In a piece for the Post’s Sunday Outlook section, Thomas Mann and Norm Ornstein write that the rise in political polarization in Congress is not the effect of both parties moving to their ideological extremes but rather of Republicans moving far further to the right than Democrats have moved to the left.

A view of the US Capitol Building March 25, 2012 in Washington, DC. The Supreme Court will hear arguments on Monday challenging the Constitutionality of the Obama Administration's health care reforms. (BRENDAN SMIALOWSKI/AFP/Getty Images)

So, are they right? Is it really Republicans’ fault that we are in the partisan pickle in which Congress is either unable or unwilling to solve problems — whether small or large — facing the country?

What’s undeniably true is that we are living in an age of hyperpartisanship. Mann and Ornstein cite a study conducted by political scientists Keith Poole and Howard Rosenthal that details that fact vividly.

Here’s one chart from their study detailing the rising polarization in the House and Senate over time:

There’s plenty of other evidence supporting the historic partisan era in which he find ourselves.

The annual National Journal vote ratings — and invaluable resource — tell the story well. In 2010 and 2011, there was no Senate Democrat with a more conservative voting record than any Senate Republican and no Senate Republican with a more liberal voting record than any Senate Democrat. That had happened only one other time in the previous 30 years before it happened in the last two years straight.

Mann and Ornstein are on very solid ground then in their assertion that we are in uniquely partisan times. There is considerably more disagreement about whether that blame should lie at the doorstep of the GOP, however.

“Both caucuses have moved to the polar caps as more one-party districts are created and members’ reelections are dependent on primaries and not the general elections,” said Tom Davis, a well known moderate and former Virginia Republican House Member. “The political coalitions have evolved into a parliamentary system, which doesn’t work in a checks and balances framework.”

Let’s take Davis’ perspective and play devil’s advocate to the points Mann and Ornstein use to make their “blame Republicans” argument.

Mann and Ornstein cite comments made by former Nebraska Republican Sen. Chuck Hagel, who called his party “irresponsible”, as evidence that the GOP has moved away from its once-inclusive nature.

But, for every Chuck Hagel there’s a Joe Lieberman who fell so far out of favor with the Democratic party over his stance on the war in Iraq that he was defeated in party primary, became an independent, won that race and then went on to speak at the Republican National Convention in 2008. (Yes, it is beyond odd that all of that happened in the last six years.)

Mann and Ornstein also cite the fact that moderate statesmen in the GOP are virtually non-existent these days with the departures of the likes of former Missouri Sen. John Danforth and former Illinois Rep. Bob Michel. (They could have, but didn’t, include the retiring Olympia Snowe of Maine in that construct too.)

But, a look at the recent departures from the Senate Democratic ranks suggests their number of moderates is also very much on the decline. Already in 2012, Sens. Ben Nelson (Neb.), Jim Webb (Va.) and Kent Conrad (N.D.) have called it quits. Add to that the likes of Sens. Evan Bayh (Ind.), Byron Dorgan (N.D.), Arlen Specter (Pa.) and Blanche Lincoln (Ark.) all of whom left in 2010, and its clear that the centrist Democratic ranks have taken a major hit over the last four years too.

There is a least some reason then to look slightly askance at the anecdotal evidence cited by Mann and Ornstein to prove their point. And yet Davis’ point that both parties have moved to their respective partisan poles doesn’t necessarily run counter to the idea that Republican pole is further to the right than Democrats is to the left.

Mann and Ornstein seem to lay the further, faster movement to the right on the Republican leadership. But, what if it’s the other way around? What if the Republican rank and files have grown more and more conservative over the past few decades, a progression that has forced its leaders to move to the right in order to, well, remain leaders?

Look to the debt ceiling negotiations. There was clearly a desire on behalf of Speaker John Boehner to craft a grand bargain with President Obama. What was lacking was the will from the House GOP conference to sign on. And where did that collective lack of will come from? From the fact that when talking to their constituents at home, Republican members grasped the fact that a compromise was not what the people who elected them wanted. At all.

Yes, you can make the case that elected office is about leading not following, that the best politicians are those who can convince a wary public to follow them down a course that not everyone agrees is the right one.

The truth of the matter though is that most House Members — Republicans and Democrats — are not (nor do they aspire to be) inspirational leaders. What they want to do is not lead the country but simply keep their job. And, in a representative democracy, the best way to keep your job is to, well, represent the people who sent you to Washington.

That those people are increasingly uninterested in compromise speaks less to the quality of their representation in Washington than to the fact that deal-making has become a bad word in our (political) culture.

None of the above is to take away from the points made by Mann and Ornstein in their thought-provoking essay (and book). Instead, it’s simply aimed at pointing out that few things in politics are as black and white as we would all like to believe they are — or at least could be.