How To Create A Mind Part 8

In support of this distinction, Chalmers introduces a thought experiment involving what he calls zombies. A zombie is an ent.i.ty that acts just like a person but simply does not have subjective experience-that is, a zombie is not conscious. Chalmers argues that since we can conceive of zombies, they are at least logically possible. If you were at a c.o.c.ktail party and there were both "normal" humans and zombies, how would you tell the difference? Perhaps this sounds like a c.o.c.ktail party you have attended.

Many people answer this question by saying they would interrogate individuals they wished to a.s.sess about their emotional reactions to events and ideas. A zombie, they believe, would betray its lack of subjective experience through a deficiency in certain types of emotional responses. But an answer along these lines simply fails to appreciate the a.s.sumptions of the thought experiment. If we encountered an unemotional person (such as an individual with certain emotional deficits, as is common in certain types of autism) or an avatar or a robot that was not convincing as an emotional human being, then that ent.i.ty is not a zombie. Remember: According to Chalmers's a.s.sumption, a zombie is is completely normal in his ability to respond, including the ability to react emotionally; he is just lacking subjective experience. The bottom line is that there is no way to identify a zombie, because by definition there is no apparent indication of his zombie nature in his behavior. So is this a distinction without a difference? completely normal in his ability to respond, including the ability to react emotionally; he is just lacking subjective experience. The bottom line is that there is no way to identify a zombie, because by definition there is no apparent indication of his zombie nature in his behavior. So is this a distinction without a difference?

Chalmers does not attempt to answer the hard question but does provide some possibilities. One is a form of dualism in which consciousness per se does not exist in the physical world but rather as a separate ontological reality. According to this formulation, what a person does is based on the processes in her brain. Because the brain is causally closed, we can fully explain a person's actions, including her thoughts, through its processes. Consciousness then exists essentially in another realm, or at least is a property separate from the physical world. This explanation does not permit the mind (that is to say, the conscious property a.s.sociated with the brain) to causally affect the brain.

Another possibility that Chalmers entertains, which is not logically distinct from his notion of dualism, and is often called panprotopsychism, holds that all physical systems are conscious, albeit a human is more conscious than, say, a light switch. I would certainly agree that a human brain has more to be conscious about than a light switch.

My own view, which is perhaps a subschool of panprotopsychism, is that consciousness is an emergent property of a complex physical system. In this view a dog is also conscious but somewhat less than a human. An ant has some level of consciousness, too, but much less that of a dog. The ant colony, on the other hand, could be considered to have a higher level of consciousness than the individual ant; it is certainly more intelligent than a lone ant. By this reckoning, a computer that is successfully emulating the complexity of a human brain would also have the same emergent consciousness as a human.

Another way to conceptualize the concept of consciousness is as a system that has "qualia." So what are qualia? One definition of the term is "conscious experiences." That, however, does not take us very far. Consider this thought experiment: A neuroscientist is completely color-blind-not the sort of color-blind in which one mixes up certain shades of, say, green and red (as I do), but rather a condition in which the afflicted individual lives entirely in a black-and-white world. (In a more extreme version of this scenario, she has grown up in a black-and-white world and has never seen any colors. Bottom line, there is no color in her world.) However, she has extensively studied the physics of color-she is aware that the wavelength of red light is 700 nanometers-as well as the neurological processes of a person who can experience colors normally, and thus knows a great deal about how the brain processes color. She knows more about color than most people. If you wanted to help her out and explain what this actual experience of "red" is like, how would you do it?

Perhaps you would read her a section from the poem "Red" by the Nigerian poet Oluseyi Oluseun: Red the colour of bloodthe symbol of lifeRed the colour of dangerthe symbol of death.

Red the colour of rosesthe symbol of beautyRed the colour of loversthe symbol of unity.

Red the colour of tomatothe symbol of good healthRed the colour of hot firethe symbol of burning desire.

That actually would give her a pretty good idea of some of the a.s.sociations people have made with red, and may even enable her to hold her own in a conversation about the color. ("Yes, I love the color red, it's so hot and fiery, so dangerously beautiful...") If she wanted to, she could probably convince people that she had experienced red, but all the poetry in the world would not actually enable her to have that experience.

Similarly, how would you explain what it feels like to dive into water to someone who has never touched water? We would again be forced to resort to poetry, but there is really no way to impart the experience itself. These experiences are what we refer to as qualia.

Many of the readers of this book have experienced the color red. But how do I know whether your experience of red is not the same experience that I have when I look at blue? We both look at a red object and state a.s.suredly that it is red, but that does not answer the question. I may be experiencing what you experience when you look at blue, but we have both learned to call red things red. We could start swapping poems again, but they would simply reflect the a.s.sociations that people have made with colors; they do not speak to the actual nature of the qualia. Indeed, congenitally blind people have read a great deal about colors, as such references are replete in literature, and thus they do have some version of an experience of color. How does their experience of red compare with the experience of sighted people? This is really the same question as the one concerning the woman in the black-and-white world. It is remarkable that such common phenomena in our lives are so completely ineffable as to make a simple confirmation, like one that we are experiencing the same qualia, impossible.

Another definition of qualia is the feeling of an experience. However, this definition is no less circular than our attempts at defining consciousness above, as the phrases "feeling," "having an experience," and "consciousness" are all synonyms. Consciousness and the closely related question of qualia are a fundamental, perhaps the ultimate, philosophical question (although the issue of ident.i.ty may be even more important, as I will discuss in the closing section of this chapter).

So with regard to consciousness, what exactly is is the question again? It is this: Who or what is conscious? I refer to "mind" in the t.i.tle of this book rather than "brain" because a mind is a brain that is conscious. We could also say that a mind has free will and ident.i.ty. The a.s.sertion that these issues are philosophical is itself not self-evident. I maintain that these questions can never be fully resolved through science. In other words, there are no falsifiable experiments that we can contemplate that would resolve them, not without making philosophical a.s.sumptions. If we were building a consciousness detector, Searle would want it to ascertain that it was squirting biological neurotransmitters. American philosopher Daniel Dennett (born in 1942) would be more flexible on substrate, but might want to determine whether or not the system contained a model of itself and of its own performance. That view comes closer to my own, but at its core is still a philosophical a.s.sumption. the question again? It is this: Who or what is conscious? I refer to "mind" in the t.i.tle of this book rather than "brain" because a mind is a brain that is conscious. We could also say that a mind has free will and ident.i.ty. The a.s.sertion that these issues are philosophical is itself not self-evident. I maintain that these questions can never be fully resolved through science. In other words, there are no falsifiable experiments that we can contemplate that would resolve them, not without making philosophical a.s.sumptions. If we were building a consciousness detector, Searle would want it to ascertain that it was squirting biological neurotransmitters. American philosopher Daniel Dennett (born in 1942) would be more flexible on substrate, but might want to determine whether or not the system contained a model of itself and of its own performance. That view comes closer to my own, but at its core is still a philosophical a.s.sumption.

Proposals have been regularly presented that purport to be scientific theories linking consciousness to some measurable physical attribute-what Searle refers to as the "mechanism for causing consciousness." American scientist, philosopher, and anesthesiologist Stuart Hameroff (born in 1947) has written that "cytoskeletal filaments are the roots of consciousness."2 He is referring to thin threads in every cell (including neurons but not limited to them) called microtubules, which give each cell structural integrity and play a role in cell division. His books and papers on this issue contain detailed descriptions and equations that explain the plausibility that the microtubules play a role in information processing within the cell. But the connection of microtubules to consciousness requires a leap of faith not fundamentally different from the leap of faith implicit in a religious doctrine that describes a supreme being bestowing consciousness (sometimes referred to as a "soul") to certain (usually human) ent.i.ties. Some weak evidence is proffered for Hameroff's view, specifically the observation that the neurological processes that could support this purported cellular computing are stopped during anesthesia. But this is far from compelling substantiation, given that lots of processes are halted during anesthesia. We cannot even say for certain that subjects are not conscious when anesthetized. All we do know is that people do not remember their experiences afterward. Even that is not universal, as some people do remember-accurately-their experience while under anesthesia, including, for example, conversations by their surgeons. Called anesthesia awareness, this phenomenon is estimated to occur about 40,000 times a year in the United States. He is referring to thin threads in every cell (including neurons but not limited to them) called microtubules, which give each cell structural integrity and play a role in cell division. His books and papers on this issue contain detailed descriptions and equations that explain the plausibility that the microtubules play a role in information processing within the cell. But the connection of microtubules to consciousness requires a leap of faith not fundamentally different from the leap of faith implicit in a religious doctrine that describes a supreme being bestowing consciousness (sometimes referred to as a "soul") to certain (usually human) ent.i.ties. Some weak evidence is proffered for Hameroff's view, specifically the observation that the neurological processes that could support this purported cellular computing are stopped during anesthesia. But this is far from compelling substantiation, given that lots of processes are halted during anesthesia. We cannot even say for certain that subjects are not conscious when anesthetized. All we do know is that people do not remember their experiences afterward. Even that is not universal, as some people do remember-accurately-their experience while under anesthesia, including, for example, conversations by their surgeons. Called anesthesia awareness, this phenomenon is estimated to occur about 40,000 times a year in the United States.3 But even setting that aside, consciousness and memory are completely different concepts. As I have discussed extensively, if I think back on my moment-to-moment experiences over the past day, I have had a vast number of sensory impressions yet I remember very few of them. Was I therefore not conscious of what I was seeing and hearing all day? It is actually a good question, and the answer is not so clear. But even setting that aside, consciousness and memory are completely different concepts. As I have discussed extensively, if I think back on my moment-to-moment experiences over the past day, I have had a vast number of sensory impressions yet I remember very few of them. Was I therefore not conscious of what I was seeing and hearing all day? It is actually a good question, and the answer is not so clear.

English physicist and mathematician Roger Penrose (born in 1931) took a different leap of faith in proposing the source of consciousness, though his also concerned the microtubules-specifically, their purported quantum computing abilities. His reasoning, although not explicitly stated, seemed to be that consciousness is mysterious, and a quantum event is also mysterious, so they must be linked in some way.

Penrose started his a.n.a.lysis with Turing's theorems on unsolvable problems and G.o.del's related incompleteness theorem. Turing's premise (which was discussed in greater detail in chapter 8 chapter 8) is that there are algorithmic problems that can be stated but that cannot be solved by a Turing machine. Given the computational universality of the Turing machine, we can conclude that these "unsolvable problems" cannot be solved by any machine. G.o.del's incompleteness theorem has a similar result with regard to the ability to prove conjectures involving numbers. Penrose's argument is that the human brain is able to solve these unsolvable problems, so is therefore capable of doing things that a deterministic machine such as a computer is unable to do. His motivation, at least in part, is to elevate human beings above machines. But his central premise-that humans can solve Turing's and G.o.del's insoluble problems-is unfortunately simply not true.

A famous unsolvable problem called the busy beaver problem is stated as follows: Find the maximum number of 1s that a Turing machine with a certain number of states can write on its tape. So to determine the busy beaver of the number n n, we build all of the Turing machines that have n n states (which will be a finite number if states (which will be a finite number if n n is finite) and then determine the largest number of 1s that these machines write on their tapes, excluding those Turing machines that get into an infinite loop. This is unsolvable because as we seek to simulate all of these is finite) and then determine the largest number of 1s that these machines write on their tapes, excluding those Turing machines that get into an infinite loop. This is unsolvable because as we seek to simulate all of these n n-state Turing machines, our simulator will get into an infinite loop when it attempts to simulate one of the Turing machines that does get into an infinite loop. However, it turns out that computers have nonetheless been able to determine the busy beaver function for certain n ns. So have humans, but computers have solved the problem for far more n ns than una.s.sisted humans. Computers are generally better than humans at solving Turing's and G.o.del's unsolvable problems.

Penrose linked these claimed transcendent capabilities of the human brain to the quantum computing that he hypothesized took place in it. According to Penrose, these neural quantum effects were somehow inherently not achievable by computers, so therefore human thinking has an inherent edge. In fact, common electronics uses quantum effects (transistors rely on quantum tunneling of electrons across barriers); quantum computing in the brain has never been demonstrated; human mental performance can be satisfactorily explained by cla.s.sical computing methods; and in any event nothing bars us from applying quantum computing in computers. None of these objections has ever been addressed by Penrose. It was when critics pointed out that the brain is a warm and messy place for quantum computing that Hameroff and Penrose joined forces. Penrose found a perfect vehicle within neurons that could conceivably support quantum computing-namely, the microtubules that Hameroff had speculated were part of the information processing within a neuron. So the Hameroff-Penrose thesis is that the microtubules in the neurons are doing quantum computing and that this is responsible for consciousness.

This thesis has also been criticized, for example, by Swedish American physicist and cosmologist Max Tegmark (born in 1967), who determined that quantum events in microtubules could survive for only 1013 seconds, which is much too brief a period of time either to compute results of any significance or to affect neural processes. There are certain types of problems for which quantum computing would show superior capabilities to cla.s.sical computing-for example, the cracking of encryption codes through the factoring of large numbers. However, una.s.sisted human thinking has proven to be terrible at solving them, and cannot match even cla.s.sical computers in this area, which suggests that the brain is not demonstrating any quantum computing capabilities. Moreover, even if such a phenomenon as quantum computing in the brain did exist, it would not necessarily be linked to consciousness. seconds, which is much too brief a period of time either to compute results of any significance or to affect neural processes. There are certain types of problems for which quantum computing would show superior capabilities to cla.s.sical computing-for example, the cracking of encryption codes through the factoring of large numbers. However, una.s.sisted human thinking has proven to be terrible at solving them, and cannot match even cla.s.sical computers in this area, which suggests that the brain is not demonstrating any quantum computing capabilities. Moreover, even if such a phenomenon as quantum computing in the brain did exist, it would not necessarily be linked to consciousness.

You Gotta Have FaithWhat a piece of work is a man! How n.o.ble in reason! How infinite in faculties! In form and moving, how express and admirable! In action how like an angel! In apprehension, how like a G.o.d! The beauty of the world! The paragon of animals! And yet, to me, what is this quintessence of dust?-Hamlet, in Shakespeare's Hamlet Hamlet

The reality is that these theories are all leaps of faith, and I would add that where consciousness is concerned, the guiding principle is "you gotta have faith"-that is, we each need a leap of faith as to what and who is conscious, and who and what we are as conscious beings. Otherwise we could not get up in the morning. But we should be honest about the fundamental need for a leap of faith in this matter and self-reflective as to what our own particular leap involves.

People have very different leaps, despite impressions to the contrary. Individual philosophical a.s.sumptions about the nature and source of consciousness underlie disagreements on issues ranging from animal rights to abortion, and will result in even more contentious future conflicts over machine rights. My objective prediction is that machines in the future will appear to be conscious and that they will be convincing to biological people when they speak of their qualia. They will exhibit the full range of subtle, familiar emotional cues; they will make us laugh and cry; and they will get mad at us if we say that we don't believe that they are conscious. (They will be very smart, so we won't want that to happen.) We will come to accept that they are conscious persons. My own leap of faith is this: Once machines do succeed in being convincing when they speak of their qualia and conscious experiences, they will indeed const.i.tute conscious persons. I have come to my position via this thought experiment: Imagine that you meet an ent.i.ty in the future (a robot or an avatar) that is completely convincing in her emotional reactions. She laughs convincingly at your jokes, and in turn makes you laugh and cry (but not just by pinching you). She convinces you of her sincerity when she speaks of her fears and longings. In every way, she seems conscious. She seems, in fact, like a person. Would you accept her as a conscious person?

If your initial reaction is that you would likely detect some way in which she betrays her nonbiological nature, then you are not keeping to the a.s.sumptions in this hypothetical situation, which established that she is is fully convincing. Given that a.s.sumption, if she were threatened with destruction and responded, as a human would, with terror, would you react in the same empathetic way that you would if you witnessed such a scene involving a human? For myself, the answer is yes, and I believe the answer would be the same for most if not virtually all other people regardless of what they might a.s.sert now in a philosophical debate. Again, the emphasis here is on the word "convincing." fully convincing. Given that a.s.sumption, if she were threatened with destruction and responded, as a human would, with terror, would you react in the same empathetic way that you would if you witnessed such a scene involving a human? For myself, the answer is yes, and I believe the answer would be the same for most if not virtually all other people regardless of what they might a.s.sert now in a philosophical debate. Again, the emphasis here is on the word "convincing."

There is certainly disagreement on when or even whether we will encounter such a nonbiological ent.i.ty. My own consistent prediction is that this will first take place in 2029 and become routine in the 2030s. But putting the time frame aside, I believe that we will eventually come to regard such ent.i.ties as conscious. Consider how we already treat them when we are exposed to them as characters in stories and movies: R2D2 from the Star Wars Star Wars movies, David and Teddy from the movie movies, David and Teddy from the movie A.I A.I., Data from the TV series Star Trek: The Next Generation Star Trek: The Next Generation, Johnny 5 from the movie Short Circuit Short Circuit, WALL-E from Disney's movie Wall-E Wall-E, T-800-the (good) Terminator-in the second and later Terminator Terminator movies, Rachael the Replicant from the movie movies, Rachael the Replicant from the movie Blade Runner Blade Runner (who, by the way, is not aware that she is not human), b.u.mblebee from the movie, TV, and comic series (who, by the way, is not aware that she is not human), b.u.mblebee from the movie, TV, and comic series Transformers Transformers, and Sonny from the movie I, Robot I, Robot. We do empathize with these characters even though we know that they are nonbiological. We regard them as conscious persons, just as we do biological human characters. We share their feelings and fear for them when they get into trouble. If that is how we treat fictional nonbiological characters today, then that is how we will treat real-life intelligences in the future that don't happen to have a biological substrate.

If you do accept the leap of faith that a nonbiological ent.i.ty that is convincing in its reactions to qualia is actually conscious, then consider what that implies: namely that consciousness is an emergent property of the overall pattern of an ent.i.ty, not the substrate it runs on.

There is a conceptual gap between science, which stands for objective objective measurement and the conclusions we can draw thereby, and consciousness, which is a synonym for measurement and the conclusions we can draw thereby, and consciousness, which is a synonym for subjective subjective experience. We obviously cannot simply ask an ent.i.ty in question, "Are you conscious?" If we look inside its "head," biological or otherwise, to ascertain that, then we would have to make philosophical a.s.sumptions in determining what it is that we are looking for. The question as to whether or not an ent.i.ty is conscious is therefore not a scientific one. Based on this, some observers go on to question whether consciousness itself has any basis in reality. English writer and philosopher Susan Blackmore (born in 1951) speaks of the "grand illusion of consciousness." She acknowledges the reality of the meme (idea) of consciousness-in other words, consciousness certainly exists as an idea, and there are a great many neocortical structures that deal with the idea, not to mention words that have been spoken and written about it. But it is not clear that it refers to something real. Blackburn goes on to explain that she is not necessarily denying the reality of consciousness, but rather attempting to articulate the sorts of dilemmas we encounter when we try to pin down the concept. As British psychologist and writer Stuart Sutherland (19271998) wrote in the experience. We obviously cannot simply ask an ent.i.ty in question, "Are you conscious?" If we look inside its "head," biological or otherwise, to ascertain that, then we would have to make philosophical a.s.sumptions in determining what it is that we are looking for. The question as to whether or not an ent.i.ty is conscious is therefore not a scientific one. Based on this, some observers go on to question whether consciousness itself has any basis in reality. English writer and philosopher Susan Blackmore (born in 1951) speaks of the "grand illusion of consciousness." She acknowledges the reality of the meme (idea) of consciousness-in other words, consciousness certainly exists as an idea, and there are a great many neocortical structures that deal with the idea, not to mention words that have been spoken and written about it. But it is not clear that it refers to something real. Blackburn goes on to explain that she is not necessarily denying the reality of consciousness, but rather attempting to articulate the sorts of dilemmas we encounter when we try to pin down the concept. As British psychologist and writer Stuart Sutherland (19271998) wrote in the International Dictionary of Psychol International Dictionary of Psychology, "Consciousness is a fascinating but elusive phenomenon; it is impossible to specify what it is, what it does, or why it evolved."4 However, we would be well advised not to dismiss the concept too easily as just a polite debate between philosophers-which, incidentally, dates back two thousand years to the Platonic dialogues. The idea of consciousness underlies our moral system, and our legal system in turn is loosely built on those moral beliefs. If a person extinguishes someone's consciousness, as in the act of murder, we consider that to be immoral, and with some exceptions, a high crime. Those exceptions are also relevant to consciousness, in that we might authorize police or military forces to kill certain conscious people to protect a greater number of other conscious people. We can debate the merits of particular exceptions, but the underlying principle holds true.

a.s.saulting someone and causing her to experience suffering is also generally considered immoral and illegal. If I destroy my property, it is probably acceptable. If I destroy your property without your permission, it is probably not acceptable, but not because I am causing suffering to your property, but rather to you as the owner of the property. On the other hand, if my property includes a conscious being such as an animal, then I as the owner of that animal do not necessarily have free moral or legal rein to do with it as I wish-there are, for example, laws against animal cruelty.

Because a great deal of our moral and legal system is based on protecting the existence of and preventing the unnecessary suffering of conscious ent.i.ties, in order to make responsible judgments we need to answer the question as to who is conscious. That question is therefore not simply a matter for intellectual debate, as is evident in the controversy surrounding an issue like abortion. I should point out that the abortion issue can go somewhat beyond the issue of consciousness, as pro-life proponents argue that the potential for an embryo to ultimately become a conscious person is sufficient reason for it to be awarded protection, just as someone in a coma deserves that right. But fundamentally the issue is a debate about when a fetus becomes conscious.

Perceptions of consciousness also often affect our judgments in controversial areas. Looking at the abortion issue again, many people make a distinction between a measure like the morning-after pill, which prevents the implantation of an embryo in the uterus in the first days of pregnancy, and a late-stage abortion. The difference has to do with the likelihood that the late-stage fetus is conscious. It is difficult to maintain that a few-days-old embryo is conscious unless one takes a panprotopsychist position, but even in these terms it would rank below the simplest animal in terms of consciousness. Similarly, we have very different reactions to the maltreatment of great apes versus, say, insects. No one worries too much today about causing pain and suffering to our computer software (although we do comment extensively on the ability of software to cause us suffering), but when future software has the intellectual, emotional, and moral intelligence of biological humans, this will become a genuine concern.

Thus my position is that I will accept nonbiological ent.i.ties that are fully convincing in their emotional reactions to be conscious persons, and my prediction is that the consensus in society will accept them as well. Note that this definition extends beyond ent.i.ties that can pa.s.s the Turing test, which requires mastery of human language. The latter are sufficiently humanlike that I would include them, and I believe that most of society will as well, but I also include ent.i.ties that evidence humanlike emotional reactions but may not be able to pa.s.s the Turing test-for example, young children.

Does this resolve the philosophical question of who is conscious, at least for myself and others who accept this particular leap of faith? The answer is: not not quite quite. We've only covered one case, which is that of ent.i.ties that act in a humanlike way. Even though we are discussing future ent.i.ties that are not biological, we are talking about ent.i.ties that demonstrate convincing humanlike reactions, so this position is still human-centric. But what about more alien forms of intelligence that are not humanlike? We can imagine intelligences that are as complex as or perhaps vastly more complex and intricate than human brains, but that have completely different emotions and motivations. How do we decide whether or not they are conscious?

We can start by considering creatures in the biological world that have brains comparable to those of humans yet evince very different sorts of behaviors. British philosopher David c.o.c.kburn (born in 1949) writes about viewing a video of a giant squid that was under attack (or at least it thought it was-c.o.c.kburn hypothesized that it might have been afraid of the human with the video camera). The squid shuddered and cowered, and c.o.c.kburn writes, "It responded in a way which struck me immediately and powerfully as one of fear. Part of what was striking in this sequence was the way in which it was possible to see in the behavior of a creature physically so very different from human beings an emotion which was so unambiguously and specifically one of fear."5 He concludes that the animal was feeling that emotion and he articulates the belief that most other people viewing that film would come to the same conclusion. If we accept c.o.c.kburn's description and conclusion, then we would have to add giant squids to our list of conscious ent.i.ties. However, this has not gotten us very far either, because it is still based on our empathetic reaction to an emotion that we recognize in ourselves. It is still a self-centric or human-centric perspective. He concludes that the animal was feeling that emotion and he articulates the belief that most other people viewing that film would come to the same conclusion. If we accept c.o.c.kburn's description and conclusion, then we would have to add giant squids to our list of conscious ent.i.ties. However, this has not gotten us very far either, because it is still based on our empathetic reaction to an emotion that we recognize in ourselves. It is still a self-centric or human-centric perspective.

If we step outside biology, nonbiological intelligence will be even more varied than intelligence in the biological world. For example, some ent.i.ties may not have a fear of their own destruction, and may not have a need for the emotions we see in humans or in any biological creature. Perhaps they could still pa.s.s the Turing test, or perhaps they wouldn't even be willing to try.

We do in fact build robots today that do not have a sense of self-preservation to carry out missions in dangerous environments. They're not sufficiently intelligent or complex yet for us to seriously consider their sentience, but we can imagine future robots of this sort that are as complex as humans. What about them?

Personally I would say that if I saw in such a device's behavior a commitment to a complex and worthy goal and the ability to execute notable decisions and actions to carry out its mission, I would be impressed and probably become upset if it got destroyed. This is now perhaps stretching the concept a bit, in that I am responding to behavior that does not include many emotions we consider universal in people and even in biological creatures of all kinds. But again, I am seeking to connect with attributes that I can relate to in myself and other people. The idea of an ent.i.ty totally dedicated to a n.o.ble goal and carrying it out or at least attempting to do so without regard for its own well-being is, after all, not completely foreign to human experience. In this instance we are also considering an ent.i.ty that is seeking to protect biological humans or in some way advance our agenda.

What if this ent.i.ty has its own goals distinct from a human one and is not carrying out a mission we would recognize as n.o.ble in our own terms? I might then attempt to see if I could connect or appreciate some of its abilities in some other way. If it is indeed very intelligent, it is likely to be good at math, so perhaps I could have a conversation with it on that topic. Maybe it would appreciate math jokes.

But if the ent.i.ty has no interest in communicating with me, and I don't have sufficient access to its actions and decision making to be moved by the beauty of its internal processes, does that mean that it is not conscious? I need to conclude that ent.i.ties that do not succeed in convincing me of their emotional reactions, or that don't care to try, are not necessarily not conscious. It would be difficult to recognize another conscious ent.i.ty without establis.h.i.+ng some level of empathetic communication, but that judgment reflects my own limitations more than it does the ent.i.ty under consideration. We thus need to proceed with humility. It is challenging enough to put ourselves in the subjective shoes of another human, so the task will be that much harder with intelligences that are extremely different from our own.

What Are We Conscious Of?If we could look through the skull into the brain of a consciously thinking person, and if the place of optimal excitability were luminous, then we should see playing over the cerebral surface, a bright spot with fantastic, waving borders constantly fluctuating in size and form, surrounded by a darkness more or less deep, covering the rest of the hemisphere.-Ivan Petrovich Pavlov, 19136

Returning to the giant squid, we can recognize some of its apparent emotions, but much of its behavior is a mystery. What is it like being a giant squid? How does it feel as it squeezes its spineless body through a tiny opening? We don't even have the vocabulary to answer this question, given that we cannot even describe experiences that we do share with other people, such as seeing the color red or feeling water splash on our bodies.

But we don't have to go as far as the bottom of the ocean to find mysteries in the nature of conscious experiences-we need only consider our own. I know, for example, that I am conscious. I a.s.sume that you, the reader, are conscious also. (As for people who have not bought my book, I am not so sure.) But what am I conscious of of? You might ask yourself the same question.

Try this thought experiment (which will work for those of you who drive a car): Imagine that you are driving in the left lane of a highway. Now close your eyes, grab an imagined steering wheel, and make the movements to change lanes to the lane to your right.

Okay, before continuing to read, try it.

Here is what you probably did: You held the steering wheel. You checked that the right lane is clear. a.s.suming the lane was clear, you turned the steering wheel to the right for a brief period. Then you straightened it out again. Job done.

It's a good thing you weren't in a real car, because you just zoomed across all the lanes of the highway and crashed into a tree. While I probably should have mentioned that you shouldn't try this in a real moving car (but then I a.s.sume you have already mastered the rule that you shouldn't drive with your eyes closed), that's not really the key problem here. If you used the procedure I just described-and almost everyone does when doing this thought experiment-you got it wrong. Turning the wheel to the right and then straightening it out causes the car to head in a direction that is diagonal to its original direction. It will cross the lane to the right, as you intended, but it will keep going to the right indefinitely until it zooms off the road. What you needed to do as your car crossed the lane to the right was to then turn the wheel to the left, just as far as you had turned it to the right, and then then straighten it out again. This will cause the car to again head straight in the new lane. straighten it out again. This will cause the car to again head straight in the new lane.

Consider the fact that if you're a regular driver, you've done this maneuver thousands of times. Are you not conscious when you do this? Have you never paid attention to what you are actually doing when you change lanes? a.s.suming that you are not reading this book in a hospital while recovering from a lane-changing accident, you have clearly mastered this skill. Yet you are not conscious of what you did, however many times you've accomplished this task.

When people tell stories of their experiences, they describe them as sequences of situations and decisions. But this is not how we experience a story in the first place. Our original experience is as a sequence of high-level patterns, some of which may have triggered feelings. We remember only a small subset of those patterns, if that. Even if we are reasonably accurate in our recounting of a story, we use our powers of confabulation to fill in missing details and convert the sequence into a coherent tale. We cannot be certain what our original conscious experience was from our recollection of it, yet memory is the only access we have to that experience. The present moment is, well, fleeting, and is quickly turned into a memory, or, more often, not. Even if an experience is turned into a memory, it is stored, as the PRTM indicates, as a high-level pattern composed of other patterns in a huge hierarchy. As I have pointed out several times, almost all of the experiences we have (like any of the times we changed lanes) are immediately forgotten. So ascertaining what const.i.tutes our own conscious experience is actually not attainable.

East Is East and West Is WestBefore brains there was no color or sound in the universe, nor was there any flavor or aroma and probably little sense and no feeling or emotion.-Roger W. Sperry7 Rene Descartes walks into a restaurant and sits down for dinner. The waiter comes over and asks if he'd like an appetizer."No thank you," says Descartes, "I'd just like to order dinner.""Would you like to hear our daily specials?" asks the waiter."No," says Descartes, getting impatient."Would you like a drink before dinner?" the waiter asks.Descartes is insulted, since he's a teetotaler. "I think not!" he says indignantly, and POOF! he disappears.-A joke as recalled by David Chalmers

There are two ways to view the questions we have been considering-converse Western and Eastern perspectives on the nature of consciousness and of reality. In the Western perspective, we start with a physical world that evolves patterns of information. After a few billion years of evolution, the ent.i.ties in that world have evolved sufficiently to become conscious beings. In the Eastern view, consciousness is the fundamental reality; the physical world only comes into existence through the thoughts of conscious beings. The physical world, in other words, is the thoughts of conscious beings made manifest. These are of course simplifications of complex and diverse philosophies, but they represent the princ.i.p.al polarities in the philosophies of consciousness and its relations.h.i.+p to the physical world.

The East-West divide on the issue of consciousness has also found expression in opposing schools of thought in the field of subatomic physics. In quantum mechanics, particles exist as what are called probability fields. Any measurement carried out on them by a measuring device causes what is called a collapse of the wave function, meaning that the particle suddenly a.s.sumes a particular location. A popular view is that such a measurement const.i.tutes observation by a conscious observer, because otherwise measurement would be a meaningless concept. Thus the particle a.s.sumes a particular location (as well as other properties, such as velocity) only when it is observed. Basically particles figure that if no one is bothering to look at them, they don't need to decide where they are. I call this the Buddhist school of quantum mechanics, because in it particles essentially don't exist until they are observed by a conscious person.

There is another interpretation of quantum mechanics that avoids such anthropomorphic terminology. In this a.n.a.lysis, the field representing a particle is not a probability field, but rather just a function that has different values in different locations. The field, therefore, is fundamentally what the particle is. There are constraints on what the values of the field can be in different locations, because the entire field representing a particle represents only a limited amount of information. That is where the word "quantum" comes from. The so-called collapse of the wave function, this view holds, is not a collapse at all. The wave function actually never goes away. It is just that a measurement device is also made up of particles with fields, and the interaction of the particle field being measured and the particle fields of the measuring device results in a reading of the particle being in a particular location. The field, however, is still present. This is the Western interpretation of quantum mechanics, although it is interesting to note that the more popular view among physicists worldwide is what I have called the Eastern interpretation.

There was one philosopher whose work spanned this East-West divide. The Austrian British thinker Ludwig Wittgenstein (18891951) studied the philosophy of language and knowledge and contemplated the question of what it is that we can really know. He pondered this subject while a soldier in World War I and took notes for what would be his only book published while he was alive, Tractatus Logico-Philosophicus Tractatus Logico-Philosophicus. The work had an unusual structure, and it was only through the efforts of his former instructor, British mathematician and philosopher Bertrand Russell, that it found a publisher in 1921. It became the bible for a major school of philosophy known as logical positivism, which sought to define the limits of science. The book and the movement surrounding it were influential on Turing and the emergence of the theory of computation and linguistics.

Tractatus Logico-Philosophicus antic.i.p.ates the insight that all knowledge is inherently hierarchical. The book itself is arranged in nested and numbered statements. For example, the first four statements in the book are: antic.i.p.ates the insight that all knowledge is inherently hierarchical. The book itself is arranged in nested and numbered statements. For example, the first four statements in the book are: 1 The world is all that is the case.1.1 The world is the totality of facts, not of things.1.11 The world is determined by the facts, and by their being all the facts.1.12 For the totality of facts determines what is the case, and also whatever is not the case.

Another significant statement in the Tractatus Tractatus-and one that Turing would echo-is this: 4.0031 All philosophy is a critique of language.

Essentially both Tractatus Logico-Philosophicus Tractatus Logico-Philosophicus and the logical positivism movement a.s.sert that physical reality exists separate from our perception of it, but that all we can know of that reality is what we perceive with our senses-which can be heightened through our tools-and the logical inferences we can make from these sensory impressions. Essentially Wittgenstein is attempting to describe the methods and goals of science. The final statement in the book is number 7, "What we cannot speak about we must pa.s.s over in silence." The early Wittgenstein, accordingly, considers the discussion of consciousness as circular and tautological and therefore a waste of time. and the logical positivism movement a.s.sert that physical reality exists separate from our perception of it, but that all we can know of that reality is what we perceive with our senses-which can be heightened through our tools-and the logical inferences we can make from these sensory impressions. Essentially Wittgenstein is attempting to describe the methods and goals of science. The final statement in the book is number 7, "What we cannot speak about we must pa.s.s over in silence." The early Wittgenstein, accordingly, considers the discussion of consciousness as circular and tautological and therefore a waste of time.

The later Wittgenstein, however, completely rejected this approach and spent all of his philosophical attention talking about matters that he had earlier argued should be pa.s.sed over in silence. His writings on this revised thinking were collected and published in 1953, two years after his death, in a book called Philosophical Investigations Philosophical Investigations. He criticized his earlier ideas in the Tractatus Tractatus, judging them to be circular and void of meaning, and came to the view that what he had advised that we not speak about was in fact all that was worth reflecting on. These writings heavily influenced the existentialists, making Wittgenstein the only figure in modern philosophy to be a major architect of two leading and contradictory schools of thought in philosophy.

What is it that the later Wittgenstein thought was worth thinking and talking about? It was issues such as beauty and love, which he recognized exist imperfectly as ideas in the minds of men. However, he writes that such concepts do exist in a perfect and idealized realm, similar to the perfect "forms" that Plato wrote about in the Platonic dialogues, another work that illuminated apparently contradictory approaches to the nature of reality.

One thinker whose position I believe is mischaracterized is the French philosopher and mathematician Rene Descartes. His famous "I think, therefore I am" is generally interpreted to extol rational thought, in the sense that "I think, that is I can perform logical thought, therefore I am worthwhile." Descartes is therefore considered the architect of the Western rational perspective.

Reading this statement in the context of his other writings, however, I get a different impression. Descartes was troubled by what is referred to as the "mind-body problem": Namely, how does a conscious mind arise from the physical matter of the brain? From this perspective, it seems he was attempting to push rational skepticism to the breaking point, so in my view what his statement really means is, "I think, that is to say, a subjective experience is occurring, so therefore all we know for sure is that something-call it I I-exists." He could not be certain that the physical world exists, because all we have are our own individual sense impressions of it, which might be wrong or completely illusory. We do know, however, that the experiencer exists.

My religious upbringing was in a Unitarian church, where we studied all of the world's religions. We would spend six months on, say, Buddhism and would go to Buddhist services, read their books, and have discussion groups with their leaders. Then we would switch to another religion, such as Judaism. The overriding theme was "many paths to the truth," along with tolerance and transcendence. This last idea meant that resolving apparent contradictions between traditions does not require deciding that one is right and the other is wrong. The truth can be discovered only by finding an explanation that overrides-transcends-seeming differences, especially for fundamental questions of meaning and purpose.

This is how I resolve the Western-Eastern divide on consciousness and the physical world. In my view, both perspectives have to be true.

On the one hand, it is foolish to deny the physical world. Even if we do live in a simulation, as speculated by Swedish philosopher Nick Bostrom, reality is nonetheless a conceptual level that is real for us. If we accept the existence of the physical world and the evolution that has taken place in it, then we can see that conscious ent.i.ties have evolved from it.

On the other hand, the Eastern perspective-that consciousness is fundamental and represents the only reality that is truly important-is also difficult to deny. Just consider the precious regard we give to conscious persons versus unconscious things. We consider the latter to have no intrinsic value except to the extent that they can influence the subjective experience of conscious persons. Even if we regard consciousness as an emergent property of a complex system, we cannot take the position that it is just another attribute (along with "digestion" and "lactation," to quote John Searle). It represents what is truly important.

The word "spiritual" is often used to denote the things that are of ultimate significance. Many people don't like to use such terminology from spiritual or religious traditions, because it implies sets of beliefs that they may not subscribe to. But if we strip away the mystical complexities of religious traditions and simply respect "spiritual" as implying something of profound meaning to humans, then the concept of consciousness fits the bill. It reflects the ultimate spiritual value. Indeed, "spirit" itself is often used to denote consciousness.

Evolution can then be viewed as a spiritual process in that it creates spiritual beings, that is, ent.i.ties that are conscious. Evolution also moves toward greater complexity, greater knowledge, greater intelligence, greater beauty, greater creativity, and the ability to express more transcendent emotions, such as love. These are all descriptions that people have used for the concept of G.o.d, albeit G.o.d is described as having no limitations in these regards.

People often feel threatened by discussions that imply the possibility that a machine could be conscious, as they view considerations along these lines as a denigration of the spiritual value of conscious persons. But this reaction reflects a misunderstanding of the concept of a machine. Such critics are addressing the issue based on the machines they know today, and as impressive as they are becoming, I agree that contemporary examples of technology are not yet worthy of our respect as conscious beings. My prediction is that they will become indistinguishable from biological humans, whom we do regard as conscious beings, and will therefore share in the spiritual value we ascribe to consciousness. This is not a disparagement of people; rather, it is an elevation of our understanding of (some) future machines. We should probably adopt a different terminology for these ent.i.ties, as they will be a different sort of machine.

Indeed, as we now look inside the brain and decode its mechanisms we discover methods and algorithms that we can not only understand but re-create-"the parts of a mill pus.h.i.+ng on each other," to paraphrase German mathematician and philosopher Gottfried Wilhelm Leibniz (16461716) when he wrote about the brain. Humans already const.i.tute spiritual machines. Moreover, we will merge with the tools we are creating so closely that the distinction between human and machine will blur until the difference disappears. That process is already well under way, even if most of the machines that extend us are not yet inside our bodies and brains.

Free WillA central aspect of consciousness is the ability to look ahead, the capability we call "foresight." It is the ability to plan, and in social terms to outline a scenario of what is likely going to happen, or what might happen, in social interactions that have not yet taken place.... It is a system whereby we improve our chances of doing those things that will represent our own best interests.... I suggest that "free will" is our apparent ability to choose and act upon whichever of those seem most useful or appropriate, and our insistence upon the idea that such choices are our own.-Richard D. Alexander Shall we say that the plant does not know what it is doing merely because it has no eyes, or ears, or brains? If we say that it acts mechanically, and mechanically only, shall we not be forced to admit that sundry other and apparently very deliberate actions are also mechanical? If it seems to us that the plant kills and eats a fly mechanically, may it not seem to the plant that a man must kill and eat a sheep mechanically?-Samuel Butler, 1871 Is the brain, which is notably double in structure, a double organ, "seeming parted, but yet a union in part.i.tion"?-Henry Maudsley8

Redundancy, as we have learned, is a key strategy deployed by the neocortex. But there is another level of redundancy in the brain, in that its left and right hemispheres, while not identical, are largely the same. Just as certain regions of the neocortex normally end up processing certain types of information, the hemispheres also specialize to some extent-for example, the left hemisphere typically is responsible for verbal language. But these a.s.signments can also be rerouted, to the point that we can survive and function somewhat normally with only one half. American neuropsychology researchers Stella de Bode and Susan Curtiss reported on forty-nine children who had undergone a hemispherectomy (removal of half of their brain), an extreme operation that is performed on patients with a life-threatening seizure disorder that exists in only one hemisphere. Some who undergo the procedure are left with deficits, but those deficits are specific and the patients have reasonably normal personalities. Many of them thrive, and it is not apparent to observers that they only have half a brain. De Bode and Curtiss write about left-hemispherectomized children who "develop remarkably good language despite removal of the 'language' hemisphere."9 They describe one such student who completed college, attended graduate school, and scored above average on IQ tests. Studies have shown minimal long-term effects on overall cognition, memory, personality, and sense of humor. They describe one such student who completed college, attended graduate school, and scored above average on IQ tests. Studies have shown minimal long-term effects on overall cognition, memory, personality, and sense of humor.10 In a 2007 study American researchers Shearwood McClelland and Robert Maxwell showed similar long-term positive results in adults. In a 2007 study American researchers Shearwood McClelland and Robert Maxwell showed similar long-term positive results in adults.11 A ten-year-old German girl who was born with only half of her brain has also been reported to be quite normal. She even has almost perfect vision in one eye, whereas hemispherectomy patients lose part of their field of vision right after the operation.12 Scottish researcher Lars Muckli commented, "The brain has amazing plasticity but we were quite astonished to see just how well the single hemisphere of the brain in this girl has adapted to compensate for the missing half." Scottish researcher Lars Muckli commented, "The brain has amazing plasticity but we were quite astonished to see just how well the single hemisphere of the brain in this girl has adapted to compensate for the missing half."

While these observations certainly support the idea of plasticity in the neocortex, their more interesting implication is that we each appear to have two brains, not one, and we can do pretty well with either. If we lose one, we do lose the cortical patterns that are uniquely stored there, but each brain is in itself fairly complete. So does each hemisphere have its own consciousness? There is an argument to be made that such is the case.

Consider split-brain patients, who still have both of their brain hemispheres, but the channel between them has been cut. The corpus callosum is a bundle of about 250 million axons that connects the left and right cerebral hemispheres and enables them to communicate and coordinate with each other. Just as two people can communicate closely with each other and act as a single decision maker while remaining separate and whole individuals, the two brain hemispheres can function as a unit while remaining independent.

As the term implies, in split-brain patients the corpus callosum has been cut or damaged, leaving them effectively with two functional brains without a direct communication link between them. American psychology researcher Michael Gazzaniga (born in 1939) has conducted extensive experiments on what each hemisphere in split-brain patients is thinking.

The left hemisphere in a split-brain patient usually sees the right visual field, and vice versa. Gazzaniga and his colleagues showed a split-brain patient a picture of a chicken claw to the right visual field (which was seen by his left hemisphere) and a snowy scene to the left visual field (which was seen by his right hemisphere). He then showed a collection of pictures so that both hemispheres could see them. He asked the patient to choose one of the pictures that went well with the first picture. The patient's left hand (controlled by his right hemisphere) pointed to a picture of a shovel, whereas his right hand pointed to a picture of a chicken. So far so good-the two hemispheres were acting independently and sensibly. "Why did you choose that?" Gazzaniga asked the patient, who answered verbally (controlled by his left-hemisphere speech center), "The chicken claw obviously goes with the chicken." But then the patient looked down and, noticing his left hand pointing to the shovel, immediately explained this (again with his left-hemisphere-controlled speech center) as "and you need a shovel to clean out the chicken shed."

This is a confabulation. The right hemisphere (which controls the left arm and hand) correctly points to the shovel, but because the left hemisphere (which controls the verbal answer) is unaware of the snow, it confabulates an explanation, yet is not aware that it is confabulating. It is taking responsibility for an action it had never decided on and never took, but thinks that it did.

This implies that each of the two hemispheres in a split-brain patient has its own consciousness. The hemispheres appear not to be aware that their body is effectively controlled by two brains, because they learn to coordinate with each other, and their decisions are sufficiently aligned and consistent that each thinks that the decisions of the other are its own.

Gazzaniga's experiment doesn't prove that a normal individual with a functioning corpus callosum has two conscious half-brains, but it is suggestive of that possibility. While the corpus callosum allows for effective collaboration between the two half-brains, it doesn't necessarily mean that they are not separate minds. Each one could be fooled into thinking it has made all the decisions, because they would all be close enough to what each would have decided on its own, and after all, it does have a lot of influence on each decision (by collaborating with the other hemisphere through the corpus callosum). So to each of the two minds it would seem as if it were in control.

How would you test the conjecture that they are both conscious? One could a.s.sess them for neurological correlates of consciousness, which is precisely what Gazzaniga has done. His experiments show that each hemisphere is acting as an independent brain. Confabulation is not restricted to brain hemispheres; we each do it on a regular basis. Each hemisphere is about as intelligent as a human, so if we believe that a human brain is conscious, then we have to conclude that each hemisphere is independently conscious. We can a.s.sess the neurological correlates and we can conduct our own thought experiments (for example, considering that if two brain hemispheres without a functioning corpus callosum const.i.tute two separate conscious minds, then the same would have to hold true for two hemispheres with a functioning connection between them), but any attempt at a more direct detection of consciousness in each hemisphere confronts us again with the lack of a scientific test for consciousness. But if we do allow that each hemisphere of the brain is conscious, then do we grant that the so-called unconscious activity in the neocortex (which const.i.tutes the vast bulk of its activity) has an independent consciousness too? Or maybe it has more than one? Indeed, Marvin Minsky refers to the brain as a "society of mind."13 In another split-brain experiment the researchers showed the word "bell" to the right brain and "music" to the left brain. The patient was asked what word he saw. The left-hemisphere-controlled speech center says "music." The subject was then shown a group of pictures and asked to point to a picture most closely related to the word he was just shown. His right-hemisphere-controlled arm pointed to the bell. When he was asked why he pointed to the bell, his left-hemisphere-controlled speech center replied, "Well, music, the last time I heard any music was the bells banging outside here." He provided this explanation even though there were other pictures to choose from that were much more closely related to music.

Again, this is a confabulation. The left hemisphere is explaining as if it were its own a decision that it never made and never carried out. It is not doing so to cover up for a friend (that is, its other hemisphere)-it genuinely thinks that the decision was its own.

These reactions and decisions can extend to emotional responses. They asked a teenage split-brain patient-so that both hemispheres heard-"Who is your favorite..." and then fed the word "girlfriend" just to the right hemisphere through the left ear. Gazzaniga reports that the subject blushed and acted embarra.s.sed, an appropriate reaction for a teenager when asked about his girlfriend. But the left-hemisphere-controlled speech center reported that it had not heard any word and asked for clarification: "My favorite what?" When asked again to answer the question, this time in writing, the right-hemisphere-controlled left hand wrote out his girlfriend's name.

Gazzaniga's tests are not thought experiments but actual mind experiments. While they offer an interesting perspective on the issue of consciousness, they speak even more directly to the issue of free will. In each of these cases, one of the hemispheres believes that it has made a decision that it in fact never made. To what extent is that true for the decisions we make every day?

Consider the case of a ten-year-old female epileptic patient. Neurosurgeon Itzhak Fried was performing brain surgery while she was awa