Dana Milbank had an interesting column over the weekend countering the conventional wisdom on Joe Lieberman: rather than undergoing some recent conservative conversion, he writes, Lieberman has a long-standing record of sticking it to the Democratic leadership on high-profile issues and supporting them the rest of the time. What’s different now is the intolerance with which his transgressions are received:

In our increasingly tribal politics, both sides are more demanding of ideological purity than they were when Lieberman came to the Senate in 1988. The constant purging of heretics has left Congress ever more polarized. This, more than anything done by Lieberman or Ben Nelson or Olympia Snowe, is why the government can’t get anything done.

Milbank is correct that Congress is more polarized than it was a generation ago (this is in part because a generation ago—when many members of today’s media elite were undergoing their political education—ideological polarization in Congress was at one of the lowest points in the history of the modern two-party system). And there is some support for his claim that polarization contributes to legislative gridlock. But in focusing solely on polarization Milbank is adopting another form of conventional wisdom, one that pins much of the blame for D.C.’s woes on the increasing use of nasty words. And in the process, he elides a major development in American politics: the standardization of the filibuster and the creation, in recent decades and especially in recent years, of an effective sixty-vote requirement in the U.S. Senate.*

The inability of government to “get things done” is not only a preoccupation of political journalists, but a rich area of study for political scientists. In the opening of an influential book on this subject, Revolving Gridlock, the political scientists David Brady and Craig Volden write:

Our explanation… will not focus on the role of political parties, nor of special interests, nor of the media, and it does not rely heavily on presidential leadership. This is not to say that those variables don’t play a role in making public policy—clearly they do. Nevertheless, our explanation for gridlock focuses on two primary factors: (1) the preferences of members of Congress regarding particular policies, and (2) supermajority institutions—the Senate filibuster and the presidential veto.

Another way to put this is that policy change depends on what legislators want, and new rules that require more legislators to agree that they want the same thing make policy change less likely. The rules of the game go a long way in determining the outcome. This seems obvious—it is obvious—and political journalists no doubt understand it. Still, the leading press outlets tend to overlook the importance of this shift.

For example, as James Fallows noted yesterday, a typically solid piece by Robert Pear of The New York Times took for granted the need to get sixty votes for health care in the Senate, without noting that that need is a fairly recent innovation (the word “filibuster” does not appear). And that was in an otherwise-good story focused on the machinations of Senate negotiations! Consider how little attention is paid to this issue the rest of the time.

So why does the rise of the filibuster get underplayed? For one thing, it’s not just modestly technical, it’s technical-sounding. For another, while it’s a historically recent development, it’s not really “news,” in the sense of something that occurred in the last day or week, or that was unforeseen during the last election cycle. (Think of a sports analogy here: When a rule change is introduced, its implications are typically the subject of great debate among both the press and participants. But once it’s implemented, everyone adjusts to the new normal pretty quickly.)

But while the relative lack of attention to the filibuster is understandable, that doesn’t mean it’s right. In terms of shaping legislative outcomes, this is a major story—and it’s not possible to explain the way government works, or doesn’t, without telling it.

*In fairness to Milbank, he wrote a whole column about filibustering of judicial nominees—or more precisely, about Senate hypocrisy over that subject—just last month. The point here is his most recent column is part of a broader trend in the political press.

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Greg Marx is a CJR staff writer. Follow him on Twitter @gregamarx.