“When danger reared its ugly head, he bravely turned his tail and fled.” —"Monty Python and the Holy Grail"

The open letter’s signatories read like a who’s who of the literate Left, from novelist Martin Amis to CNN talkinghead Fareed Zakaria. But what was most striking was the letter itself, which appeared in Harper’s Magazine last week and began, “Powerful protests for racial and social justice are leading to overdue demands for police reform, along with wider calls for greater equality and inclusion across our society, not least in higher education, journalism, philanthropy, and the arts. But this needed reckoning has also intensified a new set of moral attitudes and political commitments that tend to weaken our norms of open debate and toleration of differences in favor of ideological conformity. As we applaud the first development, we also raise our voices against the second.”

Since when have liberals, who founded the Free Speech Movement on American college campuses more than a half-century ago, felt the need to so vigorously defend a principle — open debate — that has long since been a fundamental part of American culture?

Well, ever since their side declared open war on it.

What began on our nation’s campuses as collegiate censorship of hard-hitting conservatives such as Ann Coulter and Ben Shapiro has since morphed into the heckler’s veto for anyone who dares express a viewpoint that departs from leftist orthodoxy. These days, not even doctrinaire liberals are safe from the college mob — to say nothing of serious scholars like libertarian Charles Murray, who was shamefully chased from the stage at Vermont’s Middlebury College back in 2017.

“The free exchange of information and ideas, the lifeblood of a liberal society, is daily becoming more constricted,” the Harper’s letter continues. “While we have come to expect this on the radical right, censoriousness is also spreading more widely in our culture: an intolerance of opposing views, a vogue for public shaming and ostracism, and the tendency to dissolve complex policy issues in a blinding moral certainty. We uphold the value of robust and even caustic counter-speech from all quarters. But it is now all too common to hear calls for swift and severe retribution in response to perceived transgressions of speech and thought.”

Translation: We on the Left are increasingly being threatened by the culture we created.

Indeed, rather than calm the canceling crowd, the letter merely egged them on. As National Review’s Jim Geraghty noted, “Vox contributor Emily VanDerWerff wrote a letter to Vox management — and publicly posted it for all the world to see — that the decision of her colleague, Matt Yglesias, to sign the letter ‘makes me feel less safe at Vox and believe slightly less in its stated goals of building a more diverse and thoughtful workplace.’”

When a lefty like Matt Yglesias isn’t sufficiently woke enough, free speech is really on borrowed time. But perhaps most telling about the intolerance on the Left is what author and letter signatory Jennifer Finley Boylan did when she started taking heat for her principled stand in support of free speech: She retracted her signature, because she wasn’t comfortable with some of the other names on the letter.

We can’t make this stuff up.