#264 — Consciousness and Self (Rebroadcast)
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Summary
Anil Seth is a neuroscientist and the co-director of the Sackler Center for Consciousness Science at the University of Sussex, where he conducts research on consciousness. He is also the author of the new book, Being You: A New Science of Consciousness, which is out now. In this episode, Anil talks about his journey into consciousness, and how he became interested in consciousness and consciousness research, and why he decided to pursue a career in cognitive and computational neuroscience. He also talks about how he got into the field of consciousness and what it means to him, and what he thinks about consciousness in general, in the context of his work on consciousness and AI. We don't run ads on the podcast, and therefore, therefore, are made possible entirely through the support of our listeners.If you enjoy what we're doing here, please consider becoming a supporter of the podcast by becoming a subscriber. You'll get access to the full-length episodes of the Making Sense Podcast wherever you get your podcasts, and you'll be helping to shape the future of what we re making sense. Thanks for listening to the podcast! Sam Harris - The Making Sense PodCast Copyright 2019, made possible by Anchor.org. This episode was produced in partnership with Waking Up, a podcast I'm working on, and edited by, and the podcast is made possible in part 1 of a 3-hour conversation with Anil Seth Seth, which runs to 3 hours of this podcast. . This podcast was originally aired in 2015. We are working on a podcast that runs to three hours of a three-hour podcast on consciousness, so you can expect more episodes in the future. in the coming months. and we hope you'll listen to the rest of it in the next two weeks. If you're looking for a good time to get a copy of this episode? Thank you, I'm looking forward to hearing the first part of the second part of this conversation, which will be out soon. - Sam Harris, too! - making sense of consciousness, coming soon, so don't miss it? - if you're listening to this podcast, subscribe to the second half of the making sense podcast, I'll be listening to it, and more soon, you'll get a chance to hear the full episode of Making Sense podcast, right here on the Making sense podcast and other stuff like that?
Transcript
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No housekeeping today, apart from mentioning that big things are happening.
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over at Waking Up, we have redesigned the app, and I'm really happy with the result.
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Props to the team over there at Waking Up, and many good things happening on that front that
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Okay, well today I'm releasing a podcast that we originally aired a few years ago.
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This is with Anil Seth, a quite celebrated neuroscientist, and this was a really good conversation on
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Anil has a new book out, available today, titled Being You, A New Science of Consciousness.
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And I have not yet read the book, he was beginning to write it when we last spoke, but I'm told
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And it has received wonderful reviews, and been endorsed by many smart people.
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David Eagleman, Nicholas Humphrey, Alex Garland, the director of the film Ex Machina,
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Sean Carroll, Nigel Warburton, and it's been endorsed by none other than my wife, Annika Harris.
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He remains a professor of cognitive and computational neuroscience at the University of Sussex,
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and the co-director of the Sackler Center for Consciousness Science.
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I think I first discovered you, I believe I'd seen your name associated with various papers,
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but I think I first discovered you the way many people had after your TED Talk.
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Perhaps you can briefly describe your scientific and intellectual background.
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I mean, I think my intellectual interest has always been in understanding the physical and
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biological basis of consciousness, and what practical implications that might have in neurology
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But when I was an undergrad student at Cambridge in the early 1990s, consciousness was certainly
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as a student then, and then in a place like Cambridge, not a thing you could study scientifically.
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And I was still, at that time, I still had this kind of idea that physics was going to be
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the way to solve every difficult problem in science and philosophy.
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So I started off studying physics, but then through the undergrad years, I got diverted
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towards psychology as more of a direct route to these issues of great interest, and ended
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up graduating with a degree in experimental psychology.
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After that, I moved to Sussex University, where I am now, actually, again, to do a master's
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And this was partly because of the need, I felt, the time to move beyond these box and
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arrow models of cognition that were so dominating psychology and cognitive science in the 90s towards
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And the rise of connectionism and all these new methods and tools in AI seemed to provide
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So I stayed at Sussex and did a PhD, actually, in an area which is now called artificial life.
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And I became quite diverted, actually, ended up doing a lot of stuff in ecological modeling
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and thinking a lot more here about how brains, bodies, and environments interact and co-construct
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But I'd sort of left consciousness behind a little bit then.
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And so when I finished my PhD in 2000, I went to San Diego to the Neuroscience Institute
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to work with Gerald Adelman, because certainly then San Diego was one of the few places, certainly
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that I knew of at the time, that you could legitimately study consciousness and work on
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Francis Crick was across the road at the Salk Institute.
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So I stayed there for about six years and finally started working on consciousness, but
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bringing together all these different traditions of math, physics, computer science, as well
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And then for the last 10 years, I've been back at Sussex, where I've been running a lab,
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and it's called the Sackler Center for Consciousness Science.
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And it's one of the growing number of labs that are explicitly dedicated to solving or studying
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at least the brain and biological basis of consciousness.
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I've read his books, and I'm familiar with his work on consciousness, but he was famously
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I don't want you to say anything you're not comfortable with, but everyone who I've ever
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heard have an encounter with Edelman was just amazed at how much space he personally took
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I've heard that too, and I think there's some truth to that.
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What I can say from the other side is that when I worked for him and with him, firstly,
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it was an incredible experience, and I felt very lucky to have that experience because
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he had a large ego, but he also knew a lot too.
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I mean, he really had been around and had contributed to major revolutions in biology and in neuroscience.
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But he treated the people he worked with, I think, often very kindly.
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And one of the things that was very clear in San Diego at the time, he didn't go outside
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But when you were within it, you got a lot of his time.
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So I remember many occasions just being in the office, and most days I would be called
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down for a discussion with Edelman about this subject or that subject or this new paper
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And that was a very instructive experience for me.
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I know he was quite difficult in many interviews and conversations outside the NSI, which is
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a shame, I think, because his legacy really is pretty extraordinary.
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But one of the other reasons I went there was, one of the main reasons I went there was
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because I'd read some of the early work on dynamic core theory, which has later become
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Giulio Tononi's very prominent integrated information theory.
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And I was under the impression that Giulio Tononi was still going to be there when I got
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And he wasn't really speaking much with Edelman at the time.
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And it was a shame that they didn't continue their interaction.
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And when we tried to organize a festschrift, a few of us, for Edelman some years ago now,
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it was quite difficult to get the people together that had really been there and worked with him
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I think of the people that have gone through the NSI and worked with Edelman, there are
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extraordinary range of people who've contributed huge amounts, not just in consciousness research,
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but in neuroscience generally, and of course, in molecular biology before that.
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But yeah, I know he could also be pretty difficult at times, too.
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So, well, we have a massive interest in common, and no doubt we have many others, but consciousness
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is really the center of the bullseye as far as my interests go.
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And really, as far as anyone's interests go, if they actually think about it, it really is
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the most important thing in the universe because it's the basis of all of our happiness and suffering
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It's the space in which anything that matters can matter.
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So the fact that you are studying it and thinking about it as much as you are just makes you
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I think we should start with many of the usual starting points here because I think they're
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Let's start with a definition of consciousness.
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I think it's kind of a challenge to define consciousness.
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There's a sort of easy folk definition, which is that consciousness is the presence of any
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For a conscious organism, there is a phenomenal world of subjective experience that has the
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character of being private, that's full of perceptual qualia or content, colors, shapes,
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beliefs, emotions, other kinds of feeling states.
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There is a world of experience that can go away completely in states like general anesthesia
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To define it more technically is always going to be a bit of a challenge.
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And I think sometimes there's too much emphasis put on having a consensus technical definition
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of something like consciousness because history of science has shown us many times that definitions
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evolve along with our scientific understanding of a phenomenon.
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We don't sort of take the definition and then transcribe it into scientific knowledge
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So, so long as we're not talking past each other and we agree that consciousness picks
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out a very significant phenomenon in nature, which is the presence of subjective experience,
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Many of these definitions of consciousness are circular.
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We're just substituting another word for consciousness in the definition, like sentience or awareness
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or subjectivity or even something like qualia, I think is parasitic on the undefined concept
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But then there's also a lot of confusions people make too.
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So I'm always surprised by how often people confuse consciousness with self-consciousness.
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And I think our conscious experience of selfhood are part of conscious experiences as a whole,
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And then there are arguments about whether there's such a thing as phenomenal consciousness
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that's different from access consciousness, where phenomenal consciousness refers to this
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impression that we have of a very rich conscious scene, perhaps envisioned before us now,
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that might exceed what we have cognitive access to.
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And other people will say, well, no, there's no such thing as phenomenal consciousness beyond
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So there's a certain circularity, I agree with you there, but there are also these important
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distinctions that can lead to a lot of confusion when we're discussing the relevance of certain
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And I want to just revisit the point you just made about not transcribing a definition of a
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concept that we have into our science as a way of capturing reality.
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And then there are things about which we have a folk psychological sense which completely break
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apart once you start studying them at the level of the brain.
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So something like memory, for instance, we have the sense that it's one thing intuitively,
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We have the sense that to remember something, whatever it is, is more or less the same
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operation regardless of what it is, remembering what you ate for dinner last night, remembering
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your name, remembering who the first president of the United States was, remembering how to
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These are things that we have this one word for, but we know neurologically that they're
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quite distinct operations and you can disrupt one and have the other intact.
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The promise has been that consciousness may be something like that, that we could be similarly
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confused about it, although I don't think we can be.
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I think consciousness is unique as a concept in this sense.
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And this is why I'm taken in more by the so-called hard problem of consciousness than I think you
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But before we do, I think the definition that I want to put in play, which I know you're
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quite familiar with, is the one that the philosopher Thomas Nagel put forward, which is that consciousness
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is the fact that it's like something to be a system, whatever that system is.
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So if a bat is conscious, this comes from his famous essay, What is it like to be a bat?
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If a bat is conscious, whether or not we can understand what it's like to be a bat, if it
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is like something to be a bat, that is consciousness in the case of a bat.
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However inscrutable it might be, however impossible it might be to map that experience onto our
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own, if we were to trade places with a bat, that would not be synonymous with the lights
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There is something that it's like to be a bat if a bat is conscious.
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That definition, though, it's really not one that is easy to operationalize, and it's
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There's something sufficiently rudimentary about that, that it has always worked for me.
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And when we begin to move away from that definition into something more technical, my experience
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has been, and we'll get to this as we go into the details, that the danger is always that
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we wind up changing the subject to something else that seems more tractable.
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We're no longer talking about consciousness in Nagel's sense, we're talking about attention,
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or we're talking about reportability or mere access or something.
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So how do you feel about Nagel's definition as a starting point?
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I think it's pretty difficult to argue with that as a very basic fundamental expression
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I partly disagree with you, I think, when we think about the idea that consciousness might
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And here I'm much more sympathetic to the view that, heuristically at least, the best
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way to scientifically study consciousness and philosophically to think about it as well
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is to recognize that we might be misled about the extent to which we experience consciousness
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And there's a lot of mileage in recognizing how, just like the example from memory, recognizing
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how conscious experiences of the world and of the self can come apart in various different
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Just to be clear, actually, I agree with you there.
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But I completely agree with you there that we could be misled about how unified consciousness
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The thing that's irreducible to me is this difference between there being something that
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But there are many different ways in which the lights can be on in ways that would surprise
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Or, for instance, it's quite possible that the lights are on in our brains in more than
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We'll talk about split brain research, perhaps.
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But there are very counterintuitive ways the lights could be on.
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But just the question is always, is there something that it's like to be that bit of information
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And that is always the cash value of a claim for consciousness.
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I think that it's perfectly reasonable to put the question in this way, that for a conscious
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organism, it is something like it is to be that organism.
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And the thought is that there's going to be some physical, biological, informational basis
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Now, you've written about why we really don't need to waste much time on the hard problem.
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David Chalmers has been on the podcast, and I've spoken about it with other people.
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But perhaps you want to introduce us to the hard problem briefly.
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The hard problem has been, rightly so, one of the most influential philosophical contributions
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to the consciousness debate for the last 20 years or so.
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And I think it encapsulates this fundamental mystery that we've started talking about now,
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that for some physical systems, there is also this inner universe.
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There is something it is like to be that system.
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But for other systems, tables, chairs, probably most computers, probably all computers these
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days, there is nothing it is like to be that system.
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And what the hard problem does, it pushes that intuition a bit further, and it distinguishes
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And the easy problem, according to Chalmers, is to figure out how the brain works in all its
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So to figure out how we do perception, how we utter certain linguistic phrases, how we move
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around the world adaptively, how the brain supports perception, cognition, behavior, in all its
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richness, in a way that would be indistinguishable from, and here's the key, really, in a way that
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would be indistinguishable from an equivalent that had no phenomenal properties at all, that
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The hard problem is understanding how and why any solution to the easy problem, any explanation
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of how the brain does what it does in terms of behavior, perception, and so on.
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How and why any of this should have anything to do with conscious experiences at all.
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And it rests on this idea of the conceivability of zombies, and this is one reason I don't
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I mean, the hard problem has its conceptual power over us because it asks us to imagine
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systems, philosophical zombies, that are completely equivalent in terms of their function and behavior
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behavior to you or to me or to any or to a conscious bat, but that instantiate no phenomenal properties
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The lights are completely off for these philosophical zombies.
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And if we can imagine such a system, if we can imagine such a thing, a philosophical zombie,
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you or me, then it does become this enormous challenge.
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You think, well, then what is it or what could it be about real me, real you, real conscious
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That requires or entails that there are also these phenomenal properties, that there is
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something it is like to be you or me or the bat.
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And it's because Chalmers would argue that such things are conceivable, that the hard
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Now, I think this is a little bit of a, I think we've moved on a little bit from these
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Firstly, I just think that they're pretty weak.
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And the more you know about a system, the more we know about the easy problem, the less convincing
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Think about, you know, you're a kid, you look up at the sky and you see a 747 flying overhead.
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And somebody asks you to imagine a 747 flying backwards.
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But the more you learn about aerodynamics, about engineering, the harder it is to conceive
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And that's my worry about this kind of conceivability argument.
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That to me, I really don't think I can imagine in a serious way the existence of a philosophical
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And if I can't imagine a zombie, then the hard problem loses some of its force.
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I don't think it loses all of its force, or at least it doesn't for me.
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For me, the hard problem has never really rested on the zombie argument, although I know
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I mean, so let's just stipulate that philosophical zombies are impossible.
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They're at least, you know, what's called in the jargon, nomologically impossible.
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It's just a fact that we live in a universe where if you built something that could do what
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And let's just also add what you just said, that really, when you get to the details,
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you're not even conceiving of it being possible.
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And if you did, you would notice it break apart.
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But for me, the hard problem is really that with consciousness, any explanation doesn't
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seem to promise the same sort of intuitive closure that other scientific explanations do.
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It's analogous to whatever it is, and we'll get to some of the possible explanations.
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But it's not like something like life, which is an analogy that you draw and that many scientists
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have drawn to how we can make a breakthrough here.
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It used to be that people thought life could never be explained in mechanistic terms.
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There was a philosophical point of view called vitalism here, which suggested that you needed
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some animating spirit, some Elan Vital in the wheelworks to make sense of the fact that
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living systems are different from dead ones, the fact that they can reproduce and repair
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themselves from injury and metabolize and all the functions we see a living system engage,
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It was thought very difficult to understand any of that in mechanistic terms.
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And then, lo and behold, we managed to do that.
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The difference for me is, and I'm happy to have you prop up this analogy more than I have,
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but the difference for me is that everything you want to say about life, with the exception
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of conscious life, we have to leave consciousness off the table here, everything else you want
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to say about life can be defined in terms of extrinsic functional relationships among material
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So, you know, reproduction and growth and healing and metabolism and homeostasis, all of this
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is physics and need not be described in any other way.
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And even something like perception, you know, the transduction of energy, you know, let's say,
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you know, vision, light energy into electrical and chemical energy in the brain and the mapping
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All of that makes sense in mechanistic physical terms until you add this piece of, oh, but for some
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of these processes, there's something that it's like to be that process.
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And with or without zombies, the hard problem still stays hard.
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I think it's an open question whether the analogy will turn out to be false or not.
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It's difficult for us now to put ourselves back in the mindset of somebody 80 years ago,
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100 years ago, when vitalism was quite prominent and whether the sense of mystery surrounding
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something that was alive seemed to be as inexplicable as consciousness seems to us today.
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So it's easy to say with hindsight, I think, that life is something different.
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But, you know, we've encountered or rather scientists and philosophers over centuries have
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encountered things that have seemed to be inexplicable, that have turned out to be explicable.
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So I don't think we should rule out a priori that there's going to be something really different
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There's, I think, a more heuristic aspect to this is that if we run with the analogy of life,
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what that leads us to do is to isolate the different phenomenal properties that co-constitute
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You know, we can think about, and we'll come to this, I'm sure we think about conscious
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selfhood as distinct from conscious perception of the outside world.
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We can think about conscious experiences of volition and of agency that are also very sort
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of central to our, certainly our experience of self.
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These give us phenomenological explanatory targets that we can then try to account for with particular
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It may turn out at the end of doing this that there's some residue.
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There is still something that is fundamentally puzzling, which is this hard problem residue.
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Why are there any lights on for any of these kinds of things?
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And I think to give us the best chance of it not turning out like that, there's a positive
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The positive aspect is that we need to retain a focus on phenomenology.
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And this is another reason why I think the hard easy problem distinction can be a little
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bit unhelpful because in addressing the easy problem, we are basically instructed to not
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All we should worry about is function and behavior.
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And then the hard problem kind of gathers within its remit everything to do with phenomenology
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in this central mystery of why is there some experience rather than no experience.
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The alternative approach, and this is something I've kind of caricatured as the real problem,
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but David Chalmers himself has called it the mapping problem and Varela, Francisco Varela
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talks about a similar set of ideas with his neurophenomenology, is to not try to solve the
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hard problem to court, not try to explain how it is possible that consciousness comes to be
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part of the universe, but rather to individuate different kinds of phenomenological properties
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and draw some explanatory mapping between neural, biological, physical mechanisms and these
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Now, once we've done that and we can begin to explain not why is there experience at all,
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but why are certain experiences the way they are and not other ways, and we can predict when
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certain experiences will have particular phenomenal characters and so on, then we'll have done a lot
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more than we can currently do. And we may have to make use of novel kinds of conceptual frameworks,
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maybe frameworks like information processing will run their course and will require other more
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sophisticated kinds of descriptions of dynamics and probability in order to build these explanatory
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bridges. So I think we can get a lot closer. And the negative aspect is, why should we ask more of a
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theory of consciousness than we should ask of other kinds of scientific theories? And I know people
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have talked about this on your podcast before as well, but we do seem to want more of an explanation
00:27:54.080
of consciousness than we would do of an explanation in biology or physics, that it somehow should feel
00:28:00.880
intuitively right to us. And I wonder why this is such a big deal when it comes to consciousness,
00:28:09.520
consciousness. Because we're trying to explain something fundamental about ourselves doesn't
00:28:14.600
necessarily mean that we should apply different kinds of standards to an explanation that we would
00:28:19.220
apply in other fields of science. It just may not be that we get this feeling that something is
00:28:27.060
intuitively correct when it is in fact a very good scientific account of the origin of phenomenal
00:28:34.440
properties. Certainly, I mean, certainly scientific explanations are not instantiations. There's no
00:28:39.900
sense in which a good theory of consciousness should be expected to suddenly realize the phenomenal
00:28:44.780
properties that it's explaining. But also, I think we, yeah, we do, I worry that we ask too much of theories of
00:28:52.520
Yeah, well, we'll move forward into the details. And I'll just flag moments where I feel like the hard problem
00:28:58.360
should be causing problems for us. I do think it's not a matter of asking too much of a theory of
00:29:04.360
consciousness here. I think it's, there are very few areas in science where the accepted explanation
00:29:10.360
is totally a brute fact, which just has to be accepted because it is the only explanation that works, but it's not
00:29:19.700
something that actually illuminates the transition from, you know, atoms to some higher level
00:29:26.400
phenomenon, say. Again, for everything we could say about life, even the very strange details of
00:29:33.900
molecular biology, just how information in the genome gets out and creates the rest of a human body,
00:29:41.680
it still runs through when you look at the details. It's surprising, it's at parts difficult to
00:29:49.320
visualize, but the more we visualize it, the more we describe it, the closer we get to something that is
00:29:56.240
highly intuitive, even something like, you know, the flow of water, the fact that water molecules in its
00:30:03.040
liquid state are loosely bound and move past one another. Well, that seems exactly like what should be
00:30:09.600
happening at the micro level. So as to explain the macro level property of the wetness of water, and the fact that
00:30:16.500
it has characteristics, higher level characteristics that you can't attribute to atoms, but you can
00:30:21.900
attribute to collections of atoms, like turbulence, say. Whereas with, you know, if consciousness just
00:30:27.320
happens to require some minimum number of information processing units knit together in a certain
00:30:34.260
configuration, firing at a certain hertz, and you change any of those parameters and the lights go out,
00:30:41.420
that for me still seems like a mere brute fact that doesn't explain consciousness. It's just a
00:30:50.280
correlation that we decide is the crucial one. And I've never heard a description of consciousness,
00:30:56.320
you know, of the sort that we will get to, like, you know, integrated information, you know,
00:31:00.320
Tononi's phrase, that unpacks it any more than that. And you can react to that, but then I think we
00:31:07.360
just get into the details and see how it all sounds. Sure. I'll just, I'll just react very
00:31:11.660
briefly, which is, which is that I think I'd also be terribly disappointed if the, you know,
00:31:16.300
you look at the answer in a book of nature and it turned out to be, yes, you need 612,000 neurons
00:31:21.700
wired up in a small world network and, you know, that's, that's it. You know, the hope is that does
00:31:27.760
seem, of course, ridiculous and arbitrary and unsatisfying. I mean, the hope is that as we progress
00:31:33.480
beyond, if you like, just brute correlates of conscious states towards accounts that provide
00:31:41.940
more satisfying bridges between mechanism and phenomenology that explain, for instance,
00:31:48.100
why a visual experience has the phenomenal character that it has and not some other kind
00:31:53.880
of phenomenal character like an emotion, that it won't seem so arbitrary. And that as we follow
00:31:59.960
this route, which is an empirically productive route. And I think that's important that if we,
00:32:05.700
we can actually do science with this route, we can try to think about how to operationalize
00:32:10.000
phenomenology in various different ways. Very difficult to think how to do science and just
00:32:14.580
solve the hard problem head on. Yeah. At the end of that, I completely agree. There might be
00:32:19.800
still this residue of mystery, this kernel of something fundamental left unexplained.
00:32:27.160
But I don't think we can take that as a given because we can't, well, I certainly can't predict
00:32:33.900
what I would feel as intuitively satisfying when I don't know what the explanations that bridge
00:32:39.900
mechanism and phenomenology are going to look like in 10 or 20 years time. We've already moved further
00:32:45.300
from, you know, just saying it's this area or that area to synchrony, which is still kind of
00:32:51.120
unsatisfying to now, I think some emerging frameworks like predictive processing and integrated
00:32:56.940
information, which aren't completely satisfying either. But they hinted a trajectory where we're
00:33:04.380
beginning to draw closer connections between mechanism and phenomenology.
00:33:08.780
Okay. Well, let's dive into those hints. But before we do, I'm just wondering,
00:33:13.460
phylogenetically, in terms of comparing ourselves to so-called lower animals, where do you think
00:33:20.000
consciousness emerges? Do you think there's something that it's like to be a fly, say?
00:33:24.860
Okay. That's a really hard problem. I mean, I have to be agnostic about this. And again,
00:33:31.900
it's just striking how people in general's views on these things seems to have changed
00:33:37.840
over the last recent decades. It seems completely unarguable to me that other mammals, all other
00:33:47.260
mammals have conscious experiences of one sort or another. I mean, we share so much in the way of the
00:33:53.900
relevant neuroanatomy and neurophysiology exhibit so many of the same behaviors that it would be
00:34:03.200
Well, it actually wasn't that long ago that you could still hear people say that consciousness was
00:34:08.540
so dependent on language that they wondered whether human infants were conscious, to say nothing of
00:34:17.580
Yeah, that's absolutely right. I mean, that's a terrific point. And this idea that consciousness was
00:34:23.360
intimately and constitutively bound up with language or with higher order executive processing
00:34:29.780
of one sort or another, I think just exemplifies this really pernicious anthropocentrism that we tend
00:34:38.160
to bring to bear sometimes without realizing it. You know, we think we're super intelligent,
00:34:41.460
we think we're conscious, we're smart, and we need to judge everything by that benchmark. And what's
00:34:46.080
the most advanced thing about humans? Well, you know, if you're gifted with language, you're going
00:34:51.920
to say language. And now already, with a bit of hindsight, seems to me anyway, rather remarkable
00:34:58.600
that people should make these, I can only think of them as just quite naive errors to associate
00:35:06.640
consciousness with language. It's not to say that consciousness and language don't have any
00:35:10.800
intimate relation. I think they do. Language shapes a lot of our conscious experiences.
00:35:15.320
But certainly, it's a very, very poor criterion with which to attribute subjective states to other
00:35:21.640
creatures. So mammals, for sure. I mean, mammals, for sure, right? But that's easy, because they're
00:35:27.480
pretty similar to humans and primates, primates being mammals. But then it gets more complicated.
00:35:33.020
And you think about birds diverged a reasonable amount of time ago, but still have brain structures
00:35:41.260
that one can establish analogies, in some cases, homologies with mammalian brain structures.
00:35:49.240
And in some species, scrub jays and corvids generally, pretty sophisticated behavior too.
00:35:55.520
It seems very possible to me that birds have conscious experiences. And I'm aware,
00:36:04.080
underlying all this, the only basis to make these judgments is in light of what we know about the
00:36:09.320
neural mechanisms underlying consciousness and the functional and behavioral properties of
00:36:13.100
consciousness in mammals. It has to be this kind of slow extrapolation, because we lack
00:36:16.980
the mechanistic answer, and we can't look for it in another species.
00:36:20.800
But then you get beyond birds, and you get out to, you know, I then like to go way out
00:36:27.900
on a phylogenetic branch to the octopus, which I think is an extraordinary example of convergent
00:36:35.060
evolution. I mean, they're very smart, they have a lot of neurons, but they diverged from
00:36:40.340
the human line, I think, as long ago as sponges or something like that. I mean, really very little
00:36:45.660
in common. But they have incredible differences too. Three hearts, eight legs, arms, I'm never
00:36:54.020
sure whether it's a leg or an arm, that behave semi-autonomously. And one is left here. When
00:37:02.120
you spend time with these creatures, I've been lucky enough to spend a week with them in a
00:37:05.760
lab in Naples, you certainly get the impression of another conscious presence there, but of a
00:37:11.040
very different one. And this is also instructive, because it brings us a little bit out of this
00:37:18.620
assumption that we can fall into, that there is one way of being conscious, and that's our
00:37:23.600
way. There is a huge space of possible minds out there, and the octopus is a very definite
00:37:31.700
example of a very different mind, and very likely conscious mind too. Now, when we get down
00:37:39.740
to, yeah, not really down, I don't like this idea of organisms being arranged on a single
00:37:46.980
scale like this, but certainly creatures like fish, insects, are simpler in all sorts of
00:37:51.920
ways than mammals. And here it's really very difficult to know where to draw the line, if
00:37:58.980
indeed there is a line to be drawn, if it's not just a gradual shading out of consciousness
00:38:04.240
that with grey areas in between, and no categorical divide, which I think is equally possible.
00:38:12.120
Fish, many fish display behaviours which seem suggestive of consciousness. They will self-administer
00:38:18.020
analgesia when they're given painful stimulation. They will avoid places that have been associated
00:38:24.060
with painful stimulation and so on. You hear things like the precautionary principle come
00:38:29.320
into play. Given that suffering, if it exists, conscious suffering is a very aversive state,
00:38:36.280
and it's ethically wrong to impose that state on other creatures, we should tend to assume
00:38:42.780
that creatures are conscious unless we have good evidence that they're not. So we should
00:38:53.580
Let's talk about some of the aspects of consciousness that you have identified as being
00:38:59.520
distinct. There are at least three. You've spoken about the level of consciousness, the contents
00:39:05.980
of consciousness, and the experience of having a conscious self that many people, as you said,
00:39:13.140
conflate with consciousness as a mental property. There's obviously a relationship between these
00:39:18.600
things, but they're not the same. Let's start with this notion of the level of consciousness.
00:39:23.580
Which really isn't the same thing as wakefulness. Can you break those apart for me? How is being
00:39:29.540
conscious non-synonymous with being awake in the human sense?
00:39:35.780
Sure. Let me just first amplify what you said, that in making these distinctions, I'm certainly not
00:39:41.600
claiming, pretending, that these dimensions of level, content, and self pick out completely
00:39:49.000
independent aspects of conscious experiences. There are lots of interdependencies. I just think
00:39:53.800
they're heuristically useful ways to address the issue. We can do different kinds of experiments and
00:40:00.480
try to isolate distinct phenomenal properties in their mechanistic basis by making these distinctions.
00:40:06.360
Now, when it comes to conscious level, I think that the simplest way to think of this is more or
00:40:11.300
less as a scale. In this case, it's from when the lights are completely out, when you're dead,
00:40:18.200
brain death, or under general anesthesia, or perhaps in very, very deep states of sleep,
00:40:24.300
all the way up to vague levels of awareness, which are similar, which correlate with wakefulness.
00:40:32.100
So when you're very drowsy, too vivid, awake, alert, full conscious experience that I'm certainly
00:40:40.420
having now, I feel very awake and alert, and my conscious level is kind of up there. Now,
00:40:46.840
in most cases, the level of consciousness articulated this way will go along with wakefulness or
00:40:55.680
physiological arousal. When you fall asleep, you lose consciousness, at least in early stages.
00:41:00.700
But there are certain cases that exist which show that they're not completely the same thing
00:41:09.620
on both sides. So you can be conscious when you're asleep. Of course, we know this. This is called
00:41:16.480
dreaming. So you're physiologically asleep, but you're having a vivid inner life there. And on the
00:41:23.360
other side, and this is where consciousness science, the rubber of consciousness science hits
00:41:27.340
the road of neurology, you have states where behaviorally, you have what looks like arousal.
00:41:36.100
This used to be called the vegetative state. It's been kind of renamed several times now,
00:41:40.420
the wakeful unawareness state, where the idea is that the body is still going through physiological
00:41:46.180
cycles of arousal from sleep to wake, but there is no consciousness happening at all.
00:41:53.360
The lights are not on. So these two things can be separated. And it's a very productive and very
00:42:04.680
important line of work to try to isolate what's the mechanistic basis of conscious level independently
00:42:11.380
from the mechanistic basis of physiological arousal.
00:42:15.140
Yeah. And a few other distinctions to make here. So also general anesthesia is quite distinct from
00:42:21.680
deep sleep, which is a matter of neurophysiology.
00:42:25.240
Certainly general anesthesia is nothing like sleep. Certainly deep levels of general anesthesia. So
00:42:31.460
whenever you go for an operation and the anesthesiologist is trying to make you feel
00:42:37.600
more comfortable by just saying something like, yeah, we'll just put you to sleep for a while and
00:42:41.500
then you'll wake up and it will be done. They are lying to you for good reason. You know, it's kind
00:42:46.980
of nice just to feel that you're going to sleep for a bit, but the state of general anesthesia is very
00:42:50.980
different. And for very good reason, if you were just put into a state of sleep, you would wake up as
00:42:55.200
soon as the operation started and that wouldn't be very pleasant. It's surprising how far down you can
00:43:01.280
take people in general anesthesia, almost to a level of isoelectric brain activity where there is
00:43:06.500
pretty much nothing going on at all and still bring them back. And, um, and any, most many people now
00:43:14.860
have had the, the non-experience of general anesthesia and in some weird way, I now look
00:43:21.580
forward to it the next time I get to have this because it's a very sort of, it's almost a reassuring
00:43:28.460
experience because there is absolutely nothing. It's complete oblivion. It's not, you know, when you
00:43:32.600
go to sleep as well, you can sleep for a while and you'll wake up and you might be confused about
00:43:38.500
what, how much time has passed, especially if you've just flown across some time zones or stayed
00:43:44.280
up too late, something like that, you know, might not be sure what time it is, but you'll still have
00:43:48.780
this sense of some time having passed. Except we have this problem or some people have this problem
00:43:53.900
of anesthesia awareness, which is, you know, every person's worst nightmare if they care to think
00:43:59.860
about it, where people have the experience of the surgery because for whatever reason, the
00:44:06.140
anesthesia hasn't taken them deep enough and yet they're immobilized and can't signal that they're
00:44:11.500
not deep enough. I know, absolutely. But I mean, that's a failure of anesthesia. It's not a
00:44:15.860
characteristic of the anesthetic state. Do you know who had that experience? You've mentioned him on the
00:44:20.380
podcast. I really, Francisco Varela. Oh, really? I didn't know that. I did not know that. Yeah.
00:44:26.740
Francisco Varela was getting a liver transplant and experienced some part of it.
00:44:33.480
Well, that's, that's pretty horrific. Could not have been fun. Yeah. I mean, of course,
00:44:37.620
because the thing there is that, you know, under most serious operations, you're also administered
00:44:41.980
with a muscle paralytic so that you don't jerk around when you're being operated on. And that's why
00:44:48.040
it's, it's particularly a nightmare scenario. But, you know, if anesthesia is working properly,
00:44:53.720
certainly the times I've had general anesthesia, you start counting to 10 or start counting backwards
00:45:01.120
from 10, you get to about eight and then instantly you're back somewhere else, very confused, very
00:45:07.720
disoriented. But there is no sense of time having passed. It's just complete oblivion. And that,
00:45:15.000
I found that really reassuring because you, we can think conceptually about not being bothered
00:45:20.480
about all the times we were not conscious before we were born. And therefore we shouldn't worry too
00:45:26.080
much about all the times we're not going to be conscious after we die. But to experience these
00:45:31.180
moments of complete oblivion during a lifetime, or rather the edges of them, I think is a, is a very
00:45:41.480
Although there's a place here where the hard problem does emerge because it's very difficult,
00:45:47.080
perhaps impossible to distinguish between a failure of memory and oblivion. Has consciousness
00:45:54.100
really been interrupted? Take anesthesia and deep sleep as separate, but similar in the sense that
00:46:00.480
most people think there was a hiatus in consciousness. I'm prepared to believe that that's not true of deep
00:46:07.220
sleep, but we just don't remember what it's like to be deeply asleep. I'm someone who often doesn't
00:46:12.820
remember his dreams and I'm prepared to believe that I dream every night. And we know, even in the
00:46:19.860
case with general anesthesia, they give amnesic drugs so that you won't remember whatever they don't
00:46:26.980
want you to remember. And I recently had the experience of not going under, under a full anesthesia,
00:46:33.460
but having a, you know, what's called a twilight sleep for a procedure. And there was a whole period
00:46:39.940
afterwards where I was coming to about a half hour that I don't remember. And it was clear to my wife
00:46:47.120
that I wasn't going to remember it, but she and I were having a conversation. I was talking to her
00:46:51.160
about something. I was saying how, you know, perfectly recovered I was and how miraculous it was to be
00:46:56.880
back. And she said, yeah, but you're not going to remember any of this. You're not going to remember
00:47:00.300
this conversation. And I said, okay, well, let's test it. You know, you say something now
00:47:04.860
and we'll see if I remember it. And she said, she said, this is the test dummy. You're not going to
00:47:10.580
remember this part of the conversation. And I have no memory of that part of the conversation.
00:47:18.260
You're right. Of course, that, that, um, even in stages of deep sleep, people underestimate the
00:47:24.860
presence of conscious experiences. And this has been demonstrated by, uh, experiments called serial
00:47:29.780
awakening experiments where you'll just, you just wake somebody up at various times during,
00:47:33.560
during sleep cycles and ask them straight away, you know, what was in your mind?
00:47:42.060
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