Kevin Drum is discussing a book by Larry Bartels that argues the bottom third of the US population (as measured by income) are disenfranchised, as their preferences seem to have no discernible effect on legislative votes. I have not read the book, but I find this an astounding assertion on its face, particularly given that the US government is nearly entirely paid for by the other 2/3. We exploiters don't seem to be doing a very good job of taking advantage of our oligarchy. (By the way, if "oppressed" is defined as having one's preferences have no impact on Congressmen, then add us libertarians into the oppressed.)

There are big differences in policies between Democratic and Republican elected officials, even when they represent exactly the same constituents. Political scientists have an elegant theory explaining why this shouldn't happen: if voters choose the candidate closest to their own policy positions, Democrats and Republicans alike must move to the center in order to get elected. The only problem is, they don't. A figure in the book compares the behavior of Democratic and Republican senators representing liberal and conservative states. The difference in behavior between a Democrat and a Republican representing the same constituents turns out to be much greater than the difference in behavior between a Democrat representing the most liberal state in the country and a Democrat representing the most conservative state in the country. Party and ideology dominate constituents' preferences in shaping legislators' roll call votes.