Why do some people believe conspiracy theories?

Quassim Cassam in Aeon:

The weirder the belief, the stranger it seems that someone can have it. Asking why people believe weird things isn’t like asking why they believe it’s raining as they look out of the window and see the rain pouring down. It’s obvious why people believe it’s raining when they have compelling evidence, but it’s far from obvious why Oliver believes that 9/11 was an inside job when he has access to compelling evidence that it wasn’t an inside job.

I want to argue for something which is controversial, although I believe that it is also intuitive and commonsensical. My claim is this: Oliver believes what he does because that is the kind of thinker he is or, to put it more bluntly, because there is something wrong with how he thinks. The problem with conspiracy theorists is not, as the US legal scholar Cass Sunstein argues, that they have little relevant information. The key to what they end up believing is how theyinterpret and respond to the vast quantities of relevant information at their disposal. I want to suggest that this is fundamentally a question of the way they are. Oliver isn’t mad (or at least, he needn’t be). Nevertheless, his beliefs about 9/11 are the result of the peculiarities of his intellectual constitution – in a word, of his intellectual character.

More here.