There are many important, principled arguments for free speech. But one of the most convincing is purely tactical. Why empower the powerful to police debate when that power could so easily be wielded against you in the future? The logic of censorship always leads to more censorship, and the authoritarian left is starting to bear some of the brunt of this.

Last Friday, the Socialist Workers Party announced it had been booted off Facebook. In a press release, it said Facebook had suspended the party’s main account as well as those of activists and local SWP groups. After a backlash, its main page was reinstated but, according to a follow-up statement, ‘dozens of SWP activists and local branch pages remain suspended’.

The SWP said Facebook’s censorship ‘amounts to a silencing of political activists’. Which is true. Facebook, Twitter and YouTube, in particular, constitute the new public square. Allowing these unaccountable corporations to police debate and discussion on their platforms amounts to a grave threat to free speech and democracy in the 21st century.

That said, when it comes to ‘silencing political activists’, the Socialist Workers Party also has form. Indeed, it was one of the pioneers in Britain of ‘No Platforming’ – a tactic on the activist and student left, originally designed to deny the far-right opportunities to speak in public, that has since ballooned to encompass more and more groups and individuals.

On this front, the SWP’s brush with Big Tech censorship seems not to have sparked even a moment of self-reflection. When Nigel Farage tweeted about the case, saying ‘Maybe this will teach the radical left a lesson about censorship’, the SWP made clear it hadn’t learned its lesson at all. ‘Jog on you racist bigot’, it said. ‘Free speech is not about your right to push Islamophobic, racist propaganda.’

In the US, the most pro-censorship sections of the left are similarly becoming the targets of censorship. Last week, Twitter suspended several popular accounts linked to Antifa, with a combined reach of 71,000 followers. Antifa, short for ‘anti-fascist’, is a loose association of groups known in recent times for brawling with hard-right Trump supporters.

Over time, Antifa’s definition of fascism has become increasingly elastic. This month, Antifa activists in Portland demanded a bookstore pull a book about Antifa from sale. Its author, conservative photojournalist Andy Ngo, has also been physically attacked by Antifa for documenting its tactics. Anti-fascism, it seems, now means burning books and crushing opposition.

Those on the more respectable illiberal left have also been hit by a censorious climate they have at least tolerated in the past. Will Wilkinson, a vice-president at the Niskanen Centre and writer for the New York Times, has mocked the idea that cancel culture is a big issue. He was fired by the Niskanen Centre last week, reportedly for tweeting, in jest, ‘If Biden really wanted unity, he’d lynch Mike Pence’.

Real radicals, rather than the overgrown student union types who pass for radical these days, have always recognised the importance of defending freedom even for those we hate. As Thomas Paine put it: ‘He that would make his own liberty secure must guard even his enemy from oppression; for if he violates this duty he establishes a precedent that will reach to himself.’

Censorship isn’t just morally wrong, it is tactically stupid. But the authoritarian left is apparently refusing to learn that lesson, even as the censors close in on them.