In the interests of furthering discussion about the actual subject, let me type up a few salient tidbits from Grossman’s research:
There is an instinctual resistance to killing other humans within our psyche. When confronted with any other obstacle, fight or flight is the response, but when the obstacle is another person, fight and flight are lowered beneath two other responses: posturing and submission. This allows fights to be settled without losing members of a tribe, which is vital when your paleolithic tribe is struggling to survive and needs every spare hand it can get.
This instinct can be overridden, but it requires desensitization. Historically, militaries relied on the fact that many people would be desensitized to death and violence just by the horrific nature of their day-to-day lives, but as civilization has advanced and life has been made less awful, people have become less regularly desensitized and so formal methods for desensitization have had to be added.
These have become very advanced, getting the weapon-fired rate from ~25% in WWII battles to ~50% in Korea and ~90% in Vietnam.
This desensitization, however, is not all that’s needed. He also suggest careful exposure of justifications to the soldiers, because after the events are over and things calm down, soldiers will have to reconcile their actions with their moral compass, and if they are unable to justify their actions, they will suffer badly for it.
(This is when “it was a zombie, I had to kill it” comes in, and should reduce or negate the morale penalty.)
