Sometimes people here debate issues that have been studied carefully and have evidence-based answers. Lots of studies have shown that men who have seen combat are more likely than their civilian counterparts to commit violent crimes. There is no debate about this if you look at the literature. The question is why. I suspect there are many contributing factors: psychological trauma/problems transitioning to civilian life, capability (there is lots of research showing that one of the best predictors of violent behavior is whether a person is physically capable of physically dominating another person), owning firearms, and general aggressiveness. It's important to remember that these are average differences, and give us little power to predict a given person's likelihood of committing a violent crime. I had friends on my high school football team who were talented athletes, but they didn't like the physicality and brutality of the game. I, on the other hand, loved it, and craved the physical confrontation. We need people in the armed forces who are physically and psychologically capable of violence, and at this point in our history, with our all-volunteer military, we should expect some self-selection of more aggressive personalities. As destructive as violent crime is to society, we all benefit from having military and police personnel who are more capable of physical aggression than the average person, and they deserve our respect for the risks they take and the sacrifices they make.
