There are no shortage of conspiracy theories in the halls of pseudoscience and pseudohistory, not to mention pop culture mythology. According to a 1992 New York Times survey, 77 percent of Americans hold the demonstrably wrong belief that the JFK assassination was the work of a conspiracy. Others believe there are conspiracies to suppress a cure for cancer or hide knowledge of cold fusion or other "free energy" sources. There are those who say that the AIDS virus was created in a government lab specifically to target the gay community or that vaccines are a government program designed to cause illness. The biggest conspiracy theories contend that the entire world is secretly run by a shadowy organization of megalomaniacs, like the Iluminati or the Men in Black.
So what is the appeal of such conspiracies? For one, humans have a well documented propensity for pattern recognition. We seek out patterns as a way of making sense of the complex world around us. Sometimes we see patterns that are not there. Humans also have a natural, and evolutionarily adaptive, paranoia. It's good to be wary of potential harm or abuse, otherwise we would be easily victimized or deceived. But like all adaptive mental tendencies, in some individuals paranoia can be too strong, even overwhelming.
Hard-core conspiracy theorists tend to have a cartoon view of the world, one in which all people fall into one of three groups: the conspirators, the crusaders, and the dupes. The conspirators are portrayed as evil and powerful, seeking control for its own sake. They are often granted unimaginable cleverness and resources, and their reach knows no bounds. At the same time, they are ascribed unbelievable stupidity-for how else could their conspiracy be uncovered? The crusaders are the believers themselves. They feel they are a small band of freedom-fighters saving the world from incredible malfeasance. The dupes are everyone else.
But grand conspiracies (and that's what we're talking about here) require the cooperation of countless people over long periods of time and across many institutions. This is the first major logical fault with grand conspiracy theories: They tend to collapse under their own weight. The problem is explaining how the conspirators are able to maintain secrecy and control. If the U.S. were hiding UFOs and aliens over decades, the number of people that would need to be involved is huge. How do they keep them all silent? How do they get the funding and the space to run such an operation? Have all the presidential administrations since Roswell been involved? How do they prevent leaks-say, the kinds of leaks that recently outed the government's domestic spying program? Wouldn't other governments have discovered the presence of aliens? Are they too involved? In order to answer these questions, more and more power and scope must be ceded to the conspirators, until you have to believe that they run the world.
Second, conspiracy theorists tend to believe that everything happens for a reason – a logical fallacy known as the argument from final consequences. For example, Bush’s power and popularity benefited from 9/11, therefore he must have perpetrated 9/11. The assassination of JFK had enormous consequences; therefore it could not have been the insane act of a lone nut. It must have had an equally enormous cause – a conspiracy. The more elegant view is that we simply live in a wacky world and sometimes stuff happens.
Conspiracy theorists also make much was what we don’t know. If the quirky details of a complex historical event cannot be explained and documented to an arbitrarily high degree, then there must be a reason for our ignorance. The dark hand of a conspiracy must be at work in the shadows. Again, Occam would remind us that complexity naturally leads to inexplicable chaos without the need for a purposeful conspiracy.
The final, and most insidious, problem with conspiracy theories is that they quickly become a closed belief system. Why is there no evidence for a conspiracy? Because the conspirators have hidden all the evidence. Why is there evidence that the conspiracy is wrong? Because the conspirators fabricated and planted that evidence. How could they have done that? Because they have frightening power and reach (which brings us back to the first problem). Therefore, there is no amount or type of evidence that can convince a conspiracy theorist that he's wrong, which means that his (or her) beliefs are comfortably unhinged from reality.
The alternative, alas, is to live in reality. Reality can be frightening and confusing, with questions that are difficult to answer and problems that are hard to solve. But in the real world, at least there are no all-powerful cabals, controlling us from behind the scenes.