Transcript for Guilio Tononi uncut

Steve Paulson: Speaking with Giulio Tononi whose new book is Phi: A Voyage from the Brain to the Soul. Why are you interested in trying to understand the nature of consciousness?

Giulio Tononi: Well it started a long time ago. I would say during the time in which all of us try to deal with the big questions and then usually abandon them because they are too difficult. And the number one question at the time was what should one do with one's life? Which I'm sure every adolescent has asked himself or herself, and so did I and so have many, many people before me and after me I'm sure. And it occurred to me in investigating what one should do with one's life, which, of course, has to do also with the overall meaning of life and what is around us, and in issues above all of value and ethics, that there was a conundrum. There was the world knot, as Schopenhauer called it, which is what is the place of consciousness in the universe? And without a better understanding of that, even questions of value and ethics would be very difficult to tackle. So provisionally, let's put it like that. It would be important to try and understand what conscience was, what was its place in the world.

Paulson: Did you actually think about these things when you were a teenager? I mean, sort of, wondering what the nature of consciousness is?

Tononi: Well I did know I wondered too much about the nature of consciousness early on. I was wondering more about what one should do with one's life, and what was our place in the universe. And around that time, yes, I came to the conclusion that conscience was central in all of this, and I haven't changed my mind on that.

Paulson: What is consciousness?

Tononi: One way to address it, which I have to do when I give a lecture, say, is to start with a very simple notion of what it is, which is what goes away when you're falling to cream asleep or when, you know, when you become anesthetized or somebody kicks you in the head. So we know what goes away then. Everything goes away. The world goes away with all of shapes, and colors, and sounds, and fury, if you wish. Our selves go away. We are not there anymore. Our friends are not there anymore. Nothing is there anymore, and then it comes back hopefully, when we wake up in the morning or even when we dream. So that definition tells you right away that consciousness is really, I like to say, all we have and all we are. Without consciousness, as far as I'm concerned, there would be nothing at all.

Paulson: But there is all world out there. I mean, even if there weren't human beings, there's a world full of material objects. You're saying that stuff isn't real?

Tononi: No, I'm saying that stuff of course is real, in this sense, I'm the realist, like, most sane people around here. There is a real world and we know it, and we try and control it, and we try and understand it better. And science of course is doing that, but I would venture to say that while that world is real, consciousness is the only thing that's really real, and I'll be happy to explain a little bit more about what that is.

Paulson: Sure, go ahead right now.

Tononi: So, I just said that when we fall into dreamless sleep, the universe as far as we're concerned disappears. And you know people have often asked the classic question, what is the sound that a tree makes when it falls in the forest if nobody is around? So we all sort of imagine that the world is a place where there are galaxies and stars and, in fact, many, many of them, but we also suspect that it's a little bit of a cold and perhaps dark place, not to mention empty place. But we think so, I believe, certainly after Galileo, in a way that of course recognizes the enormity of the universe and the extraordinary smallness of each of us, and certainly even of the human race in this gigantic universe, which is perhaps inhospitable, perhaps meaningless. I think this view is largely incorrect, and that perhaps is very closely tied to understanding that without consciousness this world may be really there, but, as I said, it is not really real without there being a conscious entity like one of us, and I'm sure also animals to some extent. That world wouldn't exist, for anybody, and it wouldn't exist for itself either. It wouldn't exist, you know, in and of itself. While whenever there is consciousness there is something that exists in and of itself.

Paulson: Is it another way of saying this that without consciousness there's no meaning. Once consciousness enters the picture, all the stuff that's in the universe has some meaning.

Tononi: Certainly without conscience there would be no meeting, but it's more than that. Without consciousness there really wouldn't be anything at all.

Paulson: But there still are galaxies and stars and here on earth, mountains and trees and all of that.

Tononi: Well would they really be there in and of themselves? What is it like to be a galaxy? That's one good question to put to yourself. Our philosopher, Thomas Nagel has actually, and perhaps may have given a definition of conscience, which I very much subscribe to, which many people have adopted, which is, what is it like to be something? And one thing I've sort of learned to do or forced myself to do whenever, for instance, as a scientist, but just also as a human being, I encounter complicated things or grand things like the universe, the galaxies, the mountains, the oceans, the sky, whatever, when I encounter them I can ask myself, it's almost a reflex now, what would it be like to be that thing? What is it like to be the Moon? Or the sun? Or a mountain? And the answer as far as I can tell, and certainly on the basis of the work that we've been doing, is nothing at all, or hardly anything at all. So there would be such a thing, yes, if there are observers like us who discuss it, measure it, and climb it for a mountain. But there is nothing it is like to be a mountain, and that is a fundamental distinction about what's actually out there, what I call the merely real and the really real, what is illuminated by the light of consciousness and what is not. It makes all the difference.

Paulson: To return then to the philosopher Thomas Nagel who wrote that famous essay, "What is it like to be a Bat?" then trying to imagine being a bat is actually profoundly mysterious.

Tononi: It is, and of course Nagel, to some extent implied that science would never be able to give us the answer, whether the bat is conscious and even less so of what. I think that is wrong too, and one way to look into that, I have sort of exploited, at least in my thinking, from early on, is to contrast two big pieces of our brain. The cerebral cortex, let's call it the cerebrum, and the cerebellum. I think it's a very good way to look into the paradoxes that consciousness poses and perhaps even to get a glimpse of understanding about how one might solve this. So let me elaborate a little bit on that. The cerebellum is, you know, in the back of your brain. It's a rather old structure. It's very beautiful. It's very complicated looking, and it has actually more nerve cells than the cortex does. It has probably around 50 billion nerve cells. It has probably as many connections. It has all kinds of neurotransmitters, neuro-modulators. It has maps of the external world, visual, auditory, vestibular, you name it. And it can definitely control the outputs, including motor outputs from the brain. So it is, indeed, you know it's called the small brain because size-wise, it's a little bit smaller than the rest of the brain, but, nevertheless, it is certainly as complicated by most measures that one might think of, in terms of what is it to be complex. The cerebellum cannot only control our movements, not only deal with inputs it gets from all sensory modalities, but also it's in constant dialogue with cortex itself. Yet this is a very established fact, if you take out the cerebellum even all of it, what will happen is that your consciousness would remain essentially intact. You will be the same person. You will have the same thoughts. You will see the same things. You will hear the same things, have the same feelings, ambitions, desires, and so on and so forth.

Paulson: We may not be able to walk across the room, but we could still think.

Tononi: Yeah, I mean, you will be able to walk across the room, but not very well. You're sort of like drunk, but could not only think, you will have your experiences very much like now. So there is in a way a big mystery and a big paradox. What is so special about the rest of the cortex, you know the brain and the cortex or at least some parts of it, that give rise to all you are and all there is for you. The cerebellum is sort of lacking this. While it is certainly a very, very sophisticated piece of neurobiology. But I think about that, and when you move to the cortex itself, you actually see that many parts within the cortex are also a little bit like the cerebellum, so there are many things going on in our cerebral cortex and in the connected brain regions like the basal ganglia and perhaps even the thalamus in which nerve cells are firing all the time. They are doing very complicated things. They are essential for doing things such as parsing language and sounds, and then controlling motor output, so that you can actually understand speech and produce speech. But may have nothing to do with what you're conscious of. So all this buzzing along of neurons seems to be somehow devoid of this very special thing, which is experience or subjectivity, and yet these are also complicated. These do sophisticated things. They perform interesting functions, but no consciousness associated with them. Obviously, though, some other parts of the cortex, and we don't still don't understand very well which ones, and not even which layer in the cortex--there are six layers, maybe some layers are more important than others--when they are in working order they generate who you are and all your experience. So there is clearly a fundamental fact of science there supported by a very large number of experiments, at this point, that say, of nerve cells that are very much like each other that do complicated things and fly along, some are arranged in such a way that it can give rise to experience, to consciousness, and most are not. Or if they do, it's so minimal that nobody even cares. There's nobody there from that.

Paulson: So the question is why? Why are some nerve cells crucial to consciousness and others not?

Tononi: Yes, and one of the principles organizationally, in one case, allow consciousness to emerge. In the other case, they don't. So much of the work we did over the past, decade at this point, I would say is trying to identify those principles. And, in fact, it's important in my mind to begin from phenomenology, that is what consciousness is like, and then go back to these facts about the brain to understand what is crucial for consciousness.

Paulson: The actual experience of consciousness.

Tononi: Yes, because if you just look at it from the outside, you wouldn't be able to tell. Let me just mention the obvious here. If you are a neuroscientist and you look at the brain as a very complicated machine, which it is, and you studied its anatomy and its physiology, so how things are connected to each other, how they're made, and then how they work together, you know, who fires when and what they do when they fire together, you know, it is indeed perhaps the most complicated machine we know. But you might as well continue studying, just as we are doing now and with great success, to understand exactly how it performs this or that function. In the cerebellum it might ask how was it able to do error correction when we perform a movement. And why? We don't really know the answer very well. We have some good ideas about what might be going on, and for the cortex we can certainly ask how can we find out whether an image is in 3-D or in 2-D and what neuro-circuits are able to figure that out. How do we parse language and sounds? And then how do we string together the right kind of sounds to produce language. All these things, difficult as they are, are being studied. The neuroscientist, studying this from the outside, is making progress, but if we didn't know about our own consciousness, well we would have no idea. We would have not even a reason to think that behind the cerebellum there is nobody at all. There is nobody home there. And behind some parts of the cortex instead there is a feeling and experiencing human being. It would simply not be in the thing itself.

Paulson: Because the mystery is that the brain, what you've just been talking about, what neuroscientists study, is made up of stuff, of matter, and the mind, this mental experience, consciousness, is immaterial. Is not, apparently, made of anything.

Tononi: Yeah, and more than that, I would say that if you take it from the outside, you know, you can describe circuits that are more or less complicated, arranged in this or that way, perform this and that function, but you have no indication or inkling of the notion that in some cases there is somebody there. In some cases there isn't. So you must start from consciousness itself, and you must ask yourself, so the only thing I'm really sure about, and the cards say this very clearly a long time ago, is that I am conscious. So there is an experiencing being that is me. That is certainly really real. You cannot deny that. It's sort of an axiom, as they call it the zeroeth axiom of consciousness. Consciousness exists, of that we are sure. Almost everything else is sort of a conjecture, or a postulate. Now, in addition to that, there are a few things of our experience that are obviously true. One is, and is typically not remarked upon perhaps because it's taken for granted, that every experience is what it is by its virtue of differing in its own particular way from a huge number of other possible experiences. So I often use the example of being in a completely dark room. So you wake up in a hotel room in a city you don't know, and, for a moment, all you have is sort of a pure experience of darkness and silence. Now that is a conscious experience. You obviously have that, and the question is what makes that experience what it is? So we take it for granted. We think it's just dark and silent, a very very simple state to be in, but I insist that to be what it is, to be experienced as that particular experience, which is rather peculiar and unusual if you think about it, it must be distinguished. There must be some mechanism that distinguishes it from trillion and trillions of other possible experiences which are not that. They're not pure darkness and silence because of some very, very specific features that each of them has. So if the moment we recognize that, we say every experience is extraordinarily specific because it is what it is in that it differs so very specially from every other experience. We recognize one key feature which one might call perhaps, for lack of a better term, information, meaning that it is one out of many. And being one out of many, being that one, it generates, if you wish, a large amount of information.

Paulson: So the question is for that unique experience, that's unlike every other conscious experience, are there specific neural correlates? Can you pinpoint a specific thing, I mean I know we can't do this now, but theoretically, could we find the very specific thing that's happening in the brain that produces that conscious experience?

Tononi: Yes, you can do that, and, in fact, scientists have been doing this more and more successfully. In many ways, Crick and Koch very explicitly said we should look for the neural correlates of consciousness. Many scientists have started doing just that, and I think we have learned a lot. But the neural correlates is not enough. We need to understand what consciousness is because otherwise, you know, you find neural correlates, for instance, in your brain and my brain, hopefully they're not that different from when you're conscious and when you're not, but then if you move to a newborn baby or you move to an animal who has a brain very different from ours, not to mention one day to a machine, how would we know if there if there is consciousness if you just have some neural correlates in a  human being?

Paulson: So the scientists could conceivably find the correlation, at least talking with humans. You know, "so what are you experiencing?" and then you can match that with brain imaging, but the whole question of causation, that's more mysterious, isn't it?

Tononi: Well, more than that, I think it's an issue of theory that is needed in addition to experiments. We need to be experiments, and we have already so many experiments. If you think about it, the one I started with, the cortex versus the cerebellum is a big experiment that we now know the answer to. One is generating consciousness, at least some part of it, the other one is not. And there are many other experiments. One key one is, for instance, if you compare the cortex when it is awake and when it is in deep sleep, which is what I initially started with by saying it's when you lose consciousness early on in deep sleep. When you compare that, it's the same cortex. It's the same neurons. They are firing essentially just as much when you are deep asleep and when you are awake, and yet you vanish. Consciousness vanishes. That's another experiment, which we have known for a long time, and we better try and understand, not only that consciousness changes when some particular aspect of neural firing changes between waking and sleep, but also why. And this is why we need not only experiments, but also a theory. And I worked for a long time to try and develop a theory that can explain, based on a few basic postulates, many of the findings that we already know are true about consciousness.

Paulson: And in this theory you've dubbed the "integrated theory" of consciousness. So, in a nutshell, what is this?

Tononi: Yeah, the integrated information theory. Let me just continue for a moment then with phenomenology, with where we were starting from. I said every experience is what it is by virtue of differing in its particular way from many, many other experiences. This is the information part. But as people have accurately recognized, especially philosophers, every experience is also unified, or integrated. So when you have an experience, like the one you're having now looking at me and talking to me, this experience is one. It's made, you may think, of many pieces. You know, you see shapes and you hair, and face, and shirt, and all kind of other things, and you hear sounds on top of that, but the experience is what it is as a single entity. If you were to divide it in two, let's say, try to experience the right side of what you're seeing with the left, or the left without the right, or the color without the shape, and so on and so forth, you couldn't even do that. So every experience is a single integrated entity, which of course has parts in it, but, as such, it is what it is by being one. And that's the integration part. So we have the information. You have repertoire from the experiences and each of them is a single entity, is a single integrated experience. So information and integration. This is all coming from just looking at what your experience is like without even doing an experiment. Now, the next thing we can do is say, what kind of mechanism can I put together to generate a system that has both a large amount of information, so a huge repertoire of states, so to speak, and yet it is a single entity. And this is beginning of a theory in which you can ask yourself, all right, what are the necessary ingredients to generate a system which is both highly informative, it has this huge repertoire so that when it enters a particular state it rules out all the others, and that state differs in that particular way from the others, and yet it is integrated. This and entity cannot be decomposed into independent pieces. It's just one. After you think this, and you postulate that this may be necessary in order to generate consciousness, you can actually develop a way of measuring this. We have the concept, and you can try to make it into a mathematical construct and then progress along that route. One big important aspect of a theory is then, first you mathematize reality. You say, "These are the two key features. How can I express them mathematically?" Then, based on a few ingredients, in principle, you can go back and try to explain, on the basis of the same few principles, many, many different empirical observations. You want to explain why the cortex and not the cerebellum. Why a certain area of the cortex and not others. Why, when you're awake, there is consciousness, and the same circuit buzzing along when you're in deep sleep somehow failed to generate it. You can ask yourself, why is it that all that activity in my brain that is involved right now in parsing language and producing what I'm saying is somehow not becoming conscious. I'm only conscious, so to speak, of the results of all that. I hear your words and I hear my words and I say somehow, hopefully, the right things, but all of that, you know, complicated computation that gives rise to that is not conscious. So all these questions are very basic questions. We have a lot of data on these, and a good theory needs to be able to explain many of these data together.

Paulson: So you're saying that consciousness ultimately is information? Information organized in a particular way?

Tononi: Well I say that consciousness is integrated information, not so much information. And I'd rather say that each experience is an integrated information structure, which would be a little bit harder to explain. But my metaphor, which may be helpful, is I call it a shape in qualia space. It's like a giant constellation of points, rather than stars, more or less bright, and together they configure this extraordinary shape, and it's really extraordinary because so far we have been playing with very simple models and if they are properly structured they can give rise to some of these integrated information structures, but they are trivial small things compared to what some parts of our brain can do. It's actually impossible right now to imagine how extraordinary this shape is that some parts of our brain can construct. Now, this entity is made with integrated information. It's literally a shape made with integrated information, and one of the key things, to go back to what I was saying before is, when I now look at a human in front of me, like you, and if I were to study you as an anatomist and a physiologist, and I work to go through and say, "This is the liver, and that's roughly how it works. We understand that this is the kidney and this is the heart, and this is the brain. That's a bit more complicated." Within the brain I would find the circuits in the spinal cord, and then in the cerebellum, and then in the cortex, and some other circuits in the cortex, and as I was saying before, I would want to ask myself, "What is it like to be a cerebellum?" "What is it like to be these circuits in the cortex?" and "What's it like to be these other circuits in the cortex?" and "What is it like to be the circuits in the cortex when we are in a waking mode and when we are in deep sleep mode?" And a good theory must be able to tell me that under these different circumstances, when we are a certain circuit in the cortex in the waking mode there is an integrated information structure that is being generated, and when we are that very same circuit, but in deep sleep or anesthesia or when we are equally complicated circuits, in the cerebellum there is nothing like that--nothing is being generated--the extraordinary shape that's there in one case is not there in the other. So I try to look at you, we like to call it with a qualiascope, qualia being experience itself, as opposed to the usual microscopes or brain scanning devices, where we see which neurons are active when, and if I could do that, I would imagine, assuming that the theory is going in the right direction, that, you know, most of you would be sort of rather uninteresting--a little bit of dust--and so would be your extraordinarily complicated cerebellum and your spinal cord and many, many circuits in your cortex. I would just see dust. I basically wouldn't be able to focus my qualiascope. Then, at some point, in the middle of it all there would be this fantastic shape. This extraordinary integrated information structure, and the moment I focus it, I would see what is really there, and that is, in fact, what exists in and of itself. It's your experience, which is a shape made of integrated information. Now think, I mean that's what I try to do, think of taking your qualiascope and beginning to look around. You would, I imagine, and I have a good feeling for this that this is indeed the case, that when I look at other human beings, you know, one of their bodies would dissolve into essentially dust. Some parts of their brain would give rise to these fantastic constellations, and so for every human being, and so probably for many animals, although those constellations may be less elaborate than ours. And only when they're awake and then when they are in deep sleep, and maybe it comes back when they are dreaming, and so on and so forth. And then we point the qualiascope towards the woods, and the cities, and the oceans, and the mountains, and finally the sky. My suspicion would be that most of that would be very empty except for these extraordinary stars or, better, constellations, which are conscious human beings. So this is what I'm saying when I was pointing out that maybe the view of the universe that we have grown accustomed to, according to which there's the giant empty space with some gigantic structures like the galaxies and so on, and we are just a speck in this meaningless universe, and people encourage us to be objective. Many scientists do that and just accept the evidence and realize our own insignificance. I would say they're maybe looking at the universe with just one particular instrument, which has been very successful, or the microscope, or the scanner, but another instrument, we don't really have it yet but we're trying to build something like that, for which we'd look at something just as fundamental as mass, energy, and charge. And those are the structures made from integrated information, and with that instrument the universe looks very different. I would bet it looks extraordinarily different, and I am actually saying that with that instrument, with the qualiascope, what we’re looking at is what's really real, as opposed to what's merely real because those structures exist in and of themselves. They don't need an observer to exist.

Paulson: It sounds like you're saying that consciousness is something fundamentally different from what we would ordinarily associate with the laws of nature, whether it's biology or even physics. I mean, I think there's this sort of common assumption that everything on the world can ultimately be reduced to physics. If not atoms, at least the laws of physics. It sounds like you're saying consciousness is something different than that.

Tononi: It's something different, but it doesn't mean that it doesn't, you know, the neurons, for instance, are not necessary for consciousness. Consciousness does require mechanisms. Without those mechanisms arranged in a particular way, consciousness would not be there, and we know this all too well. I am, after all, a psychologist and a doctor, you know, if you spend some time in the ward you know how much even just a small insult to some parts of the brain can radically change your conscience. Even the experiment I started with at the beginning, which is falling asleep, something changes in the way your brain works, not even that they shut off the neurons, and you disappear. So obviously the neurons are necessary, but that is not simply that. We're not just a bag of neurons. Consciousness is a fundamental ingredient of reality, as fundamental if not more than mass, charge, and energy, and we better recognize that. We all know it in a way because that's all we are. That's all we care about, but we have learned, because of the objectifying stance of science, to think that all there is things you can describe in terms of molecules interacting with each other. Francis Crick, I think, who studied conscience for a very, very long time, and made as much progress as anybody in trying to address it scientifically and suggested to many other people to do the same, and Christof Koch along the way. I have always emphasized the reductionist aspect for understanding consciousness, which is fine because we need to be able to study the brain in terms of what the neurons do.

Paulson: Pinpointing what's happening in the brain.

Tononi: Absolutely. You know, that we needed to do that and without that we wouldn't understand much. You know, in his astonishing hypothesis, he said very explicitly, but in away the reductionist credo is, which is something like you, your joys and your sorrows, your memories and your ambitions, your sense of identity and free will, are nothing but the behavior of a vast ensemble of neurocells. He ended up by saying like Alice in Wonderland, that you're just a pack of neurons. Nothing but a pack of neurons. I could not disagree more with that. So while conscience requires neurons, it definitely does not reduce them. In fact, now this is a little bit technical, but an integrative information structure, which is in the end what experience is, is not made of neurons. It's made of integrated information. It requires neurons to exist, but it's not made of them. Perhaps intrinsically, it has defined them mathematically as the most irreducible thing there is. Consciousness is really, according to this integrated information theory is the most irreducible thing there is where the irreducibility is precisely measured mathematically. So there's nothing mysterious or ghostly about it. We can actually determine when something is giving rise to a structure, an integrated information structure, which is maximally irreducible. That's what consciousness is.

Paulson: It's fascinating to hear about it as you describe your theory of consciousness. Is the place of sleep in your understanding of consciousness, and I know that's one of your particular areas of expertise is what happens when we sleep, are you saying that understanding the nature of sleep is fundamental to understanding what consciousness is all about?

Tononi: I think it's the simplest experiment we all are familiar with, which tells us that consciousness can go away and come back. In fact, sometimes I wonder, if it weren't for sleep, if we didn't have sort of the suspension of consciousness every night, would we even worry or wonder about what consciousness is in the mind-body problem. Sleep reminds us of that every night, but it also reminds us of something else, which is to me the second fundamental result that sleep brings to the study of consciousness and perhaps more than the study of consciousness. It tells us that when we dream, we can create a whole world of experience, which at time, as we all know, can be indistinguishable from the real world and have hard time telling it apart, without being actually connected with the world itself. We are disconnected on the input side and on the output side, and we makeup this fantasy world in our minds. So the brain, by itself, can do that. That's another key result, just by looking at what happens when you fall asleep.

Paulson: It's almost as if every time we go to bed at night, every time we dream, this is one of the great experiments in consciousness.

Tononi: To me it's the greatest experiment you could ever do, and we all do it every night, and animals, by the way, do it too, but at least we can reason about that. And going to sleep is not the only way to get out of consciousness, of course. It is a reasonably good starting point, which is why I actually decided to start studying sleep. Because I thought at least, in addition to being an extraordinarily interesting problem in itself, you know we still need to understand why we need to sleep, it is a way in with consciousness. Indeed, some experiments that we tried to perform when we're awake versus when we are in deep sleep and consciousness vanishes has allowed us to put to the test some aspects, some predictions of the integrated information theory. So is it really true then that when you are awake your brain is capable of generating this integrated information structure. We can't really measure this extraordinary shape. No way. We are not even remotely close to that but we can ask "Are the conditions sort of right?" “Can the cortex give rise to some activity that indicates a single entity something that cannot be partitioned into independent parts and yet a large repertoire of states?" and vice versa. When we lose consciousness be it deep sleep or anesthesia or coma for that matter is it perhaps the case that this ability to integrate information this large repertoire available to a single entity shatters into small pieces so the integration is lost or the information is lost. The experiments that were performed using primarily trans-cranium magnetic stimulation which is a way to inject a current in your brain without having to go inside and recording how your brain reacts to this perturbation have aptly indicated that consistent with the overall prediction of the theory that's exactly what changes between when you are fully conscious and when you suddenly are not even though your brain remains active.

Paulson: Your book is called Phi and the subtitle is "A Voyage from the Brain to the Soul." Where does the soul fit into all of this? Is that a word that has any meaning to scientist like yourself?

Tononi: I think that most people have a very clear meaning associated with the word “soul and there is one meaning in which soul is really synonymous with consciousness and so it was a very long time ago. For instance for the Greeks. There is also another sense in which soul becomes a loaded term in which it's assumed that there is something that may actually escape the body and the brain after death and so it can survive on its own. So different people have different usages for that and different connotations but the very basic thing I believe is agreed upon by everybody. That is you don't have a soul if you don't have consciousness.

Paulson: Is it even using that word “soul”? Or is this an attempt to co-opt certain religious vocabulary and bring it into the modern world of science?

Tononi: Well it's not so much an attempt to co-opt it but it is actually to at least indicate that what we cherish most about the soul which is really the fact that we are conscious. We are thinking beings. We have free will at least most people think they do when many scientists think we don't. Is something that is actually perfectly in line with what we can do scientifically to understand the extraordinary conditions under which something like a soul can come true and that the soul does not reduce to neurons but it needs them.

Paulson: Let me just follow up on this and sort of play with this idea for a moment because you have made the case and other people as well that consciousness is irreducible. It's a thing unto itself a fundamental property of nature I guess is what you could say. It would seem that theoretically consciousness could exist independently of the brain. It could be sort of out there and I mean there is one kind of renegade theory that the brain acts like a radio receiver. You know consciousness is out there and somehow the brain allows us to tap into the consciousness that's sort of as if floating in the air around us. Does that make any sense?

Tononi: It makes some sense. I can understand what you are saying and also what other people are saying along these lines. I would also certainly emphasize that we remain very ignorant in many many areas. We do have to be humble and be ready to be surprised. Having said that the overwhelming evidence in fact all the evidence we see says unquestionably that consciousness depends on the function of some parts of the brain and the very precise aspects of that function. It's not only whether you have it how much of it you have but also what kind of conscience you have it. If you have a lesion in some part of the brain you may not be able to recognize faces consciously anymore. You may recognize unconsciously sometimes but they simply are not part of your experiences. If you have a lesion in another part of the brain you don't' see movements happening anymore and so on and so forth. It's very precise. It's very specific. So the brain is absolutely necessary. Without the brain all we know suggests that consciousness as we know it disappears and we do. As I said we do the experiment every night.

Paulson: And yet we still don't understand how the brain, how the neurons the neurotransmitters and synapses and all of that generates this mental experience.

Tononi: No the whole point…

Paulson: The question of causation is the big mystery.

Tononi: This becomes a bit difficult to explain but the integrated information theory actually is a theory that looks at consciousness as this integrated information structure. It is actually a causal structure. So when I say consciousness is maximally reducible as this shape in qualia space it is a causal structure. Information and causation are one and the same thing according to this theory so you need mechanisms and you need causality to generate consciousness and it better be a form of causality which is irreducible. That you know maybe it sounds a little bit abstract but it's essential to this. Now it's not and we have to understand that that there is some aspects of the neurons that sort of causes consciousness. It's not a function of the brain. it's an inartistic property of some very special kind of circuits. So if you have a circuit which is built in a certain way it will generate this kind of shape. Most other circuits are mechanism want and the scientific aspect of this is to understand what kind of circuits do that and to realize that there is a real of being which is to be an integrated information structure which goes above and beyond just being a bunch of mechanisms. That is the scientific part and I think so much so far the evidence is very much in favor of this. Now let me say something else which is in regards to your previous question. It is not according to the theory that only the brain can generate consciousness in principle. In fact as I've said many times now “the brain” is a very generic term. It's only some part of the brain that seem to be able to do that. Other extremely complicated parts like the cerebellum don't. But by the same token you could also have a different kind of structure if it is properly organized that could generate consciousness. A structure made of silicon if you wish instead of carbon. Only though if it is organized in the proper way and honestly unless it is through a long process of natural election and self organization I very much doubt that at the moment we have been able to build such structures. In fact most people wouldn't even know how to begin to build such structures. But it is not inconceivable. What is inconceivable to me in the sense that no evidence suggests that that may be the case is that you could such a thing without an underlying set of mechanisms.

Paulson: We started by talking about your search for meaning. Going back to when you were a kid when you were a teenager you wanted to know what life was all about why we're here and you determined the consciousness was the path to answer some of these questions. You've devoted your whole career to these questions. Have you come up with any better understanding of how to find meaning in your own life through this study of brain and mind?

Tononi: You see when I was looking into what was the ethical thing to do what one should do with one's life and realized at least to my understanding then that we needed to know a bit more about the universe but above all about this world not of consciousness. To be able to give a proper answer to that question you set yourself on a very long path in which to understand what you should be doing you need to understand what is actually the case. And that is I think fulfilling enough and gives meaning enough to what one tries to do.

Paulson: There has to be something more there though more than just the intellectual pleasure in trying to understand how all of this works. I mean we're talking about what makes us go why we do this why it matters. Does science answer any of those questions?

Tononi: No it is not the intellectual pleasure some people may have some may not and some may find pleasure in other things. It is in a way the realization that we are in the privileged position of being able to ask ourselves: “Why?” When you start asking that question that is very much you know I would call it probably an acid something that corrodes everything and that allows us to put everything into question including why we're here where we're going and what should one do. That question can be translated into many things. You know from art to creativity of any other sort to work in the social realm to science. Science is just one way to do that I believe and it's a way which is very explicit about finding out how things are.

Paulson: One final question. We haven't even talked about the story that you tell in your book Phi. We've been talking about all the ideas in it. It's kind of a fable where you invoke a number of historical characters from Galileo to Charles Darwin to Alan Turing to Francis Crick. Why have you told the story in your book this way?

Tononi: I'm not sure to tell you the truth why it came out to be that way. I mean I certainly I did write before and I could write another scientific monograph on consciousness and of course to do this properly you need papers and technical writings. I thought though consciousness offers you the unique opportunity of talking about something which is really at the essence of every one of us is of interest to everything. It's the cracks where science meets the humanities. That perhaps it was worth giving it a try to present it in such a way that indeed everybody who was interested in how things are and who we are and our place in the world might actually read it without thinking that they were getting into a course about the latest in neuroscience.

Paulson: Thank you very much.

Tononi: Thank you.

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