In a piece for the Columbia Journalism Review, Alexis Sobel Fitts addresses one of the most fascinating topics in ideological cable television — how MSNBC and Fox News deal with the folks who disagree with the network’s prevailing ideology. In comparing the two networks, Fitts says that conservatives “occasionally” appear on MSNBC programs, but:

While the liberal hosts of MSNBC often skewer conservatives, the debates happen with villains who are not in the studio: lambasted, by proxy, in news clips. At Fox, they happen in person, with a real-live liberal who is often on staff. “I still think that Fox is the one place on the cable dial for sure where that kind of freewheeling debate takes place,” said Juan Williams, who was hired as one of the network’s first progressives.

In its immersion-viewing of MSNBC last year, the Erik Wemple Blog noted some pretty key exceptions to that characterization of MSNBC tendencies. Around the time of the government shutdown, for example, MSNBC welcomed on its air outspoken Republicans, and sharp exchanges resulted. The Erik Wemple Blog wrote up a couple of the clashes. And yes, as Fitts says, a lot of MSNBC hosts just take a clip of a Republican spouting off on a topic, then turn to their in-studio guests to conduct analsysis-cum-debunking.

Though Fitts ably explores the dynamics of cable news and partisan contributors, it’s time for a data-heavy analysis. Does MSNBC, for instance, invite GOP voices on the air steadily, or only when the Republican party is struggling, as in the government shutdown drama? As for Fox News, there’s less mystery: Strong-willed liberals are often on air and constantly outnumbered.