Voodoo history and conspiracy theories

In The Da Vinci Code, Robert Langdon uncovers a conspiracy by the Catholic Church to hide the fact that Jesus Christ married Mary Magdalene. In Angels & Demons , Robert Langdon uncovers a conspiracy by the Illuminati to destroy the Vatican because the Catholic Church massacred a group of critical scientists and intellectuals.

Conspiracy theories have made Dan Brown rich. But what is it about them that make them so popular in the first place? And why do people we think of as intelligent believe in conspiracy theories?

Let's start with Andreas Clauss. He's a former investment advisor who now travels around Germany telling people that the global financial system is collapsing. Paper money is useless, he says. We should use gold and grow our own food, he says. He's a big believer in conspiracy theories, too. Why did the US government let Lehman Brothers go bankrupt? Because it had so many European customers, says Clauss. And he doesn't believe that 19 Islamist fanatics destroyed the World Trade Center in New York on 11 September 2001, either. "It is peculiar how well many Wall Street insiders did on falling share prices after the attacks," he says. "They must have known something was going to happen."

"My truth is as good as yours"

Clauss may be crazy, but can we say the same about the famous German historian Ernst Nolte? He's just written a new book called Die dritte radikale Widerstandsbewegung: der Islamismus. In it, he says that the conspiracy theory about the Israeli national intelligence agency, Mossad, being behind the 9/11 attacks "deserves to be taken seriously".

Given this kind of nonsense, we're very fortunate that the British journalist David Aaronovitch has just written Voodoo Histories: The Role of the Conspiracy Theory in Shaping Modern History. From hateful 20th-century propaganda such as The Protocols of the Elders of Zion to absurd 21st-century fantasy such as Loose Change, Aaronovitch looks at the paranoia behind the search for the hidden "truth" that defines conspiracy theories. In the end, he concludes that the central danger we're facing here is relativism — the idea that my truth is as good as anyone's, no matter how I came to believe it.

The funny thing about all this is that while David Aaronovitch is an atheist, the world's leading opponent of relativism is an 82-year-old German Catholic who lives in Rome. Which brings us back to Dan Brown.