The Neuroscience Of Evil: A Theory

By: Shayna Herszage  |  October 29, 2020

By Shayna Herszage, Managing Editor

The word ‘evil’ is often thrown around in conversation. An irritating teacher is called evil, a particularly annoying peer from growing up is called evil, classroom morality discussions deal in the binary of ‘good versus evil.’

But what is evil? Am I evil? Are you evil? 

These are some of the questions criminal psychologist Julia Shaw examines in her book “Evil: The Science Behind Humanity’s Dark Side.” In the book, Shaw dissects and explores what the term “evil” really means, what causes evil, and who is — or is not — evil.

In the first chapter, “Your Inner Sadist: The Neuroscience of Evil,” Shaw explains a theory of the neurological basis for evil in humanity. This theory was created by Martin Reimann and Philip Zimbardo — the latter of whom is well known for his famous Stanford Prison Study. In their theory, evil follows a pathway that generates three factors which contribute to perceived evil in humans.

The first part of the pathway is based in the ventromedial prefrontal cortex, also known as the vmPFC. The prefrontal cortex is one of the most advanced aspects of the human brain, and it specializes in complex behaviors such as planning for future events. Decreased activity in the vmPFC has been linked with aggressive behavior and poor decision-making. Additionally, this decreased activity leads to deindividuation, in which a person ceases to see themself as an individual, and instead they view themself as an anonymous member of a larger group. As such, they do not feel that they should be held personally accountable for their behavior.

The second part of the pathway is heightened activity in the amygdala, which is a center of emotion. The heightened activity leads to increased feelings of anger and fear, which may lead to dehumanizing others for the purpose of self-defense from a perceived threat.

The third part of the pathway is the brainstem, reacting to the messages it receives from the vmPFC and the amygdala. The messages cause the brain stem to send messages to the central nervous system (CNS) which trigger a fight-or-flight response in the individual. When these responses are triggered regularly in social settings with no real threat, these signals are often expressed as antisocial behavior such as avoiding others and starting fights.

There is not a clear way to prevent or identify evil, as Shaw explains in the book. Rather, the capacity for “evil” exists in all of us — the ability to forget that we are responsible for our actions, the tendency to dehumanize others, the moments of fight-or-flight responses where they are not necessary — and it is our responsibility to keep ourselves in check before we mistreat those around us.