It was clear the Facebook boss was being disingenuous – either to his audience or himself. Because he is indeed a media tycoon. The most powerful there’s ever been. Facebook's billions of users spend an average of 50 minutes a day posting material and interacting with online friends. Because of this, it’s also where we get our news.

How this works is that if you've "liked" a particular news organisation, you'll see the stories it has posted, or that your friends have chosen to share. Except you don't. Unless you actually visit its page, you won't see everything it posts – just the stuff that Facebook calculates you will enjoy most.

That may mean that the worthy story about atrocities in Syria gets ignored in favour of a hilarious cat video – or, indeed, that a story about those very atrocities containing explicit images is flagged up as containing inappropriate content.

This is what happened in the recent Norwegian case when Facebook censored the iconic Vietnam war photo featuring a naked child because it violated the site's "community standards". The almighty hand of Zuck reached down and plucked out an item that offended it – even though that item happened to be one of the most powerful pieces of photojournalism of the 20th century.

The decision to take it down, whether made by human or algorithm, was bone-headed – as was the decision to suspend the account concerned after its owner protested, and to delete protest posts by other users including Norway’s prime minister. Even though the decision was reversed, it crossed the line.

Facebook has effectively annexed, and privatised, the public square. That is a position of terrifying responsibility – perhaps for Mark Zuckerberg above all.

Robert Colvile, The Telegraph