The most disturbing thing about the Colorado Batman movie shootings that killed a dozen and wounded almost 60 -- the worst such incident in American history -- is that there is no logical way to prevent such massacres.

That said, there's no shortage of psychiatrists, social psychologists, editorialists, politicians and pundits who are quick with solutions and theories (mildly sanctimonious) about early detection of potential homicidal nutbars. But these are mostly empty rhetoric. In a free society, people can't be locked up or put away until they've done something bad or wrong. Being eccentric is not enough. Nor should it be.

In the case of James Eagan Holmes, the 24-year-old who allegedly did the shooting at the premier of the Batman movie in Aurora, Colorado -- The Dark Knight Rises -- there seem few hints that he was dangerous. No criminal record (apart from parking tickets), a
university graduate, a Ph.D candidate, little reason to cause alarm despite his fixation on being the bad guy (the Joker) in the Batman series. But then that's another peculiar American custom: Dressing in the role of fictional characters.

Apparently the movie theatre was filled with people dressed in Batman regalia -- kind of like Star Trek wannabes who actually have conventions dressed like characters in the series. But these people are harmless -- a bit goofy, but also kind of endearing. Unless, of course, they are James Holmes types.

There are several reasons why America hosts most of these recent mass slaughterings. First of all, while such incidents can happen anywhere, they are most prevalent in free, or democratic countries. In autocratic or repressive regimes, mass killings by explosives are for political reasons -- Chechen terrorism in the Moscow theatre bombing or the Beslan school massacre. But not random, mindless slaughter.

The easy availability of guns and explosive in America is a contributing factor, as is the "culture" of guns and violence. So much of North America's entertainment involves violence and guns that it's hardly surprising if (when) nutbars carry it too far.

As for this latest Batman movie, the genuine horror and shock expressed by the people involved with the movie, will undoubtedly result in greater profits, as theatres will take supposed precautions against a repeat massacre -- phony, but adds to the excitement of attending.

I forget the name of the movie, but some years ago those who attended it were asked to sign a waiver that would not hold the theatre responsible if the movie was so scary that it caused a heart attack. A great advertising gimmick.

Every time there is a Columbine shooting, a fast-food massacre, or a guy going berserk with an assault rifle, there are analyses about how the signs were there if anyone paid attention. It was that way with the Virginia Tech massacre of 32 people, it's the same with James Holmes in Colorado.

It's always easier to define "why" someone commits a violent act after the violent act has been committed. There's no sure way to predict who will commit such an act. Again, in a free society quirky behavior is not a crime.

In the old Soviet Union, China, and communist countries, people who didn't fit the mold could be arrested and incarcerated, but free countries don't do that to citizens. So in American (and Canadian) society, there is no fool-proof defence against aberrant behaviour. We can be alert for it, try to prepare, but until there is an incident there is no realistic way to prevent the next James Eagan Holmes.