Peter Suderman offers the provocative thought that Washington is in "a post-policy moment." The core fact, he says, is that both parties have achieved the goals they care about most: Republicans have kept taxes low, defense spending high, and the national-security state strong. Democrats, meanwhile, have successfully defended the entitlement state and passed a near-universal health-care bill -- and he might have added their recent successes raising taxes on the rich and advancing the cause of gay marriage.

"This is what really lies underneath the recent policy stagnation," he writes, "not obstructionism, but exhausted party agendas with nowhere left to go."

(Paul J. Richards/AFP/Getty Images)

That takes it a step too far: What lies under the recent policy stagnation is clearly obstructionism -- or, if you prefer, the gridlock of divided government. After all, 2009 and 2010 were only a few years ago, and they were the most rapid period of policy accomplishment in generations. Democrats didn't run out of agenda. They ran out of votes.

The right way to approach the question of policy exhaustion, then, is to reverse the gridlock and ask what the two parties would do if they had commanding majorities in Congress.

For Democrats, the agenda is clear: Immigration reform would be the first big bill to move. The harder lift would be a cap-and-trade plan to deal with global warming, though given big enough majorities, one might pass. Universal pre-K would quickly end up on the president's desk. Congress would spend a lot of time supporting, rather than impeding, the implementation of Obamacare.

After that the size of the agenda falls quickly. A significant package of infrastructure investments would be signed into law, of course. A modest gun control package would emerge. Something along the lines of President Obama's budget would replace sequestration. And the Obama administration has a slew of housing and educations and manufacturing and retraining initiatives it would like to take off the shelf.

The Republican agenda is a bit of a trickier case. In theory, it's the Ryan budget. The problem is that Republicans, of late, are proving that they can't actually stomach the Ryan budget in practice. The appropriations bills meant to flesh it out are failing on the floor of the House -- despite the fact that House Republicans know full well they're just opening bids for negotiations with the Senate.

So if Republicans were actually in power I think the chance that they'd be willing to detail, pass, and implement the Ryan budget, as written, approaches zero. But they'd probably pass some softer version of it that would include a move toward premium support in Medicare and block grants to Medicaid and food stamps. They'd end Obamacare and replace it, for the moment, with a promise to replace it at some point in the future. They'd open up the Keystone XL pipeline and try to juice other forms of domestic energy production. They would rewrite both the individual and corporate tax codes, sharply lowering rates, and sharply lowering the effective tax burden on both richer Americans and corporations. Depending on the president, education might well make its way back onto the agenda.

These are big agendas. Enough to keep either party busy for awhile. Enough to quiet any talk of a "do-nothing congress."

Suderman's idea that policy is stagnating because the ideas simply aren't good enough is appealing to those of us who like to believe American politics runs on ideas. It's a comforting explanation of Washington's daily disappointments. It means -- to paraphrase a candidate with some big ideas of his own -- that if it's not a legitimately good policy agenda, our political system has a way of shutting that whole thing down.

But day-to-day politics -- for better and often for worse -- doesn't run on ideas. It runs on votes. And in a polarized era like our own, divided government is just another way of saying neither party has the votes.