Dialogue in its traditional meaning referred to people with divergent viewpoints coming together in hope of discovering a different, more complex and perhaps higher truth. The most famous practitioner was Plato, whose Socratic dialogues were a search for truth or, at least in the intellectually modest pose of Socrates, an acknowledgment of what we really don’t know. Four hundred years later, Plutarch often availed himself of dialogue. The most recent philosopher to use the form was George Santayana in his 1925 book “Dialogues in Limbo.”A rough notion of dialogue was taken up by newspapers in 1973, when the liberal New York Times hired William Safire, a conservative former speechwriter for Richard Nixon, as a regular columnist. Taking things a step further, The Wall Street Journal publishe...