The 112th Congress and the accelerating polarization gap

by nick

In the classic film Network, anchorman Howard Beale famously instructs his audience “to get up right now, sit up, go to your windows, open them and stick your head out and yell – ‘I’m as mad as hell and I’m not going to take this anymore!” Americans, it would seem, took Beale’s advice to heart in November as voters, upset over a number of issues ranging from health care to unemployment, delivered Democrats their worst drubbing since 1938. And although the December tax deal stirred a late sense of cheer for some this holiday season, a collective sense of nausea has been steadily growing as the ubiquitous Congressional mantra of “No compromise” threatens to taint another two years of legislative workmanship—manifesting itself first in the rhetoric of the election’s big winners and second from glum, lame duck Democrats. As one popular political commentator bluntly assessed the coming 112th Congressional session, “Compromise is off the table. They didn’t want to compromise with us, and we have no business compromising with them. They lost. Losers compromise. We don’t. We’ve got nothing to compromise.”

Dismaying as these sentiments were, however, perhaps a greater sense of alarm has arisen over the loss of centrist politicians as the bulk of “moderate” legislators across America retired (Sen. Evan Bayh, D-IN), took hard-line party stances to survive primary challengers (Sen. John McCain, R-AZ), or were  beaten outright in the general election (Rep. Gene Taylor, D-MS). To hear Texas Democrat Jim Hightower describe the new Congress, “There’s nothing left in the middle of the road but yellow stripes and dead armadillos.”

Should Americans be surprised?

Hardly. For years, statisticians Keith Poole and Howard Rosenthal have been predicting the disappearance of this vaunted middleground and quantifying the polarization that has replaced it. Using a variation of a technique called multidimensional scaling—which allows one to map a set of points relative to how “close” each pair of points is supposed to be—Poole and Rosenthal have mapped the increasing distance between the two parties based on legislator roll call votes. They write that

only two dimensions are required to account for the great bulk of roll call voting. The primary dimension is the basic issue of the role of the government in the economy, in modern terms liberal-moderate-conservative. The second dimension picked up regional differences with the United States — first slavery, then bimetallism, and after 1937, Civil Rights for African-Americans. With the passage of the 1964 Civil Rights Act, the 1965 Voting Rights Act, and the 1968 Open Housing Act, this second dimension slowly declined in importance and is now almost totally absent. Race related issues – affirmative action, welfare, Medicaid, subsidized housing, etc. – are now questions of redistribution. Voting on race related issues now largely takes place along the liberal-conservative dimension and the old split in the Democratic Party between North and South has largely disappeared. [Thus], voting in Congress is now almost purely one-dimensional – a single dimension accounts for about 93 percent of roll call voting choices in the 110th House and Senate – and the two parties are increasingly polarized. (bolded mine)

The following graph represents this first dimension, as seen in both the House and the Senate. Party polarization spikes during the Civil War years, decreases enormously after Reconstruction, and bottoms out in the years leading up to and during the Great Depression. After a relatively stable, 20-year period throughout the War years, polarization slowly begins to increase again until a rapid upswing occurred in the 1970’s, leading to today’s unprecedented gap.

While the historical reasons for this pattern are incredibly diverse, one curious, concurrent phenomenon—party unity voting—may be useful in partially explaining this volatile picture of party polarization. Indeed, examining the frequency of the two parties to vote in unison against each other (50 percent or more of one party voting against 50 percent or more of the other) reveals a pattern that roughly mirrors the behavior found in the party polarization graph.

The connection between party unity voting and polarization is a reasonable one. The stronger a party’s unity, the more power it wields as a voting block, and, during times of unusually lopsided power distribution, the more likely it will act solely in its own, partisan interests. This behavioral pattern describes both the majority and minority parties: the majority attempts to ramrod its legislation through Congress while the minority obstinately attempts to deny their opponents actions. This utter rejection of bipartisanship, in turn, creates an ultrapartisan envirionment ripe for gridlock.

If that picture sounds familiar, it should. The last two years of the 111th Congressional session were notably plagued with gridlock over stimulus spending and health care reforms as Democrats uniformly pushed their legislation through while Republicans united themselves in an attempt to block it . And if Americans thought that logjam was bad, the next two years don’t hold much more promise.

In fact, returning to Poole and Rosenthal’s work on polarization, one could attempt to forecast a rough vision of the next Congressional cycle’s polarization gap by controlling for the removal of out-going legislators. Although no one knows exactly how the newly-elected Congressmen will act, examining the current group of incumbent legislators can provide a basic, baseline picture of where the gap currently stands.

Predictably, the situation doesn’t look encouraging.

After removing defeated and retiring members, which included statistical moderates Evan Bayh D-IN, Blanche Lincholn D-AR, and George Voinovich R-OH, the polarization gap in the Senate increases from approximately .88 to .897 . In the House, the gap jumps from around .97 to 1.034, the first time polarization breaks the 1.0 barrier.

So, what do these numbers mean? First, this increase in polarity has meant the number of statistical moderates has fallen to around ten percent of members in both Houses. Second, the standard deviation for both parties, that is the distance of a given legislator in relation to the party’s rough ideological mean, decreases—suggesting that the parties are becoming further ideologically homogenized. Third, in light of the incumbents’ incredibly wide polarity gap at the outset of the 112th Session, and considering that an overwhelming portion of the outgoing legislators in 2010 were replaced by Republicans and Tea Party activists with an ideological ax to grind, the new Congressional environment doesn’t appear to be terribly conducive to bipartisan exchange.

And while it remains to be seen whether or not the newly-strengthened Republican party will, in fact, further aggravate the polarization gap, the data suggests that a steady acceleration will continue. If Poole and Rosenthal are correct, and there are few reasons to think they are not, then the 112th Congress will experience another significant increase in polarization. After all, as the great novelist Oscar Wilde once wrote, “Moderation is a fatal thing. Nothing succeeds like excess.”

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