The ability to tell stories, it is said, is one of the qualities that differentiates humans from other animals. Stories have brought us extraordinary riches – Homer, the gods (or God), perhaps even evolution: would we have left Africa without a story of destiny, greener grass or just curiosity about what lies beyond the next hill? It’s through our ability to connect utterly different elements – a butterfly’s wings and a hurricane, say – to form a narrative that we make sense of the world and allow ourselves to feel that we are in control of our lives.

But storytelling also has a darker side, as an absorbed audience heard at a February forum organised by The Foundation devoted to that complicated subject. The human-ness that allows us to recognize – or invent – a good story also inflects the way we receive it. All too often stories lead us to terrible places. In a minor key, actor Mark Rylance relates how at the Globe theatre he was forced to throttle back the famous call to arms in Shakespeare’s Henry V when he realised the frenzy of anti-French hostility he was whipping up in the groundling audience. For the real-life consequences, think no further than the Inquisition, National Socialism, or Isis.

Yet the potency of storytelling takes on an added importance today, in an age that has been widely characterised as ‘post truth’ – an age of fake news and ‘alternative facts’, where our natural inventiveness on one side and gullibility on the other are sometimes supplemented by deliberate manipulation by ever more sophisticated technological means. To such a degree that, as one Forum speaker, satirist John Morton, put it, stories become all that we have, in the sense that, in the absence of absolute truth, ‘we think, okay, we live with a collection of competing narratives, that’s all we have to sustain us’.We no longer accept to have ‘truth’ curated for us by the church, the mainstream press, or the political parties. We have had enough, Michael Gove said, of experts. So which, or whose, stories are we to privilege? How do we know which to trust and which to dismiss?

And here’s the rub. As humans, the speakers noted, we respond to stories not with Enlightenment-style logic and rationality, but with a very human logic in which ‘facts’ and ‘evidence’ are just the instruments that get us from A to B, B being the place that our emotions have already decided that we are going. As story-telling coach (and comic) Tom Salinsky compellingly showed with the example of the first and last voyage of the Titanic, the irresistible appeal of stories is fuelled by the combination of a few relatively simple components: an unexpected event or paradox – an unsinkable ship that sinks, in this case compounded by the fact that it was on its maiden voyage (you couldn’t make it up); a dramatic immediate cause (the iceberg), hiding a deeper hidden one (hubris, or human folly); and a poignant human hook (the band played on as the ship sank). What changes the account from an encyclopedia entry to a story is, first, the human hook, which plays to the overriding importance of emotion in our responses, overriding reason in the process of decision-making almost every time. ‘The factual stuff is necessary to provide the context, but it’s that moment of emotional catharsis that we remember and that moves us,’ said Salinsky. ‘That’s what gives stories their power, and why also they’re potentially so dangerous’.

The second essential feature is cause and effect. ‘Cause and effect is what stories run on – without it there isn’t a story’, Salinsky noted. No accident, then, that identifying cause and effect is the central quest of much of literature, including the entire genre of detective fiction.

Directly causal connections are of course much harder to establish in social and human affairs than it is in the physical world. Hence the flourishing of fake news, poisonous rumour and conspiracy theories which in turn augment the violence of political or ideological arguments, or assertions – about Brexit or Trump, for example – that rapidly colonise the truth-free space and crowd out less extreme interpretations. Both of these are extraordinary illustrations of the power of a good narrative (‘Make America great again!’, ‘Take back control!’), whether real or imagined, to trump mountains of earnest but story-less facts and figures. Less obviously, both, as Morton pointed out, are classic examples of stories escaping control and developing lives of their own, independent of their makers. He cited the ‘humiliating’ authorial experience of having characters or story-lines refusing to follow the course allotted to them in the outline. But it wasn’t just that stories could take you to a destination you didn’t intend – nor could you control how they landed in and interacted with the real world, sometimes even altering it in their own image, as, arguably, in the case of political satire: what started out with the relatively benign Spitting Image ended up with the scabrous The Thick of It, in which all politicians are duplicitous, stupid or borderline criminal. ‘So I’m wondering,’ said Morton, ‘whether one unintended consequence of the satirical brilliance of The Thick Of It when it got out into the real world was that it was one of the causal factors in the kind of mad, terrible world we live in now’.

Some part of the problem may be epistemological. As the Danish philosopher Søren Kierkegaard famously noted, while life is understood backwards, it is lived forwards. The only way the realities of a present life can be force-fitted to a destination decided in advance is by doing violence either to one’s own beliefs or those of others. This may help explain why we live in what might be called, as in the title of a recent BBC Radio 4 series, ‘the age of denial’. Life contains so many unspeakable, awful things that we can’t individually do much about – climate change, plunging biodiversity, exclusion, slavery, child abuse – that the only way we can deal with them is to blot them out. Complicating matters, blotting out the unacceptable – the ‘optimism bias’ – may be evolutionarily essential: otherwise why go on living? While its complement, the ‘negativity bias’ (the salience of bad news over good), is also essential in keeping us alert to the constant threat of danger. So where’s the balance?

There’s little doubt that all today’s tendencies, but particularly denial, have been supercharged by social media and the internet, both of which radically expand the scope for group polarisation. As a respected journalist and commentator, Gavin Esler has watched with concern as fantasy and malevolence make it ever harder for balance and insight to be heard. Again, Trump is the telltale example here. Never mind all the other disqualifications: how is it, Esler demanded, that a president of the United States can get away with telling, on the Washington Post’s reckoning, 15 lies a day for a total of 6,420 in two years – many of them breathtakingly blatant untruths – and still retain the confidence of 40 per cent of Americans who would never allow the same latitude to his opponents? The answer, Esler suggested, was that there was no pretence about Trump. No one could doubt that what they saw was what they got. Trump was authentically himself – a liar – knew it, and acted it to the hilt. He didn’t need to be an earnest or careful denier – it simply wasn’t important. This puts Trump so far ahead of the curve that some have termed him a ‘post-denialist’ – someone who is so unconcerned about truth or fact that he doesn’t even bother to justify his lies.

Generalised post-denialism would be an internet-age dystopia beyond anything that Orwell or Huxley could have invented, with implications that scarcely bear thinking about. If we are not to go that way, at some stage the fightback has to start. ‘At some point it seems to me we have to reassert that facts do matter’, said Esler. ‘No matter how flat I feel the world is, it isn’t, and if the facts don’t matter, any of us in the journalism or communications business might as well pack up and go home.’

Part of the answer, it was suggested, was to get beyond the facile notion of authenticity that certain demagogues have learned to play so effectively: the commonly-used justification that ‘I just say what I think’ doesn’t mean what you are just saying is right, clever or of any value at all. Sincerity, Esler proposed, was a better criterion to judge by. On the positive side, he added, belying today’s fashionable stereotypes, many politicians are good, intelligent people genuinely motivated by the desire to improve lives: their story deserves to be heard too. Another part of the answer is surely to oblige social media and tech companies to face up to their responsibilities by making them accountable for their content in the same way as the struggling traditional media, as they should have been from the beginning.

Finally, of course, the stories swirling around us are ours too, and it is up to us to handle them with as much care as we can. ‘Nowadays, anyone who wishes to combat lies and ignorance and to write the truth must overcome at least five difficulties. He must have the courage to write the truth when truth is everywhere opposed; the keenness to recognize it, although it is everywhere concealed; the skill to manipulate it as a weapon; the judgment to select those in whose hands it will be effective; and the cunning to spread the truth among such persons. These are formidable problems for writers living under Fascism, but they exist also for those writers who have fled or been exiled; they exist even for writers working in countries where civil liberty prevails.’ That text for today was penned by the great committed German poet, Bertolt Brecht. He wrote it in 1935.