Has politics entered a post-truth world? The idea that politicians are getting away with telling lies more than they used to has been boosted by the British vote to leave the EU and the American vote for Donald Trump.

I was struck by a phrase in Trump’s 1987 autobiography, The Art of the Deal. “I play to people’s fantasies … I call it truthful hyperbole. It’s an innocent form of exaggeration – and it’s a very effective form of promotion.”

Truthful hyperbole seems like a good description of “I’m building a wall”. He is not going to build a wall. “There could be some fencing,” he admitted two weeks ago, and about 700 miles of the 1,000-mile border with Mexico that isn’t river has already been fenced. But there is a lump of truth in there. He will make the border more secure, physically and by employing more border staff. He won’t make Mexico pay for it, but that isn’t the main thing for his voters.

The same goes for the Vote Leave claims, “Turkey is joining the EU” and “We send £350m a week to Brussels”. They were not true, but they weren’t without foundation. Turkey is never likely to join the EU, especially after the recent crackdown on human rights, but British government policy is still to support its accession. This has long been a polite diplomatic fiction, safe in the knowledge that France and other countries would veto it, but it is not wrong to say that Turkey is a candidate member.

And we don’t send £350m a week to the EU, we send £200m a week, which is still a lot of money. Dominic Cummings, the strategist of the Leave campaign, continued to use the £350m figure precisely because Remainers so furiously denounced it as wrong, drawing attention to the truthful bit of the hyperbole.

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This was similar to Trump’s tendency to “double down”, in the American phrase, when challenged over his claims, thus magnifying the attention given to messages that were popular with precisely the groups that would give him victory in Florida, Pennsylvania and Ohio.

Incidentally, the “truthful hyperbole” phrase wasn’t really Trump’s. It was written for him by Tony Schwartz, ghostwriter of The Art of the Deal. If you think about it, “hyperbole” is not really the kind of word Trump would use.

“I put lipstick on a pig,” Schwartz said in a remarkable interview with The New Yorker in July. “I feel a deep sense of remorse that I contributed to presenting Trump in a way that brought him wider attention and made him more appealing than he is.” Having spent time with Trump to prepare for the book, Schwartz is scathing about the President-elect’s suitability for high office: “Lying is second nature to him.”

But did Trump win because of a change in politics or the media that meant his untruths were more likely to be believed? Did fake news sway it for him? I doubt it.

An account of how fake news is produced was published on Wednesday by National Public Radio. It traced the origin of a fictional news story, “FBI Agent Suspected In Hillary Email Leaks Found Dead In Apparent Murder-Suicide,” published four days before the US election and shared on Facebook half a million times.

It tracked down Jestin Coler, who ran the fake news site that produced the story, and described his extraordinary “factory” of 20 to 25 people who write made-up news in return for the advertising revenue generated by clicks on Facebook.

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A Democrat, he got into the business, he said, as a way of baiting Trump supporters because they were gullible enough to share untrue stories as long as they fitted with their world view. “Coler says his writers have tried to write fake news for liberals – but they just never take the bait,” NPR reported.

This suggests that, if there is such a thing as post-truth, then it is not symmetrical. The Clinton campaign may have indulged in some “truthful hyperbole”. Her promise of “debt-free college”, for example, may not have been quite what it sounded.

But on the whole she was more scrupulous about the truth than Trump was. In part, this was because she ran out of libels. She called him a misogynist xenophobe who was close to the nation’s historic enemy Russia, but that was all true and it still didn’t put enough people off.

Did the fake news industry hurt her, though? Actually, I always thought that one of the stories that did damage her, the private email server, was, er, trumped up. But that was a “mainstream media” story based on facts. Coler says his fiction factory didn’t help Trump to win. All he did was to exploit the credulity of people who were already Trump supporters. And I think he is probably right.

There has always been a market for fantastic stories and conspiracy theories. I remember an English-language so-called newspaper in my childhood in India that used to enthral me with tales of children reared by animals, meetings with aliens, miracle cures and returns from the dead, all presented as true.

Elections have even been swayed by fake news in the past: the Zinoviev letter in 1924. And nor are such fables confined to the right. Just look at the way Jill Stein, the Green candidate in the US presidential election, is raising money to challenge the results on grounds of conspiracy theories about electronic voting machines.

I don’t think that untruths are more prevalent than they used to be. It is possible that people are better connected to other people who share their views, and so untrue stories might circulate faster.

I think most people are better informed and better equipped to assess news than ever before, but that there are also larger pools of self-sustaining “newsiverses” online that allow people with shared beliefs and shared hostility to conventional, establishment assumptions to reinforce each other.