As usual, Mark Evanier has it all figured out:
There are rumors swirling that McCain may dump Sarah Palin as his running mate. I don’t believe them. She could admit to having killed a nun when she was younger and he wouldn’t throw her off the ticket…and it isn’t just because the “Republican base” loves her. It’s because that base doesn’t like a leader who ever admits he was wrong. Amidst the dwindling hordes that defend George W. Bush, there’s a strong sense that never admitting a mistake is just as good as never making one.
No wonder the Republicans hate science so much. It’s based on the idea that finding and correcting mistakes is a good thing — not just a good thing, an ESSENTIAL thing. But if you’ve already decided what you want to believe, and you don’t want it to change, EVER, then you can’t allow your mistakes to surface.