Responding to a controversial column that appearing in the New York Times last week, Jonathan Haidt and Greg Lukianoff argue that telling students that words can be “violence” is a dangerous idea.

Psychologist Lisa Feldman Barrett, a researcher at Northeastern University, penned a column for the New York Times last week in which she argued that speech can sometimes be “violence.”

“By all means, we should have open conversations and vigorous debate about controversial or offensive topics,” she wrote. “But we must also halt speech that bullies and torments. From the perspective of our brain cells, the latter is literally a form of violence.”

Words, Barrett argued, can have a physical impact on humans. Certain types of speech “can make you sick, alter your brain — even kill neurons — and shorten your life,” she argued.

Social psychologist and NYU Professor Jonathan Haidt and FIRE President Greg Lukianoff responded to Barrett’s claims in a column for the Atlantic on Tuesday. First, they highlighted a logical error in Barrett’s reasoning that words are violence.

First invalid inference: Feldman Barrett used these empirical findings to advance a syllogism: “If words can cause stress, and if prolonged stress can cause physical harm, then it seems that speech—at least certain types of speech—can be a form of violence.” It is logically true that if A can cause B and B can cause C, then A can cause C. But following this logic, the resulting inference should be merely that words can cause physical harm, not that words are violence. If you’re not convinced, just re-run the syllogism starting with “gossiping about a rival,” for example, or “giving one’s students a lot of homework.” Both practices can cause prolonged stress to others, but that doesn’t turn them into forms of violence.

They go onto argue that labeling speech as “violence” justifies acts of physical violence as an act of retaliation. Ahead of MILO’s scheduled lecture at UC Berkeley, protesters who considered the event to be an act of violence retaliated by pepper-spraying, punching, and beating bystanders.

The implication of this expansive use of the word “violence” is that “we” are justified in punching and pepper-spraying “them,” even if all they did was say words. We’re just defending ourselves against their “violence.” But if this way of thinking leads to actual violence, and if that violence triggers counter-violence from the other side (as happened a few weeks later at Berkeley), then where does it end? In the country’s polarized democracy, telling young people that “words are violence” may in fact lead to a rise in real, physical violence.

Haidt and Lukianoff reference the 1993 book Kindly Inquisitors in which author Jonathan Rauch explained that freedom of speech means that no argument is ever truly over, that anyone can participate in the debate, and that no one is important or wise enough to claim a special authority to end a debate indefinitely.

In his 1993 book Kindly Inquisitors, the author Jonathan Rauch explains that freedom of speech is part of a system he calls “Liberal Science”—an intellectual system that arose with the Enlightenment and made the movement so successful. The rules of Liberal Science include: No argument is ever truly over, anyone can participate in the debate, and no one gets to claim special authority to end a question once and for all. Central to this idea is the role of evidence, debate, discussion, and persuasion. Rauch contrasts Liberal Science with the system that dominated before it—the “Fundamentalist” system—in which kings, priests, oligarchs, and others with power decide what is true, and then get to enforce orthodoxy using violence.

You can read the entirety of the column here.

Tom Ciccotta is a libertarian who writes about economics and higher education for Breitbart News. You can follow him on Twitter @tciccotta or email him at tciccotta@breitbart.com