Now 9/11 has toppled JFK as the leading conspiracy.
The U. S. Department of State calls the varying theories on 9/11 "a hodgepodge of sinister, unfounded allegations."
While some conspiracy theories are laughed off as harmless diversions, purported 9/11 plots are often viewed more harshly because many quickly devolve into anti-Semitism and anti-Americanism.
"What makes the 9/11 conspiracy theories particularly important is that they have united disparate groups of Jew haters -- American far-right extremists, white supremacists and elements within the Arab and Muslim world -- who are exchanging and echoing information, ideas, and conspiracy theories, particularly through the Internet," says a report by the Anti-Defamation League, a U. S.-based Jewish organization.
"Anti-Semites are blaming Jews for the worst terrorist act committed and for its consequences, such as military conflicts. Allegations of Jewish culpability in the 9/11 attacks may even be used as justification for future acts of anti-Semitic violence."
That the conspiracy theories would be so pervasive in Canada to pop up with the frequency they did in the election is in line with the findings in a recent survey on the topic. An Angus Reid poll conducted around the anniversary of 9/11 this year found that while the majority of Canadians believe the 9/11 attacks were carried out by al-Qaeda, 39% either disagree with that explanation or are unsure. About a third of those surveyed believed the U. S. government allowed the
attacks to happen and 16% believe the U. S. government made the attacks happen.
The events of 9/11 are perfect for spawning conspiracy theories, said Adam Galinsky, a professor at the Kellogg School of Management at Northwestern University in Evanston, Ill.
"Sept. 11 was a huge event with these massive building structures crumbling to the ground. This made people feel completely out of control -- who knew when this type of terror would happen again?" Prof. Galinsky said. "Whenever a big event happens -- a large consequential, meaningful event -- people assume there has to be some large, consequential cause of it."
His study on what draws believers to such theories was published in the latest issue of the journal Science.
"When people don't have control objectively, what they try to do is regain it psychologically and one way to do that is by seeing patterns in the world -- superstitions, conspiracies, seeing the Virgin Mary in a water stain -- all serve the same underlying purpose," he said. "They allow people to feel in control over their environment."
Charles Pigden, a philosophy professor at New Zealand's University of Otago, says there is nothing wrong with conspiracy theories, as such. "Many of them are silly, of course, but they are not silly because they are conspiracy theories, they are silly because the specific theories postulated are improbable," he said.