While conditioning makes soldiers more efficient in the moment, it does not protect them from the aftermath. Grossman identifies several "killing response" stages, including .
Grossman’s analysis begins with a striking historical observation: in World War II, only about of combat soldiers actually fired their weapons at the enemy. On killing : the psychological cost of learning...
: Evidence from the Battle of Gettysburg showed that 90% of recovered muskets were still loaded—many with multiple rounds—suggesting soldiers chose to go through the motions of loading rather than actually firing to kill. While conditioning makes soldiers more efficient in the
: He posits that this aversion is a deep-seated evolutionary adaptation. Just as many animals use ritualized combat rather than lethal force against their own kind, humans have a biological "safety catch" against intraspecies killing. The Science of Overcoming Resistance : Evidence from the Battle of Gettysburg showed
To increase combat effectiveness, military training evolved to bypass this natural reluctance through behavioral conditioning.
: Grossman notes that killing is psychologically easier when physical or emotional distance is maintained—such as through long-range artillery or the use of dehumanizing language (e.g., "collateral damage"). The Psychological Cost
The Burden of the Trigger: Exploring "On Killing" In his seminal work, On Killing: The Psychological Cost of Learning to Kill in War and Society , Lt. Col. Dave Grossman challenges the long-held assumption that human beings are naturally violent or eager to kill. Instead, Grossman argues that most humans possess an to taking a fellow human’s life. This article explores his core findings, the evolution of military training, and the lasting psychological toll on those who cross this primal boundary. The Inherent Resistance to Killing