Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas - 249 | Peter Godfrey-Smith on Sentience and Octopus Minds

Episode Date: September 11, 2023

The study of cognition and sentience would be greatly abetted by the discovery of intelligent alien beings, who presumably developed independently of life here on Earth. But we do have more than one data point to consider: certain vertebrates (including humans) are quite intelligent, but so are certain cephalopods (including octopuses), even though the last common ancestor of the two groups was a simple organism hundreds of millions of years ago that didn't have much of a nervous system at all. Peter Godfrey-Smith has put a great amount of effort into trying to figure out what we can learn about the nature of thinking by studying how it is done in these animals with very different brains and nervous systems. Blog post with transcript: https://www.preposterousuniverse.com/podcast/2023/09/11/249-peter-godfrey-smith-on-sentience-and-octopus-minds/ Support Mindscape on Patreon. Peter Godfrey-Smith received his Ph.D. in philosophy from the University of California, San Diego. He is currently professor in the School of History and Philosophy of Science at the University of Sydney. Among his books are Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness and Metazoa: Animal Life and the Birth of the Mind. Web site University of Sydney web page Google Scholar publications PhilPeople profile Wikipedia Amazon author page Here are some of the papers mentioned in this episode: Crook (2021), Octopus pain Gibbons et al. (2022), Bee pain Gutnick et al. (2011), Octopus arm behavior

At Santa Monica College, a world-class education is affordable. Just $46 a unit with free tuition for eligible first-time California students, plus flexible online and on-campus classes close to home. Summer starts June 22nd, SMC.edu. Hello, everyone. Welcome to the Mindscape Podcast. I'm your host, Sean Carroll. If you're interested in thinking about life, the very idea about biology, right, that there exist living organisms, how they function, how they go around and do their

stuff, then if your cast of mind is that of a physicist or philosopher, like myself, you are struck with the difficulty that in some loose sense there is only one data point, right? Of course, there is a wide variety of kinds of living creatures here on Earth, but they all share a common ancestor. All life on Earth, as far as we know, stems from a single kind of origin. It's very possible that life began multiple times here on Earth and either one kind of strategy, one out, or maybe it destroyed all the others, or maybe life only just began once. But life began, and then it evolved, and it's all here on the same planet. We haven't yet discovered life elsewhere in the universe.

And this is quite a handicap if the questions we're asking are, what are the general features of life? What is life and on the level of thinking and consciousness and so forth? What is thinking? What is the biological activity that we think of as cognition, the subconscious, you know, system one, system two, whatever you want to think about? We are handicapped absolutely by the fact that we have one very big example in front of us and not a lot of ones on other planets or even parallel with us here on Earth. happily, if you're specifically interested in the question of cognition and consciousness and sentience, then we do have more than one example. Now, we only have one tree of life, but as we talk about on today's podcast, the idea of higher level thinking arose more than once in the history of biology,

still with animals that have a common ancestor, but that common ancestor did not have higher order thinking. and the other animals we're talking about, of course, are octopuses and cephalopods more generally. You probably have heard, if you're interested in biology and things like that, that octopuses are pretty darn smart, even though they're not even vertebrates, right? They're very, very different than mammals or birds or insects or anything like that. So Peter Godfrey Smith, today's guest, is a very respected philosopher who thinks about consciousness. He also thinks about other things we didn't get a chance to talk about in the podcast, but he's thinking a lot about consciousness and takes the octopus as a very important touchstone for his thinking, because in some very real sense, if you go back five or six hundred million years, there was a common ancestor to octopuses and to human beings, tiny little bugger who had no higher conception of a higher neural system or anything like that. And over the course of evolution, these two threads diverged, but they both in very different ways developed elaborate, complicated nervous systems that do some level of thinking. It happened more than once for different reasons, right? So we can learn from about, we can learn about what it means to be a higher level thinker, what it means to be conscious, what it means to be self-aware, how cognition happens, how the relationship between the brain and the body work. the body of an octopus is super duper different than the body of a human being.

That's really important. We need to be able to get all the day to we can in different ways. So Peter's written a number of books, but he's in the middle of a trilogy that we'll discuss a little bit. The first book called Other Minds, which is really about octopuses in particular and what they teach us about thinking, etc. There's another book that came up more recently called Metazoa, Animal Minds and the Birth of Consciousness. And then he's working on a third book about Life on Earth that will come out hopefully soon. And I think it's a wonderful conversation here. I will point out that Peter lives in Australia and he was in the mountains. So the internet connection came and went a little bit.

But I think that we've cleaned up the audio quality so that it's actually pretty good. At the very end, at the podcast, we kind of switch channels there and it fades a little but, you know, the content is all there. It's all very understandable. And Peter is a very, very thoughtful guy thinking about these hard philosophical questions in a very evidence-based, data-driven way. So let's go. Peter Godfrey-Smith, welcome to the Mindscape podcast. It's a pleasure to be here. So one of the things about you as a philosopher is that you're doing field work in some sense. You know, you start your, the book that I read, other minds. with these wonderful stories of scuba diving down there and communicating with the octopuses and

so forth. So which came first for you? Was it, you know, philosophy led you to dive down there and talk to the octopuses? Or was that just a separate hobby that you realized had dramatic philosophical implications? It's more the latter. What happened was, you know, I've spent a long time thinking about evolution and the mind as philosophical or philosophical slagely. scientific topics, also had spent quite a bit of time thinking about the evolution of the mind. But in a way that seems a bit odd in retrospect, I'd never really gotten to know some particular animals, some particular non-human animals really well. I hadn't sort of dived into the biology of some particular kind of organism.

It was all a bit schematic. And then it just happened by chance that I began. and spending a bit more time in Australia during the northern summers. I was working in the US at that time, but was coming back a bit more and spending time in the water. And in particular, just really through a stroke of luck, I happened to choose a spot to buy a tiny holiday, you know, summer apartment, in an area that had not long before been made into a complete sanctuary, a marine sanctuary. where nothing can be taken from the water. And it's become a wonderland, an amazing, an amazing place.

I began spending time in the water there just because that's where I was spending my northern summers. And the animals that made me realize I should change my direction a little bit, change my thinking. The first ones were the giant cuttlefish, these extraordinary, you know, very large, color-changing cephalopods, relatives of octopuses, but closer to squid. I met them, and the color change, and also the fact that they have, in some cases, a kind of inquisitive mode of interaction with snorkelers and divers really intrigued me. And octopuses then,

with the next animals, I took it interest in. You know, once I began thinking about cephalopods, octopuses are the ones that we know a lot more about. And they had also been down there in the water with me when I first became interested in the giant cuttlefish. They were watching me the whole time, I now realized, without me seeing through their camouflage. So I just became very interested in the animals. And in particular, with the feature of their lives that forms the core of the book, other minds, which is the evolutionary relationship, the fact that they're so distant from us as

animals, their mollusks, you know, oysters are closer relatives to them than we are, but they have this complexity, these large nervous systems, this inquisitive in some cases, mode of interaction. And that combination of features, the complexity and the evolutionary distance made me realize, right, I need to spend a lot of time with these animals and just thinking about their importance. So that was the beginning of the kind of combined philosophical slash fieldwork side of my life. And the big picture issue that we're talking about here is consciousness, maybe, or at least that's how philosophers often and scientists for that matter like to frame it. But as you say, maybe what you're after here is more sentience or self-awareness or something like that?

Yeah, I've gotten used to the fact that the word consciousness has, I think, just changed its meaning somewhat in the last 30 years or so. When I was a student, you know, thinking about the classic mind-body problem, it was more common to think of the word consciousness as referring to some kind, not just experience, or felt experience in general, but some kind of sophisticated form of experience that includes a kind of here I am reflective kind of quality. So back then, the question is a squid conscious would not have meant what it tends to mean now, which is just does it feel like something to be a squid? And that is what it has come to mean. Largely as a consequence of Tom Nagel's enormously influential work. And Nagel's work goes way back. It's not as if he began expanding the meaning recently. He always used the word conscious in this broad sense. And there

were people who did. But I have a bit of resistance. I guess I've sort of given up the fight to some extent. I have a bit of resistance to understanding the word conscious in this super broad way where it refers to essentially the same thing as sentience. Or perhaps it's the case that the word sentience carries with it particular implications of pleasure and pain. Sometimes that's what people understand by sentience. I've become reconciled to the fact that is a squid conscious just means does it feel like something to be a squid? So the faintest glimmer of felt experience is enough for a yes answer.

Now, one reason why I have become relaxed about this is the fact that I don't think the terminology we have now is permanent. I think the language will change. I think as we learn more in a scientific context and also in a philosophical context, the language just naturally mutates. So I don't mind a certain amount of slippage in the terminology. And this has a critical side to it too. when people talk about consciousness, including in this broad sense, they sometimes suppose that

we have now latched on to a natural kind, a real feature of the world, that we can see the contours of pretty clearly and that we just have to explain with respect to how it fits in. I don't think that. I think probably the whole framework that we use in this area will shift, will permute, will mutate in a natural kind of way. Good, because actually that's what I was going to suggest and sort of ask whether or not you felt the same way. But to some extent, to me it seems like this particular usage of the word consciousness and the focusing on what it is like is, I don't want to be too prejudicial here, but it seems like it's meant to comport with a view that consciousness isn't something completely physical, right? that if you focus on the first person perspective, you're almost trying to define away the possibility

of just having it be emergent from atoms and particles and neurons bumping into each other in ways that obey the laws of physics. That's not something I've thought. I understand the thought, but that's not how it struck me. If someone, right, the word consciousness is supposed to steer us towards the first person point of view. But I think that to do this need not be to steer us away from a physical or a biological understanding. Points of view are things that have evolved. Evolution has given us animals, an animal is a kind of nexus between the causal lines coming in through the senses and the

causal lines going out through action. Point of viewness is an evolutionary product, I think. Evolution built systems that have points of view. And at least so far in what I've said, they can be wholly physical, completely biologically comprehensible systems. Once you have them, once you have these things through evolution, the things that have these points of view will be able to sort of look out from those points of view. And certain puzzles will arise from trying to marry together the world as it appears from a first-person point of view from the world as described using scientific theories that are designed to not be point-of-view dependent or point-of-view involving.

So puzzles will naturally arise, but I see those puzzles that's arising as a consequence of the fact that evolution has built systems with points of view. So, you know, in a way, I almost have the opposite view. I think when people invite us to think about the problem of consciousness using notions like subjectivity and point of view, I think, okay, good, right, fine, I can get a handle on that. I can get a biological purchase on that. The idea of qualia, these sort of pure fields that are also sometimes used to express the problem, I think of those as a bit more alien, a bit more unhelpful. Okay, that makes perfect sense. I'll buy that. And you've already kind of led us into sort of the beginning of your journey here, because if I can summarize it or at least set the stage, if you want to study what consciousness is, sentience is or something, the more data, the better. And you've been emphasizing very vividly in your work that there is another set of organism, we can look at other than we, humans, primates, mammals, etc. Right. There's another set of organisms, and these organisms are all different degrees of remove from us. When we're looking at a chimp, when we relate to a chimp, it's a close cousin. The brains have a very similar structure. We share a lot of history. There are big differences, but they're close kin.

When you look at a bird, a parrot, for example, the brain still has a vertebrate structure, but there's less shared history. It's a deeper evolutionary relationship. Then you get to an octopus, and they're just miles from us. Octopus is the same distance from us as an ant or a bee. So, you know, the common ancestor between a human and an octopus is the same animal as the common ancestor between a bee.

and a human. The lines converge there at the same place. So you have a cluster of organisms that are part of our line or our group. And in a sense, I mean, this is now using the word a little bit broadly. They're part of the same experiment, the same evolutionary experiment. And then you have a cluster of organisms that are just miles away, just really on a different road, separated by very deep history, part of a different experiment. Maybe just to get on the table for those of us who are not complete octopusophiles, how smart are octopuses? What does it even mean to say that they're smart?

I mean, we can argue about whether or not they're conscious, and you'll have some opinions about that. But, you know, let's point out that they're pretty darn smart in some ways. I've started to resist a little bit that term. I mean, in a low-key way of talking, yeah, they're smart. They have big nervous systems. They can do a lot of stuff. They can solve simple puzzles.

They're quite good at navigation. They're pretty good learners and so on. The reason I've begun to resist that word smart is the following. There's a way of being a complex animal that we share with, for example, well, crows and parrots, birds, for example, which is a kind of reflective. ruminative way of being. There are experiments on crows in particular where you present the crow with a novel problem. It's got to solve some problem to get food.

And the crow will sit there. It'll just look and a little time will pass. And after a while, it will do the right thing. You know, it will solve the problem. It's obviously turned the problem over in its head. the complexity of its handling of the problem is in there. In the case of an octopus, I mean, it's not that the contrast is completely stark and enormous, but in general, you know, that's not how an octopus would handle a novel problem.

And this is partly why experimental work on octopuses can be frustrating. Their approach to a novel situation, you know, if they're not frightened, if they're going to engage at all, is to involve their body, the complexity of the body, this extraordinary body, where everything that's being touched is being tasted, they will manipulate, turn things over. That kind of ruminative style that we share with crows, for example, is not present in them. And sometimes when I hear the word smartness, you know, how smart is an octopus, I think that we're being asked to think of octopuses as sharing that style, whereas in fact they

have a different style. Now, this is a bit of a frustrating way of answering your question, I realize. There are things, they're not just complex, behaviorally and sensually complex animals, but they do have a kind of adeptness. They learn their way around situations. They can work out what's going on in the lab. They can remember individual humans in a lab or aquarium who've treated them. nicely or less nicely and respond to those, they often seem to wait until the moment that you're

not looking at them before trying to make a break for it, before trying to make an attempt at escape. When you're not looking, that's when they go. So you could see those as a kind of smartness as well as behavioral complexity, but I would not put them in the same ballpark as parrots and crows with respect to that, that reflective, not reflective, that highly cognitive problem solving mode of complexity that they have. I hope that's not too frustrating an answer to the question.

We could follow up further with that if it was. Yeah, frustrating is completely fine as long as you're teaching us something, which is absolutely going on. But, I mean, maybe if we were being very, very literal about it, Is there a way to just quantify the size and scope of the octopus brain and nervous system compared to humans, for example? Yes, sure.

An octopus, or at least the common octopus, the one that's been studied most, which you get especially around the Mediterranean, has, at most recent measures, about 500 million neurons in its nervous system. So that puts it well below us, but getting into the range, of vertebrate nervous systems. Now, those 500 million neurons are organized differently. They are, two-thirds of them are spread around the body, especially in the upper arms, rather than being centralized in a central brain. But even the central brain itself, that's, you know, that's well over 100 million neurons. That's a big nervous system.

Now, here again, not wanting to be difficult, one of the things that's become clear over the last few years is how astounding the cognitive abilities of honeybees and bumblebees are. And they have about a million neurons. So a 500th the size of an octopus brain or nervous system. So, you know, much, much smaller. So a miniaturized brain can do a lot. As the lab of Lars Chitka has shown, bees can do things like cultural learning. They can see at one bee solve the problem and then solve the problem itself. There are hints of that in octopus work from some years ago, but they've really only remained hints.

Whereas in the case of the bees, it's pretty solid. So bees are doing that with a brain that's a 500. the size of an octopus nervous system. I think one thing that tells us is not to put too much stock in just the numbers. That's perfectly fair, and it's yet another reminder that biology is very complicated, and physics is a superior science to think about, because things are much easier in the realm of physics. But maybe we can go back to something you've already mentioned,

because I really want to drive this home about the moment when our two evolutionary lines diverged. I mean, the story we're telling is, however you think about the intelligence or whatever of an octopus, they have a quite sophisticated nervous system and ways of dealing with the world. But that's not, and so do we, but for completely independent evolutionary reasons in some sense. These are two examples of complicated nervous systems evolving very separately and maybe talk about when that happened and what the common ancestor was like. Yes, this is a great topic. I'm happy to talk in a bit of detail about this because things are changing. There's all sorts of new possibilities arising. When I wrote the book Other Minds, I said our best guess of the depth in time of the common ancestry is about 600 million years ago. An important feature of that number is the fact that it's before the Cambrian explosion, which began about 540 million years ago. It's well before that.

And it's during a time that's called the Ediacaran, named after a place in South Australia as it happens. And during the Ediacaran, we don't really know what animals were getting up to in any detail at all, but the impression we have is it was a much quieter regime of animal life than the regime that began in the Cambrian. In the Ediacarum, we have lots of fossils. They're mostly, they're sort of flat, bottom dwelling creatures. One of them looks a bit like a bath mat.

Some of them look a little bit like sort of flattened trilobites, macaroons, flattened forms like that. And there's very little evidence of any interaction between one animal another. There's a little bit that seems to have been a little crawling creature that may have tracked others presumably in the service, well, with the goal of scavenging and or perhaps the first forms of predation. But the sorts of interaction that we associate with animal life, now where there's lots of predation, lots of interaction, that seems to be missing from our evidence. Now, something that's always bothered me about reconstructions of this stage in history are the fact that you're looking at fossils which tend to be of animals that lived on the sea

floor, and there's independent genetic evidence that jellyfish or jellyfish relatives, jellyfish-like beings had already gotten going around that time, what were they getting up to? I mean, when I paint the picture of the sort of quiet Ediacaran, a time that has occasionally been referred to as sort of the Garden of Ediacara, this sort of peaceful, this peaceful early time, there is the possibility of jellyfish warfare up in the water column, which we don't know about because those animals don't tend to fossilize in a recognizable way. that even less likely to fossilize than the flattened ones that we tend to see. Anyway, so we should picture that time,

and the animal that's the common ancestor of arsar and octopus was probably perhaps a flattened worm or a worm-like creature on a scale of, you know, again, no one really knows, but maybe something like a centimeter, something like that scale. With a nervous system, we know that nervous systems had evolved already, they have either one origin or perhaps two, but the origin that's responsible for our nervous system and the octopus nervous system occurred within that historical group one time. They had a nervous system, they may have had eye spots,

they probably had a very simple behavioral repertoire. Probably even picturing worm-like beings, it was probably a pretty, a pretty simple. simple life. Now, that's how I wrote about it in other minds. The people who I'm in contact with and who I respect who are real experts in this area, people like Gaspar Yekali, he's a neuroscientist. People like him are tending to suspect that the history is not quite as deep that the common ancestor of us and an octopus may have lived about 565 million years. ago or something like that. And there was a kind of relatively concentrated cluster of evolutionary

events leading towards the Cambrian, but still before the Cambrian, because by the time you get to the Cambrian explosion, when you see fossils of the sort that Stephen Jay Gould wrote about in his book Wonderful Life, and Cambrian fossils generally, you're seeing representatives of lots of different present-day groups. You're seeing early vertebrates, early arthropods, the group that now includes insect and crustaceans and so on, early mollusks, earlier kinoderms. So the point at which those branches diverged must have been before the Cambrian because they were well established as separate once the Cambrian begins. And there's lots of unknowns about the details, but that's the basic picture. So just to add a little bit,

a little bit more. The group that we are part of and that octopuses are part of is the group of bilaterally symmetrical organisms, animals with a left and right as well as a top and bottom. And the common ancestor that the last common ancestor that we share with an octopus was probably a very early bilaterally symmetrical organism. So you get this body plan evolving, a body plan with left and right up and down. And that left-right duplicated structure seems to have been a real advance in the area of making possible behavior, motion. All of the really mobile animals that we know about have that left-right structure.

So that evolved before there was a lot of mobility. But once the Cambrian occurred some time after, once the Cambrian explosion began, the body plan that had become established in a couple of different lines, you know, it was the perfect body plan to then acquire behavioral complexity. And you get all these different lines, different evolutionary branches that evolved in their own way, the sorts of behaviors that we associate with animal life. And this combination of relationships, the fact that the branchings, the deep evolutionary branchings were before the Cambrian. And then when the Cambrian began, there was a new regime of interaction, predation, kill or be killed. You've got to start

to track what animals are around you or one of them is liable to eat you. Complex behavior evolved in that context and it evolved in a context where there were different designs that had diverged before this point and you get all this marvelous diversity, the arthropod body plan that we see in insects and crustaceans with these hard parts, the toolkit body, the tremendous facility for motion, you know, flight in the case of insects. There's the vertebrate design with a more centralized nervous system. And then you've got the cephalopods, this weird case, this weird group within the mollusks, with no or almost no hard parts, a nervous system on a different design, and evolving complexity

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Well, it's a great story because we have other examples in evolution where like site or something like that, there were independent inventions of some particular capacity. it seems to me like a very complex nervous system is highly resource intensive. There's good evolutionary reasons not to do it, but as your environment gets very complicated, maybe it comes on the scene that there are also good reasons to do it. Is it okay to imagine that the evolution of the complex nervous systems in the cephalopods was for the same reasons as for re-vertebrates?

That's a hard question, and I think perhaps we should distinguish coarser and finer grained ways of answering it. At a coarse-grained level, I think the answer might well be yes. Complex nervous systems exist in order to make possible complex behavior. Complex behavior is a way of responding to challenges and opportunities posed by your environment and lifestyle. Once the Cambrian comes along, 540 or so million years ago, animals start interacting with each other, posing problems and offering opportunities to each other. Some groups, not all, lots of groups did not evolve a lot of behavioral complexity,

but some of them found a way forward that did involve paying the expense. You rightly emphasize the expense of a complex nervous system and making use of the complexities of behavior that result. There are also finer grain differences. One interesting difference bears on the situation of the octopus in particular. And this idea goes back to the first discussion I know of this was in the first edition of a textbook, the cephalopod behavior textbook or survey written by Roger Handlin and John Messenger some years ago now. In the last chapter, they're fairly cautious writers handling and messenger,

but in the last chapter they do a little bit of speculation about why octopuses came to have such large nervous systems. And the speculation they offer is that, well, there were reasons to get this body, but it's a very hard body to control. There's so many degrees of freedom. You don't have a particular location on your arm where the elderly. is anywhere can be an elbow if you decide that that's where your elbow is going to be and the elbow can go through more directions of motion than a human elbow.

So you've got to make a lot more choices in a sense. The nervous system has to determine the details of action in a far more fine-grained way than it does in the case of us where our bodies both constrain and offer opportunities and resources for movement. So you have this, the octopus body evolved, probably through the loss of a shell of a cephalopod that was up in the water column a little bit squid-like or nautilus-like, where in one evolutionary line they got rid of all those hard parts, came to live on the sea floor, especially in reefs and things like that.

and without any hard parts, the capacities you have for motion and body changing and shape-shifting become effectively sort of endless. But you have to actually control all that stuff. And Hainlin and Messenger suggested that the octopus, the large nervous system evolved as a solution to this problem of just getting the damn body to do useful things, getting it to do things that make biological sense. And an idea that I find very attractive and I wouldn't want to overdo it.

I wouldn't want to make it sound like it was a sort of a stroke of magic or an evolutionary fluke or anything like that. But an idea I find very attractive is the idea that it was the demands of the body that gave them this very large nervous system. And then once they have this large nervous system, it was a relatively easy evolutionary road to then become, behaviorally complex in ways that have a kind of smartness and sensitivity about them. They were kind of set up to become behaviorally complex animals as a consequence of the demands

imposed by the sort of the difficulties and the opportunities of the octopus body. And I don't want to overemphasize the differences, but I don't want to under-emphasize them either. So the octopus has a very complicated nervous system. lots of neurons, but because of exactly the issues you just were talking about, there's a little bit more autonomy in those limbs, right? And I guess one of the issues in studying octopuses is how much central control is there in the brain over the limbs versus the limbs just doing what they want? Right. And this is one of the great puzzles and open questions.

to what extent is there a degree of autonomy in the limbs? The experimental work that's been done on this over the last while, a few years, especially some work by Tamar Gutnik and her collaborators, shows that the octopus can kind of pull itself together and direct an arm visually in a relatively exact way when it has reason to. So there is the capacity of that centralized control. But when you watch an octopus just hanging out,

if it's hanging out on the seafloor, it's doing its thing, quite often you see what looks at least like independent or semi-autonomous exploration that the arms are doing. They'll sort of wander off and do their own thing. And it's possible that this is controlled by the central body. brain, but probably I think it's thought not in a great deal of detail. This is in part because the connections between the central brain and the arms don't look as if they are the right kind to

support, you know, really fine grain control of all the details. There's also been work on the capacities of severed octopus arms. They can act in reasonably coherent ways for a while on their own, sort of crawling, forming, coherent-looking motions and so on. So if I had to guess, and I think we'll eventually have a more complete picture of this, I would offer a view in which the octopus is happy to allow a certain amount of autonomy in the arms in some settings. There's so much neural processing power in there, lots of sensitivity, lots of senses, an exploratory mode is a natural thing that the arms might be able to engage in.

But an octopus also has to sometimes pull itself together and do something that's coherent and coordinated as a whole organism. So, you know, it'll pull all its arms together and form itself into a missile and jet through the water or something like that. And I think of this, this is speculative, I think of this perhaps as a situation where top-down control is exerted on elements of the body that will go their own way at other times when top-down control is not being exerted. It almost sounds like an unruly family, right, with like some parents trying to exert control

over their kids, and sometimes the kids are just wandering around, and other times the parents got to say, hey, like get in line, you have to get on the train or whatever. Yeah. I've occasionally used analogies of different kinds of musical ensembles. I can see a bass guitar in the background of your office there. I imagine ensembles where you have a conductor, but the conductor is dealing with jazz musicians who are going to go their own way some of the time, but you can pull them together into a coherent thing when you have reason to do so.

The family analogy also might be offered, I agree. And so now we have the background, we can start asking about what it is like to be an octopus. Given that story you just told, it certainly sounds like if there is anything that it is like to be an octopus, it's very different than what it's like to be a centrally controlled human being. Yeah, I think trying to work out what the sensory world of an octopus might be like is something we can make a little bit of progress on. We can take some steps down that road. So if you're an octopus, you're quite a visual. animal. They have good eyes, which evolved independently from ours, but on a similar design. They

have a camera eye, more like our eye than an insect eye. They have enormous chemical sensitivity. They're touching, they're tasting everything they're touching with those suckers. There appears to be some light sensitivity in the skin of the whole body itself, probably saying too much to say they can see with their skin, but a kind of perhaps washes of light are experienced through a whole body light sensitivity. Not much of a role for hearing, if any at all. So we can imagine a kind of sensory world like that. And then we have to start adding the oddities, the fact that the loops that exist between sensing and acting in us are going to be different in an octopus because some of the actions are likely to be semi-autonomous.

The arm will just do its thing and that will have sensory consequences that the arm will track but the central brain will also track. And that's a difference. And related to that, you have the big puzzling possible difference which concerns selfhood. The question, once you have a more decentralized distributed nervous system like the octopus has, then even though there's whole body coherent behavior, is the locus of experience radically decented or just, or centerless in a way that contrasts with our own case? Now, I don't want to say, I don't want to overemphasize or overstate the degree to which human

experience is kind of centered with the kind of CEO in charge of the whole thing. But the vertebrate organization is probably one that gives more, makes for more unity, more centeredness of experience than the octopus level system. And when trying to imagine that feature, I think our imaginative capacities start to really run into the sand or run into difficulty. Well, let me ask just some very blatant, simple-minded down-to-earth questions about similarities between us and the octopuses. Do you think that the octopuses feel pain, for example? Yeah, I think that's become quite likely. The best octopus pain paper was published a couple of years ago by Robin Crook.

And it uses a good methodology. What she shows is that there's a number of different lines. of evidence that point in the same direction towards something like felt acute pain in the octopus. What she did was she used the method where she would inject a little bit of acetic acid, vinegar into an arm, and that event showed up in a number of different contexts behaviorally, and she was also able to look at the physiology and see physiological analogs of these behavioral changes. The octopus would avoid a location where that event had happened,

a location that was not avoided otherwise or before, but it would favor locations that were associated with the administration of a pain-killing or analgesic drug. Interestingly, the same sorts of drugs seem to have a pain-killing effect in many different animals, including octopus. The animals would seek out a location associated with the drug if that had the injection but not otherwise. The octopuses groomed and tended the injured spot.

Wound tending is often seen as quite good evidence for felt experience of something like pain. So there's a whole bunch of different lines of evidence she was able to bring together that don't decisively show that octopuses can feel pain. it's not as if we're, I think, going to be able to expect literal proof in a case like this, or at least not for a very, very, very long time. But a contrast between felt pain and something like a reflex has now been replaced by a picture where, well, either it's felt pain and this kind of quite integrated, centralized,

multifaceted handling of the aversive event, or it's all of those things involved. the multifaceted handling of the aversive event without any experience at all. And it's hard to rule that out. But the contrast is no longer between, you know, a mere reflex and something pain-like. It's now a very different kind of contrast. Do you see what I mean by that? So I think that the Cook experiment has made it quite likely that Octopus has feel something like pain. And are they social animals?

Do they have social structures in some sense? Not much at all. This is another wonderful, interesting fact. People often in biology think that sociality is one of the great evolutionary spurs to intelligence and the complex mind. But octopuses are not very social. For a long while, they are regarded as pretty much completely asocial. They have to meet to mate.

They've got to do that, but that was thought to be a social. about it. In the book, Other Minds, I talk quite a lot about a site, a particular site that was discovered off the coast of Australia by a friend of mine, Matt Lawrence, where you do see a lot of octopuses, a dozen or more hanging out in pretty close quarters, in pretty close proximity, a dozen or more in a few square meters diameter. And there they have to deal with each other. They have to work out a way to get on, we think. And you see a lot of the way. more interact, you see a lot more stuff going on than you do with the, with a solitary octopus. So they can deal with each other, but we think of this as pretty unusual.

It's not, they're not social animals in the way that squid, for example, are. But my impression is that at least from humans interacting with octopuses, that different individuals do have different personalities in some sense. It looks like, yeah, personality is hard, and biologists have been quite cautious about the idea of personality in octopuses, partly because a personality is supposed to remain fixed over time. You're the nice guy today and tomorrow rather than, it's not a personality difference if you're nice today and you're not nice tomorrow. So individual differences that have a kind of stability are quite hard to track with animals of this kind. But it does look like

there's, there is something like personality differences. And this is going to be a entirely unfair question, or maybe it's a fair question, but the answer is we have no way of knowing. A couple times on the podcast, I've talked with people who have stressed the mental time travel aspect of human cognition, the idea to imagine future hypothetical scenarios or to remember things from the past and how crucial this is for what we think of ourselves as humans, self-determining, et cetera. Is there any hope for wondering whether an octopus can do something like that can have different hypothetical scenarios in its head? That's part of the cutting edge right now.

There's a researcher, Alexandra Schnell, who's hoping to look at that and who has done some of the first work that's in this ballpark, that's in this area. You may have heard perhaps of a well-known study that she was involved in, that she led a couple of years ago, where she showed that cuttlefish, not octopuses, but cuttlefish, their relatives can exert a degree of self-control. They can forego an immediate lesser reward in order to get a slightly late, well, not that much, you know, a later, larger reward. It's an analog of the marshmallow test famously applied to humans.

And they passed this. They, they, she was able to show self-control in a cuttlefish, which was, remarkable. And as she sees it, that's the beginning of a sort of a research path that looks at a handling of time that's more sophisticated than we would have expected in animals of this sort. Is there any way of ever knowing whether an octopus can have a theory of mind? Can an octopus have ideas about what other octopuses or other creatures know? Is that part the sophistication? An animal would have to be, I think, pretty social in normal settings, in much of its life, in order for that to have much of a role for the animal. I mean,

I should be conscious. One of the weird things about octopuses is there's all sorts of things they can do that don't have an obvious rationale in ordinary octopus life. For example, I mentioned a few minutes ago that they can learn to recognize individual humans in a context and associate individual humans with nice and less nice behaviors, there's no reason why an octopus should be able to do anything like that. Even in the case of other octopuses, let alone humans, if they don't routinely have to deal with each other in a situation that involves at least tolerance, if not collaboration, why should they be able to recognize individuals?

It seems to be a kind of a bonus, a sort of somewhat... surprising, unexpected feature of their complexity. And because there are things like that, I don't want to make too strong an inference of the form, you know, because the octopus has no use for this, we shouldn't expect them to do it. We already have cases where it's very hard to see why the octopus has any use for something and they can do it. Okay, so with all that on board then, what have we learned? I mean, what are the lessons for how we think about consciousness or sentience that we get from having arguably two data points. I mean, sorry, maybe I should have just asked, are octopuses sentient and in what sense?

I think the answer is yes. And I think the list of animals that are probably or likely sentient is a growing list and it's probably quite a long list now. I used to be a little wary about the idea of insect felt experience or consciousness, but much less so now, mostly as a consequence of the bee work. Now, bees are special insects. One shouldn't think that everything true of a bee is going to be true of all the other insects, but it's kind of a, it's a bit of a game changer to have decent evidence for experience in bees. In the case of bumblebees, there's a good experiment from last year suggesting something like pain in bumblebees using a similar methodology that had already been taken to be pretty good in the case of

crustaceans, their arthropod relatives, where this involved an experiment that asks, will the animal make trade-offs? Will it handle the relationship between apparently aversive events and rewards in a sophisticated way, a way that suggests that the aversive event is felt to be aversive. In the case of bees, I think we have pretty good evidence that they do feel aversive events. If they feel them, then they're feeling something, and they have remarkable sensory abilities. Lots of insects have remarkable sensory abilities. We have them. We have the octopuses. We have the pain experiment I talked about a little while ago. Something else I

emphasize is the fact that if you get a consciousness researcher on from psychology or neuroscience, someone like Stan De Hain, if you put such a person on the spot and say, what are the behavioral indicators, not proofs, but indicators of consciousness? What's something that we can see from the outside that's at least very strongly suggestive of the right kind of machinery to be conscious? one thing that at least some of those people might say to you, and I mention Stan DeHane as an example, is, well, dealing with novelty, producing novel and temporally organized behaviors, behaviors that are far from routine. Because in humans, even if you think that humans can do a lot of things unconsciously,

the evidence that we can do a lot of things unconsciously stops when you get to novel, temporally organized behaviors, sequential behaviors that are new, then people are conscious of what they're doing. And octopuses are full of behaviors like that. They like novelty. Their response to novel objects is very much non-routine. They're curious about objects. They'll do, you know, an octopus today can do something that no octopus has ever done before because of their inclination towards novelty. So we have the pain work. We've got this, this, this orientation towards novel behaviors. We've got the large nervous system. We've got the, we've got, I think, lots of, lots of indicators of felt experience or consciousness in this broad sense in octopuses.

So that's interesting because, as you already told us, the octopus nervous system is wildly different than ours. There's some similarities, but a lot of differences. So can we draw conclusions then about what are the features of a nervous system or of a brain that would then lead to what we think of as sentience? Yeah, let's, there's a few ideas I'd like to put on it on the table in this area. Some of them fairly speculative. And there's something I'd like to ask you about it actually as well. Stepping back a moment, one question we might ask is, well, do you need a brain at all? Is there anything special about the biological hardware that a brain comprises? Or could the complexity of

operation that a brain enables also be seen in a totally different sort of device? So, you know, are brains necessary at all? Philosophers have tended to think for quite a long time that brains are not in principle required for consciousness, even if you're a physicalist, because the right kind of structure could exist in a properly programmed computer. An artificial system could be a kind of functional isomorph of a brain, and it would be perfectly fine as a basis for consciousness. I don't believe those views. This is partly because I don't believe the arguments for them anymore,

and we could talk about that, But one thing I wanted to perhaps spend a bit of time on if we can is an alternative picture of what matters and a picture in which some of the particularities of brains are quite important. So here's one picture of what brains do. And then I'll describe another picture, which is the one I'm interested in. One picture of what brains do is, well, it's essentially a network. The old analogy between a brain and a telephone exchange wasn't too far off. It's been replaced by an analogy between a brain and a network where you have nodes connected to other nodes and excitatory and inhibitory links between them.

Neurons fire and make other neurons fire. But the firing of a neuron is just an event that, defines activity in a network and you could have other sorts of physically different networks with similar patterns of interaction. That's a view of the brain in which the discrete cell-to-cell or point-to-point connections are all that really matters and the rest of what's going on is just kind of life support for the network. Here's another picture of brain activity.

You do have those point-to-point cell-to-cell influences, and they're tremendously important to the computational side of what a brain does. But you also have large-scale dynamic patterns which are not straightforwardly reducible to those network properties. The simple example, or the most conspicuous example, is the sorts of patterns that you see in an EEG reading, where there are oscillatory rhythms in a brain, which do have a relation to the neurons firing, but probably also have a lot of connection to sub-threshold movements of ions over membranes, which create large-scale electrical events,

which can be detected from the skin with an EEG device, and which, well, then, the question is what do these things do, if anything? A lot of people have thought that the sorts of oscillatory patterns that we pick up with an EEG are just kind of epiphenomena or froth on the surface that don't really matter. But there is a tradition in neuroscience of saying that there's an important cognitive role played by these large-scale rhythms and oscillatory dynamics. There was a particular moment which changed my thinking about this.

When I first, so, you know, two of the people who early on argued that large-scale dynamics, especially gamma oscillations around the sort of 40 hertz rate of oscillations in a brain, two of the people who argued that oscillations of that kind might be important to consciousness were Francis Crick and Christoph Koch. some decades ago. And Wolf Singer and some other people argued that the binding together of perceived parts of an experienced situation might be facilitated by these large-scale brain level, you know, not just neuron-to-neurone oscillatory patterns.

And I always, when I heard about that, I thought, well, that is very interesting. but this just sounds like a kind of quirk of some brains or vertebrate brains. It might just be true of us. And then I met a guy Bruno Van Swinderen, who's a fly researcher here in Australia, who studies exactly the same kind of thing, the role between large-scale oscillations in the brain, brain rhythms essentially, and cognitive processes, but he studies it in flies.

and it turns out that flies show an association between selective attention, attending to a particular part of a scene, and particular large-scale brain rhythms. There's an apparent cognitive role for these oscillations, which are not straightforwardly reducible to the point-to-point neuron fires, then other neurons fire properties. There's an association between those properties and an experientially relevant cognitive role in flies. And when I learnt that, I thought, right, my whole view of what a nervous system is suddenly is being changed here. I shouldn't just think of them as these big networks with one cell affecting another cell.

I should think of a nervous system as a different kind of thing, where you have a combination of those point-to-point interactions and these more diffuse more integrated, wholly biological. When I say they're not straightforwardly reducible to the network properties, I don't mean they're not reducible to the biological properties. They involve the movement of ions across membranes within the brain. But they're not networkish in the way that I'd been told by everybody, I've been told everybody that the networkish properties are all that matters, and the rest is just life support. And it turns out that these oscillatory dynamics that are, again, not reducible

to the network properties, they're all over the animal kingdom. They're there in flies, they're there in octopuses, they're even there in animals with much simpler nervous systems, jellyfish-like animals, including jellyfish. So it's a feature of nervous. systems, that they have this duality between the network properties and the more diffuse electrical rhythm type properties. And I think it's possible to start to suggest some mappings between that combination of features in nervous systems and experience as a phenomenon, felt experience. Should I dive on into that, or should we talk a bit about I'm curious what you think about the general electrical profile that brains have, the role of field effects, things like that.

Yeah. Yeah, let me just say a little bit about that. And then I would love to hear, you know, you continue on about experience and its connection here. I am very much one who argues against things like strong emergence. or downward causation and things like that, when the lower level of description that we're talking about is truly microscopic physics, right? Atoms or particles or fields.

We know in the physics of individual elementary particles that their dynamics are entirely local. What an electron does only depends on what its immediate environment is. It does not depend on whether or not its broader environment is a rock or a brain or an interstellar gas cloud or whatever. But I do think that that fact may be obscures the fact that when you're talking about the relationships between two levels, both of which are kind of complex themselves, right? Like the relationship between neurons and the brain.

Neurons are not elementary particles. They're not entirely local. I'm very much open to them being influenced by not just the neurons that they're talking to in the network, but wider scale phenomena. Certainly if we talk about societies where the lower level is people and the upper level is countries or communities or whatever, of course, people are highly non-local things. They're affected not only by the other people they talk to nearby, but by things going on in the wider world. So I would guess, not being an expert on the brain at all, but I would guess that maybe this could be an example where our enthusiasm for a certain kind of reductionism

takes us too far, thinking about neurons and their connections with each other and ignoring more holistic aspects, which are perfectly compatible with physicalism, but maybe a little subtle from the point of view of what individual neurons do. Does that make any sense? Yes, and you used a word there that you are avoiding and that I would also avoid the word emergence. I don't like emergence as a theoretical tool in this area.

I think it causes more trouble. It causes trouble more than it solves problems. So I wouldn't describe the sorts of things I'm talking about here in terms of emergence. It's only in the, if you have in mind that sort of wholly network-based view of a brain, then it's surprising to be told that there are these more diffuse and holistic electrical phenomena which can make a difference. Let me offer a little bit more of the view of brain activity that Van Swindoran, the guy who has influenced me, you know, well, inspired at least some speculations.

say a bit more about what he thinks. He thinks that there are two important processes in brains going on at once. One is neurons making other neurons fire. The ordinary point-to-point-to-cell interactions through synapses where this neuron fires and it contributes to or inhibits another neuron firing. The other process is these electrical movements, the movements of iron, ions across membranes in particular, which are below the level at which action potentials will be triggered. They're sub-threshold in that sense. But they affect the temporal properties of everything else that happens, and they affect

the temporal properties of firings. So the sub-threshold movements of ions affect the firings of neurons. The firings of neurons affect the sub-threshold movements of ions. the sub-threshold movements are more diffuse. It's not sort of, you know, there are particular cells involved, but as evidenced by the fact that you can pick up the large-scale pattern with an EEG, it has a more holistic character in a low-key, non-threatening sense of the world. It's more of a whole brain or large parts of the brain activity.

Okay, suppose you think a brain is like that. suppose you think it has this almost miraculous combination of properties, the point-to-point, more computational interactions and the more diffuse electrical oscillatory interactions. Here's something that was noticed by a few people who've written in this area from different angles over many decades, in fact. They've noticed that if you have a system with that combination of properties, then it's going to be affected by sensory events. You know, incoming influences will make a difference. But many different events will simultaneously affect the state of the whole and the actions

going on in the whole. There's a kind of integration for free that you get when you have a system with this combination of properties. One of the first guys to study electrical oscillations, rhythms in a jellyfish-like animal, a guy called Mac Pissano, just mentioned this in passing way, way back decades ago,

and the thought has been, I think, independently picked up by a number of different people in both neuroscience and around neuroscience. The idea of a natural integrative role that you get from this combination of properties as characteristic of brain activity. Okay, what is he? experience like? What is it like to have an experience, any everyday experience, like the

experiences we're having right now? Well, something I think is central and that is occasionally underplayed or outright denied is the kind of gestalt-like character of experience. I'm seeing the screen, I'm hearing some stuff. There's a certain subtle effect in my total experiential profile played by what the chair is like, the ambient temperature, all my mood, the fact that I have had coffee within the last hour or so rather than not, and so on. There's a sort of natural fitting together of facets that ordinary experience has. And one thing we want a biological account of experience, felt experience to do is explain that property. And I think that the view of brain activity that I was describing a moment ago as the

newer or the unorthodox view, it lends itself very much to an explanation of that gestalt-like view of experience. Suppose I think it's that sort of combination of properties in us, in our brains, that makes experience a feature of our lives. I then look through the animal kingdom. I see all these different kinds of nervous systems, but they all have this combination, this peculiar combination of properties is characteristic of animal nervous systems in general. And I want to know, as we all do, which of these organisms has feelings or sentience or consciousness in a broad sense. Then I find myself saying, well, I can imagine a two-part story.

about the biology of experience. The first part involves something we talked about earlier in this conversation, which is the evolution of point of view, perspective, the fact that some systems, animals, as a consequence of the evolution of action, have been formed to have a perspective on the world, a point of view on the world.

With the senses coming in, actions being emitted, there's a kind of nexus that we are as animals. as a consequence of the evolution of behavior. That set of properties is one part of the explanation of the biology of experience. And the other part is the peculiarities of nervous systems, the way that nervous systems have a unique combination of properties that features these gestalt-like patterns of activity being perturbed simultaneously by various different events.

So from there I think, right, to be conscious is to be an animal with a nervous system that has subjectivity as a feature of its relationship to its environment. It has a perspective. It has a point of view. It deals with the world and acts upon the world as a subject. And there's not going to be a cutoff such that some animals are below the line with respect to the important properties and others are going to be above the level. line and have the lights on, a gradualist picture is almost inevitable once you have this general

outlook. There's going to be all sorts of gradations and shades of grey. And one overall picture I would offer using all this is a picture in which a whole bunch of animals really are sentient, really are conscious. Lots of vertebrates, octopuses, some arthropods, the crustaceans, the honeybees, the bumblebees and so on. And you have a kind of shading off, very gradual diminution and dimming and transformation that takes you into

neurally less complex animals. But there's not some point at which the lights just switch off. There's a hard to understand grey area. You know, I wonder whether animals like earthworms and starfish much more neurally simple than us or an octoberer. are in an area like that. So gradualism, the importance of nervous systems as unique physical objects, and the evolution of subjectivity. Those are the sort of, those are my, those are the parts of my

view. Yeah, I think it all sounds very, very interesting and plausible to me. The gradualism aspect in particular, you know, is almost inevitable if you believe in evolution and so forth, although I do, I do at least want to keep open the possibility that there are in physics phase transitions, right? There's underlying things that happen very gradually, which lead to dramatic sudden shifts in the macroscopic properties of things. So I think you can be both gradualist about the foundations and suddenness catastrophist about some of the manifestations of that. And I don't know. And, you know, in principle, some things change slowly and some things change rapidly. I do think in human beings, there was, we're in the midst of a rapid change on biological time scales, stemming from our first acquisition of language and symbolic ways of communicating with each other,

which I don't think other animals have at all. So I think there is some difference, even though the DNA difference between humans and other primates is tiny, the manifestations are large. And I don't know. I'm just very open-minded, and I don't know the empirical information about whether or not there's some similar thing about sentience or consciousness that might be an open question about whether or not an octopus has crossed this barrier to the point where I can hurt its feelings by treating it badly. Yeah. I agree very much with one particular thought there. This reminds me of a conversation I had.

I gave an online talk a couple of years ago, and I said the thing that you and I both agree with, which is in an evolutionary setting, gradual change is likely. We have to get used to the possibility of gray areas and gradations and no sharp boundaries. And I also said the thing, that I've said in this conversation about the importance of large-scale oscillatory dynamics

in nervous systems. And a woman whose name I didn't write down, I've come to think of this is a really important point. I need to track her down so I can give her proper credit for this. In the question time, said, well, there could be a tension between the two things you just said, basically. If you think that those oscillatory dynamics in nervous systems are really important, they are natural candidates for phase transitions.

They're the sorts of things that can just sort of come into being when things are just right with relatively small underlying substrate changes. And that would potentially be at odds with the sort of ultra-gradualist view that you're telling us. And especially after the event was over, I thought to myself, that really was a very good point. That was a good observation. I agree with that. One reason I do emphasize the gradualist picture here is the fact that if you look across

animals now, there's such a diversity of nervous system sizes and complexities and different sorts of lifestyles. And the idea of a sharp line between the ones who are in and the ones who are out just seems very artificial to me. There was a conference at NYU a few years ago, which I remember very vividly, animals minds conference organized by the philosophers at NYU. And I gave a talk at that one and said some things about gradual change and gray areas, no light switch, no sudden moment where the lights come on. And I was surprised that quite a lot of people in the audience, quite a lot of philosophers,

very prominent philosophers in some cases, they just wanted to resist. They wanted to resist that gradualist view because they thought, we can just see from the nature of consciousness that it's a yes or no matter. It just has to be a yes or no matter. If we use the Tom Nagel formulation, is there something it's like to be you? They said, well, look, the distinction between something and nothing is a sharp distinction. It's not a graded gray area distinction. There's either something it's like to be you or there's nothing it's like to be you. Or there's nothing it's like to be you. There can't be something it's a bit like there being something it's like to be you. It's a yes or no matter.

And this also takes us back to a very early stage in our conversation. My response to that was to think, when you say that, you think we already understand the kind of contours of the problem very fully. We can see from what we know and have explored and it can experience now. that there has to be a yes or no distinction such that animals are either in or they're out. I don't think we know enough to think we can see that. I think our knowledge is far too rudimentary. And is there something it's like to be you language, that terminology?

It's quite a helpful way of gesturing towards the problem, but it doesn't constrain solutions such that there has to be a sharp divide. So I accept very much the idea that once I start to talk about physical properties where phase transitions are real possibilities, then I have to be open to suddenness, as you said. I also think there are reasons to favor a gradualist view when you look at the animal kingdom badly. That makes a lot of sense to me. I will, just to clarify one thing, you know, there can be, there may or may not be phase transitions. If there's underlying gradualism, it's open to the possibility. There are sudden changes in the macroscopic behavior, but maybe not, and that's an empirical

question we have to look at. The other thing that I'll just throw out there is that I tend to think that consciousness, the question what is consciousness has some analogs to the question, what is life, as in, biological life, because in the sense that there's probably not a unique thing that it is, right? There's a bundle of aspects that it is, and not only can some of them be sudden changes and some of them gradual, but some of them can be existent in a certain organism and others not. So the idea that it's just a yes or no switch seems kind of implausible to me. I completely agree. I think life in non-biology has been part.

partly explained and partly dissolved. It's been dissolved in the sense that there's not some single property such that, you know, here is my theory of life. Instead, we understand a cluster of properties that are broadly metabolic that involve energy use and self-maintenance, and there's a cluster of properties that involve evolution and reproduction, and we understand those as well, and put them together and we understand life. There are some of it is in a number of it is in that have one cluster without the auto viruses have the production evolution related properties without having their own metabolism, and that makes total sense. If viruses didn't exist, if we hadn't discovered viruses, it would make sense to predict

their existence because you can see how it would make sense for them to fit in and to be sort of odd cases with respect to the paradigm cases of life. if we look at Madden origin of life scenarios, many of which involve deep sea vents and the gradual formation of chemical cycles in situations where the containment that prevents everything just diffusing away is initially inorganic. It's the environment that's helping things remain relatively or partly controlled. compartmentalized, and when the self-maintaining, surf-reproducing systems began to produce their own boundaries, and hence their own compartmentalization, there are a model like that that have an intensely gradualist flavor to them. At that point in a system like that, do you go from just having a chemical, an autocatalytic cycle that's keeping its breath going, but doing so in

favorable physical circumstances? At that point, you go from merely that. And that's, and that's nearly that to being a little said that has its own firm of life, well, the answer is, you know, don't look for a line, don't look for a divide. It's misunderstanding the picture to think that there'll be a sharp line. So I think the analogy with life is a very rich one and quite helpful in this setting. Good. So we've gone on for a while. I want to just put one more final idea on the table that you can respond to because it's one that resonated with me a lot when I was reading your book, which is the externalism idea, the importance for consciousness of how we relate to the outside world. And the reason why it struck me is because I've just done a couple of podcasts where that same kind of move appeared in very different circumstances,

one with Brian Lowry, who is a social psychologist who says that our notion of the self is fundamentally social one, one that we use to pick out our role in society. And another one with Hugo Merci, who claims that the reason that we have reasons for our actions is fundamentally a social one. Now, we don't just do something. We say, here is why I did it. That's ultimately social.

So in both cases, there are things that you might think of as very, very internal. And these folks are claiming that the reasons why we have that internal feature is actually because of our relationship to the external world. Is it plausible that consciousness is another thing that has that property? If the view that I was sketching is anywhere near right, then consciousness itself doesn't have that property. But lots things, I think, probably do have that property. I think that the internalization of external cognitive tools is a big thing in human evolution. I mean, language is the outstanding case.

There's a discussion in the book other minds of inner speech and the ideas of Vygotsky, the Soviet-era psychologist who made much of the power of inner speech as a internal cognitive tool. I think that's a very important set of ideas. Inner speech and linguistic organization of thought more generally is a kind of gift from the public to the private. It's something that makes our individual minds more powerful than they would otherwise be, but it's something that would never have existed if there wasn't a social setting

in which the tool for interaction developed. I've just finished a third book in the series that began with other minds, and it's going to be a longer discussion of these gifts from public to private in that one. So I think that, you know, the octopus reminds us that you can be a solitary or pretty sanitary animal with a somewhat messed up self, you know, a rather unclear theme of selfhood given that neural dispersal. And there to be very good evidence that you are conscious in the verb sense of conscious. The octopus reminds us of that. It's one of the lessons of the octopus, but it's also true that social life rebuilds,

reshapes our internal landscapes, where language again is the outstanding case, and there are probably others as well. And these are important in the explanation of human consciousness, even if they're not important in the explanation of consciousness as a general phenomenon. You got to tell us what the title of your upcoming book is. Living on Earth.

Living on Earth. All right. Well, we very much look forward to it. Is that Earth including the oceans, I hope? Yes, although it is the most terrestrial of the books. Other Minds was mostly marine. The second book, Metazoa, we worked up onto land at a certain point in the book.

And the third book, Living on Earth, is a lot of it is set in forests. It's a forest book to a large extent, but with quite a regular tendency to go back into the water from time to time as well. So there are no octopuses. There are more marine animals, but there's also a kind of arboreal forest-based vibe to the book.

It's all very complicated. I admire you folks who can really try to take this all in. So Peter Godfrey-Smith, thanks very much for being on the Mindscape podcast. It's been a pleasure. Thank you.