During yesterday's show, one of your callers asked how it was that so many conservatives don't believe in global warming. I beleve that either you or he also mentioned the recent studies showing how many don't believe in evolution. You blamed the global warming thing on misinformation spread by big oil.
While I think you're right about that, I also think there's something more basic amiss in the conservative mindset. (I grew up fundamentalist, and got to know how they think while I was getting out.) Essentially, conservatives believe that your perception of the evidence is entirely colored by your presuppositions. You think the evidence supports evolution because you already believe in it. You think Obama's good for the economy because you're already a liberal. It is only when you have the right beliefs -- creationism, conservatism, whatever -- that you can truly see the evidence for what it is.
This means that conservatives are free to dismiss any evidence that contradicts their positions because it comes from people who disagree with them. Any news stories that undermine the Fox narrative must show liberal bias. The statistics Paul Krugman quotes must be bogus because they come from Paul Krugman. Obama's birth certificate must be a fake because it comes from Obama.
At its most extreme, you have Sarah Palin and Michelle Bachman saying with a straight face things that are patently false -- Paul Revere was warning the British, or the founding fathers fought tirelessly against slavery. Thise things must be true, because Bachman and Palin believe them, and their hearts are pure.
Given that this mindset is leading the country -- and possibly the planet -- over a cliff, I think it's up to progressives to show it for what it is every chance we get.