Not very much, at first glance. Americans love firearms: there are some 150 million in circulation. Half of all Americans own weapons. Welcome to Dodge City. In Puritanical America, it’s ok to show people being sawed in half and skinned alive on TV but illegal to show the nude human body.

Attacks on schools are not just an American problem: they have occurred in Europe, Canada, Pakistan, and, last week, China.

The Second Amendment of the US Constitution, enacted in 1791, guarantees: “A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.” This basic right was reaffirmed by Supreme Court decisions in 2008 and 2010.

The right to bear arms was designed to enable citizen’s militias and to protect individuals against “tyranny.” The United States had just battled Britain for its independence and feared the rise of a home-grown monarchy.

America was not alone in arming its citizens. In Switzerland, the country of my youth, citizen soldiers keep their automatic weapons at home. As far as I know, there has been only one case in half a century of a Swiss running amok and using his military rifle against civilians.