“In a world of complex and continuing problems, in a world full of frustrations and irritations, America’s leadership must be guided by the lights of learning and reason, or else those who confuse rhetoric with reality, and the plausible with the possible will gain the popular ascendancy with their seemingly swift and simple solutions to every world problem.”

John F Kennedy’s last speech reads like a warning from history, as relevant today as it was when it was delivered in 1963 at the Dallas Trade Mart. His rich, Boston Brahmin accent reassures us even as he delivers the uncomfortable message. The contrast between his eloquence and the swagger of Donald Trump is almost painful to hear.

Quite soon it will be all but impossible for ordinary people to tell what’s real and what’s not

The problem is, Kennedy never spoke these words. He was killed before he made it to the Trade Mart. You can only hear them now thanks to audio technology developed by a British company, CereProc. Fragments of his voice have been taken from other speeches and public appearances, spliced and put back together, with neural networks employed to mimic his natural intonation.

The result is pretty convincing, although there’s a machine-like ring to some of the syllables, a synthetic stutter. Enough to recognise, if you already know, that this is a feat of technology, not oratory.

But if you didn’t know? Perhaps you’d be fooled. And that’s why this breezy exercise has a darker side.

We like to think of innovation as morally neutral. We empower scientists and engineers to range freely in the hope they might discover things that save labour and lives. The ends to which these are put aren’t the responsibility of the researchers. The agile robots produced by Boston Dynamics might look like they could cheerfully pin you up against a wall and snap your neck, but do we really want to close off this avenue of research? After all, they might equally be capable of performing life-saving surgery. The methods used to resurrect JFK can also help people with illnesses such as motor neurone disease – like the late Stephen Hawking – that affect their ability to speak.

“Dual use” of technology is not a new problem. Nuclear physics gave us both energy and bombs. What is new is the democratisation of advanced IT, the fact that anyone with a computer can now engage in the weaponisation of information. 2016 was the year we woke up to the power of fake news, with internet conspiracy theories and lies used to bolster the case for both Brexit and Donald Trump. We may, however, look back on it as a kind of phoney war, when photoshopping and video manipulation were still easily detectable. That window is closing fast. A program developed at Stanford University allows users to convincingly put words into politicians’ mouths. Celebrities can be inserted into porn videos. Quite soon it will be all but impossible for ordinary people to tell what’s real and what’s not.

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What will the effects of this be? When a public figure claims the racist or sexist audio of them is simply fake, will we believe them? How will political campaigns work when millions of voters have the power to engage in dirty tricks? What about health messages on the dangers of diesel or the safety of vaccines? Will vested interests or conspiracy theorists attempt to manipulate them? Unable to trust what they see or hear, will people retreat into lives of non-engagement, ceding the public sphere to the already powerful or the unscrupulous?

The potential for an “information apocalypse” is beginning to be taken seriously. The problem is we have no idea what a world in which all words and images are suspect will look like, so it’s hard to come up with solutions. Perhaps not very much will change – perhaps we will develop a sixth sense for bullshit and propaganda, in the same way that it has become easy to distinguish sales calls from genuine inquiries, and scam emails with fake bank logos from the real thing. But there’s no guarantee we’ll be able to defend ourselves from the onslaught, and society could start to change in unpredictable ways as a result.

Like the generation JFK was addressing in his speech, we are on the cusp of a new and scary age. Rhetoric and reality, the plausible and the possible, are becoming difficult to separate. We await a figure of Kennedy’s stature to help us find a way through. Until then, we must at the very least face up to the scale of the coming challenge.