It's funny that I read past this line without even thinking about how unusual it is that it needs a source. I've read so many blogposts and tweets about how it's justifiable to punch people in the face over specific disagreements that I'm completely desensitized to the hilarious image of grown, educated adults lashing out just because they're losing an argument.
It seems like every time I make a politically controversial post on Reddit and increasingly HN, I can just CTRL-F my comment inbox and assure myself that there's some reference to punching in there.