Why politicians wouldn't want to talk about science

The headline on wired.com today is an article about Clinton, Obama, and McCain spurning a debate that was supposed to be about science. You'd think that would be a warm place for Democrats: there is no fundamentalist Christian base out there asking them to refute basic tenants of modern science, and yet neither of them wanted to show up at the event. It's pretty telling, though, of electoral strategies: debating science is a very technical topic, and actually requires expertise. Which isn't a bad thing – if a president is going to be making decisions that are ultimately rooted in science, they ought to know something about it. But people don't campaign on facts, they campaign generalities. What's Obama going to say when someone confronts him about the environmental and humanitarian costs of ethanol subsidies? Or when McCain is questioned about his statement that marijuana has no unique medicinal value? Or when any of the candidates are pressed on how likely any of their plans are to actually address America's contribution to general environmental degradation? So much of electioneering is based on trying to get people to not pay attention to numbers and facts, so it doesn't seem to be in anyone's advantage to embarrass themselves when they have to concede that they really don't know much about science at all.