When critics decry the current state of our public discourse, one reliably easy target is television news. It's too dumbed-down, they say; it's no longer news but entertainment, celebrity-obsessed and vapid.

The critics may be right. But, as Charles L. Ponce de Leon explains in That's the Way It Is, TV news has always walked a fine line between hard news and fluff. The familiar story of decline fails to acknowledge real changes in the media and Americans' news-consuming habits, while also harking back to a golden age that, on closer examination, is revealed to be not so...