On Killing: The Psychological Cost of Learning to Kill in War and Society

by Dave Grossman

There is strong evidence that there exists a genetic predisposition for aggression. In all species the best hunter, the best fighter, the most aggressive male, survives to pass his biological predispositions on to his descendants. There are also environmental processes that can fully develop this predisposition toward aggression; when we combine this genetic predisposition with environmental development we get a killer. But there is another factor: the presence or absence of empathy for others. Again, there may be biological and environmental causes for this empathic process, but, whatever its origin, there is undoubtedly a division in humanity between those who can feel and understand the pain and suffering of others, and those who cannot. The presence of aggression, combined with the absence of empathy, results in sociopathy. The presence of aggression, combined with the presence of empathy, results in a completely different kind of individual from the sociopath.