Was it Facebook 'wot won it'?

In the United States, newspapers take their responsibilities to the democratic process very seriously.

So seriously, in fact, that they can come across as rather pompous to a British reader. When it comes to a presidential election they seem to believe that their endorsements are of huge significance and that their words will be weighed with utmost seriousness by their readers.

Well now we know how wrong that is because just about every major newspaper either backed Hillary Clinton or at least failed to endorse Donald Trump - and that went for papers who had faithfully swung behind Republican candidates in the past.

Now both the newspapers and the rest of the mainstream media are waking up to the fact that their influence may be as nothing compared with that of Facebook.

In 1992, a British tabloid newspaper claimed that it was "the Sun wot won it" when the Conservatives pulled off a surprise election victory. In the United States, some are asking whether the social network pulled off the same trick for Mr Trump.

The argument goes like this. A total of 156 million Americans are Facebook members and, according to recent research, two-thirds of them get news on the site.

Now that news may often come from mainstream media outlets - perhaps from papers endorsing Mrs Clinton - but what you end up seeing will be determined by who your friends are and what they share.

That's where the idea of a filter bubble comes into play - those inclined to vote for Mr Trump will only see stories that reflect their view of the world and the same will apply to those of a liberal mindset.

Now you could say the same filtering has always applied - liberal people tended to read liberal newspapers, conservatives got their views reflected back in what they read.

The difference was that most editors have tried to do two things - present at least some alternative views and make sure that the facts in any story stand up to scrutiny.

Neither applies on Facebook. The News Feed algorithm serves you up whatever it thinks you and your friends want to believe and it certainly does not do any fact-checking.

Stories that accused the Clintons of murder or maintained that Barack Obama was a Muslim will have cropped up in the feeds of millions of people inclined to support Mr Trump.

This cuts both ways - a made-up quote from Mr Trump saying in 1998 that he might one day run as a Republican because "they're the dumbest group of voters in the country" is still being widely shared on social media by his opponents.

Both the Democrats and Republicans have long made ample use of Facebook - indeed it was the Obama campaign of 2008 that pioneered the use of social media in elections.

But for a Trump campaign that saw much of the mainstream media as hostile and biased, both Facebook and Twitter offered a powerful way of getting its message direct to voters unchallenged by any pesky journalists.

If Facebook or something similar had not existed, would Donald Trump still be heading for the White House?

That is hard to say but what does seem likely is that social media served to polarise views in what was already a bitter election and may have encouraged a few hesitant voters to come out for Mr Trump.

This makes Facebook's claims that it just a technology platform, rather than a hugely powerful media company with Mark Zuckerberg as editor-in-chief, look very thin indeed. But there are few signs that the company is ready to face up to this heavy responsibility or engage in some serious soul-searching.

On Wednesday, my colleague Jane Wakefield went to meet the company's chief technology officer Mike Schroepfer, who was on a visit to London. She asked him what role he thought social media had played.

Here is his extraordinarily unilluminating response: "It's hard to speculate. Our angle is that people can communicate and share what they want to talk about - that's what our endgame is."

Mind you, the editor-in-chief has shared some thoughts.

In a Facebook post adorned with a "feeling hopeful" emoji and a photo of him holding his baby daughter as he watched election coverage, Mr Zuckerberg told us that he'd been thinking about "all the work ahead of us to create the world we want for our children".

That apparently means "curing all disease, improving education, connecting everyone and promoting equal opportunity" and that will take a long time, and stretch beyond any presidency.

It was all very Californian, but the comment writers seemed to love it. "Thank you for your awesome comments and for being socially responsible leveraging your influence for good," was a typical response.

But no word of reflection from Mr Zuckerberg on how he had "leveraged" his influence over the way Americans understood the presidential campaign and whether its impact had been positive for the democratic process.

Media barons from William Randolph Hearst to Rupert Murdoch have sought to shape politics to their will. But they have revelled in their powers.

Mr Zuckerberg seems determined to pretend he is no more or less influential than any of his 1.6 billion readers sitting in front of the TV and watching the world change.