What are the essential principles of America's political parties?
Paul Krugman seeks enlightenment. But I think he looks in the wrong place. He looks in the works of German Charlie from Trier:
Partisan Classiness: "Many people in the commentariat are utterly committed to the view that the two major parties are mirror images of each other...:
...despite vast evidence to the contrary. But until Harry Enten directed me to... Grossman and Hopkins, I hadn’t really registered the extent to which the same assumption of symmetry is often made by political scientists.... Grossman and Hopkins... document the very real differences in the two parties’ structure... in terms of how they work....
The Republican Party is the agent of an ideological movement, while the Democratic Party is best understood as a coalition of social groups.