In the early months of 2004, a Harvard student called Mark Zuckerberg got so drunk, he tripped over a coiled snake of cables in his dorm room, smashed through his ground floor window and ended up face down in the wet grass, whereupon the girl he had admired came round the corner, arms linked with her friends, who, all three, had to step over the fallen norm-core future billionaire before he puked on himself. It was, Zuckerberg has noted, the most humiliating moment of his life.

None of that is true. But what does it matter? We are fully ensconced in the post-truth world. The greatest editor this paper ever had, CP Scott, had it that “facts are sacred”. CP Scott, by the way, apparently used to have this thing where he brushed his teeth a certain way so the flecks of toothpaste would make a rude shape as they hit the bathroom mirror.

Zuckerberg has said: “Personally, I think the idea that fake news – of which it’s a small amount of content – influenced the election is a pretty crazy idea.” Let’s address these comments. Comments that were made using the method of letters written on A4 cards lit up by fairy lights, a la Stranger Things.

The influence of verifiably false content on Facebook cannot be regarded as “small” when it garners millions of shares. And yes, it runs deep. The less truthful a piece is, the more it is shared. In Zuckerberg’s follow-up statement, he seems to have shot himself in the foot, by saying it was “extremely unlikely” fake news on Facebook had an impact on the election, but also boasting that Facebook was responsible for 2 million people registering to vote. So which is it, Zuck? Does Facebook have influence or not?

Where do these stories originate? Well, some are created by teenagers in Macedonia. That isn't a joke

Where do these stories originate? Well, some are created by teenagers in Macedonia. Wait, that one isn’t a joke – non-partisan kids looking for cash just catering to demand. Many more come from people we now term the “alt-right”, who cook up stories on boards such as 8chan, 4chan and social media, and are then co-opted either by genuine right-leaning sites or shill sites, and are then shared again on social media by accounts with Pepe the Frog or eggs as their avatars. It’s a bit like the water cycle, but if the water cycle were diarrhoea.

Some of these stories are frankly ridiculous (myth busted: Hillary Clinton is not the leader of an underground paedophile ring), and cater to an increasing number of conspiracy theorists. But others are relatively benign if wildly inaccurate. They have still begun on message boards created by the same people who – and I will not sugarcoat this – refer to people who are not white as “shit-skins”.

A better term for many of the alt-right, therefore, might be “far-right”. For “alt-right” is an ambiguous term and encompasses many forms. Sure, they are internet-savvy millennials who reject mainstream conservatives and despise Paul Ryan. But they’re also far-right lurkers who probably bid on Nazi memorabilia and have moved from white supremacist sites such as Stormfront. Then there’s the Russian faction; online commenters bought in bulk. And on social media, there are the bots and sockpuppet accounts to inflict automated insult to injury.

But let’s be clear: the internet alt-right is more successful as an In Real Life political force than the online left. Years ago I wrote about how filter bubbles and Facebook likes did not translate to direct political change. And yet, in 2015, I was writing about whether Trump’s social media strategy would take him all the way to the White House.

A Trump protester (left) arguing with a Trump supporter who repeatedly slapped his hands in Miami. Photograph: Ian Witlen/RMV/Rex Features

Things have changed, at least for the right. The silent Trump vote? Many board discussions in the lead up to 8 November advocated this as a strategy. In fact, alt-rightists worried sometimes that Trump’s rhetoric was too strong, and might jeopardise his chances. They had a gameplan. What the alt-right collective does is the opposite of trolling. Trolling – a term misused often – originally referred to winding people up for the “lulz”. The alt-right had an end game; it wasn’t for the lulz, and, unlike the left’s efforts, it extended to snaring the general electorate.

Unfortunately, the left cannot combat this online rise of the right, of fake news and social media vitriol, without the help of tech companies. The problem is, to use ex-Twitter CEO Dick Costolo’s term, they “suck” at it. Twitter is a company whose abuse problem might have been the reason nobody would buy it.

Facebook, meanwhile, like a child standing over a broken vase declaring that he didn’t break the vase and that the vase isn’t broken and also, what vase, continues to maintain that it is not a media company. This, despite the fact that 66% of Facebook users get news from the site. If that isn’t a media company, then what is?

The friction here is that if one says that companies such as Facebook and Twitter need to make editorial judgments, then people shout censorship. Except that, well, Facebook already censors. Instagram, owned by Facebook, removes any photograph with a female nipple in it (although if you run it through the Prism app so it looks like a painting, that’s fine). Thanks to this policy, Facebook removed one of the most famous journalistic photographs of all time. Twitter removes Isis propaganda videos. All journalism, if it’s a decision of what to publish and not to publish, of what stories are worth pursuing and which aren’t, is, if you want to call it such, censorship. Anything else is stenography.

Getting better at social media and online activism (previously disparagingly known as clicktivism) is imperative at a time when trust in mainstream media is low. To rebuild that trust is partly down to the media itself: by diversifying for a start, becoming more reflective of demographic makeups. But also, sensible citizens should fight back online. Don’t just read sources that align entirely with your worldview, but equally don’t indulge bullshit. Question sources. Read closely. No, a picture that clearly shows the Champions League Liverpool winners from 2005 is not a Jeremy Corbyn rally in 2016. No, Corbyn is not dancing at the Cenotaph. No, that picture widely shared of a disgruntled looking bunch of White House staffers was not them watching Obama greet Trump. But a retweet is a retweet is a retweet.

We now have, in Stephen Bannon, a chief of strategy to Trump who has overseen, as executive chairman of Breitbart, articles such as “Birth control makes women unattractive and crazy” and thinks nothing of building a whole piece on casual antisemitism. We have a president-elect who penned in journalists at his rallies, has continued to goad the press even after his election win, and who has history of threats against journalists. Yet his team ran a highly successful social media operation, which took advantage of targeted Facebook ads and scooped up millions of email addresses in the process.