Was Princess Diana the victim of drunk driving or a plot by the British royal family? Did Neil Armstrong really walk on the moon or just across a film set in Nevada? And who killed President John F. Kennedy - the Russians, the Cubans, the CIA, the mafia... aliens? Almost every big event has a conspiracy theory attached to it. The truth, they say, is out there - but where exactly? Perhaps psychology can help us find at least some of the answers.
Whether you are a dyed-in-the-wool conspiracy theorist, a confirmed anti-theorist, or somewhere in between, one thing's for sure: conspiracy theories pervade modern culture. Thousands of films, talk shows and radio phone-ins are built around them. US lecture tours from prominent theorists such as radio host Alex Jones can draw audiences of tens of thousands, while books raking over the evidence sell millions of copies worldwide. The internet documentary Loose Change, which claims that a CIA plot lay behind the 9/11 attacks in New York and Washington, is approaching its 10-millionth download.
Belief in conspiracy theories certainly seems to be on the rise, and what little research has been done investigating this question confirms this is so for perhaps the most famous example of all - the claim that a conspiracy lay behind the assassination of JFK in 1963. A survey in 1968 found that about two-thirds of Americans believed the conspiracy theory, while by 1990 that proportion had risen to nine-tenths.
One factor fuelling the general growth of conspiracy beliefs is likely to be that the internet allows new theories to be quickly created, and endlessly debated by a wider audience than ever. A conspiracy-based website built around the death of Princess Diana, for example, sprang up within hours of the car crash that killed her in 1997.
So what has been the impact of the growing conspiracy culture? Conspiracy theories can have a valuable role in society. We need people to think "outside the box", even if there is usually more sense to be found inside the box. The close scrutiny of evidence and ...
