The evidence is overwhelming: The so-called culture split is largely nonsense, pure hokum. We should not let pundits divide America by falsely claiming there is already a deep rift, and then trying to deepen it.
Telling two people they are natural enemies is a good way to make them suspicious of each other. Telling two segments of the population the same thing, doubtless has the same effect. The more we think of our nation as two inimical constituencies, the less we will be able to fight genuine enemies outside our borders - such as the terrorist network that still persists.
He cites various factors arguing for his position. Actually, I do think a lot of the "red state/blue state" hype is a bit overblown. Dean cites poll data indicating that partisan affiliation is going down, which seems to argue against an increasing partisan polarization.
Part of my reservation about his particular argument is that he blames "partisans" for promoting the notion for self-serving reasons:
Of course, it's true that there have been regional shifts of political parties: No one would deny that. But are they seismic shifts - tremors emanating from a deeper rift? No: That is nonsense. In fact, the available polling shows that all the noise about our supposed political divide is coming from partisans and the media, while in reality - the hard evidence, not the parallel reality created by constant spin -- the nation remains largely in the center and thus, mainly united.
But it's actually the Republican Party that has become more and more willing to demonize it's critics. For better or worse, the Democrats have not yet mounted a sustained partisan counteroffensive that compares. Establishment Dems are much more tempted to act like Mr. Rogers than like Andrew Jackson, as cartoonist Tom Tomorrow has been noticing: The great debate.