The more militant members of the N.R.A. and most of its leaders may be un-American. By “militant” I don’t mean those who wish to protect recreational shooting and hunting; nor do I mean those who, like Justice Antonin Scalia, believe that there is a constitutional right to defend one’s home and family with firearms. These are respectable positions (although I am deeply unpersuaded by the second). I mean those who read the Second Amendment as proclaiming the right of citizens to resist the tyranny of their own government, that is, of the government that issued and ratified the Constitution in...