Bryan Appleyard finds some research to support what I've long suspected:

Writing about Jonah Lehrer's book on decision making in The Sunday Times, I didn't mention the findings of Philip Tetlock at Berkeley. He studied pundits and discovered they were, to a rough approximation, always wrong when making predictions. He took 284 pundits and asked them questions about the future. Their performance was worse than chance. With three possible answers, they were right less than 33 per cent of the time. A monkey chucking darts would have done better. This is consoling. More consoling still is Tetlock's further finding that the more certain a pundit was, the more likely he was to be wrong. Their problem being that they couldn't self-correct, presumably because they'd invested so much of their personality and self-esteem in a specific view. (That makes me think of so many people, almost everybody, in fact.)