I'm nervous. I actually have a cute story to... We've only been married for 20-plus years, so it takes a while to get comfortable.
What, you have a story? A violent story you might want to hear? Let's hear it.
Okay, well, I was driving the kids to school this morning. I was feeling nervous about doing this, and I said to Violet, 'I'm nervous about my interview with Daddy today.' I said, 'Do you have any advice?' And she said, 'Well, I don't know what you do in interviews. How could I give you advice for an interview?' And I said, 'Yeah, but you know me. Like, could you give me advice, you know, because I feel nervous.' And she said, 'Well, don't cry.'
Funny. Well, I'll try not to cry.
Okay, well, you have an amazing audiobook series. It's really an audio documentary, but it's being framed as an audiobook. It's available on Audible and elsewhere, which just dropped this week. Normally we would have recorded this earlier, but I've been sick for 10 days. But now we're free to talk about the contents of what you've done here, and we're also going to release one of the chapters on the podcast and on Waking Up. It's about 11 hours of content for the whole series. And you did how many interviews of scientists for this? How many hours of...
I did about 35, but I believe 15 made it into the documentary. Right, so I could be wrong about those numbers, but about 35 and 15.
So you had something like 60 or 70 hours of content.
Yeah, at least more, yeah.
And you spoke to some fascinating people. Who did you speak with?
I talked to physicists like Brian Greene and Jan Eleven and Adam Frank, Sean Carroll, and then I spoke to many neuroscientists, Anil Seth and David Eagleman and others. I think the list is actually 18. I spoke to people who specialize in consciousness like Sue Blackmore, Christof Koch. Yeah, the list was long, and the whole thing is organized around a single question, really, which is: what if consciousness is fundamental?
Yeah, it is. I mean, it started with a less extreme question. I think the first question I went into it with was really: is it possible that consciousness goes deeper in nature than the sciences have assumed, and kind of how deep does it go? But I became convinced over the course of years of having these conversations that if it does go deeper than we have assumed, and much deeper than we have assumed, then I have an argument that it has to really go all the way down. And so then, yes, the question became: is consciousness fundamental?
So we might want to review the starting point here, which is inevitably the hard problem as David Chalmers described it. We've talked about this before, I've talked about it many times, and you cover it in depth in your book Conscious, and you also start the series reviewing it. But I just think any conversation here needs to at least touch on why it's a difficult intellectual problem to situate consciousness in the order of things.
Yeah, it's a problem I didn't get for a long time, actually. But really what it comes down to is the way in which consciousness — and by consciousness I mean in the most fundamental sense the fact that there is something that it's like, the fact that there is any felt experience, internal felt experience at all, to any system, really. And the question is, you know, because consciousness is different from everything else we study in science in that it can never be directly observed from the outside. You can communicate a lot about conscious experiences, we can talk about them, we can talk about how we think they're generated, but to actually, you know, know my experience right now of looking at a brown wood table, there's nowhere else in the universe that that direct experience can be talked about or felt except from the experience itself. And so the question that I finally understood to be mysterious is: if the universe is made of non-conscious matter, how and why is it — how really is it that some non-conscious matter gets configured in a way that suddenly there's this other property of there being something that it's like to be that matter, which is what we mean by consciousness.
Yes, we have that from that formulation, the 'something that it's like to be a system or creature,' is the explicit framing of the philosopher Thomas Nagel in his famous essay 'What Is It Like to Be a Bat?' Right. And it's interesting because a couple of — more than a couple of — the scientists I spoke with feel about consciousness the way I did for most of my life and most of my career, which is that it seems mysterious now, as life did at some point in our history, and eventually the sciences and neuroscience in particular will understand enough about the workings of the brain that it will no longer seem mysterious once we understand it. And it's funny, actually, I don't even know if you remember this, but so you were one of the first people to help me actually understand that the hard problem is a hard problem. And when we first met we were arguing about it, and I was arguing for the physicalist side, and I said, you know, it seems mysterious that when you flip a switch a room fills with light, a previously dark room fills with light, but once you understand the physics it doesn't seem magical in the same way. And so I used that analogy of the lights coming on, which is where this title came from, which I don't know if you know or remember. I don't think we even said it, that the title of the series is Lights On. So yes, so I think I'm a good proponent of this argument because I really came from the other side of it. And so I speak to a lot of physicists in particular who either don't think there really is a hard problem or think we'll resolve it soon, but I was surprised at how many of them, in particular Brian Greene, seem to really understand how it could be different from other problems we've faced.
Well, let me pull out a few points here because I think it could still be unclear why the hard problem is hard, because the analogies to things like life or to the mind in general make it seem like consciousness must be reducible to what some properties of the physical world are accomplishing, right? Because obviously intelligence is just a matter of information processing, and we're doing that in machines, and if our machines become conscious then there must be some way of explaining that in terms of information processing, and there should be no mystery there. Life is no longer mysterious. But the crucial difference is that intelligence and life and virtually any other thing you can name that science explains can be defined by virtue of its extrinsic properties — what it does to other things in the universe, its behavior, its covert internal behavior — and it's completely explained by the behavior, by the external. Yeah, there's nothing — once you explain all the input-output characteristics of life, nothing has been left out, except obviously consciousness if you're talking about conscious life, right? And so it is with the mind. I mean, you know, a visual system can function perfectly in a robot, and the only residual mystery once you've explained everything about its input-output characteristics is if there's something that it's like to be that system intrinsically, if there's a visual experience. Yeah, then you have to confront the mystery of consciousness. So consciousness is intrinsically defined: if there's nothing on the inside, then there's nothing to explain; if there is something on the inside, it is just a fact that there is. The only evidence for its existence is on the inside, it's not on the outside. You can't see a brain do anything which announces that there's something that it's like to be that brain or part of it. And so it will be with a perfectly functioning robot that unless we know how consciousness arises, or that it does arise, based on information processing, we'll have robots that seem conscious to us, but we won't know whether they're conscious.
Yeah, this actually points to an example I've been using a lot lately that I think also helps highlight why the hard problem is hard, and also why I think our intuitions have been misleading us about what consciousness is. But you know, we're so used to it — I mean, in some sense it's everything that we are. We don't know how to know anything or talk about anything that happens outside of our conscious awareness. It's all playing out for us in consciousness, and so in a sense we take it for granted, and we don't think about it too much. It seems — yes, you know, so if you think of something like sight, if I see the color yellow, it seems like, oh yeah, there's this advantageous evolutionary system that gets put in place where we understand that there are light waves and there are wavelengths that appear red to us, appear yellow. There's a spectrum of light, we don't perceive the whole spectrum, but there's one that we refer to as yellow because when it hits our retina and gets processed by the brain, an experience, a felt experience of seeing yellow materializes in the universe. This is something that comes into existence, this experience of seeing yellow, and we know that yellow isn't something that exists out there in the world. It exists as a light wavelength, but in terms of the felt experience of it — and you know, scientists and everyone else used to think that yes, yellow does exist out there. We used to think we kind of had this perfect window onto reality, and it turns out that the brain is actually generating this experience of seeing yellow. And so that kind of all seems natural to us until you realize that cameras and computers also process light waves and can distinguish between different wavelengths of light. There's a whole category of fascinating plant research that I get into in my documentary also, which talks about how plants process light waves and how their subsequent behavior is based on how they process those light waves. But we can easily imagine that computers and cameras and plants do all of this without — we don't think they're seeing yellow, we don't think they're having an experience from the inside. But for some reason it seems natural to us that we do. But the more you kind of interrogate these intuitions we have about what consciousness is doing, what it's there for, what function it serves, and why we think it comes out of complexity, our reasons for it really do start to fall apart, and I think that's incredibly interesting.
And so you realize that it is completely mysterious why a brain produces an experience of seeing yellow and other systems in the universe that process yellow light waves do not, and whether we're right about that or not.
Right, right. So that's the hard problem. No matter how much you explain about the behavior of a system or its input-output characteristics, there seems to be this remaining mystery as to why it should be like something to be associated with any part of that behavior. And the hard problem is really based on what I think you call in the series a primary assumption.
The strong assumption is what I term it.
The strong assumption, yeah. So what is the strong assumption?
So the strong assumption is the assumption that the sciences have made, and that I include myself in until somewhat recently, that consciousness arises out of some sort of complex processing, namely in brains, probably doesn't exist outside of brains and central nervous systems, that those are required. But that we've kind of come to this assumption because we are conscious creatures, and the only evidence we can really get is in the form of communication, and we can only communicate with systems that are similar to us. So you know, I look at all your behavior, even the behavior of my cat, and there's enough communicated to me that they are a similar system to myself. You think that I'm at least as conscious as our cat. And so we've made this assumption that because we are the most complex things we know of in the universe — the human brain is the most complex thing we know of in the universe, we do all of these complicated things and we have this high level of intelligence — that because we only seem to get evidence from other systems like ourselves that they're conscious, we have no way of communicating with other types of systems, we've assumed that consciousness arises out of complexity, and we have a lot of assumptions about where we're likely to find it in the universe. And so that is what I call the strong assumption. And what I discovered was we actually have no good reason to begin with that assumption, and that the sciences, when we don't know something — and in this case when we don't know how consciousness arises in the universe — we're actually, when it comes down to it, we're faced with starting with two assumptions. So we have to start with the starting point. We look at the universe, at all these collections of atoms, and say, okay, which of these systems are conscious or might be conscious? And the simple answer is either all or some. We know the answer isn't none because we at least have direct experience of our own. I know the conscious experiences I'm having, whatever the cause of them is, whatever kind of crazy situation I'm in — I could be a brain in a vat, who knows what reality is — but these experiences are arising in the universe. I'm experiencing them directly, something is happening and it's being experienced. And so the sciences have assumed that only some things in the universe are conscious, which is a totally natural starting place. There are all the good reasons we have for starting there. I think we've made a ton of progress in neuroscience with that starting assumption. But what I realized is we don't actually have strong evidence for assuming that.
And where might the science lead if we started with the other assumption? It doesn't even make sense, you know, how it sounds completely crazy even to me, but you know, sometimes interesting science comes out of ideas that at first sound crazy. And I found more and more evidence in my conversations to support the fact that this is actually a legitimate starting position, at least, you know, to leave as a question mark. But to say, what if we assume consciousness is fundamental, and then how do we analyze the data that we find, and how do we interpret the phenomena we find in all of the sciences, and where might that lead us? Or do we hit all kinds of roadblocks and it actually doesn't make sense?
Yeah, so then you take it in a slightly different direction where the focus is still on consciousness, but rather than simply hurl yourself at the hard problem, you come at it somewhat more obliquely by asking the question: what are the implications for physics of all this? So could treating consciousness as a fundamental property of the universe help us make progress on any current theories in physics? And sort of the flip side of that, or another facet of that, is: do any of the established understandings in physics rule out the possibility that consciousness is fundamental?
And I actually expected that I might find answers there in my searching, but yeah, I mean, what became obvious to me pretty quickly when I thought, okay, let's do this, let's do this thought experiment, and just start thinking — you know, I was just doing this on my own, and then I was doing it in conversation with the scientists and philosophers. But if consciousness is fundamental, what does that mean, and what implications does that have for everything we understand, everything we don't understand? And I realized almost immediately that this is a question for physics. The science of the fundamental is physics, and that was where I needed to go. And it was pretty early on. It was, I think, the second conversation I had was with Adam Frank, and that led to many more conversations with physicists. And actually, I should say that I think this line of thinking really needs to be heavily informed by neuroscience, but the question itself — is consciousness fundamental, or a fundamental property of the universe — it truly is a question for physics.
And you spoke to some neuroscientists who have a fairly deep connection to physics, people like Christof Koch, and I think Anil Seth actually studied physics as well before he became a neuroscientist.
That rings a bell, yeah. And those conversations are great. Christof has some mystical experience he likes to talk about, which is fascinating. One of my favorite parts of the series.
Yeah, okay, so let's just linger on this claim that consciousness might be fundamental. What are the implications of that? Or what are you visualizing or imagining could be true if consciousness goes all the way down in some sense? Are there different versions of that claim? What's the picture of reality that you're...
Yeah, I think there are, and I think if more people get on board with believing that this is a legitimate path forward, I think we're just at the very beginning of what the implications are, and I think this will go in directions that no one can yet imagine, really, which is kind of how science works. It will be the next paradigm shift, I think, if we become as convinced that consciousness could be fundamental as we are convinced at this point that it emerges, because then that will lead all of the new questions. Before I answer that, though, I'm aware I've been talking about this so much that I'm aware that I've made my case in many other contexts, but I'm suddenly aware how insane — no, to you I have, but to your audience this may be the first time they're hearing about this, and I don't want to sound too crazy. And so I just wonder if we should backtrack a little bit, or if I should just say that I spend — meet my crazy wife — that I spend much of the documentary and have spent much of my work explaining and making an argument for how I have come to the belief that this is a legitimate and important scientific question to ask. And my argument is based in neuroscience. It was working with neuroscientists for 20 years and learning more and more about how the brain works that convinced me that our assumptions about what we think consciousness is, how it's causal, all the rest — actually many of them have already been proven to be illusions of sorts. And so we don't need to get into the details there. But if anyone has read my book Conscious, there are two questions that I raise in that book that I think are interesting, intuition-shattering questions once you start to look closely at the details of how we try to answer them, because they feel like questions we know we have the answer to, and we feel confident that our answers are right. And the first question is: can you find evidence of consciousness from outside a system? And we feel the answer is obviously yes. So we think, you know, you know when you see it. If I see my friend coming toward me with her arms outstretched, I have a very strong belief that she is conscious and feeling love and excitement, and you know, I think we're very likely right about that. But the idea that we can always be sure that the behavior of a system, or that we could list behavior in a system that is conclusive evidence that consciousness is present — I think one, if we're starting to already get confused with the advancements in AI, because as you mentioned, there could soon be a system that looks like my friend running toward me with its arms outstretched, and we won't know whether there's a conscious experience on the other side of that. So it turns out the answer to that question — is there conclusive evidence we can find from outside a system — the answer there is, you know, at the very least maybe, but very likely no.
I would say that if your friend has a credit card reader on her face...
I see, I could see the joke brewing. Anywhere on her face, if the credit card can be scanned, she's probably not conscious yet. And the second question is: is consciousness causal? Is it behind many of our behaviors? And this is where a lot of the neuroscience disproves our strong intuitions that consciousness — that our felt experience of certain brain processing is the thing that causes us to then act. And there's now a ton of research, I'm sure you've talked to many neuroscientists on the podcast about binding processes, you know, almost every process in the brain actually kind of is a clue that our feeling, our conscious feeling of making a decision, of trying to think of another example, being the actual authors of our action, thoughts and actions, right? As if there's kind of this conscious — consciousness initiates the thing that happens. And the truth is that most processes in the brain that we know about, the conscious experience, at least the one that we can report on, is at the tail end of all of that, and that all of the processing kind of happens before.
But doesn't the second point cut the other way? Because if you knew that about the mind — which in fact we do, or it certainly seems to be the case that much of what's going on is going on in the dark — then what is the motivation to imagine that consciousness might go all the way down, if it seems like even mental processing is going on in the dark?
Well, if consciousness is fundamental, then whatever seems to be in the dark to us is just other conscious experiences arising that don't enter our stream of memory. And so yes, there's another way to talk about all of that if we're assuming that consciousness is fundamental. But speaking straight from the neuroscience — so there's a lot of self-contradiction here in the neuroscience in terms of assuming that consciousness is causal and assuming it evolved, but then all of the research showing that it isn't consciousness actually that is behind all of these things. So there are two ways to talk about it here. Another point I was going to make about that, because I think it's interesting that if again, if we shift our perspective and we start looking at these things and we ask the question: if consciousness is fundamental, what does it mean that a person seems to be unconscious when they're under anesthesia, or when we're in deep sleep, or that there are all these unconscious brain processes that go on that we are completely unaware of, or seem to be unaware of? You know, what does that mean if consciousness is fundamental? And so I've been thinking a lot about this, and one of the last chapters where I talk to Sara Walker, the astrophysicist, really focuses on this. She really is willing to go there with me on this idea of, you know, what does it mean to be a human mind and have a self, and how much memory comes into play. And so the truth is there could be countless conscious experiences happening in my brain and maybe elsewhere in my body that don't enter the stream of memory that I call me, right? And so the split-brain research is really interesting to look at here. I think just kind of to break open your creativity to think about other things that might be happening besides — if I report on it, if I can feel it and talk about it, that means it's conscious, and if I don't remember it or don't feel it, it means it's not conscious. Even a simple example of a pregnant woman, which I thought a lot about when I was pregnant, you know, even conjoined twins is another example. Split-brain research gives the best, the cleanest examples, but I'll just go back to pregnant woman. You know, we don't know when human babies become conscious, but it's not that hard to imagine that it happens at some point in utero, in some late stage. And so, you know, babies could be experiencing sound and light and very minimal experiences of consciousness that you would never expect the mother to be feeling, right? It's a separate system. And so there are many ways we might imagine that there are countless systems within the human brain and the human body that just don't get shared with what I'm calling me. You know, in the case of a split-brain patient, it really seems that you basically just split these streams of memory that you would call 'me', that what we're always referring to as 'I', and there's a whole half of the brain — the left hemisphere, which is the speaking hemisphere in a split-brain patient who can report about things — will not be aware of, or doesn't seem to be aware of, and can't answer questions that have been posed to the other hemisphere. And so, you know, there's already evidence that there can be many different streams of consciousness. And I actually think that's probably the wrong way to think about it. I think it's more useful to think about memory and how different experiences get tied through time in the form of memory. Lately I've been thinking about the fact that, you know, even my own memories of a week ago, 10 years ago, each moment is a new moment. And so I have this memory and I have this kind of false sense that I'm this concrete entity that moves through time and kind of touches on all these conscious experiences. But the truth is this new conscious experience has been generated a new now, and it's been affected by previous experiences through memory. So I have some relationship to, you know, even though I was a completely different person with a very different brain when I was four years old, there's some continuity there. There's some way that this conscious experience in this moment is being affected by a conscious experience that happened in my four-year-old self. And there's a way in which I've been thinking more about how conscious experiences affect one another in time and in space. And so there's a way in which also everything in this room with me, especially you, is affecting my conscious experience right now. So you're having conscious experiences, and the look on your face or the sounds that you make, in those ways they shape the conscious experiences that are arising over here. And so conscious experiences kind of affect each other through space in the moment and through time through memory.
Yes, so all of this deconstructs a standard notion of a self, which I guess we can leave aside. That's something that I've spent a lot of time talking about.
Yeah, and there's a whole chapter devoted to it.
Yeah, and you also talk about the split-brain research, which is interesting.
Yeah, I should also say, just for listeners who want to go deep, I also have chapter notes for every chapter, so on my website.
Yeah, it's clear when you're listening, but all of this research...
Yeah, people can go deep if they want to.
