The problem with Fox “News,” the cable TV channel, isn’t just what it is — it’s also what it isn’t. It is often a purveyor of propaganda and misinformation. What it’s not is a source of “news” — at least not by any normal definition. That’s one of the conclusions I drew from a fascinating new study in which arch-conservative Fox TV viewers were paid to watch CNN for a month. The study was performed by a pair of political scientists: David Broockman, who teaches at UC-Berkeley, and Joshua Kalla, who teaches at Yale. According to Broockman and Kalla, when...