’s dead.

What is most chilling about the murder of Charlie Kirk is that it was not in the least surprising. Not anymore.

The response to TPUSA was all too often rage and violence. Liberals and anti-free speech groups like Antifa would trash their tables and threaten the students. Recently, at UC Davis, police simply watched as a TPUSA tent was torn apart and the tent carried off.

Violent speech has long been acceptable on campuses so long as it targets conservatives. Teachers have called for others to “take out” Trump supporters and for the Secret Service to assassinate him.

University of Wisconsin Professor José Felipe Alvergue, head of the English Department, turned over the table of College Republicans supporting a conservative for the Wisconsin Supreme Court. He reportedly declared, “The time for this is over!”

At universities, professors have called for “detonating white people,” denouncing police, calling for Republicans to suffer,  strangling police officers, celebrating the death of conservatives, calling for the killing of Trump supporters, supporting the murder of conservative protesters, and supporting the  attempted assassination of President Trump. One professor who declared that there is “nothing wrong” with such acts of violence as killing conservatives was actually promoted.

At Hunter College in New York, Professor Shellyne Rodríguez trashed a pro-life display of students, telling the students that “This is bulls–t. This is violent. You’re triggering my students.”

When the students tried to engage the professor and apologized for upsetting her, Rodríguez yelled, “No you’re not — because you can’t even have a f–king baby. So you don’t even know what that is. Get this s–t the f–k out of here.” In an Instagram post, she is then shown trashing the table.

Hunter College, however, did not consider this unhinged attack on students to be sufficient to terminate Rodríguez. It only fired her after she later chased reporters with a machete. She was then hired by another college. She was shown in a later rally exciting the group with references to “slitting the master’s throat.”

At the University of California Santa Barbara, they did not even bother to fire a professor who pleaded guilty to assaulting pro-life students on campus.  Professors actually rallied around feminist studies associate professor Mireille Miller-Young. She was later honored as a model for women advocates at the University of Oregon.

In my book, I detail prior “ages of rage,” including periods of political violence by anarchists, socialists, and other groups. I previously warned that we were not only following this same trajectory, but it was accelerating. The reason is the curious nature of rage:

“What few today want to admit is that they like it. They like the freedom that it affords, the ability to hate and harass without a sense of responsibility. It is evident all around us as people engage in language and conduct that they repudiate in others. We have become a nation of rage addicts; flailing against anyone or anything that stands in opposition to our own truths.

Like all addictions, there is not only a dependency on rage but an intolerance for opposing views. The difference between rage and reason is often one’s own views. If one agrees with the underlying grievance, rage is viewed as passion or justified fury at injustice. If one disagrees with those views, it takes on a more threatening and unhinged quality. We seem to spend much of our time today raging at each other. Despite the amplification of views on both sides, there is also an increasing intolerance for opposing views. Those views are treated as simply harmful and offensive—and, therefore, intolerable. Indeed, to voice free speech principles in a time of rage is to invite the rage of the mob.”

That addiction to rage has now claimed another victim who had the audacity to speak boldly and openly about his conservative views. What will follow will be the usual perfunctory expressions of sympathy and denouncing of violence by the very politicians who have fueled the rage.

In recent months, some of us have warned Democratic politicians about their violent rhetoric. House Minority Leader Hakeem  Jeffries (D., N.Y.) has called for people to take to the streets to save democracy and posted a picture brandishing a baseball bat.

Former Democratic National Committee deputy chair Keith Ellison, now the Minnesota attorney general, once said Antifa would “strike fear in the heart” of Trump. Liberal sites sell Antifa items to celebrate the violent group.

California Governor Gavin Newsom declared, “I’m going to punch these sons of bitches in the mouth.” It follows other violent rhetoric from Democratic leaders.

One House member explained to Axios, “Some of [our supporters] have suggested … what we really need to do is be willing to get shot.” Yet another admitted that constituents have told them to prepare for “violence … to fight to protect our democracy.” Others reported that liberals are talking about the need “to storm the White House and stuff like that.”

In one encounter, a lawmaker recounted that “I actually said in a meeting, ‘When they light a fire, my thought is to grab an extinguisher’. And someone at the table said, ‘Have you tried gasoline?’”

Some have. Protesters are burning cars, dealerships, and even lawyers and reporters on the left are throwing Molotov cocktails at police. We have also seen a massive increase in attacks on ICE officers, who are now covering their faces to avoid doxxing or retaliation against themselves or their families. The left has rolled out guillotines and chanted “We got the guillotine, you better run.”

Just before he was shot at Utah Valley University, Kirk rallied the group with its signature chant of “prove me wrong.” The response was to kill Charlie Kirk.

His death could succeed in forcing the thousands of conservative and libertarian students back into the shadows of our campuses and classrooms. We cannot allow that to happen. Charlie Kirk challenged not just the left to debate but the right to be heard in higher education.

Yes, this is an age of rage. However, amidst the rage and the violence, there are a special few who have defied the threats and the attacks. The writer George Bernard Shaw once said that unreasonable people expect the world to conform to them. He then added that that was why all history is made by unreasonable people.

Kirk was one of those wonderfully unreasonable people who refused to yield; refused to be silenced. Despite unrelenting attacks by the media and the establishment, he remained undeterred and unbowed. Students need to remember not how Kirk died, but why he died. His loss is Charlie’s final challenge to all those today wringing their hands and muttering the usual expressions of shocked regret. Kirk would likely say, “prove it.” Speak. Defy those who spend their time silencing others rather than speaking themselves. If you want to honor Charlie Kirk, speak out, speak boldly on both the right and the left. Prove them wrong.

Jonathan Turley is the Shapiro professor of public interest law at George Washington University and the author of the best-selling “The Indispensable Right: Free Speech in an Age of Rage.”