Public Education

That’s a poetic way of expressing an idea that’s very much a part of the social discourse today, in an era in which our public schools are systematically being torn apart. A more prosaic phrasing goes like this: No one wants to live in a country surrounded by fools. It’s unpleasant, and, as Mann pointed out, it’s dangerous.
In what sense is it dangerous? Well, uneducated people tend to turn to crime more than their counterparts, but they are also less capable of changing their minds when they come across new facts. Also from Mann: Do not think of knocking out another person’s brains because he differs in opinion from you. It would be as rational to knock yourself on the head because you differ from yourself ten years ago.
This mental fixity is the phenomenon that gives us the modern-day Trump supporters, anti-vaxxer, etc.
