John McWhorter teaches linguistics, American studies, philosophy and music history at Columbia University and is the author of "Words on the Move." The opinions expressed in this commentary are his own.

(CNN) No one can fail to be amazed by the courage of the people who protested segregation and bigotry in the 1950s and 1960s. Those who endured physical injury justifiably stick in our minds the most.

Today's educated liberals lack the courage they admire in their forebears, at a time when it is needed more than ever. Namely, too many liberals in power lack the guts to sanction those dedicated to shouting down speakers from the right. Instead, they let pass a state of dialogue as choked as the one that Berkeley's Free Speech movement resisted.

To hurl the N-word at someone is an attempt to shut down discussion. Today, the word "racist" serves the same function. Or, today's fashionable new version is the now grievously overused "white supremacist." Such that, for example, liberal man of letters and Columbia professor Mark Lilla is accused of making white supremacy "respectable" -- for suggesting that Democrats emphasize identity politics less with the goal of winning the White House from Donald Trump.

Of course, of late, a certain crowd is not only using single words, but completely silencing that which they don't want to hear and have decided no one else should either. The way actual white supremacist Richard Spencer was treated at the University of Florida Thursday was an example, now sadly typical, of how self-appointed social justice warriors refuse to allow unpopular speakers to even open their mouths during their events.

It has become clear over the past few years that the shouting students and their civilian accomplices (the latter of whom have sometimes outnumbered the former, as at Middlebury when Charles Murray was accosted) are a charismatic minority who do not represent general opinion, even among enlightened people on the left. The verdict is in: even those of us deeply committed to battling discrimination and inequality find this shutting down of speakers barbaric: unintellectual, uncivil, crude, counterproductive.

Crucially, however, these objections make not a dent in these happy warriors' actions. We know the arguments now. As John Stuart Mill said, we must rehash even unpleasant arguments to remind ourselves what the counterarguments are: Sunshine is a disinfectant, people say. The left's tactics can become a weapon for the right, people warn.

Such that, for example, at the University of Pennsylvania , a graduate student teacher taking special pains to call on students of color and women as much as white men was removed from her position by the administration after protests by neo-Nazis that she was discriminating against whites.

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But these wise warnings clearly hit a brick wall. -- we must note that years now of editorials and forums condemning this behavior has merely preached to a choir -- i.e. most of us -- while the warriors lustily plan their next assault upon someone's right to utter some words in an auditorium. Clearly the catharsis of fighting for what they believe is The Good is too powerful for these protestors to heed advice so mild as to ask them to reflect before they perform.

That's just it: these protestors are unmoved by comparisons to fascists or Nazis or even today's neo-Nazis, because they suppose that their commitment to antiracism is "right" in a way that Mussolini, Hitler and Richard Spencer are not. They think they're different.

That presents those of us who disagree with their tactics with a special challenge: to shut them down may give the appearance of condoning racism. That's a tough one, because antiracism is educated America's religion, in almost every sense of the term. It's a sign of the extent to which, contrary to claims such as Ta-Nehisi Coates', the Civil Rights movement transformed the moral and intellectual fabric of this country.

As such, the protesters are testing us in an unprecedented way. Can level-headed university administrators muster the moral courage -- and that's what it would be -- to start having the most vocal and disruptive of these modern-day hooligans physically removed from all such events? No protester should be injured in any way. However, they should be disallowed from shouting anyone down in the name of justice," even when that means protesting racism (or, shall I put it, "white supremacy"?).

To be sure, the protesters might make videos of the officers taking people away and blocking their re-entrance. Some encounters would go viral. For days. Maybe a week. And then, well, what?

Clearly the current situation, where a certain personality type will insist for the foreseeable future on making sure no one they find unsavory can even open their mouth near a microphone on campus, is morally and intellectually untenable. It makes a mockery of anything calling itself a university. Most of the perpetrators will shake their heads 20 years from now at their intellectually dim, recreationally theatrical, and just plain mean behavior.

Yet one senses real terror in the hearts of the people -- administrators and others -- who would be responsible for getting real about this new menace. In today's America, to be called a racist is almost equivalent to being called a pedophile. And too often, the term "white supremacist" is hauled out at anything but the most timid of questions about the hard-left line on race.

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critiques However, we might think of the spate of recent of Coates' work in mainstream outlets, until now rare to see beyond conservative organs. To criticize Coates has long elicited charges of "racism," but this time out, those have been countered by more robust debate addressing Coates' work as text rather than scripture. The world spins on, no one has lost their job. Might this be a model for those so afraid now of a vocal but unpopular minority of activists?

Not so long ago there were people who put themselves on the line by allowing themselves to be called all kinds of dirty names, in the name of Civil Rights. Life went on and got better. That's exactly what would happen if today's reverse fascists were shut down for good on campus after campus until the fashion passed.

As always, fostering a genuine culture of inquiry often requires not just politeness, but bravery.