As reports began to appear of the disturbed background of Aaron Alexis, the media seems to have universally decided that mass shootings are readily explained by severe mental illness. The assumption is that as psychiatric disorder is so obviously linked to violence, there should be no surprise that the Washington Naval Yard killings involved someone with a mentally troubled history.
Much has already been written about the tragic events of 14 December in Newtown, Connecticut. It's hard to think of anything much worse than twenty small children being gunned down just before Christmas, for doing nothing worse than attending school. But what is the global perspective on this awful event?