While robust defenses of free expression and debate, like the “Chicago Principles” — a widely adopted statement developed at the University of Chicago in 2014 — are important, they do little to soften the climate of fear that has gripped our campuses. This is because such statements of abstract principle — like the liberal tradition from which they spring — neglect the concrete social norms necessary to facilitate and regulate the collective search for truth in college classrooms.

All of us who teach controversial subjects are struggling to identify and cultivate these norms, especially as our students have become more anxious in the age of cancel culture. For example, when I first taught a course on policing in the wake of George Floyd’s murder, some of my students lobbied for a version of the “Vegas rule” since they worried about their comments spilling out into social media land. So, I told them: “What happens in Government 137B, stays in Government 137B.”

I have little doubt that our “Vegas rule” allowed them to express perspectives that ranged from support for abolishing the police to center-right endorsements of the status quo. As soon as I announced it, in fact, one student let out an audible sigh of relief. But I have to confess that in asking students to maintain our classroom as a place of private deliberation I am asking them to keep quiet — and all in the name of open and free expression.