While political scientists rarely agree on anything, there seems to be a consensus in American politics that political polarization in the 2005-2006 (109th) Congress is the highest in 120 years. See the figure below (details on how these numbers were calculated can be found here).
However, there seems to be little agreement on what led to the current state of affairs. I know most people will make the argument that it’s the electorate, stupid. But Morris P.Fiorina, Samuel J. Abrams and Jeremy C. Pope in Culture Wars: The Myth of a Polarized America make a strong case that the electorate is not polarized. Well maybe the general electorate is not polarized, but maybe primary voters are, and they are the ones electing extreme candidates. But, as John notes in the previous post, Alan Abramowitz argues that primary voters are not that different from general election voters. Nolan McCarty, Keith T. Poole and Howard Rosenthal in Polarized America: The Dance of Ideology and Unequal Riches argue that is the rise of income inequality. Evan Thomas in a Newsweek article titled The Closing of the American Mind citing Markus Prior‘s book Post-Broadcast Democracy makes the case that it’s the change in the media. These explanations seem to be at odds with one another. Since each explanation deserves a little more attention, I’ll spend the next couple of posts going into the details of all these arguments to see how they help (or don’t help) us understand political polarization in Congress.