Baltimore burns, shops are looted, rioters attack firefighters with bottles and bricks. And amid all the violence and ruin, what drives the chattering class into a froth of indignation? That anyone would use the word “thugs” to describe the vandals and criminals reducing Baltimore to rubble.

As berserkers ran amok Monday, the city’s mayor, Stephanie Rawlings-Blake, deplored the destruction: “Too many people have invested in building up this city to allow thugs to tear it down.”

That set the hounds baying. Rawlings-Blake was accused of using a racial slur. Baltimore City Councilor Carl Stokes angrily told CNN that calling rioters “thugs” is just like calling them the N-word. The Rev. Jamal Bryant, who delivered the eulogy at Freddie Gray’s funeral, repeated the accusation: “ ‘Thugs’ is the 21st-century word for the N-word,” he said Wednesday, “and it is repulsive and it is offensive.” Wale, the popular Washington, D.C.-based rapper, told Baltimore teens that Rawlings-Blake owed them a direct apology for saying something so “stupid.” Others piled on.

It didn’t take long for the mayor to surrender. “We don’t have thugs in Baltimore…. We have a lot of kids that are acting out,” she told a group of church leaders. For good measure, she blamed her “little anger interpreter,” pointing to her head in self-abasement. There was more apologizing online. “I wanted to clarify my comments on ‘thugs,’” she tweeted. “When you speak out of frustration and anger, one can say things in a way that you don’t mean.”

So now in Baltimore, which has the nation’s seventh-highest violent crime rate, the nonracial word “thugs” is banished as racist — even when spoken by a black mayor. Thus the degradation of the public discourse proceeds.

Meanwhile, Rawling-Blake’s forced walk-back was nothing compared to the self-mortification of Ian Reisner and Mati Weiderpass, two gay hoteliers in New York who hosted a small reception for Senator Ted Cruz on April 20. The business partners, longtime backers of gay-rights causes, strongly disagree with Cruz on same-sex marriage, but share his views on foreign policy. They invited a dozen guests to meet the Republican presidential hopeful over dinner for a discussion of politics. Apparently they were under the impression that in America it is permissible, even admirable, for voters to talk to politicians, exchanging thoughts on a range of issues.

They know better now.

Reisner and Weiderpass were savaged for having hosted the dinner for Cruz. Activists organized a boycott of their hotels, threatening to “shut the place down” as punishment for talking to the enemy. Within days, the businessmen were begging for mercy, berating themselves as if they were inmates in a North Korean slave-labor camp, forced to confess their crimethink in public.

“I am shaken to my bones by the e-mails, texts, postings and phone calls of the past few days,” groveled Reisner on Facebook. “I made a terrible mistake. I was ignorant [and] naïve…. I sincerely apologize for hurting the gay community and so many of our friends, family, allies, customers, and employees. I will try my best to make up for my poor judgment.” Weiderpass followed suit, flagellating himself for a blunder that may have “nullified” his 20 years of supporting gay rights.

More and more, this is what the marketplace of ideas is turning into. The ruthless determination not just to silence opposing points of view, but to humiliate and crush even allies willing to hear an opposing point of view, violates every liberal principle of tolerance, reason, and dialogue in the public sphere.

The language police in Baltimore and the auto-da-fé of Cruz’s dinner hosts are but two fresh examples of a phenomenon rising all around us. Commencement speakers are disinvited from college campuses. Mozilla’s CEO is forced to resign over a donation made years earlier to a ballot campaign supporting the traditional definition of marriage. Hillary Clinton declares that abortion rights must be defended with the “political will” needed to change “deep-seated … religious beliefs.” Speech codes and “trigger warnings” are deployed to enforce a spurious — but expanding — right not to be offended or disturbed.

Increasingly, the censors and silencers are at work, stifling ideas, demonizing speakers, ostracizing open-mindedness — decreeing even certain words beyond the pale. It is a dangerous, illiberal, antidemocratic trend. If we don’t rouse ourselves to reverse it now, we may never get the chance.

Jeff Jacoby is a columnist for The Boston Globe.