Propaganda is often employed by those unable to maintain control without resorting to falsehoods and the demonization of their opponents. Certainly Brexit, the election of Donald Trump, and various recent rightwing populist movements across the world have relied, at least in part, on alarming and false characterizations of “The Other” to gain the emotional allegiance of voters.

Again and again, the far right has proven itself ready and able to disrupt democracy with weaponized misinformation and hate speech. Those who believe in democracy have seen our devotion to free speech turned against us.

Now Facebook’s CEO, Mark Zuckerberg, in refusing to ban false political advertising from his platform, is in effect defending the far right’s approach. Zuckerberg has appealed to the principle of free speech; he says he does not believe a platform should regulate political content.

That argument isn’t very persuasive. Facebook is a private platform, not subject to first amendment protections. Every media platform – whether a TV station, newspaper or giant tech company, has a reasonable moral obligation to try to mitigate lies and propaganda.

The first amendment right to speak freely has never implied a right to have whatever you say published

There is one sense in which Zuckerberg is correct: giving governments the power to decide which speech is protected – and which isn’t – is a dangerous road. When exercised by the government, the power to censor is invariably abused by illiberal forces, such as Viktor Orbán in Hungary and PiS in Poland.

There is a middle ground, however. The government cannot and should not censor speech, but in many cases the private sector should. Reporters, editors and TV anchors have always made choices about what is published and what is not. The first amendment right to speak freely has never implied a right to have whatever you say published.

With the exception of propaganda outlets such as RT (Russia Today) and Fox News, the vast majority of western news outlets do work hard to filter lies and inaccuracies out of their content. In a new age where society’s traditional news function has been largely eclipsed by individual people self-publishing on social media platforms, there must be rules of the road. Private social media companies must regulate the content on their platforms – in part because the alternative, empowering the state to restrict speech, is so dangerous.

By calling out the dishonesty and racism of Breitbart and various Fox News hosts, grassroots outfits like Sleeping Giants have successfully pressured advertisers to desert those platforms. That is one way of getting things done. But how much better if the private media sector took steps like that proactively?

As long as it continues to abdicate responsibility for content on its platform, Facebook is a very real threat to civic society. In the meantime, Facebook users should remember: every time we log on, we contribute to the company’s bottom line – and add another nail to the coffin lid of democracy.