“I’ve given up watching the news,” said the man in the other room. “It’s all lies.”

We were both in a hi-fi shop in Bath – me immersed in an arcane conversation about amplifiers, while he asked for help with his internet-enabled flatscreen television. He was sixtysomething, with the look of someone being endlessly annoyed by the world, or what he saw of it. These days, he said, all his information about current affairs came from online videos. What, I wondered, was he watching? Claims of faked bombings in Syria? False warnings about the dangers of vaccines? Or labyrinthine theories about the global cabal intent on stopping Brexit?

Here, it seemed, was an example of something self-evident but also endlessly overlooked: the fact that, as our Darwinian economy has pushed various parts of society apart, the most bog-standard technology has even further eroded the common ground that the most basic notions of democracy – and even civilisation – depend on.

YouTube, along with the usual social media platforms, is hardly the only problem. Last week Channel 4’s chief executive, Alex Mahon, gave a speech at the Royal Television Society that was focused on the increasing power of such streaming services as Amazon Prime and Netflix. “The global telly of the future will not be – and isn’t being – designed to reflect Britain back to itself, to bring the nation together at particular moments, to inform and educate a particular society or to care about promoting any kind of social cohesion,” she said. Put the kinds of media together, and things look bleak: if we’re not careful, people will soon be watching hopelessly partisan outlets for questionable “news”. Meanwhile, politicians will rejoice in the fact that the traditional media they often encourage their supporters to loathe – with its insistence on long interviews, and something approaching proper scrutiny – will at last be only a marginal part of the political game.

A Facebook post by the prime minister on 14 September.

As evidenced by the Tories’ frantic electioneering on Facebook, the supposedly looming election looks set to mark another big step into this new world. Meanwhile, as these changes gather pace, some people in the established media already seem so terrified that they have reduced their old obligations to report, explain and enlighten. Instead of giving a sense of what is actually going on in the world, too much current affairs broadcasting now consists of online agitators yelling at each other in person, while some high-profile presenters regularly join the crowd of belligerents. So long as some kind of balance is maintained, the veneer of what used to be called public service broadcasting might be just about sustained. Up close, it is nothing of the kind.

Which brings us to Brexit. The idea that the referendum of 2016 could have settled the questions it was designed to answer – not just about our membership of the EU, but also what kind of country we collectively wished to be – is now so laughable as to seem completely absurd. Clearly, it did the absolute reverse: thanks to our polarising mediascape and the UK’s awful inequalities and imbalances, it simply hardened the division between a broadly liberal constituency and a coalition of people from both post-industrial places and more wealthy areas who have a more conservative, nationalistic view of the world – and then gave each camp a word to describe itself. Three years on, the gap between hardcore leavers and remainers is still widening. If there is any hope, it lies with the weary millions who sit somewhere in the middle, but they still seem too disengaged to make their voices heard.

“Bringing the country back together” is the political cliche of 2019. But in the midst of all the polarised noise, just about every mainstream political response to the Brexit crisis looks like it will either further our divisions, or leave things much as they are. The Tories’ embrace of the headless politics of no deal, coupled with the picking of fights clearly designed to show they mean it, is by far the most egregious example. By way of a mirror-image, the Liberal Democrats’ new belief in ignoring the referendum result simply encourages the most partisan remainers to rejoice in division and self-righteousness. Labour’s belated offer of a second referendum – with, if Jeremy Corbyn gets his way, the party’s position to be decided by a “special conference” some time after the election – is probably the best thing on offer. But does anyone seriously think that another referendum campaign and a public vote would really settle the furies that Brexit has kicked up? In the absence of a no-deal option Nigel Farage and the Brexit party, using their online expertise, alongside Tory Brexiteers, would decry the whole thing as illegitimate. And whatever the result, the losing side would hardly be likely to go quiet.

There are flashes of hope, nonetheless. Travelling around, I see them in the nitty-gritty community initiatives that bring people together, and cut across the idea that we are all hopelessly estranged; in the new breed of town and parish councils that want nothing to do with ideological war, and spend their time patiently making improvements to places; in the droves of people who are unfamiliar with the latest Twitter controversy, and are keener to talk about their yearning for community and security. In that same spirit, we need more programmes like the BBC Two documentary series The Mighty Redcar, and less like Question Time. A lot of us need a renewed willingness to see things from the other side’s perspective, and rediscover the common humanity and acceptance of compromise that so often seems to be lacking from everyday politics. One obvious example: if you have stopped talking to a friend or relative because they voted leave, it is probably time you gave them a call. You could maybe have a conversation about whether – in the midst of all this chaos and strife – something like Theresa May’s original withdrawal agreement would really be that bad.

Perhaps, as some of Labour’s more devout supporters think, a Corbyn-led government might successfully get to grips with Britain’s basic problems and start to heal our wounds. Although, judging by the events of the weekend, putting those people in charge might threaten to add even more division and acrimony to the helping we have already.

If there is even the faintest chance of some kind of collective pushback against our growing culture of mutual loathing, it needs to begin with recognition of how it is sustained. When I talk to people with the most passionate political opinions, I often have the feeling of moving between different universes. One question is always obligatory: where do you get your information? In response, more and more people reach for their phones, open YouTube, Facebook or Twitter and show a tweet or meme that has reaffirmed their prejudices and added to all those northern Californian fortunes.

In 2017 Mark Zuckerberg said his company’s mission was to “give people the power to build community and bring the world closer together”. Even in an age of such rampant absurdity, that is surely among the most ridiculous things anyone has ever said.

• John Harris is a Guardian columnist