So one of the big names in U.S. election analysis, Stu Rothenberg of Roll Call, allows as how the decline in ticket-splitting made it difficult for a Democrat like Mary Landrieu to win in a red state like Louisiana. That is undoubtedly true, if not particularly novel.

But in an orgy of flawed causal analysis reinforced by false equivalency, Rothenberg blames this phenomenon on ideological extremists in both parties:

The defeat of more pragmatic Democrats — particularly in the South, but nationally as well — makes parliamentary voting more likely in the years ahead — just as the disappearance of more liberal Republicans has. The more each party is seen as representing an uncompromising ideology and certain constituencies, the more straight-ticket voting we will see.

The Democratic Party has become defined as the party of Sens. Elizabeth Warren of Massachusetts, Jeff Merkley of Oregon and Al Franken of Minnesota; just as the GOP has become defined as the party of Sens. Ted Cruz of Texas and Rand Paul of Kentucky.

Because of this, partisan voters in blue states will be increasingly hesitant to elect Republicans to the Senate, just as partisan voters in red states will be more and more reluctant to send Democrats to the Senate.

Excluded as possibilities are (a) that other factors led to more predictable and consistent partisanship, (b) one party’s extremism, not that of both parties, triggered the ideological “sorting out;” (c) it’s “parliamentary” voting that is the logical default drive, and the confusion of partisan identification with history, demographics and the individual voting records of individual pols that’s “normal.”

An awful lot of the ticket-splitting, bipartisanship and muddle-in-the-middle partisan differentiation that so much of the pundit class clearly longs for was the product of ancient history (most notably whose side your ethnic group or religious sect–now often blurred by intermarriage or abandoned by religious conversion or secularism–chose in the Civil War or the debates over U.S. intervention in World War II or Prohibition or the Great Depression or Civil Rights) colliding with contemporary electoral choices. As this history fades, and more durable partisanship reemerges, it’s just weird to act like it’s a tragic aberration.

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Ed Kilgore is a political columnist for New York and managing editor at the Democratic Strategist website. He was a contributing writer at the Washington Monthly from January 2012 until November 2015, and was the principal contributor to the Political Animal blog.