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Wed, 08 Jul 2009

Why Science Cannot Disprove the Afterlife

Part 1. The Afterlife and the Scientific Argument Against It

One of the important beliefs of traditional religions is the existence of an afterlife. Some religions teach that humans have immortal souls that leave the body at death and continue to exist afterwards. Other religions teach that there is no persisting soul, but that a person's mental life, or some aspect of it, starts up again in a new body. (This second view is typical of Buddhism.)

Science-minded skeptics often reject the idea of an afterlife out of hand. Their standard argument against the afterlife goes like this: The mind is only a process in the brain. Therefore, the mind cannot survive the death of the brain.

Is this argument against the afterlife sound? No, it is not. The reason is simple: a process can continue after its physical medium is destroyed. A process that exists in one medium now can continue in a different medium later. Therefore, the fact that the mind is a process in the brain does not imply that the mind must end with the brain. Instead, the mind might continue later in a new brain or in some other physical medium. [1]

There are many examples of processes that start on one medium and continue in another. Examples of these processes are water waves, computations, and fires.

An ocean wave is a process. A single wave can pass from one part of the ocean to another. In doing so, the wave first occupies one stretch of seawater, then another, then another. The water molecules themselves move around in place; they do not travel with the wave. If the part of the sea where the wave started were removed (say, displaced by a big ship), the wave might continue as if nothing happened - provided that the wave already had traveled to a new piece of water.

A computation is a process. It can start on one processor and finish on another. If the computation isn't going to use the first processor anymore, then the first processor normally can be shut off with no harm to the computation.

A fire is a process. It can start on one chunk of fuel and continue on another. Once the fire reaches the second piece of wood, the first piece might already be destroyed. However, the fire can continue to burn. The fire needs fuel, but the fire's existence doesn't depend on any particular piece of fuel. A different piece of fuel will do just fine. (The analogy between the spread of a fire and the continuation of the mind occurs in Buddhist thought. Apparently the old-time Buddhists understood the behavior of processes better than do today's skeptics.)

A process can continue even after the demise of its original medium. Therefore, the common "scientific" argument against immortality is neither scientific nor convincing. Even if the mind is only a process in the brain, the mind might still continue after death by continuing in another brain, or in some other physical system capable of supporting mental processes.

This finding isn't an argument for the existence of an afterlife. It is only a rebuttal to the standard "scientific" argument against the afterlife. The skeptics who use this argument are way off track. The mind may be a process in the brain, but this fact alone does not tell us whether the mind can continue to exist after the brain is gone. If the skeptics want to think that the afterlife is impossible, they are going to have to find better reasons than that one!

Part 2. Of Toads and Timing: How Might the Mind Survive Death?

It's possible for a process to outlast its medium. How could this happen for the human mind?

This question brings us to the many scientific speculations about artificial immortality. Scientists, philosophers, and science fiction writers have asked whether we might be able to become immortal by transferring our minds into new brains or into computers. This kind of artificial mind transfer is one way that the mind might outlive its brain. (I discuss an even wilder variation on this in note [2].)

Artificial immortality is an exciting prospect, but it isn't what I want to write about in this post. I am thinking about spontaneous immortality - a mind's survival of death without artificial means. Spontaneous immortality is similar to what present-day religions believe in. Is spontaneous immortality logically possible and compatible with modern scientific knowledge?

The simple answer is YES. Nothing in logic or in science rules out the possibility of a mind spontaneously starting up again after the death of its original brain. For this to happen, the mind would have to start up again in some other brain spontaneously, without artificial intervention. We have no proof that this happens, but nothing we currently know rules it out. I'll spend most of the rest of this post justifying this answer.

Could an old mind really start up again spontaneously in a new brain? How could this happen?

If it happens, it might work something like this. The mind stops operating when the brain dies. Then a new mind, starting up naturally in a newly formed infant brain somewhere, happens to have some crucial features of the old process. In fact, it is so much like the old process that the two processes constitute the same mind. The new process in the new brain acts as a continuation of the old process in the old brain.

If something like this happened, then a kind of "rebirth" could occur without the need for anything controversial like persisting souls. It wouldn't require any objects besides human bodies and their brains.

Does this scenario even make any sense? Yes! We already know of many physical processes that restart like this. They stop happening for a while, and then start happening again later.

One prime example is a computation. Someone can set up a computer program to do a specific task (for example, calculate pi to 1 million decimal places). If the program saves its in-progress data to the hard disk, then if the program is interrupted (say by a hardware reboot), the program can be started up again later and finish the same task. There is no reason to think of the second part of the computation as a totally new computation. It is part of the same computation as the first part.

Other examples of such processes come from the migration of animals. Many types of animals migrate from one geographical area to another. Perhaps the movement is caused by external stimuli alone, or perhaps internal "clocks" and interactions among animals play roles - but in any case, the result is a process that we call a migration. Now imagine a migration in which the animals' movement is triggered by external stimuli alone. Imagine further that these particular animals are not very excitable, so that only one animal is traveling at any given time. If you want a specific example, imagine a bunch of toads moving across the landscape - and imagine that the toads are rather placid, so it happens that only one toad is hopping at any given time. This process (if it really happened) would be a perfectly good example of an animal migration. However, it would not be a continuous process, but would be a frequently interrupted one. At any given time, a single toad is moving - but in between times, no animals are traveling at all. In spite of the gappy and disconnected nature of the movements, the sum total of these movements is a process of migration. A migration really is happening. It would be an abuse of language to say there is no "migration" just because the migration consists of discrete jumps. [3]

These examples show that a single process can be made up of several consecutive subprocesses or stages ("hops"), each of which spans a different interval in time and space. It's possible for a process to stop and then start up spontaneously later, even if some time elapses between the stages of the process, and even if the restart happens in a different place from the stop.

What does that tell us about the mind? The toad and computer examples show that a process can be made of several stages that happen in sequence, with time gaps (and even space gaps) separating the stages. The stages don't have to be connected directly together to make up a single process. Thus, the process that we call the mind could (for all we know) consist of several separated stages. The fact that the mind is a process in the brain does not rule out the possibility that this process has more stages later, in other brains. When a mind stops, some later process that starts up in some other brain might be a future stage of the same mind. We have no proof that this happens, but we can't rule it out by shouting that tired old skeptical battle cry, "the mind is only a process in the brain"!

If minds really could start up again like this, then after you die, your mind might start up again in the brain of some new baby who is just beginning to gain consciousness. (Babies appear to become conscious gradually, not all at once - but still they do become conscious, so we can speak of the experiences that happen as a baby becomes conscious.) In other words, you might die, then wake up as a new baby somewhere in the world. This would be a modern version of the ancient doctrine of reincarnation or rebirth. Of course, there would be nothing that actually "reincarnates," because there is no substantial soul to pass over to the new body. There also would be none of those so-called "past-life memories" that bemuse so many New Agers. Instead, your mind during this life would be only one time-phase of a larger process, which has gaps and also includes the mind of a future brain. This larger process would be your mind as a whole. Your mind as it exists during this life would be only part of your mind - a single stage.

The Buddhist idea of rebirth is much like this: a kind of restart of one's inner life in a new body, without any substantial soul to pass over to the new body. However, the idea I am proposing here is much simpler. Among other differences, my idea can do without the belief in karma, which is important to the Buddhist view.

Part 3. The Perils and Possibilities of Persons

So far I have been talking about an abstract logical possibility: a single mind that exists in two or more different bodies, one after the other. Before we can consider this a real possibility, we need to think about a huge question: Why would the mind of a new body - a body born after you die - be your mind? What would make a particular new mind a continuation of you, instead of just a new person? Could anything do that?

Offhand, it doesn't seem as if the mind of a later body could be your mind. The very idea seems bizarre. After all, the baby born after you die doesn't have your memories, and probably no information or influence has passed from you to the baby! This kind of "rebirth" isn't exactly like a fire passing from one stick to another, where the first phase of the fire causes the second phase to begin. It's more like our migration of toads, where two independent hops can be stages of the same overarching process. It's just you (hop number 1) and a future infant (hop number 2) - with no important influences passing in between.

Could the baby be the same person as you? I don't have a final answer to this question, but I do know a possible way to an answer. This way is the theory of personal identity - a field of philosophy that uses logic to analyze questions about the persistence of persons through time. Let me explain this a bit. I won't go into personal identity theory in depth here (there already are many books on that topic), but I'll try to indicate what the field is about, drawing on general background knowledge about the field. Those interested in a deeper treatment are invited to explore the many books and articles on personal identity.

During your present life, your mind and body continue through time. As they continue, you undergo many different moments and stages of life. All these time-phases of your life are stages of a single history of a unique person. There is a unity to your history; the history isn't just a scattered series of random experiences or disconnected moments of existence. There must be some shared feature that the stages have in common, or some relationship among the stages, that unites all the stages into the history of a single person. Philosophers studying personal identity have created various theories, ideas and guesses about the nature of the unifying feature or relationship.

Let's look at a few known ideas about personal identity, and what they say about the possibility that a new baby, born after your death, might be you all over again.

(Note to philosophers: As a philosopher, you might agree or disagree strongly with some of the theories I'm hinting at here. Remember that I am not advocating a specific theory of personal identity. I only want to show that different views of personal identity can give very different verdicts on the idea of rebirth. I am well aware that there are arguments for and against each of these views. If an objection is standard, I've probably already heard it.)

Idea 1. Essentialism.

According to so-called "essentialist" views of personal identity, what unites the stages in your life is a set of essential characteristics. These would be the characteristics that make you uniquely you, and that differentiate you from all other persons.

If persons or their minds really have essential characteristics like this, then a baby might be born who is literally a continuation of you. People are born with many different sets of characteristics as a result of chance and the genetic lottery. Given any possible set of essential characteristics, some future baby might happen to be born with that same set of characteristics, just by chance. The longer the time after your death, the more likely such an infant will be born somewhere. Thus, you might be "reborn" in the future by virtue of raw chance. In effect, the chance genetic processes that created you in the first place might accidentally create you again!

Idea 2. Continuity of experience.

According to other views of personal identity, what unites your stages into one history is the continuity of experiences in your life. At each conscious moment, you have certain experiences (sensations, feelings, etc.). These experiences give way to each other as you go along, creating what's called a "stream of consciousness."

If this apparent continuity is what ties your life together, then a baby might be born who is literally a continuation of you. A baby, once conscious, can have various experiences. Some of these experiences (perhaps most of them at first!) will be dreamy and unreal - so they will include experiences of things that aren't really present. Given the vast complexity of brains, some of these dreamlike experiences might even be rather random. What if the baby's earliest experiences started with impressions that just happened, by chance, to duplicate your last moments - either in detail, or at least in certain crucial respects? That might be enough to make the new baby's consciousness count as a continuation of yours.

Idea 3. Continuity of viewpoint.

Each of us has what philosophers call a "first-person point of view" - a unique standpoint from which one experiences the world. As philosophers often have pointed out, conscious experience has a subjective "feel"; it has an inner, subjective, felt aspect as well as an outer, behavioral one. [4]

This provides a clue to another way that a new baby could be literally a continuation of you. As I pointed out under Idea 2, a baby's earliest experiences may be partly random. What if the baby's earliest conscious moments just happened, by chance, to feel as though your last experiences had just happened? Given certain ideas about first-person viewpoint, that might make the baby's first-person viewpoint a continuation of yours. [5]

This idea is especially relevant if a first-person perspective is a kind of abstract object. (Elsewhere I have suggested that the first-person perspective at any given moment of awareness is a kind of modality, which can be taken to be an abstract object. See reference [6] and also here.) If a first-person perspective is an abstract object, then it might be possible for a brain not physically connected to yours to realize the same abstract feature.

Idea 4. The abstract self

As I have pointed out elsewhere, it's reasonable to assume that the self is an abstract object - a feature or property of the brain or of the brain's activity. (This idea isn't a theory of personal identity, but it has a similar impact on the rebirth scenario we are discussing.)

If this idea is true, then a new baby might be literally a continuation of you. How? The baby's brain might have the same feature that served as a self when your brain had the feature!

 

By presenting these four ideas about personal identity or the self, I'm not arguing for any of them. Nor am I arguing for any of the four possibilities for rebirth. Those who think they have fatal objections to one or more of these ideas need not be too upset. I know that much of what I have said is speculative. (Critics, pay attention to the preceding sentence before writing.) All I am trying to show is that it is not out of the question for a later human organism to be the same person as an earlier human organism. Nothing illogical, supernatural, or antiscientific is required. These four scenarios for survival of death do not violate the scientific principle known as Occam's Razor; they do not assume any extra objects (like ghostly souls) or extra complexity in the physical world. (The only objects required are human bodies and brains, with all their usual properties and features.)

Note that these four proposals do not add up to proof of an afterlife, or even to proof that an afterlife is likely. (I repeat: I am not claiming to have a proof of the afterlife.) Besides the four views of personal identity that I've hinted at here, there are other views that make spontaneous survival very unlikely. Examples are views based on the continuity of bodies or on the continuity of most of a person's memories. I am not going to argue for or against any of these theories here. I have presented the above four ideas to make one point: that we can't disprove the afterlife merely by stating that the mind is nothing but a process in the brain.

These examples also teach us another important lesson: if the mind is a process in the brain, then the possibility of an afterlife is a philosophical question, not a scientific one. If the mind is a process in the brain, then the answer to the question "Can a person spontaneously survive death?" depends on the solution to the problem of personal identity. That problem is philosophical, not scientific. Science cannot decide among alternative logically consistent solutions to that problem, for we cannot make that decision using only physical facts about bodies and their behavior. We also need philosophical analysis of concepts, such as the concept of a person. No matter which view of personal identity is right, the physical facts about bodies, brains and behavior will look exactly the same.

Part 4. Some Parting Remarks (pun intended)

What lessons have we learned from this merry romp through philosophy, logic and life? There are two.

1. The standard scientific argument against the afterlife is wrong. It might be possible for persons and their minds to survive death, even if the mind is "only" a process in the brain and the self is "only" a feature of the brain.

2. If the mind is a process in the brain, then the existence of the afterlife is a philosophical question, not a scientific one. If the mind is indeed a process in the brain, then only the philosophical analysis of personal identity can settle the question of the afterlife rationally - if anything ever can settle that question rationally. At very least, science cannot disprove the existence of the afterlife. Science can test particular ideas about the afterlife (such as beliefs about ghosts or past-life memories), but it cannot show that there is no afterlife of any kind.

If the mind is a process in the brain, then the standard "scientific" argument against the afterlife is not scientific. To present this argument as science is to practice pseudoscience! The argument is not scientific, but all too often it gets passed off on the unwary as science.

Before finishing, I should touch on the subject of religion. The ideas I have presented about the afterlife do not support any particular religious view of the afterlife. (For that matter, they don't support other specific religious beliefs either. An atheist can accept these ideas just as well as a theist can.) The ideas presented here come closer to Buddhist views than to any other religious teaching on the afterlife. However, adherents of other religions might want to speculate on the relevance of this post to their own beliefs. (For example, could "heaven" be interpreted as rebirth in some alternate universe?) Discussing these possibilities would take me too far into the realm of faith, where I do not want to go right now. My aim in this post is not to prove any part of any religion, or any specific picture of the afterlife. I only want to show that the standard "scientific" argument against the afterlife is wrong. And that, I would suggest, I have done.

-----

Notes

[1] As I will mention in a moment, the Buddhists recognized this fact long ago. It is amazing that the proponents of the skeptical argument do not take this old discovery into account.

[2] Combine artificial immortality with time travel - another staple of science fiction - and you raise the possibility of artificially continuing the minds of people who already have died. Some physicists have seriously asked whether time travel might be possible. If it were possible, and if it could take us to any past time, then why not start resurrecting everyone? The result would be every bit as good as the "general resurrection" that some religions believe in. (Liberal Christians often interpret "creation" in a non-supernatural way as the process of evolution. They might also be interested in the idea of a resurrection without supernatural miracles!)

[3] There is little question that an animal migration counts as a single process. The migration as a whole has specific overall effects on regional animal populations and on the natural environment in general. It plays a role in the natural world that goes beyond any of the individual activities of its component hoptoads. To deny that the migration is a real process, while also claiming that only the individual hops of the toads are real, would be silly.

[4] To better understand this idea, see the classic article "What Is It Like to Be a Bat?" by Thomas Nagel (The Philosophical Review, 83 (1974):435-450).

[5] See the treatment of "conscious subject identity" in chapter 5 of my book, From Brain to Cosmos. (Sharlow, Mark F. From Brain to Cosmos. Parkland, FL: Universal Publishers, 2001.)

[6] From Brain to Cosmos (cited above), chapter 3 and especially pp. 65-66.



posted at: 01:49 | path: /religion/science_and_religion | persistent link to this entry



 

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