Failure has many fathers...

Campaigns aren't just complicated, they're complex. No single factor can explain what happens, any more than one can pin the Civil War on a single event or even contain it within a single field of study.

There's a good reason for this: social phenomena operate simultaneously on multiple, irreducible planes. Wars, movements, campaigns and the like all consist of individuals. The individuals constitute sub-groups and groups, each with emergent properties. (By "emergent" I mean that the properties of the group are different from the properties of the individuals, and those properties and behaviors can be quite surprising.) We can't understand social phenomena without considering all the planes — we need to be able to talk about "the campaign" and "the Iowa ground organization" as well as about the specific actions of specific individuals — but the planes don't fit together very well: they are irreducible going down and emergent going up levels of abstraction.

So, there is no hope of a definitive account. History is like that. And we're like that: as mortals, to see at all we can't see everything. So, we deal with it through narratives and the grander narratives we sometimes call "myths."

But we're not off the hook. We can only work the narratives out through spirited conversation about specific threads. You say that the Civil War was fought over states rights, and I might adduce evidence that it was "really" about the economics of plantation-based agriculture. You say that the Dean campaign failed in Iowa and NH (and 7 more states today, very likely) because the Internet distracted it from real world organizing, and I'll argue that it failed because it tried to go around the existing political structure...and we'll very likely agree down the road. Or maybe not.

All of which is a long-winded way of saying that I liked Thomas Schaller's explanation in Salon of what went wrong with the Dean campaign in NH and Iowa.