You've probably read about the Princeton University professor who cancelled his course on freedom of speech because the students could not stand freedom of speech.

The professor, Lawrence Rosen, reportedly posed this question:

Which is more provocative: A white man walks up to a black man and punches him in the nose, or a white man walks up to a black man and calls him a n****r?

Obviously, the word Rosen used is offensive, but there is a difference between calling somebody that name and using it to start a classroom discussion of free speech. But Rosen's students didn't see it that way. One positioned his face a few inches from the professor's and said, "F–k you." A female student demanded to know if Rosen felt safe now.

Rosen has taught the course for several years, and this is the first time the reaction has been so strong and nearly violent. Instead of being outraged, the professor blames . .  . Donald Trump.

Rosen actually defended the students' reactions:

That students would react differently this year, writes Rouse, “is diagnostic of the level of overt anti-black racism in the country today.” When Obama was president, “the example seemed less real and seemed to have less power.” But now that Trump’s in office, students can’t bear to hear the N-word uttered out loud—even in a class about free expression and censorship, and even when it’s used as an example of hate speech.

But maybe there is another explanation: it's not racism but that academics and others on the political left are conditioning students to experience blind rage when they are exposed to words and ideas that they dislike. John Daniel Davidson of The Federalist argues that this is what is happening:

With apologies to Rouse, I have a different theory about why Princeton students reacted differently to Rosen this year. It’s not that racism in America is worse now than it was two years ago (although race relations did notably decline during Obama’s tenure, according to public opinion polling). It’s not that they couldn’t understand the point of their professor’s exercise. It’s because we’ve been conditioning students to have a Pavlovian reaction of blind outrage to offensive words and ideas.

Hearing the N-word spoken out loud triggers an emotional meltdown, but so does a simple policy disagreement. Consider a recent controversy at Stanford University over student fliers on immigration. In December, a student posted a flier on her door advertising a hotline to report any local activity of U.S. Immigration and Customs Enforcement. The flier was torn down and replaced with one that said, “#BuildTheWall.”

Davidson relates an incident at Stanford, where student Issac Kipust decided to satirize some posters promoting a hotline to report activity by ICE. Kipust's fliers were removed by the administration. Kipust described a meeting with the director of Stanford's policies on "Acts of Intolerance:"

Later that evening, I met with the [resident hall] Kimball RFs, RAs, three aggrieved students, Ms. Kadesia Woods of Residential Education, and Associate Dean of Students Dr. Alejandro M. Martinez, who directs Stanford’s policies on “Acts of Intolerance.” According to them, my flyers were “hate speech” and hence inappropriate for the Kimball community. Because they apparently mocked a flyer protecting an identity group, they constituted an act of intolerance. Most egregiously, because of their effect on the three crying students at the table, I was not permitted to repost my flyers.

. . .

The fact that my flyers were censored because they made students cry stunned me. If speech’s impact mattered more than its content, then the possibilities for censorship were limitless. For instance, at the meeting, the other students—some University staff—were visibly emotional; I was not. Emotions are too subjective a criterion for some arguments to be accepted and others denied.

Unfortunately, as Davidson notes, the war on free speech is not limited to college campuses:

Although there’s no question our colleges and universities have become hostile to free expression, it’s wrong to suppose that the problem begins and ends on campus. Middle and high school students today are being taught that censorship in the name of political correctness and social justice is okay. Last week in eastern Minnesota, the Duluth School District announced it would drop “The Adventures of Huckleberry Finn” and “To Kill a Mockingbird” from the district’s required reading list for English classes next year. Officials said the move is part of an effort to be more considerate of students of color, and since both of the books in question use the N-word, well, you get the idea.

Duluth isn’t the only school district to go this route. Last year, a school district in Mississippi pulled “To Kill A Mockingbird” from its eighth-grade reading list because “it makes people uncomfortable.” Never mind that Harper Lee’s depiction of racism and prejudice in 1930s Alabama is meant to make readers feel uncomfortable, or that the entire thrust of her classic novel is an indictment of the mistreatment and segregation of blacks in the South prior to the civil rights movement.

All of this is lost on students whose teachers and professors are systematically robbing them of the chance to grapple with the darker episodes in our nation’s history, or debate the complex political and policy questions of our time, or even confront the opinions and arguments of those with whom they disagree.

If we lose freedom of speech, it is the end of the liberal education which empowered our civilization and taught men and women to think.