When I was in elementary school, we watched a documentary showing epilepsy healed by a brain operation. Afterwards I told my classmates it was fake because our personality comes from the soul, not the brain, and epilepsy was a form of demonic possession. I told them stories I had heard that when Christians pray for demoniacs these have epileptic seizures, which obviously proves it’s a matter of demons, souls, and spiritual warfare not a neurological deformity.
Since that embarrassing episode, I have learned much and have been a skeptic as to the idea of a soul. I have learned that simple biology and neurology provide overwhelming evidence that our thinking and feeling is the result of physical processes in the brain, not spiritual magic in something called a soul.
What is a soul? I have spent many years asking people this question, and have heard dozens of widely diverse and almost always very ambiguous, nonspecific, opaque, and vague answers. Some people have gotten very belligerent when asked this question, responding with “stop acting like you don’t know, it’s obvious!”
The Oxford English Dictionary says that the word “soul” is used by people to refer to “The spiritual or immaterial part of a human being or animal, regarded as immortal”, which is also a ”person’s moral or emotional nature or sense of identity.”
We will use this definition in our exercise, in addition to specifics from popular Christian culture. Below are a few very short examples of functions of the soul that are far better explained by the brain.
1. The soul is the wellspring of emotion?
CLAIM: It is commonly assumed that emotions come from the soul. As put by Dr. Lehman Strauss at Bible.org “the soul is the seat of the passions, the feelings, and the desires of man.”
EVIDENCE: There are hundreds of drugs that directly influence your brain chemistry which results in a change of emotions. WebMD has a long list of pharmaceuticals that have been tested on people and produced depression or mania. Likewise, there is exhaustive evidence that traumatic brain injury causes severe emotional changes. If the spiritual soul was the source of emotions, physical injury would not cause emotional change, for a soul cannot be physically harmed.
2. The soul is the source of lusts and sinful desires?
CLAIM: The soul the root source from where all sin, crime, wickedness, and evil comes from. As put by Dr. Lehman Strauss at Bible.org “It is in the soul where fleshly lusts, desires, and appetites arise”
EVIDENCE: Yet again, brain altering drugs can affect these desires as well. Consider that sexuality is strictly biochemical, pills like Ecstasy are used to increase sexual arousal, while other drugs can kill sexual drive. Pedophiles are “chemically castrated” which is essentially drug-induced removal of the sex drive by altering the chemistry of the brain. That said, other trends, for example violence, are strongly related to the culture and time period of the person, homicide being 32 per 100,000 people in the 13th century and only 1 per 100,000 in the 20th. There were no spiritual changes, but many physical and cultural improvements that led to a striking reduction in homicide through the centuries. If the nonphysical soul was responsible, physical factors would not be able to influence it.
3. The soul controls the body?
CLAIM: In a seminary book titled Integrative Theology, two evangelical theologians say that the soul acts “as an agent acts through its body as its instrument.” Very obviously if there is a spiritual “driver” in our head, and the body is the “vehicle” it logically follows that the driver controls the vehicle (body/brain).
EVIDENCE: In many years of medical research, including the use of SPECT/PET/fMRI (which I have performed during a clinical program) scientists and doctors have been able to map which nerves and parts of the brain are responsible for certain body motions and actions. Furthermore, the evidence from thousands of injuries shows that if a certain nerve is disconnected from a certain part of the brain, body parts cease to function, or if a certain part of the brain is damaged, the body is no longer under control. The most common example of this is a stroke that damages the brain and causes the patient to be unable to control one or both sides of his body. If the soul is not a physical object, it cannot be harmed by a physical disease.
4. The soul is the source of identity, metacognition, and awareness?
CLAIM: Commonly it is assumed that the soul is the “thing” that gives each person their unique and conscious identity. As the famous theologian JI Packer put it, the “soul emphasizes the distinctness of a person’s conscious selfhood.” In other words, it is the thing that allows for “metacognition” or “thinking about thought” that separates humans from animals.
EVIDENCE: Many lines of research have shown that higher primates, dolphins, and some other mammals are capable of metacognition. At the same time, human infants and babies are not capable of metacognition. If we follow this logically we have to say that human infants do not have a soul (or are only granted a soul later in life) while adult chimpanzees have a soul. One way to test for awareness of self is the mirror test, placing a mark on a subjects face and seeing if he or she recognizes that/himself in the mirror; human infants cannot do this until a certain age, while many adult primates can. In any case, the difference between lesser primates and humans is far better explained by the fact that humans have a much larger physical brain, if the difference between man and monkey was an immaterial soul, there would be no need for man to have a physically larger and more complex brain, the soul would do the heavy lifting.
5. The soul is the life-giving force for the body?
CLAIM: Another common idea about the soul is that it is the thing that animates or allows our body to function and be alive. As the theologian RC Sproul stated “The soul of man can live without the body; the body cannot live without the soul.”
EVIDENCE: This is rather odd considering the world is filled with billions of animals, many of which are highly complex, they form “animal societies” and have a great deal of intelligence in their interactions. Their bodies function very well, they have been observed making crude tools, finding food, building shelter, learning sign language, having pack leaders, mating, raising/protecting their young and more. All of this is done even as virtually everyone argues that animals don’t have souls. It is evident that all these animals can do amazing feats, like using hundreds of sign language phrases to communicate with humans (video), and yet, this is done with their smaller-than-human brains, not with a soul. If intelligent animal bodies don’t need a soul to function, why do humans?
6. The soul exists within in space-time?
CLAIM: The soul interacts in this world of physical objects and physical people, governed by these physical rules. This is an obvious assumption by anyone who believes in a soul, for their argument is that the soul inhabits space-time and makes decisions within the physics of space-time.
EVIDENCE: Philosophers say that God, does not experience time or space because he is immaterial, spiritual, and not a part of this physical universe. Souls are ascribed the same characteristics (spiritual and immaterial) yet souls purportedly inhabit space-time and from within interact within it. The physics of this are illogical, something that exists outside of our physical space-time cannot experience the perception of being within space-time. (Someone may bring up a theological response like “Jesus is spiritual and he came into space-time.” First, the same questions apply to this theological assertion, second, we could argue that was a miraculous one time event that suspended normal laws of physics, not the daily experience of every sentient being in the world, thirdly we should note that the Bible says that Jesus became flesh, not that he continued to exist as a spiritual being trapped inside a physical body, as a driver in a vehicle.) In any case the souls presence, perception of, and interaction with space-time raises many questions about the soul, such as what is it composed of? Is it made of particles or energy? Does it have a mass? Does it have a charge? Is it influenced by the four fundamental forces?
7. The soul contains memories?
CLAIM: One of the most important figures of conservative theology, Charles Hodge wrote that “The soul in man is a created spirit of a higher order, which has not only the attributes of sensibility, memory, and instinct, but also the higher powers which pertain to our intellectual, moral, and religious life.”
EVIDENCE: That memory is stored in the neural network of the brain is now widely accepted by virtually all scientifically literate people. There are numerous real life examples of trauma to the brain causing amnesia, or the loss of memory. Other diseases of the brain that result in memory loss include common age related dementia and Alzheimers. There is even a fascinating case study of a male who suffered brain injury and forgot everything including his family, how to use electronic devices, geographical locations, religious holidays that were previously important, and very interestingly he forgot and abandoned his religion altogether. If these memories were collected by the soul, brain damage would not alter them. Finally, here is a fun video of a chimp using a computer to recall the locations of numbers, and the chimp is proving to have a better memory than I do, even though he does not have a soul.
8. The soul is the cause of intelligence
CLAIM: In the previous quote, Hodge also states the soul is responsible for “also the higher powers which pertain to our intellectual, moral, and religious life.” This is yet another common statement made about the soul, that it is the thing that enables humans to be intelligent, while the lower animals are not intelligent.
EVIDENCE: Consider that adult chimpanzees are undeniably more intelligent than a human infant. Chimps can learn hundreds of sign language phrases, a newborn baby cannot. Chimps can create complex social structures, an infant cannot. Chimps can create and use tools, a human baby cannot. Chimps have learned verbal language, and can follow complex commands, infants cannot. By this argument, primates have intelligence while human infants do not, therefore it logically follows that some chimps have souls but human babies do not. In fact, we ought to ask, when does a human first obtain a soul? In the womb? During birth? during early childhood when they develop intelligence? Something tells me the anti-abortion folks would be upset at the idea that babies do not have a soul in the womb, however, my guess is most believe that a soul is why humans are more intelligent than other animals. Also, if someone postulates that humans have a soul from the moment of conception, why then does it take the physical development of the brain to obtain intelligence? If the soul is the source, why do we see this physical correlation to the size and complexity of the brain? That is a rigorous argument for the neurological source of intelligence.
Bonus: The Bible teaches we have a soul?
CLAIM: The Bible says that when we die our soul will fly up to heaven because it is immaterial and immortal (cannot die.)
EVIDENCE: No, it does not. (First off, heaven is not up, if you fly up you will hit the clouds and then go into outer space). The Bible often says that the heart is the source of intelligence, but the physical heart pumps blood and nothing more. Theologians fumble over how to deal with this, but generally say it is a metaphor for the persons mind and intelligence. It’s conceivable that the soul is yet another pre-scientific way for ancient peoples to discuss matters of consciousness and identity. In any case, the New Testament teaches a physical resurrection in the body not a disembodied existence as ethereal beings called souls. What is the point of a separate spiritual soul if the accurate theological depiction seems to show a body with a brain capable of intelligence as the eternal condition of people?