John Rose, on classes he teaches at Duke University:

To get students to stop self-censoring, a few agreed-on classroom principles are necessary. On the first day, I tell students that no one will be canceled, meaning no social or professional penalties for students resulting from things they say inside the class. If you believe in policing your fellow students, I say, you’re in the wrong room. I insist that good will should always be assumed, and that all opinions can be voiced, provided they are offered in the spirit of humility and charity. I give students a chance to talk about the fact that they can no longer talk. I let them share their anxieties about being socially or professionally penalized for dissenting. What students discover is that they are not alone in their misgivings. […] 

On the last day of class this term, several of my students thanked their counterparts for the gift of civil disagreement. Students told me of unlikely new friendships made. Some existing friendships, previously strained by political differences, were mended. All of this should give hope to those worried that polarization has made dialogue impossible in the classroom. Not only is it possible, it’s what students pine for.

Please read the whole essay. After doing so, you may be encouraged, as Rose himself is. But you also may be depressed, as I am, to reflect that what ought to be the baseline norm of all university classes should be so much of an outlier that for many of Rose’s students it’s a one-time-only exceptional experience.

Also, there’s a mystery here, an important one: Many professors say that they’re all about open dialogue and the free play of ideas, but students are really good at discerning whether or not that’s bullshit. Like card players, all of us who teach have tells, quirks of speech or facial expression that let students know what we really think as opposed to what we say we think. Obviously John was able to convince his students that his commitment to civil discourse is real. How a teacher does that is the mystery I’m talking about, but the one essential step is for you, dear professor, to ask yourself whether you actually believe in the free play of ideas. Because if you don’t, you’re definitely not going to be able to persuade your students that you do.