As Peter Oborne will remember, because we’ve both been journalists for a long time, a couple of glorious front pages appeared in The Guardian last century. The paper’s splash headline in 1996 about litigious government minister Neil Hamilton contained only five words: “A liar and a cheat”. This was overtopped the following year with a six-word splash on Jonathan Aitken, another dishonest minister who had sued the papers for libel in that sleazy government: “He lied and lied and lied”.

In those days, ministers who were found out lying to Parliament were doomed. The 1963 political fate of John Profumo, the war minister who unwisely denied having sex with Christine Keeler, was always reverentially quoted, and Erskine May, Parliament’s official bible, as Oborne records, spelled out the rule:

In that far-off past, the public accusation of lying, showing dishonesty and unfitness for office, was very shameful. Use of the L-word guaranteed any affronted British politician an easy win in a libel suit. The word terrified the lawyers advising any would-be publisher. And that was why we reporters at The Guardian made such a meal of it when, having got hold of legal proof, we were for once officially allowed to use the L-word on Hamilton and Aitken. (Revelling in its rare potency, we even titled our subsequent book on Aitken 'The Liar’.)

But how things have changed! This book of Oborne’s now vehemently calls the prime minister a liar on almost every page, in great detail and in the most brutal terms. Here’s a typical Oborne remark: “He [Johnson] lies habitually, with impunity, and without conscience.” And our author calmly speaks of “Johnson’s record as a liar, charlatan and cheat”.

In the old days, Johnson too might have been expected to sue for libel over this stunning level of personal abuse. But instead, something has happened which is difficult to understand. The word 'liar’ has lost its potency. Johnson doesn’t seem to care if he is called a liar, just as he doesn’t seem to care about telling the lies in the first place. In the political arena, whether something is a lie or not seems to have become less relevant.

Back in those old days, the parliamentary bar on downright lying by ministers was important. It functioned rather like a set of chocks under the wheels, one of the restraints helping to stop the dodgy vehicle of British politics careering away into a swamp of idiocy and corruption.

Nowadays, however, the chocks seem to have been pulled away. Johnson is able to say what he likes with impunity. When Labour leader Keir Starmer challenged the prime minister on the homicidal early advice to care homes that their inmates shouldn’t worry because they were unlikely to get COVID, Johnson riposted: “It wasn’t true that the advice said that.”

But it did say that. Oborne notes: “Starmer has since asked Johnson to return to the House to correct the record. The prime minister has failed to do so.”

Behaviour like this by Johnson is on a relatively small scale: Donald Trump has simultaneously crowned his own career with the genuinely breathtaking false claim that he did not lose the 2020 US presidential election, but indeed won it by “a landslide”. People died in the ensuing riot. Johnson has not gone so far (yet). But the alarmingly successful populist techniques of the two politicians are similar. It appears from Oborne’s lengthy indictment that both of them lie quite openly and do not care if their lies are found out.

Probing this paradox, Oborne sails into, however, less charted waters. Why is power nowadays going to these clownish entertainers with no morals? He searches around for the reasons why democratic mechanisms in apparently advanced countries have become so corroded, and he rather veers off into blaming much of it on a conspiracy between right-wing political journalists and the formerly Dominic Cummings-led spinners at Number 10.

This is understandable. Exposure of the sordid behaviours of lobby journalists and proprietors is a cause close to Oborne’s heart. He struck a blow for morality at The Daily Telegraph by revealing its unscrupulous deference to big advertisers; and he has, he says, blown up his own mainstream career as a Tory columnist by detailing to openDemocracy the way his former pundit colleagues at the Mail group and elsewhere are prone to prostitute themselves for political “access”. I’m sure he’s right that the infiltration of Downing Street by the belligerent and radical Brexiteer crowd has led to a greater unattributable outflow of lies and smears than usual.

But history suggests that the temptation to political lying, especially during British election campaigns, is not a new one: I don’t suppose Winston Churchill really thought that the Attlee government of 1945 would set up a Gestapo, but that didn’t stop him making the false claim to the voters. Nor did it stop the then highly influential Daily Express from boosting that nonsense to its readers on its front page.

The real development has not been that politicians have started to lie. It is, it seems, that they have ceased to be ashamed of lying. One possible explanation for this degeneration, of course, could merely be that when old-style Fleet Street scribblers like Johnson get power, they bring with them their irresponsible habits of slinging together any old malarkey to get past a looming deadline and shift a few copies of their paper off the news stands. To them, it’s all a game.

But I think the problem goes deeper than that. As Oborne says: “The fact that Boris Johnson made it into 10 Downing Street ultimately tells us much more about the rest of us than about him.”

Despite all the glib talk of internet connectivity, voters actually have very little idea of what’s going on in the real world. We get nearly all our ways of evaluating political candidates from seeing them on video and TV. But TV is only a simulacrum of reality – and as anyone who has worked professionally in TV will tell you, that simulacrum is fake. As a result, we’re all suckers for celebrities these days: we like people we have seen on TV. We imagine naively that we are connected to them and we know their natures. But we don’t.

What is certainly new is that a tribe of PR spinners, political operatives and psychologists are finding increasingly sophisticated ways to manipulate us, these naive people. I was illuminated by Oborne’s book pointing me to the fascination Boris Johnson’s one-time chief adviser felt for the manipulations of Willi Münzenberg, the shadowy chief propagandist of the pre-war Communist Party of Germany and architect of the Comintern, the Soviet-controlled international organisation that promoted communism worldwide from 1919 to 1943.

Dominic Cummings, before he became the prime minister’s would-be Rasputin, wrote that Münzenberg dazzled the intelligentsia, was “frighteningly effective” and “the most brilliant propagandist”. His techniques were the basis of most modern PR, said Cummings. And chief among them was that even educated people “tend to get their political views from feelings, mood, Zeitgeist and fashion… It is a mistake to think that the better educated are ‘more rational’ in their political analysis; often they are less rational.”

He went on, somewhat sinisterly: “Much of the techniques of Soviet propaganda… rely on one principle – how to overwhelm reason and humans’ capacity for objective analysis.”

According to Cummings, in other words, as far as the successful propagandist is concerned, it is more important for people to feel like “one of us” than to have regard for actual facts.

Now add to this basic Cummings approach the other key psychological elements in the modern political operative’s toolbox – the invention of imaginary enemies; the concoction of scientific uncertainty where none exists; the doubling-down when challenged – and you have a powerful means of stirring people up and sending them in the direction you want them to go. It becomes irrelevant that lies are being told.

Oborne puts it this way: “At the heart of the new politics is the nightmare assumption that emotion is more important than thought.”

I fear that he needs to face up to it: this state of affairs is certainly a nightmare, but it is not just an assumption. Emotion is indeed so much more powerful a political force than mere facts, and the reign of Johnson is therefore not going to be stopped by calling him a liar. He needs to be combatted not by truer facts, but by better, more decent, emotions.

'The Assault on Truth: Boris Johnson, Donald Trump and the Emergence of a New Moral Barbarism’ by Peter Oborne is published by Simon & Schuster UK