In context, the phrase “civil discourse” has an alternative meaning that you arrive at by substituting the first dictionary definition of the word “civil”: > 1

In context, the phrase “civil discourse” has an alternative meaning that you arrive at by substituting the first dictionary definition of the word “civil”: > 1. relating to ordinary citizens and their concerns, as distinct from military or ecclesiastical matters. It’s a brilliant argument that works on two levels: violence is the only alternative to free speech, and raw and ugly honesty can lead to greater understanding.