One of the things we keep hearing in the aftermath of the latest instance of gunning down innocent people with assault weapons is that the cause of these tragedies is mental illness.
“How,” asks a reporter, “do we know the assailant was mentally ill?”
“Well”, goes the answer, “the fact that the assailant shot a bunch of innocent people is proof positive of their mental illness.”
At best. this dubious explanation is a tragic case of perfect prediction after the fact, and if you think about it, it’s not very helpful. If mental illness is the cause of these tragedies, then what is needed is a method of prediction what will intercept mentally defective people before they go on their rampages.
Accomplishing this act of perfect prediction is actually not very difficult. We can say with complete certainty that those who shoot masses of people with assault weapons are people who have assault weapons. Although practically speaking, we cannot interdict all mental defectives who seek to possess such weapons, we can do a good deal to stem the tide with the following screening technique.
Any person seeking to purchase, beg, borrow or steal semi-automatic weapons of any sort, or ammunition for such weapons, should be barred by law from purchasing, begging, borrowing or stealing said weapons because their desire to possess those weapons is sufficient cause to believe they are mentally unstable.
See DSM IV: persistent paranoia, delusions of grandeur, suicidal tendencies, fetishism, erectile dysfunction, sexual ambiguity, persistent sense of impotence and powerlessness, etcetera, etcetera, etcetera.