There's a perpetually simmering debate in the chattering classes of American politics over the validity of polling, or more precisely, the perceived overreliance on polling. This discourse is most common among ideologues who fear that politicians and their advisers will happily sell out the cause in an unwholesome pursuit of that soulless tyrant the "median voter," even though that involves the abandonment of principles and constituencies. And it's exacerbated, of course, whenever polls fail