Before the internet it seemed like a joke: if you provide an infinite number of monkeys with typewriters one of them will eventually come up with a masterpiece. But with the web now firmly established in its second evolutionary phase – in which users create the content on blogs, podcasts and streamed video – the infinite monkey theory doesn’t seem so funny any more.

“Today’s technology hooks all those monkeys up with all those typewriters,” argues Andrew Keen, who believes that “web 2.0” is killing our culture, assaulting our economy and destroying time-honoured codes of conduct.

An Englishman who moved from north London to California in the 1990s and swapped university lecturing for internet entrepreneur-ship, Keen has turned against the thoughtless barbarism of his Silicon Valley peers. In an alarming new book The Cult of the Amateur he argues that many of the ideas promoted by champions of web 2.0 are gravely flawed. Instead of creating masterpieces, the millions of exuberant monkeys are creating an endless digital forest of mediocrity: uninformed political commentary, unseemly home videos, embarrassingly amateurish music, unreadable poems, essays and novels.

Worse still, the supposed “democratisation” of the web has been a sham. “Despite its lofty idealisation it’s undermining truth, souring civic discourse, and belittling expertise, experience and talent,” he says. Take the much vaunted “wisdom of crowds”, which has led to the astonishing growth of the free online reference work Wikipedia. The English site alone boasts 1.8m articles freely contributed by ordinary web users and more are created every minute.

But as the sum of what we all know and agree, the wisdom of crowds has no greater value than Trivial Pursuit. Wikipedia is full of mistakes, half truths and misunderstandings. What happens if you try to do something about it? William Connolley, a climate modeller at the British Antarctic Survey in Cambridge and an expert on global warming, disagreed with a Wikipedia editor over a particular entry on the site. After trying to correct inaccuracies Connolley was accused of trying to remove “any point of view which does not match his own”. Eventually he was limited to making just one edit a day.

Arbitrating on the dispute, Wikipedia gave no weight to his expertise, and treated him with the same credibility as his anonymous opponent. “The consequences of this dismissal of traditional, credentialed experts are both chilling and absurd,” says Keen.

“What defines the best minds,” Keen argues, “is their ability to go beyond the ‘wisdom’ of the crowd and mainstream opinion.” Wikipedia is premised on a contrary theory of truth that would have seemed familiar to George Orwell: if the crowd says that two plus two equals five, then two plus two really does equal five.

At a working breakfast in 2004 Keen was alarmed to be told the new democratic internet would overthrow the “dictatorship of expertise”. And that’s happening already. Wikipedia, with its millions of amateur editors and unreliable content, is the 17th most trafficked site on the net. Britannica.com, a subscription-based service with 100 Nobel prize-winning contributors and more than 4,000 other experts is ranked 5,128. As a result, Britannica has had to make painful cuts in staffing and editorial.

These cutbacks don’t only affect the individuals laid off. They affect us all – because if Britannica and publications like it should disappear we’ll be obliged to rely on the unreliable patchwork of information parcelled out on Wikipedia by people who often don’t even reveal their identity.

“Instead of a dictatorship of experts, we’ll have a dictatorship of idiots,” says Keen, who finds classic signs of totalitarianism in Silicon Valley. “Anyone who disagrees is wrong. These people manifest some of the symptoms of 19th century Russian idealists and utopians, who think that their vision of the world is going to change everything for the better.”

This is not only about reference libraries. It’s much more important. What Wikipedia has done to reference books, bloggers do to traditional news media. Papers and magazines close down while broadcasters sell off radio and television stations, as more people turn to podcasts and streamed videos.

But as Keen shows, many blogs and “news” sites are merely fronts for public relations machines. Others conceal their agendas. They’re also unaccountable and rarely remove their mistakes. It was once said that: “A lie can make it halfway around the world before the truth has the chance to put its boots on.” That has never been more true than in the freewheeling, unchecked blogosphere.

“Many bloggers flaunt their lack of training and formal qualifications as evidence of their calling, their passion,” says Keen. But they also lack connections and access to information. A politician can avoid dealing with ordinary citizens but would be a fool to refuse calls from representatives of the press and TV news. If traditional news-gathering disappears, who will hold politicians to account?

Even if they had the talent and the connections, no blogs could afford to conduct investigations comparable to the great newspaper campaigns of the past. So the idea that content on the web is “free” is mistaken: the hidden cost may be the demise of old media and entire art forms on which the free content depends.

Already, Keen contends, illegal downloads have destroyed the music business. (He’s not alone. The great singer-songwriter Paul Simon told Keen: “I’m personally against web 2.0 in the same way as I’m personally against my own death.”) And with download speeds increasing and becoming more widespread it’s only a matter of time before film and TV studios face the same demise.

Another web idea dismantled by Keen is the concept of the “long tail” – the slow but gradual accumulation of sales by niche products such as books that could never have commanded shelf space in shops but can wait for buyers to find them on Amazon. In other words, you may never get more than 10 buyers for your little book of poetry, but thanks to the net you can publish it anyway. Somehow those 10 readers will find you.

But talent is “the needle in today’s digital haystack”, says Keen. In a world without newspapers, publishing houses, film studios, radio and TV stations there’ll be nobody to discover and – no less important – to nurture talent. The result could be no less catastrophic than Pol Pot’s decision to eliminate talent and expertise in Cambodia by mass execution.

“Once dismantled, I fear that this professional media – with its rich ecosystem of writers, editors, agents, talent scouts, journalists, publishers, musicians, reporters and actors – can never again be put back together. We destroy it at our peril,” says Keen.

He is not against technology: he just wants to see a bit more control. We must choose between sites such as Wikipedia, where the cult of the anonymous amateur prevails, and the newer alternative Citizendium, which aims to improve on Wikipedia’s model by adding “gentle expert oversight” and requiring contributors to use their real names.

Where necessary, governments should intervene, as the Americans did last year by clamping down on gambling sites. “This is not about being herded into a gulag but the complete flattening of culture so that everything becomes a commercial break,” says Keen. “‘Free culture’ is about giving it away so that you can advertise. I grew up wondering why there were no ads in novels. That was because I was prepared to spend money to buy the book.”

The Cult of the Amateur by Andrew Keen is published by Nicholas Brealey on Tuesday, £12.99

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