IT IS ironic that Facebook, to warn users about the problem of fake news, felt the need to resort to adverts in the old-style medium of print newspapers. Facebook now has almost two billion users worldwide. The UK has 32 million — far more than the combined readership of every newspaper in Britain.

So why newspaper ads? The global media giant had an ulterior motive.

Fake news has been in the public eye since the presidential election campaign in the United States. A fabricated story saying that Pope Francis had endorsed Donald Trump was shared almost a million times via Facebook. There were also bogus stories that Michelle Obama had filed for divorce because her husband had a pregnant mistress; fantasies that Hillary Clinton and her husband had killed to advance their political careers; and adverts advising dozy voters that Republicans should vote on 8 November and Democrats on 9 November (after the poll was shut).

An episode of BBC1’s Panorama this week revealed a more stealthy peril. The Trump campaign spent about $70 million using Facebook to target individual voters with “individual truths”. In the UK, the Leave campaign did the same before the Brexit vote, enticing trawlermen with the lure of changing EU fishing policy, and factory workers with scares about factory closures.

There are also long-standing complaints about Facebook’s tardiness in removing hate speech and terrorist propaganda from its website. Hearings by a House of Commons select committee on the problem have been mirrored elsewhere in Europe. In Germany, a law has been drafted to fine social-media companies as much as €50 million for failing to remove widely distributed fictitious stories, such as the one about male refugees who supposedly raped a German woman and threw her out of a car window. The lie went viral.

What has really motivated the Facebook newspaper ad is a fear of draconian crackdown by governments. The ads are actually targeted at politicians, which is why they appear in papers such as The Times and The Guardian rather than The Sun or the Daily Mail, whose readers are far more likely to be the gullible victims of fake news.

Research shows that people are more likely to believe stories sent to them by people they know than material they read in the mainstream media. What makes Facebook so clever for advertisers, and so dangerous for democracy is that it is driven by clever computer algorithms designed to present users with material similar to content that they have previously chosen. It thus presents to us a world which reinforces our own preferences and prejudices.

Now Facebook’s adverts throw responsibility for detecting fake news on to the reader. They justify that with their traditional insistence that Facebook is merely a platform rather than a publisher. When a quarter of the world is using it, that is no longer a persuasive distinction.

Facebook needs to be held accountable in the same way as the conventional media. But the British Government recently told newspaper editors that it is reluctant to do this. It seems that we might have to rely on the Germans. Now there really is an irony.