What’s wrong with partisanship in Congress?

WASHINGTON — According to the VoteView ideological ranking system, the most moderate Democratic senator in the 112th Congress is Nebraska’s Ben Nelson. The most moderate Republican senator is Maine’s Olympia Snowe. And they’re both retiring.

That shouldn’t be a surprise. For years, our increasingly polarized political system has been culling moderate members. Throughout the 1970s and even into the ’80s, a number of Democrats were more conservative than the most moderate Republicans, and vice-versa. Today, no Senate Democrats are more conservative than the most liberal Republicans. Even Nelson and Snowe are comfortably closer to their parties than they are to each other.

That’s modern American politics: Two parties, no touching. And that’s a reason why Snowe is retiring. “What I have had to consider is how productive an additional term would be,” she said in a statement. “Unfortunately, I do not realistically expect the partisanship of recent years in the Senate to change over the short term.”

She’s right. The partisanship is not likely to change anytime soon. In fact, it’s likely to get worse. Snowe probably will be replaced by a liberal Democrat. Nelson probably will hand his seat to a conservative Republican. The parties will become that much more unified, disciplined and polarized. And that’s okay. Or, at the least, it would be okay if the nation’s political institutions were prepared for it.

We use “polarization” as an epithet. It’s what’s wrong with America’s politics. It’s what’s wrong with America’s political parties. It’s what’s wrong with America’s politicians. It’s what’s wrong, finally, with America.

And polarization is certainly bad for moderate lawmakers who want to wield influence by brokering deals between the two parties. But for the political system as a whole, “polarization” is a neutral term. It simply means the two parties disagree, and clearly. It doesn’t mean they disagree angrily or unproductively or in the service of extreme ideologies.

To imagine this, consider two political systems. In one, they aren’t polarized, because the Democratic Party is filled with conservative arch-segregationists. In another, the parties are very polarized, but it’s because everyone agrees that segregation was a moral blight, and with that out of the way, the conservative Democrats who kept their seats by appealing to racism were replaced by Republicans. Which system is more extreme? Or unproductive? Or hateful?

Polarization doesn’t describe people’s opinions. It just describes how those same people, with those same opinions, sort themselves. For political scientists, it was long a puzzle and a frustration that the Democratic Party contained so many conservatives and the Republican Party so many liberals. But race was the reason for much of that, and as race has receded as a driving force in American politics, the two parties have sorted themselves in a more sensible way. The problem is, the political system hasn’t responded.

The U.S. system, as any historian will tell you, was built by men who hated parties and anticipated their absence from American politics. That didn’t quite work out. But for much of U.S. history, and particularly for much of the 20th century, the political parties have been unusually diffuse and unable to act as organized, ideological units. That has made them well suited to a system that, for reasons ranging from the division of powers to the filibuster, required an unusual level of consensus to function.

But as the two parties have polarized, we’ve learned that a system built for consensus is not able to properly function amid constant partisan competition. The filibuster has gone from a rarity to a constant. Compromise has become unusual. Crises of gridlock, like the recent showdown over the federal debt ceiling, have become common. And no one can say that this is what the American people want: Approval ratings of Congress have been on a downward slide for decades, and they have never been lower than they are today.

Snowe’s retirement will have many lamenting the endangered moderate, and wondering how the clock can be turned back. But it can’t. About that, Snowe is right. Polarization is with us now, and will be for the foreseeable future. The question is whether we will allow it to paralyze the political system and undermine the country, or whether we will accept it and make necessary accommodations.

Doing so would require taking on cherished, consensus-promoting features of the old system, such as the filibuster. But in today’s gridlocked world, those features no longer promote consensus. They simply promote gridlock.