In the weeks since one of the most divisive and momentous elections in living memory, the news has itself become the news. Consider what has been the hottest post-election media talking point: the question of fake news.

On the 4 December, a man was arrested in Washington DC after firing a gun in a pizza restaurant. This has been linked to “Pizzagate”, the bizarre conspiracy theory that holds that there is a subterranean child abuse conspiracy involving high-ups in the Democratic party, a set of food-related code words and a string of pizza parlours. Ice-cream. Cannibalism. Handkerchief. Satanism. It all makes perfect sense.

Any proposed solution or mitigation to the issue of fake news must recognise the reality that the next occupant of the Oval Office is himself an enthusiastic practitioner

The arrested man, Edgar Maddison Walsh, told reporters it was his desire to “self-investigate” this piece of poisonous nonsense that led him to walk into the Comet Ping Pong pizzeria with an assault rifle. He surrendered once he’d satisfied himself there were no child victims on the premises. “The intel on this wasn’t 100%,” he told a New York Times reporter.

The incident quickly led to the brisk departure from President-Elect Donald Trump’s transition team of Michael Flynn Jr, the son of Trump’s pick for national security advisor. Flynn the younger had tweeted this about Pizzagate: “Until Pizzagate proven to be false, it’ll remain a story.”

Until something is proven to be false, it will remain a story. Flynn’s tweet has offered us a doctrine of fake news, or perhaps more precisely, a doctrine of the political value of fake news.

Fake news is not new. Spreading false rumours for political advantage, for pure malice, or just for entertainment, is as old as the hills. And yet what’s happening now feels different. Whatever its other cultural and social merits, our digital ecosystem seems to have evolved into a near-perfect environment for distorted and false news to thrive.

Domestic cranks and political extremists have been joined by hostile foreign governments. It is now widely accepted, for instance, that Russian state-backed digital specialists are engaged in everything from the hacking which gives rise to conspiracy-theories like Pizzagate to industrial-scale fake news creation and distribution with armies of human trolls and cyberbots.

There are obvious incentives for unscrupulous politicians to spread fake news – it’s a way of viciously attacking opponents while retaining deniability and pretending only to be encouraging a “debate”. And for cynical media outlets, fake news can have its uses too – to drive traffic and revenue, spark a controversy, or just to keep a cable TV news conversation going.

Mr Trump does it himself. His recent untruthful claim that “millions of people” voted illegally in the election is just one of the more serious examples. Any proposed solution or mitigation to the issue of fake news must recognise the reality that the next occupant of the Oval Office is himself an enthusiastic practitioner.

And this is part of a wider shift in the terms of political debate, in which exaggeration, vituperation and extreme compression have crowded out the space available for explanation and evidence-based argument. In my book Enough Said, I argue that these changes have combined to weaken political language and effective political debate in ways that could ultimately threaten democracy. Fake news is the logical next stage in this broader deterioration.

So we find ourselves in a battle, not between left and right, nor elites and “ordinary” people, nor between traditional and digital media, but between facts and lies.

Some people believe that the answer is simply to identify and remove fake news content from the internet and the social media sites where it thrives. But, quite apart from the immense practical difficulties, censorship is always worse than the disease it is said to cure. Better a chaotic digital public square, even with fake news. But does this mean that the major social platforms are off the hook? Well no, not quite.

Fake news is only one concern surrounding these platforms. There’s the question of the so-called “filter bubble”, the fear that citizens who rely solely on them for news and opinion live in what TS Eliot once called a “wilderness of mirrors”, only exposed to perspectives like their own.

Should anyone, particularly any young person, get their news entirely from a source whose editorial choices and rankings are arrived at secretly?

The old advice still applies: expose yourself to multiple sources of news, including some discrete, properly funded, professional news organisations like the New York Times and the Guardian, and always include at least one whose editorial perspective differs from your own.

The digital giants need to think hard about transparency and accountability. Their ad tech and ad networks help make fake news so lucrative – here too they need to help the whole industry cut off the advertising revenue which lets fake sites flourish.

What about publishers? Well, we’re not perfect either. Professional news organisations like the New York Times, where I’m the president and chief executive officer, screw up from time to time and we have to learn from our mistakes.

But at least the user of the Times or the Guardian enjoys complete transparency when it comes to accountability. You can see who wrote the story and, if you think it’s inaccurate or biased, you know who the editor is, and the publisher. The ultimate provenance of content, and the algorithms that decide what we see and don’t see, lack this clarity.

What professional news organisations should stand for, now more than ever, is tough-minded, independent journalism edited and delivered without fear or favour. At the New York Times, we want every story we report, every column of opinion we publish, to be worth paying for.

And, to state the obvious, we believe in the opposite of fake news. We want people here and around the world to have access every day to real news, to form their own judgment about what is happening in their world.

Real journalism is vital to our democracy, and it has to be paid for. If not, it will largely disappear and leave the field open for Pizzagate, and Trump’s zombie army of illegal voters.

If you as a citizen are worried about fake news, put your money where your mouth is and pay for the real thing.

• This is an edited version of a speech Mark Thompson delivered at the Detroit Economic Club earlier this week