| ZEN PHYSICS (what is this?) The Science of Death, the Logic of Reincarnation David Darling 
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Our claim to our own bodies and our world is our catastrophe ...
—W. H. Auden, Canzone
I wake up, I wash and dress, I notice in the mirror with some alarm a few more gray hairs, an unfamiliar wrinkle. I enjoy my morning cup of tea. I venture out and feel the chill of a December morning. Who or what is this “I” that does these things and has these experiences?
Each of us takes in the world from a unique vantage point. We see our surroundings through one particular pair of eyes and feel our awareness to be seated in one particular brain. We each think of ourselves as being unique and different from the rest. In your lifetime, you have had many experiences, sensations, thoughts, and emotions. But the one thing they all have in common is that they seem to be specifically associated with you. To varying degrees you have felt angry, happy, excited, in love, gloomy, anxious, and every other emotional state a person can feel. You have fallen asleep, daydreamed, possibly had general anesthesia, probably been under the influence of alcohol, and enjoyed who knows what other altered states of mind. You have been different ages. Yet despite all of these extraordinarily diverse experiences you are firmly convinced that you have remained, in some sense, one and the same person. You believe, as do those around you, that there is something – your “self” – that remains steady, secure, and identifiable amid the unpredictable flux of life. Furthermore, you believe that this self is distinct from all others. You feel, too, as if you did not exist before you were born, that your mind flickered into existence at some point, or over a limited period, in the not-so-long-ago past. And this raises the fear that you will similarly fade from existence in the not-too-distant future, when your body and brain stop working.
This feeling each of us has of unique individual consciousness and selfhood, of having an ego inside us, is both commonly accepted and, at the same time, profoundly mysterious. How did the conscious agency inside you come to occupy this particular body? Why were you born at a certain place and time, and not, for instance, two thousand years ago in Egypt or Rome, or a million years in the future in another part of the galaxy? Why is our personal existence unique?
If we think only about other people, it hardly seems surprising that there should be different selves, different eddies of being, characterized outwardly by different personalities. Each of us has a unique collection of genes and is exposed to a unique set of circumstances, so it would be unreasonable to expect any two people to turn out the same. But as soon as we focus on our own particular consciousness, mind-boggling paradoxes seem to arise. Of all the billions of centers of human (and nonhuman) awareness that have existed and do exist and will exist throughout time and space, why are you the one individual you are, in this body, here and now?
You would hardly expect to wake up tomorrow and find yourself, literally, stepping into someone else’s shoes. You don’t expect to be looking out, from one moment to the next, through the eyes of a succession of unfamiliar people. Your consciousness doesn’t flit around like a hummingbird from one place and time to another. Why should that be? We can breathe the same air and eat the same food, so why can’t we share or swap consciousness? Why can’t you be me, and I be you?
There’s no reason to suppose that the day-to-day experiences in your life are very much different from mine or anyone else’s. In matters of detail, it is true, they may differ quite a bit. But if you and I were to look at the same tree together, it’s reasonable to assume that we would inwardly perceive pretty much the same thing. Your experience of the tree – your feeling of its “treeness” – would, in all probability, closely match mine. We can say this with some confidence because the way the human senses and brain work doesn’t vary much from one person to another, so there are no grounds to suspect that our inner perceptions differ much either. It seems as safe as it possibly could be to conclude that a lot of what goes on inside our heads is not unique to us as individuals. The warmth of the sun, the smell of a rose, the throbbing pain of a toothache, and innumerable other sensations almost certainly feel more or less the same to you as they do to me. What, then, if two people in the same place could stop thinking for a moment about anything to do with themselves – the money he owes on his car, the itch she has on her arm, and so on – and instead simply take in their surroundings. What would happen?
Imagine, for instance, you are sitting on a boulder on the shore of a remote lake in the Canadian wilderness, a place little changed since the end of the last ice age. You see the sun glinting off the cool blue water, the rocky shoreline, the tall pines stretching away on either side. You have let your mind settle into a state as clear and tranquil as the cloudless sky, undisturbed by any personal thoughts or concerns. Beside you is a friend, and together you simply absorb and enjoy all the rich sensations this wild place has to offer – the cry of a bird overhead, the exhilarating feel of a fresh breeze, the gentle lapping of waves on the shore, the aroma of leaf and flower. Both of you experience the same scene, thinking no other thoughts, just letting the sights and sounds of your immediate environment wash over you. How is your consciousness, in this entirely open and receptive state, any different from that of your friend? How could it be different if the only aspect of experience that distinguishes two people – thoughts to do with themselves – have been suspended? Two bodies, two sets of sense organs, two brains, there might be – in objective space. But what matters, and is of primary importance to each of us, is the view from the inside. How can two minds differ internally if they are experiencing, purely and simply, the same underlying reality? When experience is exclusively of what is happening here and now, uninfluenced by personal memories, then it is – and must be – the same for everyone.
Now imagine that, a thousand years ago, another person sat on this same boulder savoring this same view of the lake and shoreline under the same bright sun. How is your consciousness, your immediate experience of this situation, any different from this other individual’s? You might argue that he was a different person who lived a different life at a different time and so inevitably had different thoughts from your own. But, again, leave aside these circumstantial differences, the very differences that define individual selves, and focus only on what you and this other fellow have in common – the unadulterated awareness of sitting on a boulder by an ancient lake, with no other thoughts intruding. Under these circumstances, what distinguishes your consciousness from his?
We are brought up to suppose that the consciousness of a particular person is entirely separate and distinct from the consciousness of anyone else, that we each inhabit our own little bubble of awareness. We are led to believe that the inner experience of being a particular person, a “you” or an “I,” is an exclusively private affair. And so we accept without question that this inner experience must be associated uniquely with one particular body and brain – the one that happens to be “ours.” But this belief is groundless, a mere social convention.
Most of the elements of what you and I experience are the same. So why do we regard ourselves as being utterly different? Why does it seem as if you are only conscious of what goes on inside your own head and not mine, or anyone else’s – or, for that matter, everyone else’s? It would be easier to accept that consciousness is a partly shared affair if it were not for the fact that you and I acutely feel as if we are looking out on the world from particular vantage points. Everything apparently comes not just to any observer, but constantly and unremittingly to you or to me. If you stub your toe, the whole population of the planet doesn’t groan along with you. If you have a long, cold drink after a long, hot game of tennis, the rest of humanity doesn’t share in your moment of bliss. As William James remarked:
Other men’s experiences, no matter how much I may know about them, never bear this vivid, this peculiar brand.We are alike, and therefore able to communicate with each other, inasmuch as part of our consciousness is the same. But we are different and distinguishable in that everyone has a unique life story. I know what it is like to feel pain, but I didn’t feel pain at the same times or in the same physical surroundings or in the same psychological contexts as you did. I know what it is like to fall in love, but not with that certain blond-haired girl or boy with the out-of-state accent you met at your high school dance when you were seventeen.
For most of the time we have an overwhelming impression of there being a central unifying agency inside us that remains steadfast and secure. This agency is the power that relates sensations, from one moment to the next, as if they were experienced by the same person, that seems to will actions, erects boundaries between itself and the outside, and seeks self-preservation. The brain, in effect, appears to have a resident storyteller that works ceaselessly to link everything into a single coherent narrative. And even as you read this, the story is continuing. Your brain is drawing upon a knowledge of its own history to generate the feeling of being you, interpreting every new idea and sensation it receives in terms of the information it already has stored.
The brain manufactures us, integrates us, moment by moment, from bits and pieces it finds in its database of memories. So, inevitably the contents of this database are crucial in fashioning the particular persons we become. Childhood circumstances, especially, play a vital role in laying down the basic infrastructure of our brains. However, the process of brain modification continues throughout our lives; the network of neurons, the pattern of synaptic links, alters and evolves over time in response to the demands placed upon it. Our brains change – and so, as a result, do we.
We are never the same, objectively, from one moment to the next. As sensations and emotions fluctuate, as the brain’s repository of memories is added to or depleted, we change too. And yet the change is not apparent from within. Every moment the brain is bombarded with fresh sensory data, and every moment, without fail, it filters, sorts, and merges this data with past recollections at an unconscious level to give a single, coherent, conscious experience. Across time, too, the brain unites, building bridges between its separate conscious experiences to create the impression of a smoothly running narrative. And, as its pièce de résistance, the brain conjures up the illusion of a character as its story’s heart – the self.
All the evidence of neurology suggests that you are nothing more than what it feels like to be a particular brain at a particular moment in time. And although this experience is determined by what has happened in the past, through the influence of memory, who you were in the past is not who you are now. It is one of the cleverest and most beguiling of the brain’s tricks to foster the belief that this is so – but you do not feel now as you did ten years ago, or even ten minutes ago. You are the feeling of one brain at one moment in time, this moment, no more. And part of this feeling, the illusory part, is that you are identical and continuous with what has gone before.
We are brought up to take pride in our individuality, to value being a particular person with a mind of our own. But however well this belief serves us in many ways, it comes at a heavy cost. Our tendency to accept unquestioningly the existence of a distinct, unchanging, private ego makes us terrified at the prospect of its loss. How, in the light of what science and psychology have revealed about the self, can we come to terms with the inevitability of death.
Suppose that neurosurgery develops to the stage where whole or partial brain transplants become possible. And suppose, for some reason, that you and I decide to have our brains swapped. After the operation, your brain, and therefore your continuing sense of self, would have taken up residence in my body, and my brain and sense of self in your body. A total brain transfer like this seems to pose no serious dilemma in deciding what happens to each person involved. We instinctively accept that “you go where your brain goes,” though it might well be that having a new body and appearance would eventually lead to marked changes in how you thought and felt. This would be especially so if the new body was very different than the original – say, a man’s body instead of a woman’s, or an adult’s instead of a child’s (as comically portrayed in the movie Big).
More problematic, though, would be the case where instead of a whole brain transfer we opted for a gradual swap of our brains. After the first operation, small clumps of cells from corresponding parts of the two brains would have changed places. How would this feel for you and for me? One possibility is that, upon regaining consciousness, we might notice the presence of a few new memories, the loss of some others, and perhaps a hard-to-define feeling of being not quite ourselves. If so, then if more such operations were carried out a point would presumably be reached at which you had become me and I had become you. Is this a reasonable theory?
Of course, no progressive transfer of healthy brains is ever likely to be carried out in practice. However, the surgical repair of damaged brains through the grafting on of healthy tissue from donor brains is a possibility. And some preliminary work in this area has already been done.
As long as as 1903, Elizabeth Hopkins Dunn, an anatomist at the University of Chicago, showed that small groups of cells or fragments of nervous tissue could be successfully grafted from the brain of one newborn rat onto that of another. The brain, it turns out, is surprisingly unfussy about having foreign material patched on to it (though it may, after several weeks or months, reject it). But the graft will not take at all unless it consists of very young cells, because only these have sufficient plasticity to form viable connections with the host brain.
Like their human counterparts, old rats tend to be forgetful. They have trouble, for instance, remembering their way around mazes that they have previously negotiated. But a graft of cells from a rat fetus, providing it comes from a specific little region of the brain known as the septum, serves dramatically to boost an aging rat’s maze-solving ability. This is because the septum regulates how much of a neurotransmitter (a chemical by which nerve cells communicate) called acetylcholine is fed to the hippocampus. And the hippocampus, as already mentioned, plays a vital role in helping lay down new memories. In an old rat – or an elderly person – the supply of acetylcholine in the hippocampus dries up because the necessary signals no longer come through from the septum. Fresh septum cells grafted onto the hippocampus help restore the supply – and hence the ability of the animal to remember.
Since the 1980s, brain grafts have been given to several hundred human patients around the world in an effort to relieve the symptoms of Parkinson’s disease. Parkinson’s victims face acute problems in exercising voluntary muscle control. Although not paralyzed (at least in the early stages of the disease) they may have great difficulty in initiating or controlling movements. Their limbs may tremble violently one moment and be struck in frozen immobility the next, and the normal gait of walking may be replaced by rapid shuffling steps. Unlike Alzheimer’s disease, which is characterized by a catastrophic loss of cells from virtually all parts of the brain, the effects of Parkinsonism can be traced principally to the death of cells in one specific structure – the substantia nigra. This part of the brain regulates the amount of the neurotransmitter dopamine reaching an important motor-control center called the striatum. The experimental transplant treatment involves taking substantia nigra tissue from aborted human fetuses and attaching it to the striata of affected patients in the hope that it will trigger the production of dopamine and so suppress the symptoms of Parkinsonism. It is far from being a cure, and in many cases it produces little or no improvement. But for some Parkinson’s patients, brain grafts have led to a marked recovery of independence and mobility.
The important point about this type of graft is that the connections formed between the transplanted cells and the existing brain cells don’t have to be precise. The substantia nigra just modulates the activity of the striatum like a volume control, so the details of the circuitry aren’t crucial. All that matters is that the right amount of dopamine gets through to where it is needed. This is obviously a very different form of communication from, say, that between the eyes and the visual cortex, in which the exact plan of the neural circuitry is absolutely critical.
More extensive brain grafts may be carried out in the future. But they will continue to involve immature cells that have the capacity to bind to existing tissue. Obvious ethical problems surround the use of brains from aborted fetuses, particularly as several brains are needed to provide sufficient dopamine-producing neurons for a transplant. This process will become much more efficient – and less ethically contentious – as it becomes possible to grow large numbers of dopamine neurons in the laboratory from a tiny amount of fetal brain material. But the necessity for using foreign tissue at all is likely to be short-lived as techniques are evolved to generate new brain cells in situ through tissue and genetic engineering.
Whatever method is used for future brain repairs, there is no conceivable threat to the identity of the patient. The new tissue will simply become integrated into the structure of the existing brain without introducing foreign elements into the recipient’s memories or character.
In fact, even if it were possible to transplant tissue from one mature brain to another, this would not raise the specter of memory transfer. Neurologists no longer subscribe to the idea that specific memories are carried by specific neurons or clusters of neurons. Instead, the modern view is that memories depend upon the overall associational network of connections within the cortex.
Reality, then, precludes a would-be Dr. Frankenstein from gradually changing one person into another by progressively swapping bits of their brains. But we can still envisage another method of achieving the same end. Suppose that it becomes possible to map a living brain down to the level of every neuron and synapse. And suppose further that we develop the means to reconfigure a brain’s connections by as little or as much we we desire. This would allow us, for instance, to make any number of the connections in one brain identical to those in another brain. Thus equipped we are ready to ask again: what would such a progressive change feel like?
A contemporary philosopher who has done a great deal of groundbreaking work using thought experiments like these is Derek Parfit of Oxford University. Imagine, then, to borrow from one of Parfit’s own gedanken experiments, that the two brains involved are those of Parfit himself and Napoleon Bonaparte. The question is, at what stage in the rewiring procedure would Parfit start to think of himself as being Napoleon rather than his old self? It would be ridiculous to suppose there would be a sudden switchover of identities. Clearly, we would be dealing with a continuous spectrum of possible mental states ranging from the feeling of being 100 percent Derek Parfit (a feeling that only Parfit is privy to) to that of being 100 percent Napoleon (a feeling known only to the emperor). In between these two extremes, memories from both individuals would be present together and so, for instance, Parfit/Napoleon might be ambiguous as to his loyalties to England and France or to Mrs. Parfit and Josephine. The storyteller in the Parfit/Napoleon brain would be working overtime trying to reconcile the conflicting bits of narrative at its disposal and doubtless around the midpoint of the operation, Parfit/Napoleon would be seriously confused as to his true identity. However, there is absolutely no reason to suppose that at any stage in the neural reconfiguration there would exist the feeling in the Parfit/Napoleon brain of being two people at once. Observers would certainly be forced to agree that the person who emerged from the operation, behaving exactly like Napoleon, was very different from the original Derek Parfit. On the other hand, as experienced by the Parfit/Napoleon brain, there would never have been a moment in which the “I” inside ceased to exist or at which this “I” experienced a dual or fragmented consciousness. The “I” inside may have felt disoriented, unsettled, afraid, or uncertain as to its identity, but it would nevertheless have experienced a single continuity of awareness.
Who should we think of as being the individual who walks away from the operation? He looks like Parfit and has Parfit’s old brain (extensively rewired, but with all the original atoms). Yet he acts like Napoleon. He talks in immaculate French of his military campaigns, his love for Josephine, and his despair at being sent into exile. He is, legally and biologically, the father of Parfit’s children and the husband of Parfit’s wife, but he retains not a single memory of being Parfit. Who then is this person? As experienced internally he is Napoleon (though an extremely confused Napoleon, having suddenly found himself in twentieth-century Oxford in an unfamiliar body!). But as far as others are concerned, he has the appearance of Derek Parfit apparently having gone mad and now doing a ludicrous (but brilliant) impression of the French emperor. What label should we pin on this person?
Such a question may prove difficult or impossible to resolve unless we are prepared to adopt a radically new outlook. We have to accept that there is a difference – a very great difference – between what we conventionally believe to be true about people, including ourselves, and what is actually the case. We have had it drummed into us that particular selves exist and that personal identity is all-important. We have been conditioned, both by evolution and by the society we live in, to think that the “I” inside us is clearly defined, extremely special, and worth preserving at almost any cost. As a result, we imagine ourselves as being at a privileged focus of the world, at the center of a special bubble of awareness that is different and more significant than any other.
So intently focused are we on our own self-centered domains that we consistently overlook the fact that the “feeling of being you” is universal. Everyone has to be someone, and everyone happens to be the particular someone they are right now. Say to a crowd of five hundred people, “Put up your hand if you feel like you,” and five hundred hands will go up. The simple but underrated fact is that we all feel like you. Right now, six billion people are busily “being you” – and not one of them is anyone special.
You might argue: “But there’s only one me, one self that’s exactly like me. Why is it that, of everyone I might have been, I happen to be me?” Yet, the fact is that anyone else could reply: “I think exactly the same way – and so does she, and so does he.” So where is the problem? I may not be having exactly the same thoughts or seeing the same things or experiencing the same emotions as you are right now, but why does that matter? Neither did you feel the same way last year or yesterday or even five minutes ago. The fact is that the range of subjective experiences you have been through in your life is as great as the range of subjective experiences being felt by many different people at any given moment in time. How can you claim to be a unique, definitive thing, this supposedly immutable “you,” when the succession of many past yous and the present you are as different from each other as a large collection of totally different individuals? It may be that at this moment (the moment at which you are reading this sentence) you have more in common with the way I am feeling right now than the way you yourself were feeling at this time yesterday. How then can we avoid the conclusion that conscious experiences are much more communal, much more commonly shared among everyone, than we normally suppose?
We have to realize, difficult as it may be, that there is absolutely nothing special about any of us. Only when we can grasp at the deepest level that personal identity is not what matters can we make progress toward understanding our true nature. The fact is, you could have been anybody. If your mother had conceived five minutes later than she did, a different sperm cell from your father would almost certainly have fertilized your mother’s egg, and a child having a different genetic makeup from your own would have developed. Ask yourself: would you have been that child? Or would you instead have been the brother or the sister of who you actually turned out to be? The child that might have been conceived five minutes later would have grown up to think of itself as being a particular person, would have had an inner world of experience as rich and coherent as anyone else’s, and would have been referred to by others as “you.” Its unique genetic constitution would have made it different from you in some ways (including possibly its sex), though its almost identical upbringing and environment would inevitably have made it similar to you in other ways (just as brothers and sisters are similar). Since the child would effectively have taken your place, is it reasonable to say it would actually have been you?
Or take a different example. Imagine you have an identical twin and that your parents divorced when you were three years old. Your mother and twin went to live in New York, while your father and you remained in San Francisco. Thirty years later, having been out of contact for all that time, you learn that whereas your own upbringing, while happy, was materially modest, that of your twin was extremely privileged. He or she attended a private school, won a scholarship to a first-rate medical college, had the opportunity to make all the right social connections, and is now a successful cardiologist. You, on the other hand, sell seafood on Fisherman’s Wharf. Though content with life, you wonder aloud to yourself one day what might have happened if you had been able to take your twin’s place. I overhear and in my newly constructed time machine travel back three decades to the moment at which your mother is about to leave for New York. I surreptitiously swap her twins around. Subsequently, the twin who goes to New York becomes a cardiologist while the other twin finds eventual employment as a purveyor of clams and crabs. One question we might ask is, given this new state of affairs, would you now be your twin (the cardiologist), or would you still be you (the seafood seller) in spite of the exchange? A more meaningful question, however, might be: does it matter? In the end, there are still two people – one a heart surgeon, the other a food merchant – who are conscious and happy and have complete, continuous sets of memories and other characteristics that help define the individuals that are. They are not confused about their own identities. Nor, to go back to the earlier example, would the person who might have been conceived inside your mother five minutes later have grown up confused about his or her identity. Why then should we make such an issue of who is who?
You chose to read this book. It may revolutionize your life, or it may not. But what is certain is that, simply by having absorbed these words – whether you believe them or not – you are, in at least some small way, not quite the person you would have been had you decided to do something else instead. This is a physical fact. As a result of processing the ideas about self and consciousness and death that this book has already invoked, your brain has acquired a slightly different atomic and neurophysiological configuration than it would otherwise have done. Therefore, since you are undoubtedly influenced by the state of your brain, you are not quite the same person you would have been had you never started reading. Ask yourself: does this matter to you? Would it matter to you if I said I was going to throw a switch and turn you into this “other you” who would have existed if you had not picked up this book? Why should it matter to you? The person you would then become would still have a complete chain of memories and a secure sense of identity – a feeling of being “I.”
The future, on a human scale, is almost totally unpredictable. For example, I have no idea what I shall be doing in three years’ time. If this book sells well, I may be sunning myself on some warm Caribbean beach marveling at how wonderful a writer’s life can be. On the other hand, if you are my only reader, I may be pawning my computer and ruing the day I ignored my parents’ advice to find a real job. I know that, in any event, I shall continue to be me because I can never be anyone else (or, to put it another way, even if I did become someone else, in an existential sense, I wouldn’t be aware of it and would therefore still think of myself as being me). However, I also feel sure that the me who might be basking on some faraway desert isle would not be quite the same me who, if fortune fails to smile, ends up impecunious and untanned.
Even if we think we know who we are now, we haven’t a clue who we are going to be tomorrow or next year. Whatever happens, you will still think of yourself as being the same person – a continuation of the “old you.” But you will in fact have changed. You will be composed of different atoms, your body will have aged, your brain will be wired up somewhat differently, and your feelings about the world will have matured and evolved. Despite the fact that received wisdom tells us we retain the same personal identity throughout life, the reality of the matter is different. Personal identity does change, all the time. You are not the same “you” that you were a week ago or even a second ago. You, as a fixed entity, are an illusion that we have been persuaded to believe is real. Personal identity as a constant, enduring thing is a myth – a myth that on a day-to-day basis, it is true, serves a useful purpose. But to grow in understanding we need to move on, both individually and as a society, in the direction of laying less stress on the particular people we think we are – because being particular is not important. You and I are nobody special. We are simply brains having thoughts and that is all there is to it.