This is an edited excerpt of a speech by Professor Timothy Garton Ash, historian and author, at the St Gallen Symposium on May 5.

Almost everywhere free speech is under attack. That attack is part of a global anti-liberal counter- revolution. It's a conscious reaction against the spread of liberty and liberalism over the last 40 years.

The little magic box, the smartphone, which we all have in our pockets or bags means that we can communicate almost instantaneously with roughly half of humankind, three billion people and going up fast.

What we have already is what I call a cosmopolis, a world which is becoming like a single great city.

Now, this is a fantastic chance for free speech. But it brings with it equally large risks. Through the smartphone, through the Internet, and in a world of mass migration, we see more and more examples of what I call the assassin's veto, people like those who murdered the journalists of Charlie Hebdo, saying if you say that or publish that, we will kill you, and the threat being sufficiently credible to have a deeply chilling effect on free speech.

Through the Internet, (there is) harassment, cyber bullying, grooming for paedophile activities, surveillance and the erosion of privacy. A great expert on the Internet has said surveillance is the business model of the Internet. And it's true. How do Facebook and Google make their money? You don't pay but they sell you to advertisers.

(In such a world) we need uncensored, diverse, trustworthy media to make well-informed decisions and participate fully in political life. In other words, we need free speech for democracy.

MARKET FAILURE IN THE MARKETPLACE OF IDEAS

In ancient Athens, they talked about free speech in terms of two concepts - parrhesia and isegoria.

Parrhesia was free speech but free speech with good intention for the public good. Not saying whatever came into your head but free speech for the public good.

Isegoria was equal speech, that everyone had in principle an equal right to speak.

They listened to all the arguments for one policy or another. They listened to all the evidence that was available. They were given all the facts. And then they came to a decision. They decided to fight the invading Persian armies at sea and not on land. And thus it was that they came to win the battle of Salamis. By free speech, by deliberative democracy, they saved the world's first democracy.

So, that's why we have media. Our exchanges are mediated by the media. In all liberal democracies, the fourth estate, the media, is an essential part.

In the United States, Thomas Jefferson wrote in 1787: "Were it left to me to decide whether we should have a government without newspapers, or newspapers without a government, I should not hesitate for a moment. I'll take the newspapers."

We have the concept from Oliver Wendell Holmes of the marketplace of ideas: The best ideas will win out, the best policies will win out on the basis of evidence-based, reality-based debate.

Now, here's the problem: that as an unintended consequence of the Internet, of the digital revolution of the smartphone world we're in, we are beginning to lose the media we need for democracy.

And it's the populists who are most effectively exploiting the possibilities given by the Internet to attack liberal pluralistic democracy.

Since the Internet offers a near infinity of platform outlets for speech, the result has been a dramatic fragmentation of the media landscape. More and more people are listening in more and more disparate groups, and this has a very powerful echo-chamber effect. Increasingly, people are only hearing the news and the views of people who agree with them.

Donald Trump's supporters hear only Fox News and Breitbart and talk radio's Rush Limbaugh and their friends on Facebook. And Hillary Clinton supporters, MSNBC or CNN and NPR and The New York Times, and their friends on Facebook. There's a lot of good evidence now that this is a really powerful echo-chamber effect which already begins to undermine the core idea of free speech for deliberative democracy - which is you hear all the arguments and all the evidence and all the points of view.

These days, 30 to 40 per cent of the news that young Americans get is from Facebook. It's a question of absolute overwhelming public interest what the Facebook news feed algorithm is doing.

The other thing you get on the Internet is a massive repetition. It's not just that people are told, for example, that Britain sends £350 million a week to the EU, to Brussels (simply untrue), or that Barack Obama was not born in the United States. You are told it a thousand times every day because of this constant repetition effect.

And what makes lies effective in propaganda is sheer repetition. And misinformation, false news is as likely to go viral as reliable news. Then there is anonymity, which provides extraordinary possibilities for hostile powers, public or private, to disseminate and multiply misinformation by bots, by accounts which are actually automated but which look like a real person and a real user. Anonymity has a huge contribution to the level of hate speech and abuse and indeed death threats online.

Very simply, the Internet is destroying the business model of newspapers. For at least two centuries, we have had a public good - news, the information we need for democracy - delivered by private means. A newspaper was a means of delivering the public good of news by private means. AJ Liebling, the great writer on journalism, said the role of a newspaper is to inform but its function is to make money. Our good fortune was that, for nearly two centuries, that model worked because people would pay for a newspaper and advertising revenue. The Internet has just knocked away both these pillars. So the newspapers produce the information. Facebook and Google get the profit.

And this has a very negative effect on the newspapers on which we have relied for our news. First of all, what do you do if you're drowning? Well, you wave and you shout. So all our newspapers are becoming more sensational, more partisan, more celebrity; more sensationalist, more "if it bleeds it leads, if it roars, it scores". The desperate competition for the clickstream, clickbait.

The amount of serious news, investigative journalism and foreign reporting is going down because that's expensive. This is a real problem for the journalism we need for democracy. What we have here is potentially a market failure in the marketplace of ideas.

THE PROBLEM WITH POPULISM

I now come to populism. The characteristic features of populism (include) the fact that it's always nationalist, that it seeks direct legitimation with the people, (but) that the people turn out in fact to be only part of the people. There are always the "other people" who don't belong to the fold, defined ethnoculturally - Mexicans, Muslims, Kurds, East Europeans - or sociopolitically - the elites, the experts, the mainstream media.

The other thing that populism does is that it quite skilfully aggregates quite different social groups and social interests to create coalitions of the unwilling, everybody who is outside, who is left behind, who is disconnected, discontented for one reason or another.

They found a great glue to hold those groups together. And that glue is a powerful, simplistic, emotionally appealing nationalist narrative. Make America great again. Take back control. On est chez nous (This is our home), as Le Front National chant at their rallies, or dobra zmiana, good change, in Poland.

A strong, simplistic, emotionally appealing narrative and that glues them together. The problem is that all the characteristics which I've just described to you as the impact of the disruptive Internet on the media by and large enable and facilitate and even strengthen that kind of a rhetoric and the fake news and the alternative facts.

The echo-chamber effect? Obviously. The tendency of commercial media to shout to be partisan, less and less of them to take a neutral middle ground where you hear all views together. The facility with which misinformation and disinformation can be spread. Anonymity and so on. All of that facilitates the work of the populist.

Everybody now is talking about fake news. But I don't think fake news is the heart of the problem. The heart of the problem is this emotional, simplistic narrative. What Jacob Burckhardt, the great historian, called the terribles simplificateurs who are at work. The Sun newspaper during the Brexit campaign. Banner headline on the front page "Queen Backs Brexit". Totally untrue but very powerful. The Brexit story about the £350 million. Donald Trump said that Barack Obama was not born in the United States, whereupon Barack Obama published his birth certificate.

What did Donald Trump say? He said: "Many people feel it wasn't a proper certificate." Just think about that for a moment. He didn't even say many people think. Many people feel. It's the emotion. And your feeling is stronger than the reason. So it's the enabling of these lie-based, fake news-based emotional narratives.

So the divide is no longer right and left. It's between nationalist and internationalist, anti-European and pro-European, close and open and between emotion and reason.

The basic epistemology of liberal democracy is under attack because back in ancient Athens there was also an epistemology of democracy, which said we basically agree what are facts, what is evidence, what is rational argument although we disagree about what's a right cause and that is being undermined.

What do we do about this problem if I'm right? First of all, if you have public service media, good public service media, hang on to them for dear life because the mission of a BBC or an SRF, or whatever it may be, (is) a media where you hear all the alternative arguments and evidence in one place.

Secondly, fact checking has very rapidly become a part of the ecosystem of American journalism and the Internet actually makes it easier to fact check (in real time).

Education, we should already years ago have started doing mandatory classes in digital literacy, in media literacy in our schools and in our universities because you've got to equip citizens to understand what's going on.

Then there is what I call the public responsibilities of the private superpowers (companies such as Google, Facebook, Twitter, Amazon, Apple).

I think the path down which Germany is going - which is trying to legislate responsibility on Google and Facebook and Twitter for fake news - is quite the wrong way to go.

The state should be going after dangerous speech but it's very, very, very dangerous territory, a slippery slope if you get into the territory where the state is deciding what is false and what is true. That is really incompatible with the most basic philosophical arguments of free speech.

Last but not least, this is a challenge for the craft of journalism because the question for quality journalism, leaving aside the business questions, is not so much how do you establish the facts because that's relatively easy. The challenge for journalism is to get those facts and that evidence into the echo chambers of the populace and to get them to readers and viewers who don't particularly even want to hear them because they'd much rather have the warming solidarity of simplistic indignation.

I think we need almost a new George Orwell, a new Animal Farm to tell this story of what actually is, in powerful but simple and emotionally appealing terms, in language that reaches a wider audience.

Everybody is looking for the new business model for journalism. At the moment in many countries, newspapers still set the news agenda and Britain is a prime example. It wasn't the Internet that helped decide the Brexit referendum, it was the news agenda set by a largely eurosceptic press. But in five, 10 years, the existing business model (will be) gone and what's going to come in its place?

Nobody has one single big answer but I think public service media is part of the answer - foundations funding serious news, investigative reporting and foreign news is an important part of the answer because that means you don't have to go to the state for it.

Entirely Internet, digital native news sites like BuzzFeed or Vice are actually doing much better than legacy media. They started with fairly sensational news; they're now doing really good- quality serious foreign and political reporting. The answer is probably going to come in some mix of these things.