I just don't get why people can't accept that a punk-ass loser killed JFK

[Spider Jerusalem]

4. ...

...people who suspect conspiracies aren't really sceptics. Like the rest of us, they're selective doubters. They favour a world view, which they uncritically defend. But their worldview isn't about God, values, freedom, or equality. It's about the omnipotence of elites.

(snip)

In 1999, a research team headed by Marina Abalakina-Paap, a psychologist at New Mexico State University, published a study of US college students. The students were asked whether they agreed with statements such as "Underground movements threaten the stability of American society" and "People who see conspiracies behind everything are simply imagining things". The strongest predictor of general belief in conspiracies, the authors found, was "lack of trust".

(snip)

The common thread between distrust and cynicism, as defined in these experiments, is a perception of bad character. More broadly, it's a tendency to focus on intention and agency, rather than randomness or causal complexity. In extreme form, it can become paranoia. In mild form, it's a common weakness known as the fundamental attribution error – ascribing others' behaviour to personality traits and objectives, forgetting the importance of situational factors and chance. Suspicion, imagination, and fantasy are closely related.

The more you see the world this way - full of malice and planning instead of circumstance and coincidence - the more likely you are to accept conspiracy theories of all kinds. Once you buy into the first theory, with its premises of coordination, efficacy, and secrecy, the next seems that much more plausible.

Many studies and surveys have documented this pattern. Several months ago, Public Policy Polling asked 1,200 registered US voters about various popular theories. Fifty-one per cent said a larger conspiracy was behind President Kennedy's assassination; only 25 per cent said Lee Harvey Oswald acted alone. Compared with respondents who said Oswald acted alone, those who believed in a larger conspiracy were more likely to embrace other conspiracy theories tested in the poll. They were twice as likely to say that a UFO had crashed in Roswell, New Mexico, in 1947 (32 to 16 per cent) and that the CIA had deliberately spread crack cocaine in US cities (22 to 9 per cent). Conversely, compared with respondents who didn't believe in the Roswell incident, those who did were far more likely to say that a conspiracy had killed JFK (74 to 41 per cent), that the CIA had distributed crack (27 to 10 per cent), that the government "knowingly allowed" the 9/11 attacks (23 to 7 per cent), and that the government adds fluoride to our water for sinister reasons (23 to 2 per cent).

http://www.newscientist.com/article/dn24626-inside-the-minds-of-the-jfk-conspiracy-theorists.html?full=true#.UpcQRuJgWP8