Have you seen this video? How ‘bout this one? Or this one? If you’re reading this, you’ve likely had dozens of these little nuggets of YouTrivia show up unannounced your inbox over the past 18 months. More often than not with a subject line like “you have to see this…” Well here’s one you probably haven’t seen. (That’s right, you’re hearing God Bless the U.S.A. by Lee Greenwood.) David Plotz, editor of Slate, mentioned it in a December podcast and I thought he deserved a shout-out for noticing what seems like a persuasive example of the limitations of social media as ideology-agnostic cultural Cuisinarts.

This was seen by more than 13 million people. 13 million, 20,000 of whom clicked the link on Rush Limbaugh’s site. And neither of us was one of them. Why not? I guess no one thought we’d be interested. Sarah Silverman’s hilariously vulgar plea for intergenerational political dialogue among the chosen people? Now that sounds like it would be more up our shared alley. I think about a dozen people sent me that one. Here’s the point: Sure, the social transmission of media is breaking down some cultural walls, but it’s reinforcing others.

About six months ago, my thesis supervisor, a confirmed liberal of the Daily Kos/Nation sort, told me she’d managed to get herself into a conservative email chain. Turns out her parents belong to that curious species of American who votes Republican no matter what buffoon is on the ticket. I read a few of the emails and I felt like I’d just stolen the enigma machine. Just as I suspected: they actually think he’s a Muslim!

The tubes can connect people who think differently, but they may actually be better at connecting people who think alike.