Sean Theriault is an associate professor in the Government Department at the University of Texas. He is the author of three books, including his most recent book The Gingrich Senators.  This post is the third in our series on political polarization.  The first two posts were by Nolan McCarty and Frances Lee.

I have been studying party polarization in Congress for more than a decade. The more I study it, the more I question that it is the root cause of what it is that Americans hate about Congress. Pundits and political scientists alike point to party polarization as the culprit for all sorts of congressional ills. I, too, have contributed to this chorus bemoaning party polarization. But increasingly, I’ve come to think that our problem today isn’t just polarization in Congress; it’s the related but more serious problem of political warfare.

I think that Evan Bayh (D-Ind.), as he announced his retirement from the Senate, best articulates the conventional wisdom:

For some time, I’ve had a growing conviction that Congress is not operating as it should. There is much too much partisanship and not enough progress; too much narrow ideology and not enough practical problem-solving. Even at a time of enormous national challenge, the people’s business is not getting done… I love working for the people of Indiana. I love helping our citizens make the most of their lives. But I do not love Congress.

It could be that I’m splitting hairs, but the more I research polarization, the less I agree that “much too much partisanship” halts “progress” or that “too much narrow ideology” impedes “practical problem-solving.”

In more recent work, I explore a second – admittedly, related dimension – of political competition. Actually, I called it “partisan warfare” in the book, but I think “political warfare” is more accurate, because partisanship is not always the cause. While it, too, may have its roots in party polarization, political warfare is more combative in nature and requires more than what can be revealed in voting patterns on the Senate floor. The warfare dimension taps into the strategies that go beyond defeating your opponents to humiliating them, go beyond questioning your opponents’ judgment to questioning their motives, and go beyond fighting the good legislative fight to destroying the institution and the legislative process. Partisan warfare serves electoral goals, not legislative goals.

This warfare certainly has party polarization at its roots. Polarization may be necessary for warfare, but it is not a sufficient cause of it. Parties that are divided over policy can have a serious and honest debate, which can even become heated. In the first half of the famous idiom, the opposing sides can “agree to disagree.” Quite apart from the serious policy disagreement, though, the debate between the opposing sides can degenerate into a shouting match in which the policy prescriptions are lost in a fight over legislative games–and in which the combatants question the motives, integrity, and patriotism of their opponents. Under such a situation, the second half of the idiom–“without being disagreeable”–is never realized.

This partisan warfare dimension is harder to quantify, though it most certainly exists. What I call “warfare” is what Frances Lee characterized as “beyond ideology” in her book of the same name. Lee argues that only so much of the divide between the parties can be understood as a difference in ideology. The rest of the divide–by some accounts, the lion’s share of the divide–is motivated by some other goal. I argue that it is this portion of the divide beyond ideology is what causes the angst of those participants and observers of today’s Senate.

More often than not, congressional scholars and political pundits have opted to merge these two dimensions for a couple of reasons. First, there is no doubt that they are related. Party polarization and partisan warfare are sufficiently similar that many treat them as synonyms. Second, the second dimension of political warfare, especially in comparison to the first, is much harder to isolate, operationalize, and analyze. Nonetheless, real analytic leverage can be brought to our understanding of how the current Senate operates and how it is evaluated if these dimensions are pulled apart.

Perhaps my home state of Texas unnecessarily reinforces the distinction I want to make between these two dimensions. Little separates my two senators’ voting records – of the 279 votes that senators took in 2013, Ted Cruz and John Cornyn disagreed less than 9 percent of the time (the largest category of their disagreement, incidentally, was on confirmation votes). In terms of ideology, they are both very conservative. Cruz, to no one’s surprise, is the most conservative. Cornyn is the 13th most conservative, which is actually further down the list than he was in 2012, when he ranked second. Cornyn’s voting record is more conservative than conservative stalwarts Tom Coburn and Richard Shelby. Marco Rubio and Ted Cruz disagreed on twice as many votes as John Cornyn and Ted Cruz.

The difference between my senators is that when John Cornyn shows up for a meeting with fellow senators, he brings a pad of paper and pencil and tries to figure out how to solve problems. Ted Cruz, on the other hand, brings a battle plan.

The trick for me, and all those interested in party polarization, is coming up with systematic, repeated behaviors that differentiate ideological legislators from political warriors. The former make legitimate contributions to political discourse in the Congress; the latter don’t, and need to be called out for the havoc they wreak on our political system. The Senate has in the past and can continue in the future to accommodate senators with serious disagreements. Too many warriors in the Senate, unfortunately, will only perpetuate the dysfunction and low congressional approval we’ve seen the last couple of years.