bodies and souls
That anything so remarkable as a state of consciousness comes about as a result of irritating nervous tissue is just as unaccountable as the appearance of the djinn when Aladdin rubbed his lamp.
Thomas Huxley
Science cannot give us the taste of chicken soup. But, when you think about it, wouldn’t it be weird if it did?
Albert Einstein
In 2001, a team at the University of Victoria in Canada was reported to be developing a ‘mind-reading’ device for use by the severely disabled. Their ‘Cyberlink’ headband is designed to detect brain signals from people who are unable to speak. Linked to a voice synthesizer, the hope is that this information can be translated into electronic speech. Quadriplegics such as Professor Stephen Hawking would be spared the laborious task of communicating their thoughts one letter at a time through a computer interface. Should a working model of the Cyberlink be produced, it would change the way we think about the mind–body problem. Part of the reason we find it difficult to see how consciousness emerges from matter is that the mind and our environment seem to occupy two entirely different worlds – one internal, and the other external. What takes place in the external world is a matter of public record, but the thoughts that go on in the internal world are, we think, private and screened off from the gaze of other individuals. If the Cyberlink ever goes on sale, this privacy will have proved to be contingent rather than representing any kind of metaphysical barrier between two worlds. Hearing our thoughts broadcast over a loudspeaker as we think them might even lead us to stop speaking of two worlds at all. But perhaps we would cite a deeper, silent level of thought that the loudspeaker fails to expose. We might suspect that what we heard was not the subject’s real thoughts, but only what he or she wanted us to hear. We would be unable to prove that the subject was not deceiving us. But if everyone who was wired up to the machine reported that it worked perfectly for them, and if we also tried it out ourselves and found their testimony to be supported by our own experience, the correlation would no doubt be good enough to convince us. Such a device may prove impossible to construct, but there is no reason to think so – after all, our lips and vocal chords have no trouble translating brain signals into speech.
None of this would be possible if thoughts were not dependent upon events in the brain and nervous system. One would imagine the Cyberlink to be the world’s first machine for detecting consciousness – an engineer’s solution to the philosophical problem of how to prove the existence of other people’s minds. It would show the problem to be the thickness of the skull and not the opacity of the mind. You can’t hear my thoughts or feel my pain, but neither can you see the floater on my eyeball or feel the pretzel stuck in my throat, and no one would say that these two objects are uniquely accessible from the first-person perspective. However, some philosophers would be unimpressed, because they deny that thoughts consist in certain brain processes alone. The fear (or hope, according to one’s fancy) is that even were we to discover exactly what materials, configurations and processes are required for consciousness, we would still not have answered what the Australian philosopher David Chalmers calls the ‘Hard Problem’: that is, why any of this should result in conscious experiences. The other problems are ‘easy’ by comparison because we know how to go about solving them – it is a matter of doing more neuroscience.
Not only are we unable to say exactly how the brain produces consciousness, but we cannot explain why complicated arrangements of neurons should produce experiences at all. The brain probably does not have a choice in the matter, but our imagination tells us that God would have had. In the seventeenth century, the French philosopher René Descartes argued that he could imagine himself lacking a body and existing as a disembodied mind. This must be possible, he held, because mind and body possessed two distinct essences – thought and extension respectively. Thus they must consist of different substances that, though they are always found together in this world, could be separated if the Almighty chose. This argument for the theory known as ‘dualism’ rests on the supposed indiscernibility of identical entities, a version of ‘Leibniz’s Law’ that states that no ‘two’ objects can in fact be one and the same if there is any property that they do not both possess. Descartes was in no doubt as to which of these two substances he more closely identified with: ‘seeing that I could pretend that I had no body…but that I could not, for all that, pretend that I did not exist.…I thereby concluded that I was a substance, of which the whole essence or nature consists in thinking, and which, in order to exist, needs no place and depends on no material thing.’1 Unfortunately for Descartes, Leibniz’s Law has exceptions, such as the Masked Man fallacy: I may know who my father is, but not know the identity of a man I meet at a masked ball. This disparity does not allow me to conclude that the masked man is not my father. If the man behind the disguise is indeed my father, then it is irrelevant that I may imagine him being someone else. The way we think about an object cannot be regarded as one of its properties in quite the same way as its inherent attributes.
It is common for contemporary philosophers of mind to begin their accounts with a rejection of Descartes, the successor to the rehabilitated Aristotle as the Typhoid Mary of philosophy. David Chalmers, however, believes that Descartes was on to something, but that he approached the problem from the wrong direction. The philosophy of mind is, for most students, a process of overturning their dualist intuitions in favour of one or other form of materialism. Only the most religious survive with their fondest beliefs, if not always with the respect of their peers, intact. Chalmers, by contrast, was a mathematician and physicist by training, who started with a sentimental attachment to materialism yet went on to become the recognized leader of the ‘New Dualist’ school.
Chalmers lives and works in the desert on the fringes of Tucson, Arizona. He suggested we conduct our interview outside, and sat hatless and unblinking during a two-hour conversation. While I cowered behind sunglasses, a cap and a thick layer of Factor 20, his only protection from the midday desert sun was the poodle hairstyle of a heavy-metal guitarist. ‘The crucial thing isn’t the conceivability of mind without body,’ he told me, ‘but the conceivability of body without mind – that all this physical activity could be going on without the mental activity.’ In other words, where Descartes looked for ghosts, we should instead search for zombies. The kind of zombies that worry philosophers are not the green, flesh-eating variety portrayed in horror movies, but creatures that are outwardly just like you and me. They seem healthy and normal, hold down jobs and marriages and conduct cheerful conversations, but unbeknownst to us they are in fact automata. They have no internal lives – no hopes or fears or sensations – even though they may often talk as if they had them. They could even don a Cyberlink headband and the device would produce speech just as if it was worn by a conscious individual. They have all the physical attributes and behaviour of conscious beings, but without the mental qualities. One can certainly imagine a being that possesses brain processes without having an internal life to go with them.
Christof Koch and Francis Crick, who, with James Watson, discovered the structure of DNA, point out that much of human behaviour is already conducted in a zombie-like state.2 ‘Automatic’ activities such as driving or rock-climbing do not usually involve thought even though they did when we were learning them. There is neuronal activity that results in intelligent behaviour that does not involve conscious deliberation. Indeed, there are certain feats, such as playing the piano to virtuoso level, that can usually only be carried out so long as we do not consciously deliberate. This leads to the worry that if we became sufficiently versed in every aspect of our undertakings, our every word and deed would be carried out on autopilot. Consciousness, it would seem, is only there for those things in life that we are not very good at. But one expects that the brain processes involved in conscious and non-conscious/automatic driving or rock-climbing will be slightly different. The philosophical question is whether they must be different, for a true zombie is mindless no matter what his brain processes are like. The answer depends on how seriously we should take our imaginative powers in this instance.
For the philosopher Daniel Dennett, the answer is not very seriously at all. Dennett came to philosophy by reading Descartes as a teenager and, believing the philosopher’s dualism to be mistaken, took it upon himself to show why. Along the way he also discovered talents as a sculptor and jazz pianist that could have given him a career in either field. He is used to success and was for many years driven to distraction by philosophers who refused to see what he regards as sense. Today he seems to accept that he will never change their minds. Perhaps he lost his patience one too many times, as he seems to pity his opponents – and also himself for having expended so much breath in the cause. He chose not to mention these names when I met him. Containing himself, he told me that: ‘It’s very easy for very bright but appropriately insecure thinkers to get seduced into a little set of issues and just be unable or unwilling to step back from this and ask whether, in the larger scheme of things, it is worth doing. I call this “Hebb’s Rule” after the great Canadian psychologist Donald Hebb. He said, “If it’s not worth doing it’s not worth doing well,” and by golly if you live by Hebb’s Rule an awful lot of philosophy wouldn’t get done.’
Dennett sees no mystery in consciousness – just an engineering problem that he hopes will be solved through the application of cognitive science. To his mind:
The hard problem is one of the fascinating bits of sociology in the field. It’s a straightforward fallacy of subtraction. People just aren’t doing their sums correctly. They convince themselves and other people that there’s this extra problem when there just isn’t one. I tell a story about the ‘tuned deck’. Ralph Hull was a well-regarded card magician early in the twentieth century in America who had a trick he did for his fellow magicians, an insiders’ trick. He had people pick a card, listened to the ‘vibrations’ of the deck and then produced the card. He would change the way he did the trick each time to frustrate their guesses as to how he did it. The real trick is in the word ‘The’. They were looking too hard. He made them think there was just one trick, just one theory, and got them to look for it – he fooled them into thinking there was a ‘hard’ problem. Now if you think that consciousness is just a bag of tricks as I have been arguing for years and years – then you don’t explain all the tricks with one big explanation. You have to explain the parts independently, because they’re not all the same. And if you insist that over and above all of that there’s also the ‘hard’ problem, you have to show that there really is such a problem and that the sum of all the smaller problems does not exhaust the issue. So far, the attempts to show the existence of a hard problem have been ludicrous. Yet people just roll over and say, ‘Oh, I’m not even trying to tackle the hard problem.’
Dennett likes to compare the problem of consciousness to the nineteenth-century debate between the vitalists, who believed in a life force that animated living creatures and separated them from the dead and inorganic, and mechanists, who thought the answer lay in complex natural processes.
Imagine the vitalist saying ‘Yes, you’ve solved the “easy” problems of life – the problems of reproduction, repair and growth, metabolism and variety, but you haven’t touched on the “hard” problem, which is: what is life itself?’Well, if you’re a vitalist you still think there’s a hard problem of life, but there isn’t. When I raise this parallel it has two effects: firstly, it causes some believers in the hard problem some consternation. The other effect is to tease out of the closet latter-day vitalists who really want to believe that there is a mystery to life beyond all this darned molecular biology and DNA. They want to be vitalists still. At least I’ve teased them out of the closet.
David Chalmers refuses to accept the comparison with vitalism, saying:
I think there are some pretty serious differences. There are these easy problems about consciousness: explaining all the functional bits associated with the things people say and do. After you’ve explained all those problems there’s a residual problem: why is all this accompanied by consciousness? In the other, smaller areas, it looks like when you explained the functions you explained everything about them. In the case of the problem of life, explaining the functions, explaining the behaviours were always the central problems. But back then, around 200 years ago, people couldn’t see even how to solve the easy problems. How is it that a system of matter could reproduce, adapt and locomote? The mechanists thought that somehow it could; the vitalists thought that it couldn’t. That was a straightforward empirical question. Even the vitalists thought that it was possible in principle – they could imagine it working that way – they just didn’t think that was the way that it worked. When people did the empirical science it turned out that biological systems of the right kind could perform the functions of reproduction, locomotion and the rest. The problem went away and the vitalists just disappeared. What that suggests is that even for the vitalists, the problem was one of explaining structure and objective function all along. The easier problems of life were the only problems. What happens in the case of consciousness is that there are two different kinds of problem: there’s the problem of explaining the functions, and the problem of explaining why this is accompanied by consciousness.
I suggested that water and H2O might be a more appropriate analogy than life and matter. We might think that we can imagine water having a different molecular make-up to H2O, but chemical physicists tell us that no other configuration would work in quite the same way to deliver all the precise properties of ordinary water. Even ‘heavy’ water (D2O), in which the two oxygen atoms are replaced by deuterium, does not share all the macroscopic properties of ordinary water (it is around 10 per cent heavier than H2O). Professor Chalmers thought this was no better:
In every other domain besides consciousness we get some kind of reductive explanation, and we have this wonderful chain of explanation from physics to chemistry to biology to psychology, eventually to economics, and so on. One level seems to be in principle capable of explaining what is at the next level without residue. You find that with H2O and water. But there are the physical and the perceived aspects of liquidity, the same with heat and light. The physics doesn’t exactly explain these because those are ultimately properties of consciousness, and we cannot explain why consciousness is the way it is. The fluid mechanics of water can be given a full explanation with a micro-chemical story, but we still can’t explain why heat or wetness feel the way they do.
The view that elements of mind must be beyond the reach of science, as if consciousness requires a new physics, has a brief but notorious history. Frank Jackson – another Australian philosopher – imagined the story of ‘Mary the neuroscientist’.3 Mary is an expert on colour perception. She knows everything the sciences could ever tell us about what goes on inside someone’s brain and nervous system when they experience colours. However, Mary conducts her research from a lifelong prison cell – a black-and-white room, with a black-and-white television, and a computer with a monochrome monitor. She has never once seen a coloured object. According to the story, no matter how much she understands of the physics and neurochemistry of colour, there is something she does not understand about redness until she steps out of the room and sees a rose with her own eyes for the first time. There is thus something about conscious perceptual experience that cannot be captured in the third-person language of the sciences. Philosophers call these entitities ‘qualia’. Dennett himself describes qualia as ‘the souls of experiences’ – and dismisses them as he does the supposed souls of human beings. He deems Mary the colour scientist:
A classic provoker of Philosophers’ Syndrome: mistaking a failure of imagination for an insight into necessity. What happens is that the thought experiment begs the question. For if Mary could already understand everything about colour, and if materialism-reductionism is true and higher order properties can be read off from lower level ones – then she will indeed know about the subjective experiences attaching to redness. Asserting that she will in fact be surprised is asserting nothing more nor less than that materialism-reductionism is not in fact true, that higher-level properties cannot be so read off.
Chalmers argues that consciousness is a special case, an exception to the reductionism that has been so successful in the sciences, and his intuition demands respect due to his extensive knowledge of materialist neuroscience. The enthusiasm of some ‘new dualists’ is less because they are unconvinced by recent progress in the cognitive sciences than because they simply do not like that progress. This could not be said of their standard bearer, Chalmers, who agrees that we already know how some facets of thinking work and what brain states they correlate with, yet maintains that even in these limited areas of progress we have no idea why they should be so correlated. Dennett does not find this surprising:
Our uneasy relationship with scientific advances goes back to Copernicus – it still seems that the sun moves, after all. We’ve learned, however, not to credit that seeming. But there’s a sense in which we don’t have our heart in this, even though it’s so exposed. There are other hunches that are like that. One is the ‘zombic hunch’: that when you’ve exposed consciousness from the thirdperson point of view there’s this left-over problem – the problem of zombies. When you look at the definitions people have offered they’re ridiculous. The idea that zombies are possible is a ludicrously bad idea, but people can’t get rid of it. They can’t jettison the idea even though they know that there aren’t any good arguments for it. I can feel the zombie hunch as well as anyone, I’ve just learned not to credit that urge and regard it as something to be resisted with a grin whenever you feel the urge to assert it. David admits that he has no arguments for his decision that zombies are possible, that it’s just a brute difference between the two of us. I say to him that if you admit that arguments don’t play a role here, then can I suggest therapy? If he has a problem that reason won’t touch, then maybe a pill or exercises will help. You try argument, you try humour, you try scaring them or joking them out of it, then you just say, well, my heart goes out to you. What else can you do?
Putting on a silly voice, Dennett added: ‘We should be more ready to entertain the notion that some of our deepest convictions are just these things that get stuck in our heads and can’t be easily dislodged. You certainly aren’t going to base a science on the fact that you have this kink in your head.’
In fact, something along these lines is exactly what Chalmers would like, for he believes that the solution of the problem of consciousness requires a new leap of thought. As he said:
My own view is that you have to understand consciousness as something irreducible in the same way that a physicist takes space as irreducible – that is, you still understand space, but you don’t explain it in terms of anything more basic than itself. No one would say ‘We don’t understand space, we don’t understand time.’We take them as irreducible, but we still have theories of them. The way the science of consciousness has to proceed is more or less the same way: to admit it as an irreducible entity and then start building theories of it.
I suggested in objection that space is a building block – in that you do not need to have anything beforehand in order to have it, whereas consciousness can hardly be a building block if it requires complicated brains and nervous systems.
Chalmers replied that it was far from clear that such apparatus is essential. He assured me:
We don’t know where consciousness is. There’s this famous problem of other minds – I can’t look inside your mind and see whether you are conscious. I can’t look inside a dog’s mind and see whether it’s conscious. I can’t look inside a fly’s mind and see whether it’s conscious. I do surveys of my students from time to time – most of them are pretty confident that dogs are conscious. With mice it’s still the majority, and with flies it’s around 50:50. Its not out of the question that consciousness runs pretty deep in the natural order. I’m agnostic on this, but I don’t rule out the fact that consciousness is grounded in a pretty fundamental level of physical reality in the way that space is. There could be some kind of common building block, so to speak, in physics and consciousness. One idea which Bertrand Russell was fond of is that the intrinsic nature of physics itself is not revealed to us – it’s only revealed to us from the outside as a network of relations: for example, one particle causes this other particle, mass is a thing that resists acceleration in various ways, and so on. However, the intrinsic nature of the physical world is up for grabs. Russell was attracted to the idea that this intrinsic nature might itself have something very deep to do with consciousness. I mean, what’s the fundamental, intrinsic nature of an electron or proton? Maybe there’s consciousness right down to that level. We know from physics that electrons can be in one position or another, or can have one kind of mass or another but, on this hypothesis, they have very specific intrinsic natures which are not revealed to us from the way they appear from the outside. Everything has an inside and an outside, an intrinsic and extrinsic nature. On this hypothesis, the intrinsic nature has something to do with consciousness. Things have to have some kind of intrinsic nature, and maybe it’s something like this. And then in the right kind of configuration, it gives rise to consciousness. Russell’s idea was that maybe something about the intrinsic properties of particles inside our own brains in this kind of configuration is what gives you consciousness. It’s not a theory, it’s just a template or framework for a theory, of thinking about consciousness or proto-consciousness as irreducible there at the bottom level of the natural order, and then the question is, how do you get from there to the kind of familiar features of consciousness that we know and love?
This was sounding like the view known as ‘panpsychism’, according to which mind is a fundamental feature of the universe. To the panpsychist, every tree, every pebble, every speck of dust has a mental aspect, an internal life, however simple and uneventful. Chalmers prefers to describe his position as ‘panprotopsychism’. The difference between the two, he says, is that:
Under panpsychism, everything is conscious down to the subatomic level – there is something that it feels like to be an electron or a proton. I don’t want to say that’s completely crazy, though it’s certainly weird and counter-intuitive. But the other possibility is a property that while not intrinsically consciousness, collectively constitutes consciousness in the right kind of system. It might stand to consciousness as proto-life stands to life or as basic physical processes stand to life. The question is what that would be like, and the answer is that no one has any idea. One way to think about it is that you have complex consciousness of colour, and then you can bring it down to hue and saturation, which aren’t directly experienced but are components of an experience. You can break down experiences further and further into basic components until you get to a level that is under the surface of consciousness – not directly experienced in our consciousness except as a large collection. It may be possible for these things to be considered individually at the bottom of the natural order in a way in which we would not say they correspond to anything in consciousness. They would correspond instead to something like protoconsciousness.
Chalmers finds panpsychism so attractive because it bridges the perceived conceptual gap between the character of brain processes and that of the conscious experiences with which they are supposed to correlate. It changes the problem from one of explaining how consciousness arises from non-conscious constituents to that of how one form of consciousness arises from another. Chalmers also describes it as a ‘strangely beautiful’ picture of the world. Unfortunately, it is also a picture so far removed from what we understand of physics and biology that it is almost pure fantasy. That panpsychism has become the last redoubt of the dualist shows that this hounded species has been forced to occupy the most hostile, unforgiving niches of today’s intellectual environment. At least we now know what the options are regarding consciousness: either it is derivable from lower-order quantities, or it goes ‘all the way down’ and is a basic property of matter.
Any difficulty in reconciling mind and matter should not push us towards the panpsychist solution, for the experience of puzzlement is not limited to our encounters with brains. Some of us feel puzzled when we look inside a hi-fi or under the hood of a car. I cannot understand how these objects work because I do not know enough about their technology. But if I completed a diploma in mechanics or sound engineering I hope that I would know very well how a car runs or a hi-fi produces music. Given current science’s limited understanding of the brain, it can be difficult to see how a lump of organic tissue can give rise to the wonder of conscious experience. Brains are quiet objects unadorned with flashing lights or crackles of blue electricity running across their surfaces. However, it cannot be too difficult, as the materialist view of the mind has been accepted so widely that the debate between dualism and materialism is conducted only on the fringes of philosophy today. It may not seem this way when viewing the media, because they need to present two sides to every story in order to have a debate at all. When we listen to a radio programme in which 50 per cent of the airtime is given to someone who defends terrorism, we don’t know how difficult it was for the programme’s researchers to find this spokesperson. Mainstream opinion on mind and matter is better represented by the reviewers of Francis Crick’s book on how the brain creates the mind. Critics took issue with the great biologist’s choice of title. The problem with The Astonishing Hypothesis, they argued, was that there was nothing astonishing about it.