With the values of a diverse liberal democracy under assault at home and abroad, it's surprising that there is still the bandwidth to be outraged by seemingly self-evident statements like this: "The way to defeat bad ideas is by exposure, argument, and persuasion, not by trying to silence or wish them away."

That line, from a now-infamous letter on justice and open debate, published in Harper's Magazine and signed by 153 prominent journalists, authors and academics from across the political and demographic spectrum, provoked a firestorm of condemnation on social media. The accusations ranged from "bad timing" to the privilege of the signees that flowed from their prominence to the alleged transgressions of a few individuals against current woke wisdom to assign guilt by association to the whole group. As co-signatory and legendary leftist Noam Chomsky pointed out, "The nature and scale of the reaction reinforce the message of the letter."

Less than two weeks after the Harper's letter published online, New York Times opinion writer Bari Weiss released a searing resignation letter, in which she detailed what she called an increasingly "illiberal environment" at the paper. That same day, New York Magazine announced it was parting ways with columnist Andrew Sullivan. Their departures were greeted with a chorus of good riddance, reinforcing a creeping intolerance to heterodox views in the allegedly liberal media.

These are not writers who have spilled ink defending President Donald Trump: both Weiss and Sullivan have repeatedly condemned the President as a threat to liberal democracy. But crucially they have also criticized the far-left identity politics they see rising in the wings. Weiss wrote extensively about anti-Semitism and Sullivan supported gay rights as an early advocate for marriage equality. But they have not let their identities predetermine all of their politics and they have been demonized because of these disagreements -- not just by the usual hate parade of trolls, bots and strangers on Twitter, but from fellow journalists. According to Weiss' resignation letter, some newsroom colleagues apparently took to office message boards like Slack as well as public social media platforms with smears and bullying calls for her dismissal. You don't have to agree with everything Bari Weiss or Andrew Sullivan have ever said to defend their right to say it and rebut their arguments with reason rather than something close to contempt.

Their detractors were loud, their defenders decidedly less so -- a typical feature of the social media distortion field. But in this, there is evidence of the core concern. In an era of social media, even some columnists who get paid to put forward thoughtful but provocative opinions are reluctant to wade into debates where they know social media mobs will attack. They already get plenty of hate from one side of the aisle. The anticipated backlash leads to hesitation, a degree of self-censorship and therefore a silencing of unpopular opinions -- even modest d