Along with international football, brown grass and flaming hillsides, political swearing has been an integral part of the summer’s zeitgeist. The protests against Donald Trump’s visit to Britain were exactly the carnivals of dissent that they promised to be: I went on the march in London, and had a great time. But the subsequent media coverage also brought a pang of ambivalence about a seemingly endless array of slogans that mixed profanity with what the modern vernacular calls virtue signalling, and looked like they were unwittingly playing the president’s game: “Piss off you orange twat”, “Fuck off Trump”. One particularly subtle placard simply read: “Prick” .

The Vortex: why we're all to blame for the nightmare of online debate Read more

The word twat became a signifier for the insane mess of Brexit when the actor and Wildean raconteur Danny Dyer used it to describe David Cameron, and was temporarily honoured as a remainer hero. (By way of an example of the kind of nuance we no longer seem to have time for, he actually voted leave.) When news first broke that the east London MP Margaret Hodge had confronted Jeremy Corbyn about Labour’s failure to meaningfully get to grips with anti-Jewish prejudice, initial reports – which she denied – said she had called him “a fucking antisemite and a racist”.

A few days before, a woman called Becca Harrison had found herself in the same cafe as the TV presenter and two-bit provocateur Piers Morgan, not long after his latest encounter with Trump. She consulted Twitter about the best course of action, and then told him that he was “a fascist-enabling cunt who’s doing serious damage to our country”. Morgan tweeted back at her with his customary charm (“I’d update your profile pic – been a few years hasn’t it ... ” he said), before she recounted the episode via the obligatory online article. It was Morgan, of course, who had co-interviewed Dyer, which highlights the strand of the supposed mainstream media that now runs on the basis of wind-ups, provocations and endless shouting.

What is going on here? One explanation might be that as a sizable part of the western world tumbles into crisis and serial assaults on basic liberal values, eloquence fails us, and an entirely justified rage takes over. But the story surely runs much wider than that, into a whole attitude of mind founded on the platforms via which we not only communicate but also understand just about every facet of our collective existence.

The only beneficiaries of online discourse are the billionaires who have built empires on annoyance and misanthropy

Put another way, if swearing, Nazi analogies, decreasing interest in other sides of the argument and a tendency to get lost in explosive rows now define an increasing share of political discourse, we all know where that change is fundamentally rooted. It begins and ends online – where, as the US tech pioneer Jaron Lanier puts it, the algorithms that decide whether something gets pushed towards prominence or is buried in the digital undergrowth are “neither liberal nor conservative … just pro-paranoia, pro-irritability, and pro-general assholeness”. (He swears, too.) The only real beneficiaries are the northern Californian billionaires who have built advertising empires on annoyance and misanthropy.

And all the time, the online world’s nasty atmosphere blurs into what remains of the orthodox media, not least the broadcasters who are often at the receiving end of all that online shouting. Long before the advent of Twitter and Facebook, radio and television had a seemingly innate tendency to favour opinion and argument over on-the-ground journalism. Talk is cheap; pundits and rent-a-gobs can fill 15 minutes of airtime for the price of a couple of cab fares and a bottle of wine in the green room. Once upon a time, there was presumably a convincing argument that irate phone-ins were an entertaining manifestation of the basic spirit of democracy; in the days when its audience displayed a little more mutual understanding, and the whole thing was not symbiotically joined to social media, even BBC Question Time could be thought of in the same way.

Clearly, the new political culture spawned by the internet has put all this stuff in a completely new context. Too often, a neurosis about impartiality has seemingly led the BBC to row back from its duty to establish the facts behind any given political conflict, pluck people from newspaper comment pages, social media or partisan websites, and merely give each side the chance to sound off. In pursuit of clicks, once-august programmes now mix together the arcane and outrageous (as evidenced by a trail for a recent item on Newsnight: “Why has Ukip taken up Tommy Robinson’s cause? We hear from leader of Ukip Gerard Batten”).

Elsewhere, Morgan’s interpretation of anchoring a discussion as a matter of venting his own prejudices while baiting this or that guest – which, to be fair, he shares with plenty of other hosts – is yet another example of the orthodox media offering no alternative to the white noise that emanates from the internet.

What are all these rituals of confrontation actually for? In the face of an audience that is constantly distracted by smartphone screens, what seems to count is the duty to try and create clips that turn into online memes, so that this or that programme can crash-land in as many news feeds as possible, and thereby justify its existence. The main casualty, clearly, is any coherent sense of what might actually be happening to the world.

For the political left, life in the age of fury inevitably throws up no end of tensions and contradictions. Even if their professed beliefs are comparatively benign, plenty of supposedly progressive elements are seemingly convinced that their struggle necessarily involves Twitter spats, pile-ons, and mass takedowns of that day’s chosen foe. As proved by the treatment of everyone from Hillary Clinton to such “Blairites” as Hodge, the harshest invective sometimes seems reserved for people who were once considered to be on the same side. The ageless dictum that progressives should “be the change you wish to see in the world” often seems to have died a death.

Besides, our degraded discourse chiefly benefits the very forces that the left wants to defeat. It is no accident that as the war of online shouting escalates, the world is being menaced by a gang of political players – from Trump and his former lieutenant Steve Bannon, to Nigel Farage and the irksome Brexit donor Arron Banks – whose shared project seemingly amounts to an attempt to explode the internet on a daily basis and thereby nullify meaning, sow mistrust and break as many things as possible, in the vague hope that some kind of nationalistic, small-state future might rise from the rubble.

But perhaps the biggest winner is what some people call neoliberalism, which can grind away even in its currently weakened state, while its supposed opponents are locked into a politics in which a handful of online factions – to pick a few at random, the “FBPE” crowd (it stands for “Follow back, pro-EU”), Brexiteers, the Corbynite left, irate centrists who seem to want it to be 1997 again – engage in loud combat, to no obvious end.

Too many of the people who want something better seem to have mislaid a pretty basic insight: that you find the key to a world beyond Trump, Brexit and our grim version of capitalism not by narcissistically shouting into the void and carrying a placard that says “Prick”, but grasping the deep reasons why so many people are all right with those things, and trying to convince them to think slightly differently.

Contrary to what you might hear online, to do so is not to surrender, but to honour a basic leftwing principle I once saw stitched on to a Welsh trade union banner: “Civility always; servility never”.

• John Harris is a Guardian columnist