The belief in the immortality of the soul is common to almost all cultures in almost all eras. In our society, it is often associated with stories of ghosts, possession, and reincarnation. There are also emotions involved in it, for when a loved one passes away, we cling to the idea that something of them survives somewhere. This belief, however, has been questioned several times throughout history. From Aristotle to modern science, there are dozens of arguments that deny the separability of the soul from the body, and with it, its corresponding immortality. This essay will defend the idea that, despite how deeply rooted and cherished this belief may be, there are more and better reasons to believe that the soul is mortal. Let us begin by first clarifying what the soul is, and then proceed to the formulation and examination of the arguments given on both sides.
The word "soul" has various meanings, but of all of them, there are at least two that are relevant to the topic at hand: the soul as vital energy and the soul as mind. Let’s examine them below.
The soul as vital energy. Some philosophies and religions have considered the soul as a kind of energy. It is a type of energy different from those known to current physics, which would give life to things, enter bodies with different configurations, and depending on that, the body would be capable of nourishing itself, growing, perceiving, moving on its own, thinking, or reasoning. We will return later to the discussion of whether this type of energy exists.
The soul as mind. There are at least four features that are believed to be defining of the mind and its processes or events. The first is that the mind is not something physical; mental events do not occupy a place in space, do not interact with gravity or light, have no mass, or weight, and for that reason, cannot be studied as we do with ordinary objects. The second feature is privacy: each person can access their own mental states, but not those of others. The third is that the mind consists of faculties and their contents. Some philosophers have called this feature "intentionality" because faculties are always exercised over something: I perceive something, I love something, I remember something, I imagine something. Finally, the mind always has an owner; we do not simply say: there is a memory of the apple, but we say that this memory belongs to someone: to Maria or Juan. The mind, then, is an entity made up of faculties whose events or processes are immaterial, private, intentional, and have an owner (they refer to someone).
Relationship of the mind to the body. Now, there are two ways to conceive of this mind in relation to the body. It is either a consequence of the physical, chemical, and electrical processes that occur in the body or it is independent. In the latter case, we would be forced to accept that the mind is also some kind of energy. This latter way of understanding the soul seems to be implicated in beliefs about ghosts, spirits, possessions, and reincarnation. A ghost or spirit, for example, would be a mind that would have the ability to produce certain physical events: producing sounds, moving objects, changing the ambient temperature, manifesting as a translucent or fluorescent body. Possession would be the act by which a mind enters a different body and takes control of its functions (this would explain some strange behaviors in humans and animals). Reincarnation, in turn, would be the passage of the mind from a dying body to a newly born one, and so on. This disembodied mind, without a body, could be in another world or dimension or wander in this one or alternatively move from one world to another according to various religions and popular beliefs.
The existence of the soul.
These, then, are the meanings of “soul” relevant to determining its immortality. However, understanding the meaning does not indicate that souls exist. We can understand what a unicorn, a centaur, an angel, or a winged crocodile is, which does not mean they exist. Is there any reason to believe in the existence of vital energies or disembodied minds?
Let’s start with vital energy. If it is something physical, it should be observable intersubjectively and measurable. If it is not, it should still manifest in some way. Today’s scientists do not need to propose a special energy to explain the fact of life. They do so using observable and unobservable physical objects, so it does not seem to be a physical type of energy. It seems, then, that it is a non-physical energy that should manifest in the physical world for us to know of its existence. One might say that the movements of living beings, their growth, reproduction, and behavior are the manifestation of that immaterial energy. In that case, we would have two theories: one that says life is the product of the interactions of physical objects and nothing more, and another that says there is something more, and that something is vital energy. This theory, however, seems unnecessary as the first explains everything that needs to be explained with physical elements alone. Vital energy seems superfluous. Moreover, proposing it generates more problems than it solves.
Now let’s evaluate the mind. What kind of existence is this mind? It is not physical, as we have seen. However, if it exists, it must be able to manifest somehow. One way is through internal experience. I can "see" what I imagine, I can feel my joy or my sadness, I have an internal experience of my mind, and this experience does not seem questionable. It also cannot be equated with the brain states or physicochemical processes of neurons, no matter whether we conceive of the mind as a product of those processes or as detached from them. These internal states, this internal experience, lead us to say that the mind exists.
And what about the minds of others? We do not have direct experience of other minds. If we attribute a mind to other organisms, it is because they have behavior similar to ours or a similar anatomy, but never because we have direct experience of their minds. Similarly, if someone died and appeared to us in the form of a translucent or fluorescent body, we would indirectly attribute a mind to them. Of the internal states of that specter’s mind, however, only it would have experience. Nonetheless, our attribution of a mind to other organisms or objects is not infallible. It could be that only one mind exists and that others are imitations of people: androids or virtual images of human beings that appear to have minds. Thus, we can accept that minds exist, not so much because they manifest in the behavior of others, but primarily because we have an internal experience of it.
Now, suppose someone dies and their mind survives, though unable to manifest its existence. It would be a mind locked within itself, disembodied, without a body, and without the possibility of communication—pure mental experience. It would exist, yes, but only it would know it, without anyone being able to prove it. If, however, it could manifest, it would have to do so by producing some physical event: an immaterial object causing material events. Is there evidence of the latter? People believe so, offering testimonies from others or their own experiences in favor. Even so, we cannot vouch for the testimonies of others; it could be that these people believed they perceived disembodied minds when it was actually something else. On the other hand, when we critically analyze our own experiences, we find that almost everything we thought was the physical manifestation of a disembodied mind was perhaps a common physical event. The matter becomes more complicated when science tries to investigate whether there are physical manifestations of such minds. To date, everything that has been taken as such has ended up being a common and ordinary event. How could we prove the existence of such minds without their manifestation in the physical world? How could we know what they think or feel if they do not show themselves?
Let’s suppose, for the sake of discussion, that a strange event occurs, one we usually attribute to ghosts. Suddenly, the temperature drops, objects begin to levitate, and a moan or laughter is heard in a room. Scientists arrive with their instruments to investigate, and at the end of the investigation, they conclude that they don’t know why the temperature dropped, nor did they identify any physical object that caused those movements and sounds that literally came out of nowhere. This would be the closest we would have to the physical manifestation of a ghost. But let's not celebrate too soon. Could it be an extraterrestrial with an invisibility cloak playing a prank on us? Could it be some unknown state of matter causing all of this? Just because such events occur does not mean that ghosts exist; they could be caused by other events or entities that are not ghosts.
Let’s try another approach. Suppose this mind we believed to be disembodied actually does have a body, this body being of some kind of physical matter or energy we do not know. This would mean either that at this moment each of us has two bodies made of two different materials or that when we die, our soul passes from one body to another. How would this be explained? How could it be demonstrated or proven? Proposing a body made of antimatter or dark matter or any other type produces more problems than it solves. It’s difficult to fit a theory like that with what we know about the physical world.
In summary, there is no proof that there are minds without bodies. However, assuming there were, several problems would arise that would be difficult to answer well: Where were those minds before relating to bodies? What happens to them once they separate from bodies? Where do they go, and what do they do? Do those minds have an origin? What is that origin? Do they have an end? What is the end? How does an immaterial mind produce physical events? How do brain states, which are physical, produce events in an immaterial mind? Thus, there are good reasons to believe that the mind exists, but not vital energy or the mind without a body. The problem of immortality has not yet been touched. However, by elimination, it already seems easier to accept that souls emerge from the body and do not survive without it.
Dependence of the Mind on the Body
The mind could survive without the body and still be mortal. It could wander for a few years through the world and then disappear or pass from one body to another and, after a few reincarnations, cease to exist. Still, what we commonly believe is that the mind is immortal. We must note that there are two ways of understanding this. In one, minds are eternal, not created by anyone, and will never perish. In the other, souls have an origin. Both cases give rise to questions whose solutions are not easy to defend. There is, however, a simpler answer: namely, that the soul emerges from the body and dies with it. Let’s see then, on what basis this theory stands.
There are abundant reasons to believe that the soul depends on the body, more specifically on the central nervous system. Let’s start with the most basic: if we affect the chemistry of our brain, we also affect our mental experience. If the soul is independent of the body, it should not be affected by changes occurring in the physical plane. Now, consider the case of general anesthesia. When it is applied, it is as if the soul turns off: we don’t feel, we don’t perceive, we don’t imagine, or remember anything. It is a lapse in which we seem not to exist. How can the soul, if it does not depend on the body, be affected to such an extent unless it has a dependent relationship with the body?
But if this argument is not enough, we now have the case of physical impairment of the brain, where part of the brain is lost or ceases to function, or where the brain is divided or sectioned; we also have the case of conjoined twins sharing part of their brain or that of electrodes or chips connected to the brain for interaction between both. All these cases represent a significant challenge for those who believe that the soul does not depend on the brain. Abilities commonly attributed to the soul, such as reasoning, abstraction, or intellection, can be lost or affected by removing part of the brain; two minds or souls emerge when the corpus callosum is severed, and what happens to the souls of those who share part of their brain? Are they one soul, two souls, three souls? We have no contact with any soul without a body; instead, we have plenty of evidence that the soul changes or is affected when the brain is affected. All this leads us to think that there is a strong dependency of the soul on the brain, so it is not improbable to think that if neuronal activity ceases, the activity of the soul ceases as well.
This does not mean that all problems are solved. There still remains the issue of how something material, like the brain, can produce something immaterial like the mind. But that is only one problem, compared to the many that emerge from postulating a soul that exists without the body. Moreover, the idea fits well with the theory of evolution, the origin of life and the universe, as well as with our current physical theories.
Plato’s Arguments on the Immortality of the Soul
Until now, the idea has been defended that the soul arises from the brain and dies with it, without considering the arguments of those who defend the immortality of the soul. All that has been said so far is that the belief that the soul is separable from the body and survives without it is unlikely and leads to unnecessary complications. But perhaps there are convincing arguments that show us otherwise. Plato is one of the main authorities on the matter, and his arguments in favor of the immortality of the soul have a good reputation among philosophers, so we will have to analyze them carefully.
The argument of reminiscence is based on Plato’s theory of ideas and on the notion that the soul existed before being in the body. It basically asserts that if we remember something we had no reason to know, this proves that we obtained it elsewhere. For example, a person who has never studied geometry should not know the Pythagorean theorem. However, Plato, in one of his dialogues, shows how by asking the right questions, such a person can come to remember this knowledge. And how could they remember that knowledge if they had never seen geometry? Plato’s answer is that they remember it because they knew it before; they had acquired that knowledge elsewhere: in the world of ideas. When we analyze this supposed demonstration, however, what we find is that what Plato calls reminiscence more closely resembles a thought process called inference, where implicit information in other elements is made explicit. If we have better reasons—and in fact we do—to accept that the ignorant person in geometry can infer the Pythagorean theorem from knowledge acquired in this world, the argument of reminiscence does not work, and we must conclude that everything we know was acquired here.
The weakest argument is the argument of opposites. Here Plato commits a fallacy of begging the question, that is, he includes among his premises that the soul is immortal or that it continues living outside this body, to then be able to affirm that souls come and go, entering and leaving bodies. It requires assuming that the soul is immortal to then talk about living bodies and dead bodies, embodied and disembodied souls, as this argument does. It is not the most fortunate of them.
The argument of the vital principle says that since the soul is the principle of life, it cannot die, because then it could not give life. In other words, what gives life must be alive and cannot die. This is false. A single-celled organism is alive, but its components are not. And it could be that in the realm of disembodied souls the same thing happens. The vital principle might not be alive, so Plato has to prove to us not only that the soul is the principle of life but also that it is alive. But, even if it is alive, he should further prove that its life does not end. It could well be that life ends and the soul ceases to exist, or that it continues to exist but without life. On the other hand, we must examine what Plato means when he says that the soul is alive. It would not be the biological concept of life we currently use, for this applies to organisms that are born, grow, reproduce, and die, and obviously the immaterial soul does none of this, or at least if it is immortal, it does not die. So the word “life” must mean something different to him. The above shows us that the argument of the vital principle is full of assumptions without proof, making it difficult to accept it at face value.
Some might believe that the most promising argument is the argument of simplicity. However, this is an ambiguous argument full of assumptions. Let’s see. The argument basically says that only what has parts can be destroyed, and since the soul is simple (it has no parts), therefore the soul is immortal. In this argument, Plato seems to equate indestructibility with immortality. But this equivalence is questionable. To say that something is immortal means that it has perpetual life. Evidently, one can conceive of something indestructible that, nonetheless, has no life, or better yet, does not have perpetual life. If the above is correct, then the argument of simplicity does not establish that the soul is immortal, but that it is indestructible by being simple. The question of whether the soul has life or not and whether it lasts perpetually is something left untreated in this argument.
Let’s try to construct an argument of Platonic inspiration that demonstrates the immortality of the soul. First, we will have to modify the concept of life for the reasons already mentioned. What Plato understands by life must be some kind of "self-produced activity" (in quotes because that activity for Plato is really receptivity, which seems to be more passive). According to him, souls, before being trapped in a body, are engaged in capturing ideas. So we can accept without problem that the proper activity of the soul is the act of capturing. But is this activity self-produced or is something external producing it? If we follow Plato, we will have to accept that the soul is self-produced capture, and with this, we have the first part of our argument.
The second part of the argument would have to explore whether that capturing activity is perpetual or whether it ends. Let’s assume for a moment the latter. There would be two ways to interpret this. In the first, the capture ceases, but the soul continues to exist. It would not be immortal because, if its activity ceases, its life would cease; it would continue to exist but dead. Under this view, the soul is distinct from its activity, and what would need to be proven to demonstrate immortality is that this activity does not cease. We would also need to explain what the soul consists of when it is dead. Does it have parts? Does it have any structure? What remains when the activity ceases?
In the second interpretation, if the soul’s activity ceases, the soul ceases to exist. In this case, it is not the same as the first. In the first, the soul continued to exist but was inactive, that is, dead. In this case, the cessation of activity implies the soul's disappearance. Thus, there is no distinction between the soul and its activity, and we avoid the problem of explaining what remains when the activity ceases. However, just like in the first case, the immortality of the soul would consist in its activity being perpetual. Which of the two interpretations would be best to reconstruct our argument? Evidently, the second, as it avoids the problem of explaining what the soul is or how it is when it is not active. We are left, then, with the problem of demonstrating that the soul's act of capture is perpetual. How can this problem be solved?
We said at the beginning of this essay that the soul could be understood as the mind and that the mind was immaterial, that it had several faculties, that it was intentional (therefore, that it had a self and content). This is not, however, the way Plato understood the soul. First, neither for Plato nor for most Greeks did what was captured, perceived, or desired (the intentional content) form part of the soul. Second, for Plato, a soul within a body is not the same as a soul without a body. The soul within a body has parts: the rational part (the one in charge of capturing), the appetitive (the one of desires and pleasures), and the spirited part, the one of noble and strong emotions. The soul without a body would only be the rational part, that is, the part that captures.
With this in mind, we can then return to the matter of simplicity. The soul, free of the body, would be a simple action: pure capturing. And with this, we would have the second part of the argument: the act of capturing is simple. We only need to make a small terminological adjustment to give the argument more consistency. Instead of saying that the simple is indestructible, we might say that it is perpetual, that it cannot cease to exist. In this way, our Platonic-inspired argument would be as follows:
P1: The simple is perpetual (it cannot cease to exist)
P2: The soul is simple
Conclusion A (from P1 and P2): The soul is perpetual (it cannot cease to exist)
D1: The soul is self-produced capturing activity
Conclusion B (from Conclusion A and D1): The capturing activity is perpetual
This argument establishes that the act of capturing cannot cease because its simplicity prevents it from doing so. And this is what it means for the soul to be immortal. To refute it, one would have to question premises 1 and 2 or definition 1. Refuting premise 1 is not easy, and definition 3 seems to be the best reconstruction of the statement "the soul has life"; premise 2 is the one that would be most problematic, although the simplicity of capturing seems evident. It is important to note, however, that the argument assumes, rather than demonstrates, that the soul is separable from the body. Moreover, it contradicts some parts of Plato’s philosophy, for example, his claim that souls had an origin or that evil souls, upon separating from the body, have a different destiny than contemplating the ideas. Distancing ourselves from him, the argument has its own advantages, solving problems such as the soul's fate once free of the body or what it was doing before being trapped in a body, in both cases: contemplating the ideas.
Let’s not be overly optimistic though. The argument leaves many questions unanswered. Why does the soul get trapped in the body? If souls are immaterial, meaning non-spatial, and also eternal, what distinguishes one soul from another when they are not trapped in a body? How and why does the simple soul become composite upon entering a body? And if it does not become composite, how does it acquire other faculties it did not originally have? How can the immaterial act on the material and vice versa? How can we detect a soul that is outside a body? That is to say, immortality generates more problems to solve; giving a well-argued solution to these problems is no easy task, and it is difficult to see the need to do so when we have a simpler solution that does not generate so many difficulties, namely: that the soul is immaterial, born with the body, and dies with it.
Origin of the Belief in Immortality and Separability
The best solution, then, due to its simplicity and ability to be integrated with scientific theories, seems to be that the soul is mortal and depends on the body. The problem of how the body produces the soul remains, but the issue of its dependency seems resolved. Assuming, then, that this is the case, we may ask how and why humans came to the idea that there can be a soul without a body that lasts forever, to also understand why, despite having good reasons against it, people persist in this belief.
The first key element to believing in the soul's immortality is establishing its separability from the body. There are several paths that can lead us to this conclusion. In one of them, people's bodies appear to us in dreams, and we thus believe there is something separable from the normal body. And this body continues to appear when the other ceases to exist. Hence, we conclude that the soul continues to exist without the body. Another path to the separability of the soul is through attributing purpose or agency to certain natural events. This led to the belief that there were various distinct, invisible entities wandering around, which occasionally decided to manifest by pushing a ship’s sail, moving a tree, whispering through a cave. The next step would be to believe that these invisible entities are, in fact, family members, powerful enemies, or important leaders whose bodies perished but who continue among us in that other form.
The question of immortality, in turn, would have more to do with the desire of people to feel the presence of their loved ones or cherished leaders. We can think that the soul is separable from the body and still believe that it can die at any moment. Where, then, does the idea that it does not die come from? Behind this are emotional reasons: it is not easy to face the loss of loved ones, to overcome loneliness, the sense of insecurity and vulnerability with their passing. Thus, believing that they continue to exist indefinitely offers consolation, relief to those who have lost family members. It also offers a way out for those who see in death the loss of all individual and collective efforts, for those who believe that life is not worth it since we are going to die, that it makes no difference whether one lives 5 or 100 years, whether one strives for something or not because in the end, everything will end. Only eternity can give meaning to someone like this; only that can remove the idea that life is a waste.
Thus, both things combine: the idea that the soul survives the body with the desire that it continues living indefinitely, giving rise to the soul's immortality. These ideas become part of religious beliefs and then, at a later stage of development, philosophy and mathematics make them sophisticated by defending them with complex arguments that lend them more credibility. In this way, the soul ends up becoming something immaterial, of infinite duration, capable of grasping the most abstract notions and the noblest and most sublime aspirations. The idea of the immortal soul thus travels two paths: one among academics and scientists who combine it with the theories of the time, and another among common people who mix it with stories of mystery, miracles, and wonders.
Aside from personal reasons, there are also social and political reasons to ensure that belief in the immortality of the soul is not abandoned. Religion and power have always gone hand in hand. Through education, these ideas are instilled and perpetuated not only to maintain cultural identity but also to use it to control people. The idea of a soul that is eternally punished for its evil or, conversely, is rewarded for its humility and obedience, is an example of this. The immortality of the soul does not come alone but with stories that use it to instill fear or hope, support ideas, and sustain wars. Therefore, it is not easy to abandon these ideas. It would be emotionally overwhelming for people, especially for those who cling to the existence of their loved ones or their own existence. And it would be an affront to the powers behind those ideas using them to their advantage. However, these are emotional and political reasons, not concerned with the truth. If truth is the concern, one thing is clear: a mortal soul makes things easier for us; an immortal one complicates them, and truth prefers simplicity.