Everyone agrees that politics in Washington are deeply broken. It's become a mantra for every politician — even the ones who live and work in Washington.

What no one can figure out or agree on is why a federal government that once worked (albeit in fits and starts) no longer does.

Mark Dunkelman has a theory. He outlined it in his 2014 book, "The Vanishing Neighbor: The Transformation of the American Community" (which I loved), and revisited it in a recent TED talk. That's here:

The whole talk — it's only 15 minutes! — is worth watching/listening to. But, for you busy types, Dunkelman's argument boils down to this: We no longer have collegial or cordial relationships with people with whom we are familiar but not intimate.

In the last two decades, we have grown closer to our intimates (family, very good friends) and closer with people we have never met (people you follow on Twitter, for example), according to Dunkleman. What has been lost is those middle-ground relationships: the person you run into regularly at the coffee shop or the guy down the street you talk cars with.

"American democracy is premised on a community-level strength," Dunkleman argues.

And the erosion of those community-level/middle-ground relationships has all sorts of negative consequences for how we think about politics, policy and what our government and our elected leaders should do. The most important of which is the death of reasoned compromise or even believing that someone with whom you disagree is capable of it.

"There's a big chasm between thinking that the person who is sitting across the table from you who has a different point of view is wrong and thinking that they are totally whackadoodle," says Dunkleman. "If they're just wrong, maybe there's a chance of working out a deal. If they're whackadoodle, there's no chance. Can't do it."

That is both deeply insightful and profoundly disturbing.  The lack of comity in our politics derives not from whom we send to Washington but rather from us. (The title of Dunkelman's TED talk is "Why You're the Reason Washington is Broken.") We don't talk to anyone who doesn't agree with us. And, even more than that: We don't know anyone at even a familiar level with whom we regularly talk about lots of things — from politics to sports to knitting. The result is painfully obvious: When confronted with people who disagree with us, we villainize them — calling them misinformed, at best, and outright malignant at worst.

To change Washington, then, we need to change how we go about our daily lives: who we talk to and about what. That's a hell of a lot harder than just blaming "Washington" or throwing our hands up in frustration.