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On Killing:

The Psychological Cost of Learning to Kill in War and Society

Bibliographic Content

Lt. Col. Dave Grossman


Back Bay Books

Kindle, Paperback (426 pages), Audible (10hrs:23min)

Synopsis from Author

The good news is that the vast majority of soldiers are loath to kill in battle. Unfortunately, modern armies, using Pavlovian and operant conditioning, have developed sophisticated ways of overcoming this instinctive aversion.

The psychological cost for soldiers, as witnessed by the increase in post-traumatic stress, is devastating. The psychological cost for the rest of us is even more so: contemporary civilian society, particularly the media, replicates the army's conditioning techniques and, according to Lt. Col. Dave Grossman's thesis, is responsible for our rising rate of murder among the young.

Upon its first publication, On Killing was hailed as a landmark study of the techniques the military uses to overcome the powerful reluctance to kill, of how killing affects the soldier, and of the societal implications of escalating violence.

Now, Grossman has updated this classic work to include information on 21st-century military conflicts, recent crime rates, suicide bombings, school shootings, and much more. The result is a work that is sure to be relevant and important for decades to come.

If you are interested in purchasing this book, ebook, or Audible audiobook, we have provided a helpful link directly to its storefront page on Amazon; purchase any version of the book and we get a small affiliate bonus for every referral. “As an Amazon Associate, I earn from qualifying purchases.”

On Killing, psychology, dave grossman, business, war is my business, war, society

“Like the blind men of the proverb, each individual feels a piece of the elephant, and the enormity of what he has found is overwhelming enough to convince each blindly groping observer that he has found the essence of the beast. But the whole beast is far more enormous and vastly more terrifying than society as a whole is prepared to believe.” [Section Two, Chapter Eight]

Lt. Col. Dave Grossman's book On Killing: The Psychological Cost of Learning to Kill in War and Society is a controversial book, to say the least. But I could say that about most books covering military studies, as its content brings up topics that are hotly contested, yet rarely experienced by the majority of the populace. The topic of violence and what compels people to harm or kill fellow human beings is a difficult one, as the necessary and controlled experiments needed to develop case studies might be considered unethical - look at the Milgram Shock Experiment. So, as a result, we have to look towards case studies and after-action reports from combat and domestic incidents to develop our understanding further. But that being said, Grossman tries his best to develop that understanding with those available reports, and interviews with numerous combat veterans and civilians involved in traumas related to killing and death. We will now go over some of what he talks about - a few points, but not all.

Summary of Book from War Is My Business

Fight, Flight, Posture and Submit

“The fight-or-flight dichotomy is the appropriate set of choices for any creature faced with danger other than that which comes from its own species. When we examine the responses of creatures confronted with aggression from their own species, the set of options expands to include posturing and submission.” [Section One, Chapter One]

Grossman brings up the concept of fight-or-flight as the behavioral response of creatures in peril, and that, in order to survive, they must either choose to fight back against the threat or flee from it. He adds two more potential responses that can help in survival. By posturing, one attempts to force the other to cease fighting and flee or submit to avoid harm. By submitting, one tries to save themselves from further harm by surrendering their fate to their attacker and hoping for mercy and leniency. Humans can flow between these responses as events unfold. They can posture to attempt to intimidate an enemy into capitulating, and if that doesn't work, go into the fight, flee when they start losing and submit when they are caught. You can see this unfold in various ways during street fights as much as you might see on the battlefield.

He identifies that, throughout history, there has been a lot of fighting, but not necessarily a lot of killing that one would expect for the amount of fighting witnessed. Looking at casualty reports, anecdotal evidence, and scenario experiments, he predicted that there were many individuals throughout history involved in posturing and submissive activities that didn't involve intentionally killing the enemy. Evidence and stories indicated that many fired over their adversary's heads, fired into the general direction of the enemy without intending to aim the weapon, and some preoccupied themselves with other tasks - caring for wounded, running messages, loading ammunition for others, etc.

The idea that human beings don't actually want to kill other human beings, and conversely, try to avoid it even at their own expense is the result of human evolution. It isn't good for a species to actively try to kill its own members, and this is especially so for humans that have developed strong social inclinations against it. Even if entirely justified and expected to take another human's life, the person may simply freeze up and fail to respond as we would expect them to. There are always expectations, but this is generally found to be the case that most humans will find it difficult to kill and will do anything other than killing. Those that can overcome this inclination will survive and thrive on the battlefield.

Classical, Operant and Social Conditioning

"The soldier intuitively understands what he or she is getting into and generally tries to cooperate by "playing the game" and constraining his or her own individuality and adolescent enthusiasm, and the army systemically wields the resource and technology of a nation to empower and equip the soldier to kill and survive on the battlefield." [Section Eight, Chapter Three]

The combat environment requires entirely different habits and values than those generally espoused in a peaceful environment. Combat happens so rarely in our lives - if at all - that when it does occur, the very things we have been raised to do may actually threaten our continued survival. As a result, the things that warfighters must do to survive in a combat environment, and achieve objectives, would not be acceptable in a peaceful setting; it is accepted and expected when thrust into combat. But the individual must be trained to not only think in terms of what is required to survive and thrive in battle, but they must also train those elements of human thought and action that are automatic.

Three types of conditioning occur to allow this to happen:

Classical Conditioning (Pavlovian) - which helps shape the person's perspective through forms of positive and negative reinforcement. By promoting desirable action and punishing undesirable action, they can slowly shift the individual into a desired way of thought and action.

Operant Conditioning - Trains the individual to act reflexively/automatically under certain conditions. It allows them to react fast in a certain way to increase survivability and improve performance. In combat, there is little time for critical thought, and automatic thought takes control - you must train. If you have ever heard the phrase, "I just did what I was trained to do" or "I just fell back on my training," then this has the earmarks of operant conditioning.

Social Conditioning - When are shaped vicariously through the actions of others. How we should act, how we should talk, and how others treat us is learned through the efforts of others. We learn from our fellow human beings, we see them rewarded or punished, and we vicariously feel that. This is what role models are all about.

Through these forms of conditioning, we can shape the individual in such a way that they are better suited to succeed in the combat environment. Failing to do so puts them and the mission they support, at risk, and our contemporary understanding of this can be considered unethical… This means that we send our people to fight, yet don't psychologically prepare them to undertake the tasks they must do to win and to make it back home.

“This conditioning is a necessary part of allowing a soldier to succeed and survive in the environment where society has placed him. Success in war and national survival may necessitate killing enemy soldiers in battle. If we accept that we need an army, then we must accept that it has to be as capable of surviving as we can make it. But if society prepares a soldier to overcome his resistance to killing and places him in an environment in which he will kill, then that society has an obligation to deal forthrightly, intelligently, and morally with the psychological event and its repercussions upon the soldier and the society.” [Section Seven, Chapter Three]

Trauma and Returning Veterans

“Commanders, families, and society need to understand the soldier’s desperate need for recognition and acceptance, his vulnerability, and his desperate need to be constantly reassured that what [they] did was right and necessary, and the terrible social costs of failing to provide for these needs with the traditional acts of affirmation and acceptance. It is to our national shame that it has taken us almost twenty years to recognize and fulfill these needs with the Vietnam War Memorial and the veterans’ parades that have allowed our veterans to ‘wipe a little spit off their hearts.’” [Section Seven, Chapter Four]

The act of killing, the experience of watching others - friends and enemies - die in combat, and the knowledge of people intentionally trying to kill you can be one of the most traumatic events a human can encounter. An event that happens multiple times during a conflict, and something the individual may have to contend with for the rest of their life. In Section Six, Chapter One, "The Killing Response Stages," Gross lays out what he sees as the psychological steps for managing the reality of killing for a human being. This is partially related to elements of the Kübler-Ross model called the "Five Stages of Grief" just with a more focus on the unique aspects of the killing environment and could be itself evidence of underlying human thought processes.

The Killing Response Stages of Grossman are:

  • 1. The Concern Stage - This happens when a person enters into the combat environment where one may be required to kill. It is a type of performance anxiety. Can they kill another human being, or will they freeze? Will they act fast enough to avoid being killed? What if their inaction or hesitation gets their buddies killed?

  • 2. The Killing Stage - This is the actual kill. Sometimes it is an automated response where the individual reflexively reacts to a threat and kills it. Other times, they witness events unfolding before them where they have time to analyze, and as those events culminate into a decision to act, they choose to kill.

  • 3. The Exhilaration Stage - This is the stage that follows the killing act. Depending on the situation in which the kill transpired, this stage may not occur, but the feeling of exhilaration is the result of a hormonal release. They survived, they saved their friends, and they defeated a threat. These are considered good things for the individual and their group, so the brain reinforces this behavior by releasing hormones like dopamine. Doing good things like this is beneficial for you, evolutionarily-speaking.

  • 4. The Remorse Stage - Follows the kill, over after the intense feeling of satisfaction from the exhilaration stage, as those feel-good hormones start to dissipate. The individual can reflect on their actions, and begin to regret what they felt they had to do. This can be even more intense if the individual can witness the results of their work - the dying enemy or a mangled corpse. Seeing a fellow human being - even an enemy who may have done horrible things - triggers an empathetic response, which is itself an evolutionary beneficial thought process for us as social creatures. By causing harm, the brain begins to punish itself by denying those same hormones.

  • 5. The Rationalization Stage - This process can prove to be the longest, and may never actually end. They need to justify and rationalize their actions to not only others but also themselves. We may see their efforts as totally justifiable, and even expected and desired, but they will nonetheless work to convince themselves the same thing. They may vocalize it or internalize it, but they will rack themselves over the events - the what-ifs and the reasons why - at great expense to their psychological well-being.

  • 6. Acceptance - With enough rationalization and validation from society, the killer may be able to push past the trauma and begin to focus on other topics and engage more effectively with other people. The trauma will never truly leave, just like other forms, but here they don't necessarily linger for unhealthy lengths of time.

From this process and resulting anecdotes and studies from those that went through traumatic killing events, Grossman identified that post-traumatic stress disorders could occur based on two different factors - 1) The severity of the trauma, and 2) the amount of social support. After the Second World War, veterans received great accolades from the public, but after Vietnam, the people turned against their veterans.

“Psychiatric casualties increase greatly when the soldier feels isolated, and psychological and social isolation from home and society was one of the results of the growing antiwar sentiment in the United States… These psychiatric casualty ratings were similar to home-front approval ratings for the war, and an argument can be made that psychiatric casualties can be impacted by public disapproval.” [Section Seven, Chapter Two]

On Killing for Business

Humans are Emotional Creatures

Humans are emotional creatures by nature. Emotions are the result of those various hormones released by our bodies to compel us to action based on perceived situations. In a way, being in combat is similar to being in a romantic relationship, in competition, or alone, in that it is merely a relationship between hormonal responses and your current perception. For example, you perceive threats to your safety, and your body releases adrenaline to raise your heartbeat and makes you alert of your surroundings. It also releases endorphins to help alleviate any pain you have or may experience to facilitate your action. Combing these hormones and perceptions of the environment creates a state of readiness that allows you to maximize your survival, and its collective impact on your mind and body gets referred to as "fear." Change the conditions, change the hormones, and you get different emotions. Oversimplified, yes, but necessary to understand that we are first and foremost emotional creatures.

Logic and rationality are what humanity strives to achieve, as it can help control those emotions that may not be inherently beneficial in the long run. People regret emotional outbursts since they impact long-term relationships and their capacity to thrive in a social environment. Logic and reason are elements of critical thought; aspects of our frontal cortex helped facilitate our ability to develop complex social dynamics. Underlying that, emotional responses can overpower our capacity to control it with logical and rational thought when the impact of the hormones is too powerful or if our capacity for critical thinking is not strong enough.

In business, we must remember that underneath that contemplative decision-making human being is an emotional creature. Their actions are influenced by what they perceive and how their bodies/brains react to that, and after that, they may or may not try to control those actions through critical analysis. As a result, you can't expect human beings to be logical and rational all the time. At times when they are stressed and time is critical, or when they are overwhelmed by multiple issues, they may react emotionally. By understanding - or shaping - your customers' environment, you can influence their actions.

For example, we know that restaurants will sometimes pump out "scents" based on their menus in an attempt to entice you to grab some food. Businesses will seek out strategic locations to market their product/service in your path. By changing the world around your customers you can compel them to act - everyone does it, but may not realize the psychology behind it.

Conditioning Can Shape Desirable Responses

Grossman saw that through effective conditioning that warfighters could be trained to execute actions that went against natural aversions to killing human beings. This allows them to accomplish their objectives and return home from a combat environment. They need to be conditioned to survive the combat environment, which is significantly different than the peaceful environment from which they came. This means that certain habits, conditioned since childhood for their benefit in a peaceful environment, need to be reconditioned into something else that will help them in the combat environment.

The business environment is not a combat environment, but it can come with unique environmental aspects that are not shared with the rest of the general public. Dealing with angry customers is a unique environmental consideration. Dealing with crises - active shooters, fires, earthquakes - and having to look out for our employees and customers. Dealing with certain systems and processes that are specific to our professions and our places of work.

We can institute certain conditioning techniques to be more effective at our jobs and improve our employees' responses. We can go through numerous and varied conditioning drills to ensure that their responses are desired and timely - operant conditioning. We can - and do - reward desired behaviors and discourage undesirable ones to develop the desired perspective on how they should act - classical (Pavlovian) conditioning. We can validate the desired actions in others in the form of public acknowledgment, promotion ceremonies, awards, etc. that can be vicariously experienced by everyone - social conditioning.

By focusing on how to engage our people, we can shape desirable responses that benefit themselves, the business, and the customer.

Peoples Need Validation and Positive Reinforcement For Work

Grossman saw that veterans, especially those that saw combat, needed to both rationalize their action and receive validation from their people for those actions. The nation sends its warfighters to kill on its behalf, and while they are trained to kill, most kill by necessity and not by a desire to do it. They desire to know that the rest of society understands this issue, and don’t hate the warfighter for doing what their nation sent them to do. Without validation, trauma can be severe, and with it, it can be mended.

In business, the need for validation isn't as vital since most business activities are not as socially abhorrent as killing. However, people still need to have their work validated. Be it a Soldier, a teacher, a custodian, or a lawyer, they need to know that their contributions to society - even if just for a few people - has a value that is appreciated. They need to know that they are wanted and that their work is desirable. People that are happy and satisfied with their work will be more productive and loyal to the business and support their colleagues.


On Killing: The Psychological Cost of Learning to Kill in War and Society by Lt. Col. Dave Grossman compares the uniqueness of the combat environment and that of human psychology. It looks at how society views warfare, its warfighters, and the act of killing to achieve its ends. It looks at how the individual chooses to kill or not to kill, and for those that kill, how they deal with the trauma involved. It looks at how we can condition our warfighters to kill more effectively, but also how to care for them after their return. What we see here is a scientific examination of the human condition taken to a particular extreme.

While business will not be taken to such an extreme as that of combat, except maybe in situations when the business deals with security and threats may need to be killed to protect people and assets, it can be useful as a limit. Meaning that if we look at a human's anticipated behavioral responses on a spectrum - between doing nothing and doing the extreme - that in business, we can predict the array of potential human reactions and plan accordingly. We can assess the psychology of the people, condition our employees, and validate their hard work to shape the work/consumer environment for the betterment of all involved.

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