There's an essay here from Spiked that makes some good points on the philosophical and intellectual causes of the Intelligent Design problem. (And it quotes me, so therefore it's very good!) It's a little long, but the thesis is that
It is suspicion of all groups who claim authority rather than excessive respect for religion that drives hostility to science....[T]he theme of anti-intellectualism on the American right has drawn vigour from the critique of expertise developed since the 1960s by their opponents in the culture wars. It was radicals who pioneered the idea that children should educate the teachers, that doctors were no more expert than their patients, and that claims to expertise generally were little more than an excuse to assert power by marginalising the voice of the victim. In this picture scientists are not disinterested investigators of the truth so much as spin doctors for their paymasters in business or government. It is the coming together of these two strands from left and right that represents the real danger for science.
I think that goes a little far. I would certainly agree that there is just as much quackery and hoodooism on the left as on the right--I live in Northern California, so I should know--and I agree that the tendency to ignore what a person says on the grounds that "he's funded by so-and-so" is an illogical and childish attitude that is all too common. But the problem isn't just hostility to people who claim authority. Such hostility can actually be pretty helpful; I understand the motto of the Royal Society is "On the Words of No One," which is a pretty anti-authoritarian sentiment. Rather, the problem (other than simple ignorance) is hostility to reason and objective science. That hostility takes the form of both traditional fundamentalism (by which reason and science subvert the unquestioning faith demanded of us by God and society) and newfangled Pomo tergiversation (by which science is exploitative, inherently racist, and part of an intellectual scheme to oppress the proletariat and deprive them of their health insurance coverage).
Thanks to reader Kelvin Kean for the pointer.