Spirituality and the notion of the Soul are ubiquitous throughout human culture. All through human history, in every corner of the world, we can find examples of belief systems based on an eternal soul and an afterlife. But as we look closer and begin to unpack the ambiguity and dissimilarity between different beliefs, it becomes increasingly difficult to work out what the soul is, what it does, and whether it even exists at all.

For the sake of clarity, I should define what I mean when I use the word soul. There are, of course, various definitions depending on what region, religion or era you look at. Ranging from the colourful: “The True Self; The inner, most sacred part of each person. The soul exists before birth and lives on after the death of the physical body. As a spark of God, the soul can see, know, and perceive all things.” to the sober: “the non-perishable part of every living organism”.

A soul, as defined by the Oxford English Dictionary, is “the spiritual or immaterial part of a person, regarded as immortal”. For for the sake of this article, it’s this definition of soul I am using.

A long history of misunderstanding

When we think back to the earliest humans, life must have been quite a confusing and mystifying experience. Born into the world conscious and self-aware, but with no real understanding of the natural phenomena around them, there was a lot for stone-age humans to ponder. And ponder they did. The ancients shortly came up with their own answers to explain all of the things happening around them. The sun, the moon, stars, weather, plants, animals, and even the Earth, rivers, and rocks were all ascribed myths to answer the questions of their origins and nature, and our own existence was no exception.

Over time, the spirits of the sun, the moon, water etc., became the gods of the ancient mythologies and cults, and their stories were passed on from each generation to the next as a means of explaining natural phenomena. Originating from human imagination, these myths were as diverse and as fantastic as they could be. And in the absence of any other rational explanation, mythologies were successfully spread until they were well accepted as truths.

Since then, we’ve learned a lot about the world around us. Instead of turning to mystics, shamans, and clerics to answer our questions about the natural world, we now look to scientists and philosophers who spend the majority of their lives studying particular phenomena to help us better understand these things. Instead of chanting, incense, and hallucinogenic drugs, we now use controlled experiments and empirical evidence to help us discover more about how the natural world works.

Since the ancient times, we’ve learned the true nature of phenomena such as the weather, the winds, plants, rocks, the Earth and celestial bodies and have now put these myths to rest. In fact, the more we learn about our natural universe, the more apparent it seems that at every point throughout history where the religions and cults have been left to ponder the nature of our world they got it wrong. Is it possible that dualism, the belief that humans are both physical and spiritual, is just another example of this? Could immortal souls be just another huge misunderstanding?

Are our souls what remains of us in the afterlife?

In most religions it’s generally agreed that the spiritual realm is metaphysical; existing outside of what physically exists. Our bodies, on the other hand, are physical and as such play no part in our life after death. The physical body rots and deteriorates here on earth, while the soul goes on to the eternal afterlife. As the old adage goes: “You can’t take anything with you when you go”.

No books, no money, no change of clothes, no toothbrush, and no brain. This gives rise to a few very apparent, although seemingly overlooked problems.

Billions of people, the vast majority of us, believe that when we die we go to an afterlife where we continue our existence. Here we reunite with loved ones, are judged for all of the naughty things we’ve done, and we pay our respects to the being who created us. But the evidence against this has been available to us for centuries.

Science has taught us that our memories are stored in the brain. More recently it is understood that our memory is not one thing, but rather we have different types of memory that work in harmony. Semantic memory, for example, is where we store factual information such as ‘a dog is an animal’. Episodic memory is remembering details of incidents and events such as ‘I went home today’ and ‘she grew a moustache last year’. Procedural memory, remembering how to achieve tasks, takes place across different parts of the brain, and moves as we become more familiar with that task. It is believed that each of these forms of memory evolved at different stages, as life developed to handle increasingly complex tasks.

Patients with amnesia often have a deficit in their episodic memory. They are still able to carry out everyday functions such as getting dressed and how to speak (procedural memory), and they usually remember facts such as ‘a spoon is for eating’ (semantic memory), but they often have difficulty recalling events in their past. If our lifetime of memories were metaphysical in nature—if they were part of our soul and not simply electric processes in our physical brain, how could conditions like amnesia be possible. A bump to the soul?

Memories are physical, not spiritual. They begin and end with the physical body and do not survive death.

From this, I’m fairly confident that if there is such a thing as the afterlife, we would not be able to remember anything from our natural life when we get there. We wouldn’t remember our friends or family, we wouldn’t remember our life on earth or all of those events that shaped our personality, and we wouldn’t remember all of those nasty things we did, that we were about to be judged for.

While this argument alone does not disprove the existence of souls, it does challenge the Judeo-Christian concept of the afterlife as a continuation of this life.

Are our souls the source of our free will?

In the 1960s a neuropsychologist named Roger Sperry conducted experiments known as the Split-Brain experiments to help treat patients with a specific type of epilepsy. The experiments involved separating the left and right hemispheres of the brain—essentially splitting the brain into two. Although this was successful in treating the epilepsy, Sperry and his associates made some surprising discoveries about how the patients behaved afterwards.

In one particular case, a split-brain patient was found trying to pull his trousers up with one hand and down with the other. In another case, a patient tried to beat his wife with his left hand, whilst defending her with his right. It was also common to find differences in personalities, opinions, and desires between the two hemispheres in split-brain patients: The emotional, creative, and impulsive right; and the logical, linguistic, and rational left.

Many people argue that souls are what give us our sense of self-determinism and of free will — the thing that sets us apart from the lower animals that can only act instinctively. But if free will is spiritual, rather than of the brain, how can these conflicts of intentions and personalities seen in the Split-Brain experiments be explained?

You may argue that the Split-Brain patients are not a fair example, because their brains had been drastically changed by surgery—but that argument is itself logically invalid, because it still allows that these patients’ behaviour changed because their physical brains were changed.

Free will originates in the brain and, in the case of split-brain patients, can be unique between the two separated parts of the same brain.

How does a non-physical thing control a physical thing?

Another question arising from the free-will arguments is this: If souls are responsible for our free will, how do they actually control our physical brains?

All physical effects have physical causes, and all physical causes have physical effects. Therefore, nothing that is physical can have non-physical cause. How can something non-physical (the soul), have a physical effect on our physical brains?

We know that our brains control our bodies by tiny cascades of chemical changes in our cells, triggered by nerve sensory impulses, hormones, and neurotransmitters, etc. Do souls also trigger chemical changes in our cells? How? If we agree that the soul is metaphysical then by very definition it cannot have any physical effect in the physical world.

Self-determinism and cat parasites

A parasite named Toxoplasma gondii has two life cycles: First the parasite is picked up by rats and mice when they eat cat faeces (gross, I know). Once inside the rodent, Toxo’ has a direct effect on the rodent’s brain, disarming its instinctive fear of cats. Without its natural instinct to flee from cats the rodent is quickly eaten and the parasite continues its life cycle inside the body of the cat, where it reproduces and its offspring leave the cat’s body to continue this cycle. Toxo’ is just one of the many cases in the animal kingdom where a parasite hijacks its host’s brain to serve its own selfish purpose.

Toxo’ can also influence human behaviour and may make men “more likely to disregard rules”, “more expedient, suspicious, jealous, and dogmatic”, while making women “more warm hearted, outgoing, conscientious, persistent, and moralistic”.

Much of our behaviour is based on environment, habit, instinct, past experience, and reflex, as well as impulses from the brain to fulfil our desires and needs. The rest, the part we experience as free will, is based on decisions we make through reasoning and understanding. …And reasoning and understanding is absolutely the brain’s job. Think about any time you’ve been drunk. Did your inhibitions drop because your soul got drunk or because your brain function was disrupted?

Clinging to the belief that our souls are what determine our free will means denying experiential evidence in favour of a stone-age misunderstanding.

Do our souls provide us with our sense of right and wrong?

It is often argued that, without souls, how can we know the difference between right and wrong? Surely our morals are spiritual, God’s way of imparting in us a sense of how we should behave. This argument seems to originate from a naïve idea of the nature of morals. It is based on the flawed assumption that morals are universally constant and that our inclination towards civil behaviour is of a divine origin.

Morals, what’s right and what’s wrong, varies vastly from place to place and from era to era. To list just a couple of examples:

Polygamy is, in most of the western world, considered a sin (and illegal). In other cultures, in Sudan for example, it’s common practice. In the Bible, some of God’s favourites; Abraham, David, Moses, and Solomon were polygamists.

Slavery has been commonplace throughout history and is condoned by God in the Bible. God even provides guidelines on how you should keep your slaves (Exodus 21). Despite God’s advice, most of us now agree that slavery is, without question, absolutely wrong.

The idea that our moral code is something innate and spiritual is fatuous. The majority of what we consider appropriate is determined by our surroundings and our culture. We learn how to act, and what’s right and what’s wrong, from the people around us. Even on a day-to-day basis, our idea of ‘appropriate’ changes with our environment and company.

Do our souls determine our individual nature?

Possibly the most difficult claim to dispute is the claim that our souls are what determine our individual nature. What makes Steve more argumentative than Sally, and Ian more adventurous than Jake?

I believe a lot of this is inherited genetically, and we see a lot of anecdotal evidence of this in common discourse. For example, when children are said to have their father’s or mother’s nature.

It is through this principle that humans have been able to domesticate dogs and other animals from their wild ancestors. By selecting only those dogs with desirable personality traits, breeders were able to transform the nature of these animals, eliminating the undesired traits. This suggests that a great deal of a creature’s nature is genetic.

However, a lot of our nature can also be manipulated by our immediate environment. Hormones like testosterone and estrogen influence behavioural traits such as assertiveness, confidence, and aggressiveness. Our past experiences seem to shape us heavily too, and factors like learned helplessness, and resilience seem to be directly linked to the experiences we’ve had. Stress can bring out the worst aspects of an individual’s personality, showing that it is not fixed, but highly dependent on the environment.

Lastly, I think there is a lot to be said for chance occurrence, and self-guided development. People are constantly changing as they interact with others and their environment. To quote the humanist psychologist Carl Rogers:

a person is a fluid process, not a fixed and static entity; a flowing river of change, not a block of solid material; a continually changing constellation of potentialities, not a fixed quantity of traits.

― Carl R. Rogers

Souls are what give us life

In antiquity, it was believed that the soul was the vital force that gave life to our otherwise inanimate bodies—the force that distinguished people, animals, and plants as different from rocks and other lifeless matter. When a person died, it was because their soul left their body, leaving it lifeless.

In recent years, we now understand the body as an organism of trillions of tiny cells, each of which contribute to keeping the whole system ticking over through a complex arrangement of chemical processes.

But the origins of the life force that animates our cells has always been a point of dispute, and a bastion for religious arguments against life as a purely natural phenomenon.

In 1935, Bertrand Russell addressed this point by writing: “…we must either succeed in producing living matter artificially, or we must find the reasons why this is impossible.”

By the 1950s, biochemist Sydney Fox had succeeded in doing just that. Fox observed that when he mixed some inorganic molecules (amino acids) with water, and introduced volcanic heat, these molecules spontaneously organised themselves into proteins. When placed in water, these proteins organised themselves into proteinoids (little spheres that look and act like simple bacteria). Fox’s experiments showed that nature could organise molecules into higher order, spontaneously.

More recently, physicist Jeremy England at MIT has proposed a theory of thermodynamics which pairs nicely with Fox’s observations. Simply put: in an open system (like Earth), when energy is constantly added from an external source (like the sun), matter will re-arrange itself into increasingly complex structures in order to store and dissipate energy more efficiently.

You start with a random clump of atoms, and if you shine light on it for long enough, it should not be so surprising that you get a plant

—Jeremy England

Simple life forms have been created in labs from inorganic matter, and we now know that this should be a fairly normal occurrence in nature. Once the environment has created simple replicator molecules, the rest is quite incontrovertibly explained by evolution.

Rather than our ‘life energy’ coming from a non-physical soul, it seems far more probable to me that life is a natural phenomenon that can happen readily when the environmental conditions are suitable. On Earth, this process was probably started billions of years ago, and we today are the result of billions of years of increasing natural complexity.

Accounting for all of the lost souls

The typical religious stance is that souls enter the body at the point of conception. This belief gives rise to a few arguments. Firstly, if a soul enters the body at conception, what happens in the case of identical twins?

In identical twins, it is usually the case that the fertilised zygote splits into two embryos two days after conception. Does this mean then that, for the first two days, two souls shared the same zygote? Or do the souls split in two with the zygote?

If our soul is present from conception, then why is it that newly born babies are not fully conscious and self-aware, as adults are? Why do these traits, along with our sense of free will, develop along with our brains? Shouldn’t they be present from birth?

And with 30%-50% of fertilised embryos naturally aborting without the mother even knowing she was pregnant, does that mean that almost half of the people in the afterlife will be the souls of unborn foetuses?

Another interesting, natural objection is the existence of animals with extraordinary regenerative properties. Hydrae are small aquatic animals that are able to completely regenerate if cut in two along their middle. That is, one hydra can be separated into two unique and independent creatures. The logical assumption then must be that these animals do not have souls, otherwise we must account for the doubling of the souls each time a Hydra is cut in two.

Of course, one could argue that these animals do not have souls, and are excluded from this discussion. But if that is the case, then the entire theory of evolution must be discarded as wrong in order to protect the notion that humans have souls, while animals do not. This is not a leap of faith I am willing to make.

Feeling optimistic about a physicalist view

With the information available to us today, there doesn’t seem to be many excuses left for believing in the existence of immortal souls. To some people though, this naturalist interpretation of life is a depressing one. I don’t think it should be.

Even though they are not metaphysical in nature, we still do have memories, emotions, and feelings, thoughts, desires, personalities, hopes dreams and all of those other things that make life an experience we should cherish.

The most important realisation my own exploration has brought me is that life is short. It’s really short and we really shouldn’t waste any of it, because it’s probably all we have. If there are things you would like to experience then do so while you can. Motivate yourself to start now. Instead of spending your free time watching re-runs of bad sitcoms, start taking steps towards achieving the things you want to achieve.

You don’t need goals and targets to be a happy human being, but it helps to have something to wake up for in the morning. And it feels even better when that something is a goal you’ve set for yourself, and not one you’re trying to achieve to meet someone else’s demands.

For me, accepting that I probably don’t have an eternal soul doesn’t mean that I’m missing out on any of the fun. It just means I’m more likely to have fun while the dualists are still looking up to the sky and checking their wristwatch.