Is Alzheimer’s disease evidence for the non-existence of the soul?

Question

As Alzheimer's disease kills off neurons, a person's personality and cognitive abilities gradually fade away. Doesn't this suggest that the self or "soul" is simply an emergent property of the brain's physical structure and function, rather than some immaterial essence or spirit that exists independently of the body?

The classical notion of the soul as an immaterial, eternal essence that exists independently of the physical body is challenged by the way Alzheimer's systematically dismantles a person's mental faculties and sense of identity over time. As the disease destroys neurons and neural connections, the patient's personality, memories, and very "self" seem to disintegrate, suggesting that these aspects of the human experience are products of the brain's physical structure and function, rather than some non-physical soul.

Answer 1

Alzheimer's disease (and other brain disorders with some observable physical effect along with psychology and neuroscience generally) does seem to make the existence of an immaterial soul much less plausible and less useful or necessary for explaining anything.

Science tells us that:

• Different parts of the brain correspond to different neural functions.
• Physical changes in the brain affects your memories, your emotions, your ability to reason, etc.
• People consistently behave in certain ways given certain environments and stimuli (which isn't direct evidence against a soul, but does support the claim that we're merely the result of our biology and environment).
• Etc.

But the existence of a soul is ultimately unfalsifiable, so someone can accept all of that and still hold that there's an immaterial soul by saying roughly either of the following:

• The soul sort-of mirrors the brain, with some unclear connection between the two (which seems to render the soul completely unnecessary as a hypothesis)
• There's some separate part of your being that is your soul (but we have no reason to think such a part exists, we don't know what that part would do, and we already know parts of your physical brain affects memories and emotions and your reasoning ability, so does the soul exclude all of that?)

Also, if one accepts evolution and common descent, the human-only soul is also a lot less plausible, given the unclear line between humans and other apes. Related answer.

Answer 2

No, not really, the disease is just evidence for the corruption of the region of the brain that houses memory due to aging. It is just evidence for the degeneration of the human body and consecutively the mind as one grows older. Soul does not mean memory. Memory does not mean soul. In any philosophy i.e., medieval to modern, these two things are not necessarily mutually inclusive. I would say it would make more sense to syllogize consciousness and soul rather than memory and soul.

Edit: Consciousness is more multifaceted than just its parts i.e., memory, thoughts, self awareness, emotions and other arising traits. Alzheimer's might affect these attributes to some degree but that doesn't mean it annihilates (devoid) one's consciousness, let alone the evidence for the existence of one's "soul" (which as mentioned in the comments might be vaguely defined).

Answer 3

No.

If you allow for the existence of the soul, then the question of how the brain and soul interact arises.

Alzheimer's and its impact on personality, at most, would indicate that the condition of the brain impacts the expression of the soul.

It would not be an unreasonable hypothesis to state that, by some mechanism, as Alzheimer's progresses, the soul remains intact and unaltered but becomes constrained in its action, leading to the observed symptoms.

This would not be without precedent. Mental illness has, in the past, been blamed on all manner of metaphysical influences. In particular, the four humors theory blamed melancholy on excessive black bile. While we now know that these humors don't exists, it was, at the time, a theory that realized that dysfunctional internal processes can affect how we present to the world.

Today, we may have a more refined understanding of the internal workings of the human body, but that does not preclude the existence of the soul.

Answer 4

Short Answer

Absolutely yes. The simplest spiritual dualist model, in which personality is off-board, and interacts with the body in the mode of a drone operator with a drone, is challenged by all observations of selfhood being degraded or affected more than a drone operator would be by neural or chemical influences.

Longer Answer

Straightforward falsification is itself refuted as a science methodology, and instead counter-evidences call for patches to a theory. The decline of predictability/power of a model as it complexifies in the face of test data is how one evaluates the plausibility consequences of observations.

There are ways to patch spiritual dualism to be compatible with Alzheimer's, mechanical brain injury, chemicals affecting consciousness, etc. There are not many spiritual dualists who adopt methodological naturalism, and I have not seen anyone else's proposal on this issue, but I will offer mine.

• Given that we observe willing affecting the body, as well as body affecting willing, two way causal spiritual interaction is a first order plausible model
• But the over 1000X advantage of thruput for neural processing over spiritual processing revealed in the Thinking Fast and Slow studies, shows that there are significant limits of processing thruput for the spiritual side of spiritual dualism, and evolutionary benefit for neural mental process assist to what is nominally a spiritual feature.
• If the thruput of a spiritual mind is fungible, then allocating most of that thruput to coordinating the mental function assist by neurons is evolutionarily advantageous.
• Damage to the neurons, chemical affects, etc. while the spiritual side is so allocated, would be seen as a loss of consciousness function.
• The possibility of recovery of full mental function for a spirit upon disengagement from ensoulment, due to fungible reallocation, is a possible outcome for this model, and is testable under OBE, NDE, past life, and ghost telepathy experiments. The data from these experiments support the fungible-reallocation model revision.

When one is evaluating the plausibility of a scientific model, this is a comparative process, as almost all models encounter similar contrary data, and need to be complexified to address it.

Note that the most widely postulated alternative model family is physicalism, which has for the last 150 years been unsuccessful in even coming up with a valid complexification that can address the hard problem of consciousness. The inability for physicalism to explain consciousness is what is behind the "Delusionist" school of thinking, which tries to deny the existence of consciousness due to the failure of these models to account for the data. A model that needed to be complexified, but now matches the data, is always superior to one that instead denies the data.

Answer 5

What is a soul? At the least it's whatever is making these moral decisions I'm going to get judged for.

What is a brain? It's that gooey hardware that turns stimuli into reaction.

Does Alzheimer's degrading the performance of my brain disprove my soul? Nope. You can burn down the casino and still leave the dice intact. Whether fire proof dice exist is another question altogether.

Alzheimer's doesn't prove anything here any more that death does. Whatever a soul is, our time casually interacting with them in this world is limited. After that their continued existence is only supposed by those who believe in object permanence.

Answer 6

Personality and cognitive abilities are not the self, even though they are deeply cherished parts of the self. Their corruption alone doesn't make a person any less a person. There is something that a person with Alzheimer's has (or, perhaps better, is) that makes them different from dead matter. That something, if anything, is what the soul is.

To analogize, I notice a peculiar inability of those with an amputated left arm to ball their left hand into a fist at will. By altering their matter, they've lost a capacity they once had. Does this prove that there is no such thing as a soul? I might argue on the contrary. The fact that the hand becomes incapable of being balled into a fist at will after being separated from the body suggests there is something the hand partakes of while it is part of the body that it no longer does once separated. That something is what some people call a soul. A hand is a hand and not just organic matter by virtue of its participation in an organized, living body, i.e. by being subject to the soul.

More provocatively: is it okay to murder someone with Alzheimer's who, as you say, has had their mental faculties and sense of identity dismantled? If not, why not? What property does their matter have that makes it wrong to kill them? This property is, again, what some might call a soul.

Answer 7

It was suggested that I elaborate my Comment in to an Answer, so don't shoot the messenger. One way to reason is to use analogies and metaphors. Sometimes the metaphors are too colorful and warp thinking. But I approached this question as being a form of communication between prospective soul and visible body. Does communication support the idea of a soul?

If we think of an ordinary phone connecting you and another person, that could be like the mind connecting with the soul. Using the metaphor, if your phone started having problems relaying texts and calls, would that cast doubt on the other person existing? Only if communication completely ended and you couldn't tell if it was your phone or that the other person stopped answering. But you still feel that there must have been another person (or, soul, in the metaphor) because it seems impossible that a handheld device could mimic the complex communication of another 'you'. We don't feel replaceable by a phone, just yet.

So the other side of the connection could feel too complex for just a brain to fabricate, like how I wondered as a child how they got all the musical instruments in the stereo, or all the little people inside the TV.

So it seems like I am arguing for a soul. But we don't know the capacity of the brain and mind, because it is too complicated for us to understand. (If we could understand the blessed thing, it would be pretty disappointing.)

Arguments about souls run aground on the fact that we can't see any difference that they could visibly, definitely make, unlike people at the other end of a call who come by and we can see them. The question seems not well put, because the metaphor says that something is missing.

Answer 8

As far as I can tell, nobody earnestly would suggest that the brain does not have some functions, like memory, pre-processing of data coming in from the senses, processing input and output from motor nerves, processing some emotions (especially deeply ingrained ones like fear, fight/flight responses) and so on and forth.

Many of these functions can be proven by looking at brain damage, be it via Alzheimer's, Mad Cow's disease, or plain old physical damage caused by bullets, sharp implements and so on and forth.

One thing that is still considered a hard problem is that humans seem to have a feeling of a "self" or "me", or an "observer" that is somehow observing the input from the senses (and this includes things we don't usually count as a senses, like thoughts, which if you meditate, very clearly are also happening very much on their own and are simply "observed").

It is absolutely unkown whether this "self" is an illusion or not; whether it is purely physical; or whether there is some non-physical "soul" which somehow lives out of reality as it is known to us. Sure, you find many people who tell you otherwise (i.e. who are totally convinced of some variants of those questions), but there definitely is no concensus.

It is the same as for religion or other "spiritual" questions: if you believe that something is the case, then things follow a very different logic for you. I.e., if you believe in a soul, you can easily come up with reasons why Alzheimer's does not disprove the soul (for example by positing that the brain is just an interface between body and soul). As someone who does not believe in a soul, Alzheimers does not help to disprove anything because to disprove a soul, you would need first to define or figure out what the soul actually is.

Same as science-vs-religion, brain science is ever more encroaching on all kinds of aspects in this regard. It is not a totally far-fetched standpoint to define the "soul" as all parts of the brain whose function we have not quite understood so far (i.e., a great many of them). This means that over time, as brain science figures this stuff out, the "turf" of the soul would become ever smaller. Whether it will disappear completely is the same question as whether science will ever completely "remove" religion. And even if we were able to explain absolutely every known feature of human brains scientifically, including what the "observer" is, I am sure that this would not convince people who believe in the soul of its non-existance.

The reason being that almost by definition, the soul is not subject to scientific approaches, so science cannot "disprove" it. Same as religion in general is not subject to scientific approaches, so science cannot "disprove" religion either. They are disjunct concepts.

Answer 9

Why does it have to be Alzheimer's? What about getting drunk? Getting drunk is a bodily phenomenon that affects the mind, and people have known about it for millennia and still believed in souls.

What about illnesses in general? For as long as humans have been humans, we've known that getting sick affects the mind. It makes you feel down, it keeps you from thinking straight. And yet people have still believed in souls.

The only reason the existence of the soul is a problem in the modern mind is because we take a mechanistic view of the physical world. Therefore, the soul, which isn't mechanistic, must be a different thing from the body, which is physical and hence must be mechanistic. So we need to either solve the problem of how the body and soul interact, or dispense with souls.

But this view is wrong to begin with. Neither the body nor the soul is a "thing." There's only one thing, the human, of which the body and soul are just parts. The whole human unit functions under its own rules, not the rules of mere matter nor of pure mind, which the body and soul follow in tandem.

Alzheimer's challenges the idea of the soul? Alright, then. The placebo effect challenges the idea of a purely physical body. The existence of logic and mathematics challenges the idea of a mind formed purely from the brain. After all, the physical is always particular, so how can we form ideas of the universal if our minds are purely physical? And no, an AI-like trial and error algorithm is not a sufficient explanation, because universal ideas apply to things we've never seen before.

I don't expect you to suddenly accept my views or anything, but I hope this gives you a clearer idea of the position you're trying to argue against.

Answer 10

That's one possible conclusion, but it does not constitute a proof. Neuroscientist David Eagleman, in his book Incognito, explains why this isn't so using the analogy of a radio. A radio is a physical object, which plays music. If you damage the radio, you damage the sound quality of the music. If the radio degrades enough, the music stops entirely. As a naive conclusion, it's reasonable to think that the radio is creating the music, and that destroying the radio destroys the music. But in fact, the radio is just a receiver. As ludicrous as it sounds to say that some distant source is beaming the music inaudibly through invisible waves that penetrate walls and other solid objects, that's exactly what's happening.

The brain is a physical object, which seems to be the seat of the mind. As the brain degrades, the conscious mind also appears to degrade, nor can consciousness be maintained in the absence of a functional brain. But if we accept that "soul" might be broadcast from a remote source ("God") then the disappearance of the mind isn't a proof of the non-existence of the soul.

To express this in a different way, it has never been the position of most religious people that "the soul" is identical with "the mind", and therefore that the disappearance of the mind means the extinction of the soul. "Mind" is the more accepted (although not uncontroversial) concept in the modern scientific discourse, but it does not fully capture the notion of soul in a way that would allow this argument to succeed. In other words, this is (an illegitimate) proof by redefinition. Once we reduce soul to mind, then the disappearance of the mind is the death of the soul by definition--our conclusion is hidden in our assumptions.

Answer 11

Evidence for a soul existing = 0

How much evidence can be needed to refute zero?

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If at some future date, evidence for a soul existing becomes > 0...

... then it could make sense to start looking for evidence against. To counter the evidence for.

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A good rule of thumb... no evidence for = no need for evidence against.

Answer 12

It's a waste of time to try to argue with dualists. A dualist will claim that the soul (as eternal substance) still exists when the body is dead and gone and has been totally dissolved into atoms; even when all the atoms in the universe would disappear, the soul would still exist. So proof (apriori or aposteriori, or whatever kind), evidence, falsification - none of that apply.

The absence of any verifiable, shared criteria to establish the existence of "souls" (and the continual resetting of whatever criteria may have been proposed in the past - as demonstrated with the ad hoc "radio theory"), make the debate totally pointless. The dualist always "wins".

But has a dualist stance ever led to an actual increase in understanding of mental processes? Or to a new method of treating particular neurological or medical issues? No - it's a sterile view of human personality.

It's also an ethically challenged, ethically shallow, purely anthropocentric view. Even small children realize this when they are told (as some are in some subcultures) that -- no, their pets will not go to heaven. Some children will find this 'strange' and 'unfair' - and sometimes this contributes to them growing up to become atheists and non-dualists, like me. For me this was one of the first 'little' inconsistencies in religion that I became aware of.

Answer 13

Those who claim that consciousness comes from matter, or that the existence of the soul must depend on the body, have the strongest evidence that death leads to the destruction of consciousness, but I would say that this is an untestable hypothesis. The same is true of Alzheimer's damage to consciousness.

We believe that death leads to the extinction of consciousness only by observing that a person is unable to respond to external stimuli after death. But whether the consciousness of the dead man really disappeared there, no one knows. In fact, not only the dead, but even the living we can't feel each other's conscious presence.

It's an objective fact that we can't feel each other's consciousness. With any person, we judge each other consciously only by the other's response to ourselves, and deduce facts only from phenomena. Is the other party a programmed NPC or a subject that responds autonomously, and how do you identify and prove it?

This is the natural defect of consciousness. While we, as conscious beings, can observe the world, talk to other people and even guess what they are thinking at certain times, we ultimately cannot feel what they are feeling. The only thing we can be sure of is our own existence.

"I think, therefore I am" is a great idea, but it can only prove the existence of "I" itself.

Answer 14

No.

If the soul is the "software" and brain is the "hardware", Alzhaimer disease is like running Windows in a Pc with RAM/disk deteriorating.

An example could be the Voyager probe. Its systems aren't 100% functional and NASA technicians are fixing problems here and there to let the mission continue.

Answer 15

Doesn't this suggest that the self or "soul" is simply an emergent property of the brain's physical structure and function, rather than some immaterial essence or spirit that exists independently of the body?

No, it does not. Or at least it doesn't until one defines "self" or "soul" more carefully to ensure the individual you are suggesting to agrees with the meanings you are using. That being said, it is quite common in philosophy to talk about the "mind," a word which is a different word from "brain." If one chose to use the word "mind" instead of "self" or "soul," I think it would be fair to say the deterioration due to Alzheimer's suggests the mind and brain may be the same. "Suggests" is a great word because it's so much weaker than "proves" or even "demonstrates." You could enter a debate with a dualist and use this argument. You would, of course, need to follow it up because it's not a full argument in and of itself. But it could be done.

... and very "self" seem to disintegrate ...

This would be interesting to bring into a debate. "Seem" is a very subjective term. One is appealing to the assumption that the other individual, upon seeing this deterioration, must come to the same conclusion about the self you do. One would need to be ready for the other individual to simply disagree on this front.

And, of course, with any scientific theory we have to be very careful with correlation and causality. Just because one sees mental deterioration at the same time as seeing neural deterioration does not imply the latter causes the former. It is common to choose to think it does, but that's very much a choice of the individual.

I could easily see a dualist arguing that as the neurons deteriorate, the "soul" detaches from the physical body, and it is that detachment that causes the "self" to seem to fade away rather than the neural degeneration (making the detachment of the soul the proximate cause). Whether one finds this explanation to be more or less credible than yours likely depends heavily on decisions already made about the veracity of physicalism.

Answer 16

TL;DR: No.

What is a soul?

Some have observed that we can't answer this question without first addressing the question "what is a soul?". While there is some truth to that, I don't believe that answer is so ambiguous or lacking in consensus as to cause a real issue. Therefore, I will define "soul" thusly; that part of a person, spiritual (that is, immaterial) in nature, in which volition resides. Often the soul is believed to incorporate some aspect of memory and/or personality as well, although this seems debatable even by those who presume that souls exist. Additionally, it is unknown what abilities (if any) a disembodied soul possesses.

To those wondering about the nature of souls, I would recommend Orson Scott Card's Enderverse series, as his notion of "philotes" offers a plausible-seeming explanation as delivered from a more scientific, rather than theological, perspective.

What is the argument?

It should be noted that there are a variety of similar "attacks" on the soul of this form, with "damage-induced personality change" being a leading factor. Harry Potter and the Methods of Rationality also explores the question (from a Materialist perspective) and comes to a conclusion which I disagree with. In general, the question isn't limited to just Alzheimer's.

What shall we conclude?

For the sake of argument, we'll assume that the soul exists. The inability to explain the semblance of free will (whose existence is also sharply debated) in purely material terms would seem to argue in favor of this existence, but since the Question asks whether the claim of existence is undermined, for our purposes it is satisfactory to take the soul as a presupposition.

The main issue with arguments that "X disproves the soul" is that they tend to assume that the material realm cannot affect the spiritual realm. If this assumption is false, it's easy to see how physical (material) trauma could "spill over" into spiritual trauma, with corresponding effects on memory and/or personality, even if memory is a spiritual phenomena.

It seems more plausible, however, that the soul is only part of an intricately connected system, of which the material brain is an integral part. It seems beyond question that the brain (and even neurons outside the brain) play an integral role in processing both input and output signals. A person with no eyes, for example, can't see, and a person with nerve damage can't move their limbs. This, however, in no way invalidates the existence of the soul; it only indicates that the action of the soul is mediated by material substances.

Moreover, if we take a person's actions to be a combination of the material function of the brain and the soul, we can also see how chemicals or physical damage could alter a person's behavior, even if the soul exists. A good analogy might be to think of the physical person as a horse, and the soul as a rider. The rider "steers" the horse and provides higher-level guidance that what the horse can achieve on its own, but the horse also has the ability to override or ignore the rider. Even from a strictly material sense, we see this as in the case of reflexes wherein the body acts without instruction from the brain.

Consider also the brain as the "house" of the soul. Just as one's external environment influences behavior and mood, so too might brain chemistry "propagate" to influence the behavior of the soul. This seems especially relevant if we assume that certain functions, such as maintaining separation between one's "inner voice" and one's tongue or accessing memories, involve material function of the brain (hence explaining why chemicals can "loosen inhibitions", or why material causes can influence memory retrieval). Imagine, also, the frustration one must feel trapped in a body and mind that are not functioning correctly, and how the resulting frustration and sense of dissonance could influence personality.

Therefore, the long version is that such phenomena must certainly influence how we view the (two-way!) interaction of the soul with the physical world, but they do not preclude the existence of the soul.

Answer 17

Alcohol or drug use can affect one's memory and personality, at least for a certain period of time. So, you can ask this question very simply without using the term Alzheimer's disease :)

We often say that our body exists. We experience this fact with our senses. But the thing behind our body - the soul - always remains unchanged. Since the senses are parts of our body, the realization of truth like this is not necessarily through our senses.

I believe the explanation given in other scriptures is similar to this explanation given in the Bagavad Gita -- The soul is neither born, nor does it ever die; nor having once existed, does it ever cease to be. The soul is without birth, eternal, immortal, and ageless. It is not destroyed when the body is destroyed.

https://www.holy-bhagavad-gita.org/chapter/2/verse/23

https://www.holy-bhagavad-gita.org/chapter/2/verse/24

So the premise you have proposed is not sufficient to support your argument.

Answer 18

Alzheimer's disease kills off neurons

is NOT correct.

"The process of the dying of neurons" is called Alzheimer's disease.

A disease is not a thing, it's just a description of a process.

What prevents us for assuming that Alzheimer's disease is the symptom of a soul unable, or unwilling to live in this world, because of its disassociation with its initial goals, or for other reasons?

Answer 19

It would seem you've retold me a legend. Something along the lines of "should have known there were no such things as souls because of brain damage". The evidence is real, and should be counted against souls.

But it's not very strong evidence. I will proceed by analogy. When you have a glass tube containing a noble gas, and bare metal plates, you can get an electric current across the plates that is carried by the gas in the tube. As you remove gas from the tube, the current drops, which is evidence the current is carried by the gas. However, when the amount of gas drops below a certain point, the current rises rapidly with no apparent upper limit. By removing enough gas you changed the nature and the current flows on something else without gas. If you know your physics you can tell me why this works, and that's the point. This is the experiment that proved electrons are real things.

Suppose you had the hypothesis, the soul is dependent upon the brain as long as the brain is alive. (Awhile back I wrote a bunch on default hypotheses; and I can't tell whether or not this should be one; but it does not seem to be an unreasonable initial hypothesis.) Would this evidence shake your position that souls exist. Absolutely not.

If you're willing to sift through the trash of people making stuff up for attention, you can find real stories exhibiting the kind of thing where awareness returned to a person with a sufficiently degenerate brain state so that we may be reasonably certain the brain is not carrying awareness. I will tell you the filter that I have used; verifiable information must be gained by this awareness and proven afterwords. Readers Digest did an article on this stuff back in the nineties, and others I have found as well. Yes this exactly mirrors the current carried across the plates.

Here we sit at the unusual place. There isn't sufficient scientific evidence one way or the other and the existing evidence is weak evidence against souls; but the recent historical observations totally separated from religion have weak evidence in favor of souls. It ought to be testable directly; we have the means to test it but I dare not run this test. It is dangerous. All of the cases involved somebody pulled back from the brink of death by medical ability.

Answer 20

Blessed is he that hath a soul;
Blessed is he that hath none;
But woe and sorrow to him that hath in himself its conception
Gurdjieff — Beelzebub's tales to his grandson

In other words, it's not a binary: immaterial, eternal essence or no such thing.

It could also be that soul is like a talent — like some can have a mathematical proclivity which can be developed into a consummate mathematician; or a musical talent that can be made into a musician, likewise some people may have "soul-possibility" that can be "grown" into an eternal soul.

While Gurdjieff may seem too fringe for these circles, it's important to realize that even "old Christianity" was closer to this than post Cartesian strong duality. See psyche → pneuma.

Note how much more physicalish pneuma (gas-air-breath) is than "soul"

Likewise in Hinduism there's the gross body, subtle body, causal body, atma which is a sequence that can be pealed off one by one onion like.

Answer 21

Software and hardware can have different levels of dependency. ​But they are almost never independent.

I like the expression: "A small hole in the body can make a gaping hole in the soul."