Dick Smothers, who is eighty-six, took the long view the other day. “It sure didn’t start with us,” he insisted, when asked about politicians’ recurring habit of attempting to muzzle TV performers. “In my lifetime, it started with Edward R. Murrow, of course. But they didn’t fire him. They just switched him to a time slot not many people watched.” This is true. In 1954, Murrow exposed many of Joseph P. McCarthy’s lies on his CBS news-magazine show, “See It Now,” a tipping point in the senator’s downfall. Just a year later, the series lost its sponsor, Alcoa, and was shunted from its Tuesday-night prime-time slot to random, irregular dead zones on the schedule.