What does produce polarization? This seems like a good cut at it:
There are two main reasons why the parties are so polarized today. One is that we have the best-educated, best-informed electorate that we’ve ever had in American history, so elected officials are under more pressure to reflect the ideological views of their backers. The other is that we lack a major, high-salience issue that’s uncorrelated with the main fights in American politics. In the middle of the 20th century, some economic populists were also white supremacists and some business friendly conservatives had progressive views on race and racial politics was very important to a lot of people. If something brand new (barbershop licensing, parking regulation, etc.) were to become highly salient that might cut across existing partisan divisions.I'll also refer everyone to a useful article by Paul Quirk reviewing four recent books that touch on polarization. I should note that in general, the literature puts a lot more weight on elite-level players, whether it's activists or politicians or other political professionals, than on the electorate as a whole. There's considerable debate, however, on exactly who the key players are and which way causation runs.
My own view is that we should promote political regulation that supports strong parties, but discourages ideological lockstep or internal party hierarchy. I don't believe that districting matters much one way or another, but I do think that a floor, not ceilings approach to campaign finance would be helpful. In two ways. Well-financed minority party candidates might sometimes win; therefore, parties might attempt to nominate candidates who match their districts (in other words, Mark Pryors and Scott Browns), and those candidates will have a much stronger incentive to run. Even more likely is that majority-party candidates in lopsided partisan districts will have a much greater incentive to care about median voters in the general electorate, rather than just caring about primary election voters and party activists. Sarah Binder wrote an excellent post the other day about Members who are "single-minder seekers of re-nomination," rather than re-election. If every major-party candidate had, say, $250K or even $500K in publicly provided campaign funds, re-election would at least stand a chance of remaining as a major goal.
Hmmm...I could have more to say, but this is already long for a CotD post. So I'll leave it there, except for adding: Great catch!