Nick Bostrom: Simulation and Superintelligence | Lex Fridman Podcast #83

The following is a conversation with Nick Bostrom, a philosopher at University of Oxford and the director of the Future of Humanity Institute. He has worked on fascinating and important ideas in existential risk, simulation hypothesis, human enhancement ethics, and the risks of superintelligent AI systems, including in his book, Superintelligence. I can see talking to Nick multiple times in this podcast, many hours each time, because he has done some incredible work in artificial intelligence, in technology space, science, and really philosophy in general. But we have to start somewhere. This conversation was recorded before the outbreak of the coronavirus pandemic, that both Nick and I, I'm sure, will have a lot to say about next time we speak. And perhaps that is for the best, because the deepest lessons can be learned only in retrospect, when the storm has passed. I do recommend you read many of his papers on the topic of existential risk, including the technical report titled Global Catastrophic Risks Survey that he co-authored with Anders Sandberg. For everyone feeling the medical, psychological, and financial burden of this crisis, I'm sending love your way. Stay strong. We're in this together. We'll beat this thing. This is the Artificial Intelligence Podcast. If you enjoy it, subscribe on YouTube, review it with five stars on Apple Podcast, support it on Patreon, or simply connect with me on Twitter at Lex Friedman, spelled F-R-I-D-M-A-N. As usual, I'll do one or two minutes of ads now, and never any ads in the middle that can break the flow of the conversation. I hope that works for you and doesn't hurt the listening experience. This show is presented by Cash App, the number one finance app in the App Store. When you get it, use code LEXPODCAST. 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At the risk of asking the Beatles to play yesterday or the Rolling Stones to play Satisfaction, let me ask you the basics. What is the simulation hypothesis? That we are living in a computer simulation. What is a computer simulation? How are we supposed to even think about that? Well, so the hypothesis is meant to be understood in a literal sense, not that we can kind of metaphorically view the universe as an information processing physical system, but that there is some advanced civilization who built a lot of computers, and that what we experience is an effect of what's going on inside one of those computers, so that the world around us, our own brains, everything we see and perceive and think and feel, would exist because we are in a computer simulation. This computer is running certain programs. So do you think of this computer as something similar to the computers of today, these deterministic, sort of Turing machine type things? Is that what we're supposed to imagine, or are we supposed to think of something more like a quantum mechanical system, something much bigger, something much more complicated, something much more mysterious from our current perspectives? The ones we have today would do fine. I mean, bigger, certainly. You'd need more memory and more processing power. I don't think anything else would be required. Now, it might well be that they do have additional, maybe they have quantum computers and other things that would give them even more oomph. It's kind of plausible, but I don't think it's a necessary assumption in order to get to the conclusion that a technologically mature civilization would be able to create these kinds of computer simulations with conscious beings inside them. So do you think the simulation hypothesis is an idea that's most useful in philosophy, computer science, physics? Sort of where do you see it having valuable kind of starting point in terms of a thought experiment of it? Is it useful? I guess it's more informative and interesting and maybe important, but it's not designed to be useful for something else. Okay, interesting, sure. But is it philosophically interesting or is there some kind of implications of computer science and physics? I think not so much for computer science or physics per se. Certainly it would be of interest in philosophy, I think also to say cosmology or physics in as much as you're interested in the fundamental building blocks of the world and the rules that govern it. If we are in a simulation, there is then the possibility that say physics at the level where the computer running the simulation could be different from the physics governing phenomena in the simulation. So I think it might be interesting from point of view of religion or just for kind of trying to figure out what the heck is going on. So we mentioned the simulation hypothesis so far. There is also the simulation argument, which I tend to make a distinction. So simulation hypothesis, we are living in a computer simulation argument. This argument that tries to show that one of three propositions is true, one of which is the simulation hypothesis, but there are two alternatives in the original simulation argument, which we can get to. Yeah, let's go there. By the way, confusing terms because people will, I think probably naturally think simulation argument equals simulation hypothesis, just terminology wise, but let's go there. So simulation hypothesis means that we are living in a simulation. The hypothesis that we're living in a simulation, argument has these three complete possibilities that cover all possibilities. So what are they? Yeah, so it's like a disjunction. It says at least one of these three is true. Although it doesn't on its own tell us which one. So the first one is that almost all civilizations at our current stage of technological development go extinct before they reach technological maturity. So there is some great filter that makes it so that basically none of the civilizations throughout, I mean, maybe vast cosmos, will ever get to realize the full potential of technological development. And this could be, theoretically speaking, this could be because most civilizations kill themselves too eagerly or destroy themselves too eagerly, or it might be super difficult to build a simulation. So the span of time. Theoretically, it could be both. Now, I think it looks like we would technologically be able to get there in a time span that is short compared to, say, the lifetime of planets and other sort of astronomical processes. So your intuition is to build a simulation is not... Well, so there's this interesting concept of technological maturity. It's kind of an interesting concept to have for other purposes as well. We can see, even based on our current limited understanding, what some lower bound would be on the capabilities that you could realize by just developing technologies that we already see are possible. So, for example, one of my research fellows here, Eric Drexler, back in the 80s, studied molecular manufacturing. That is, you could analyze using theoretical tools and computer modeling the performance of various molecularly precise structures that we didn't then and still don't today have the ability to actually fabricate. But you could say that, well, if we could put these atoms together in this way, then the system would be stable and it would rotate at this speed and have these computational characteristics. And he also outlined some pathways that would enable us to get to this kind of molecularly manufacturing in the fullness of time. And you could do other studies we've done. You could look at the speed at which, say, it would be possible to colonize the galaxy if you had mature technology. We have an upper limit, which is the speed of light. We have a lower current limit, which is how fast current rockets go. We know we can go faster than that by just making them bigger and have more fuel and stuff. And you can then start to describe the technological affordances that would exist once a civilization has had enough time to develop at least those technologies we already know are possible. Then maybe they would discover other new physical phenomena as well that we haven't realized that would enable them to do even more. But at least there is this kind of basic set of capabilities. Can you just linger on that? How do we jump from molecular manufacturing to deep space exploration to mature technology? What's the connection there? Well, so these would be two examples of technological capability sets that we can have a high degree of confidence are physically possible in our universe and that a civilization that was allowed to continue to develop its science and technology would eventually attain. You can intuit, like, we can kind of see the set of breakthroughs that are likely to happen. So you can see, like, what did you call it, the technological set? With computers, maybe it's easier. One is we could just imagine bigger computers using exactly the same parts that we have, so you can kind of scale things that way, right? But you could also make processors a bit faster. If you had this molecular nanotechnology that Eric Drexler described, he characterized a kind of crude computer built with these parts that would perform at a million times the human brain while being significantly smaller, the size of a sugar cube. And he may not claim that that's the optimum computing structure, like for what you know, you could build faster computers that would be more efficient, but at least you could do that if you had the ability to do things that were atomically precise. Yes. I mean, so you can then combine these two. You could have this kind of nanomolecular ability to build things atom by atom and then say at this as a spatial scale that would be attainable through space colonizing technology. You could then start, for example, to characterize a lower bound on the amount of computing power that a technologically mature civilization would have if it could grab resources, you know, planets and so forth and then use this molecular nanotechnology to optimize them for computing. You'd get a very, very high lower bound on the amount of compute. So, sorry, just to define some terms. So, technologically mature civilization is one that took that piece of technology to its lower bound. What is a technologically mature civilization? Well, okay, so that means it's a stronger concept than we really need for the simulation hypothesis. I just think it's interesting in its own right. So, it would be the idea that there is some stage of technological development where you've basically maxed out, that you developed all those general purpose, widely useful technologies that could be developed or at least kind of come very close to the 99.9% there or something. So, that's an independent question. You can think either that there is such a ceiling or you might think it just goes, the technology tree just goes on forever. Where does your sense fall? I would guess that there is a maximum that you would start to asymptote towards. So, new things won't keep springing up, new ceilings. In terms of basic technological capabilities, I think there is like a finite set of those that can exist in this universe. Moreover, I mean, I wouldn't be that surprised if we actually reached close to that level fairly shortly after we have, say, machine super intelligence. So, I don't think it would take millions of years for a human originating civilization to begin to do this. I think it's more likely to happen on historical timescales. But that's an independent speculation from the simulation argument. I mean, for the purpose of the simulation argument, it doesn't really matter whether it goes indefinitely far up or whether there is a ceiling, as long as we know we can at least get to a certain level. And it also doesn't matter whether that's going to happen in 100 years or 5,000 years or 50 million years. The timescales really don't make any difference for the simulation. Can you linger on that a little bit? Like, there's a big difference between 100 years and 10 million years. Yeah. So, does it really not matter? Because you just said, does it matter if we jump scales to beyond historical scales? So, will you describe that? For the simulation argument, doesn't it matter that if it takes 10 million years, it gives us a lot more opportunity to destroy civilization in the meantime? Yeah, well, so it would shift around the probabilities between these three alternatives. That is, if we are very, very far away from being able to create these simulations, if it's like, say, billions of years into the future, then it's more likely that we will fail ever to get there. There's more time for us to kind of go extinct along the way. And similarly for other civilizations. So, it is important to think about how hard it is to build a simulation. In terms of figuring out which of the disjuncts. But for the simulation argument itself, which is agnostic as to which of these three alternatives is true. Yeah, yeah, okay. Like, you don't have to... Like, the simulation argument would be true whether or not we thought this could be done in 500 years or it would take 500 million years. For sure. The simulation argument stands. I mean, I'm sure there might be some people who oppose it, but it doesn't matter. I mean, it's very nice those three cases cover it. But the fun part is at least not saying what the probabilities are, but kind of thinking about, kind of intuiting reasoning about, like, what's more likely, what are the kind of things that would make some of the arguments less and more so. But let's actually, I don't think we went through them. So, number one is we destroy ourselves before we ever create simulation. Right. So, that's kind of sad, but we have to think not just what might destroy us. I mean, so there could be some, whatever, disaster, some meteorite slamming the earth a few years from now that could destroy us, right? But you'd have to postulate in order for this first disjunct to be true, that almost all civilizations throughout the cosmos also failed to reach technological maturity. And the underlying assumption there is that there is likely a very large number of other intelligent civilizations. Well, if there are, yeah, then they would virtually all have to succumb in the same way. I mean, then that leads off another, I guess there are a lot of little digressions that are interesting. Let's go there. Let's go there. I'll keep dragging us back. Well, there are these, there is a set of basic questions that always come up in conversations with interesting people, like the Fermi paradox. Like there's like, you could almost define whether a person is interesting, whether at some point the question of the Fermi paradox comes up. Well, so for what it's worth, it looks to me that the universe is very big. I mean, in fact, according to the most popular current cosmological theories, infinitely big. And so then it would follow pretty trivially that it would contain a lot of other civilizations. In fact, infinitely many. If you have some local stochasticity and infinitely many, it's like, you know, infinitely many lumps of matter, one next to another, there's kind of random stuff in each one. Then you're going to get all possible outcomes with probability one infinitely repeated. So then certainly there would be a lot of extraterrestrials out there. Even short of that, if the universe is very big, there might be a finite but large number. If we were literally the only one, yeah, then of course, if we went extinct, then all of civilizations at our current stage would have gone extinct before becoming technological material. So then it kind of becomes trivially true that a very high fraction of those went extinct. But if we think there are many, I mean, it's interesting because there are certain things that possibly could kill us. Like if you look at existential risks. And it might be a different, like the best answer to what would be most likely to kill us might be a different answer than the best answer to the question, if there is something that kills almost everyone, what would that be? Because that would have to be some risk factor that was kind of uniform overall possible civilization. So in this, for the sake of this argument, you have to think about not just us, but like every civilization dies out before they create the simulation. Or something very close to everybody. Okay, so what's number two in the picture? Well, so number two is the convergence hypothesis. That is that maybe like a lot of some of these civilizations do make it through to technological maturity. But out of those who do get there, they all lose interest in creating these simulations. They have the capability of doing it, but they choose not to. Not just a few of them decide not to, but out of a million, maybe not even a single one of them would do it. And I think when you say lose interest, that sounds like unlikely because it's like they get bored or whatever. But it could be so many possibilities within that. I mean, losing interest could be anything from it being exceptionally difficult to do to fundamentally changing the sort of the fabric of reality if you do it, ethical concerns, all those kinds of things could be exceptionally strong pressures. Well, certainly, I mean, yeah, ethical concerns. I mean, not really too difficult to do. In a sense, that's the first option that you get to technological maturity where you would have the ability using only a tiny fraction of your resources to create many, many simulations. So it wouldn't be the case that they would need to spend half of their GDP forever in order to create one simulation. And they had this like difficult debate about whether they should invest half of their GDP for this. And they would more be like, well, if any little fraction of the civilization feels like doing this at any point during maybe their, you know, millions of years of existence, then that would be millions of simulations. But certainly, there could be many conceivable reasons for why there would be this convert, many possible reasons for not running ancestor simulations or other computer simulations, even if you could do so cheaply. What's an ancestor simulation? Well, that would be the type of computer simulation that would contain people like those we think have lived on our planet in the past and like ourselves in terms of the types of experiences they have and where those simulated people are conscious. So like not just simulated in the same sense that a non-player character would be simulated in the current computer game where it's kind of has like an avatar body and then a very simple mechanism that moves it forward or backwards or, but something where the simulated being has a brain, let's say, that's simulated at a sufficient level of granularity that it would have the same subjective experiences as we have. So where does consciousness fit into this? Do you think simulation, like is there different ways to think about how this can be simulated? Just like you're talking about now, do we have to simulate each brain within the larger simulation? Is it enough to simulate just the brain, just the minds and not the simulation, not the big universe itself? Like is there different ways to think about this? Yeah, I guess there is a kind of premise in the simulation argument rolled in from philosophy of mind. That is that it would be possible to create a conscious mind in a computer and that what determines whether some system is conscious or not is not like whether it's built from organic biological neurons, but maybe something like what the structure of the computation is that it implements. So we can discuss that if we want, but I think it would be, for as far as my view, that it would be sufficient, say, if you had a computation that was identical to the computation in the human brain down to the level of neurons. So if you had a simulation with 100 billion neurons connected in the same way as the human brain and you then roll that forward with the same kind of synaptic weights and so forth, so you actually had the same behavior coming out of this as a human with that brain would have, then I think that would be conscious. Now, it's possible you could also generate consciousness without having that detailed simulation. There I'm getting more uncertain exactly how much you could simplify or abstract away. Can you look on that? What do you mean? I missed where you're placing consciousness in this second. Well, so if you are a computationalist, you think that what creates consciousness is the implementation of a computation. So some property, emergent property of the computation itself. Yeah. That's the idea. Yeah, you could say that. But then the question is, what's the class of computations such that when they are run, consciousness emerges? So if you just have something that adds one plus one plus one plus one, like a simple computation, you think maybe that's not going to have any consciousness. If on the other hand, the computation is one like our human brains are performing, where as part of the computation, there is a global workspace, a sophisticated attention mechanism, there is self-representations of other cognitive processes, and a whole lot of other things that possibly would be conscious. And in fact, if it's exactly like ours, I think definitely it would. But exactly how much less than the full computation that the human brain is performing would be required is a little bit, I think, of an open question. You asked another interesting question as well, which is, would it be sufficient to just have, say, the brain, or would you need the environment? Right, that's a nice one. In order to generate the same kind of experiences that we have. And there is a bunch of stuff we don't know. I mean, if you look at, say, current virtual reality environments, one thing that's clear is that we don't have to simulate all details of them all the time, in order for, say, the human player to have the perception that there is a full reality in there. You can have, say, procedurally generated, where you might only render a scene when it's actually within the view of the player character. And so similarly, if this environment that we perceive is simulated, it might be that all of the parts that come into our view are rendered at any given time. And a lot of aspects that never come into view, say, the details of this microphone I'm talking into, exactly what each atom is doing at any given point in time, might not be part of the simulation, only a more coarse-grained representation. So that to me is actually, from an engineering perspective, why the simulation hypothesis is really interesting to think about. Right. Is how much, how difficult is it to fake, sort of in a virtual reality context, I don't know if fake is the right word, but to construct a reality that is sufficiently real to us to be immersive in the way that the physical world is. I think that's actually probably an answerable question of psychology, of computer science, of how, where's the line where it becomes so immersive that you don't want to leave that world? Yeah, or that you don't realize while you're in it that it is a virtual world. Yeah, those are two actually questions. Yours is the more sort of the good question about the realism. But mine, from my perspective, what's interesting is it doesn't have to be real, but how can we construct a world that we wouldn't want to leave? Yeah, I mean, I think that might be too low a bar. I mean, if you think, say, when people first had Pong or something like that, I'm sure there were people who wanted to keep playing it for a long time, because it was fun, and they wanted to be in this little world. I'm not sure we would say it's immersive. I mean, I guess in some sense it is, but like an absorbing activity doesn't even have to be. But they left that world, though. So I think that bar is deceivingly high. So you can play Pong or StarCraft or whatever more sophisticated games for hours, for months, while the Warcraft could be a big addiction, but eventually they escaped that. So you mean when it's absorbing enough that you would choose to spend your entire life in there? And then thereby changing the concept of what reality is, because your reality becomes the game, not because you're fooled, but because you've made that choice. Yeah, and people might have different preferences regarding that. Some might, even if you had a perfect virtual reality, might still prefer not to spend the rest of their lives there. I mean, in philosophy, there's this experience machine, thought experiment. Have you come across this? So Robert Nozick had this thought experiment where you imagine some crazy super duper neuroscientists of the future have created a machine that could give you any experience you want if you step in there. And for the rest of your life, you can kind of pre-programmed it in different ways. So your fondest dreams could come true. You could, whatever you dream, you want to be a great artist, a great lover, have a wonderful life, all of these things. If you step into the experience machine, it will be your experiences, constantly happy. But you would kind of disconnect from the rest of reality and you would float there in a tank. And so Nozick thought that most people would choose not to enter the experience machine. I mean, many might want to go there for a holiday, but they wouldn't want to check out of existence permanently. And so he thought that was an argument against certain views of value, according to what we value is a function of what we experience. Because in the experience machine, you can have any experience you want, and yet many people would think that would not be much value. So therefore, what we value depends on other things than what we experience. Okay, can you take that argument further? What about the fact that maybe what we value is the up and down of life? You could have up and downs in the experience machine, right? But what can't you have in the experience machine? That then becomes an interesting question to explore. But for example, real connection with other people, if the experience machine is a solar machine where it's only you, that's something you wouldn't have there. You would have this subjective experience that would be like fake people. But if you gave somebody flowers, that wouldn't be anybody there who actually got happy. It would just be a little simulation of somebody smiling. But the simulation would not be the kind of simulation I'm talking about in the simulation argument, where the simulated creature is conscious. It would just be a kind of smiley face that would look perfectly real to you. So we're now drawing a distinction between appear to be perfectly real and actually being real. Yeah. So that could be one thing. I mean, like a big impact on history, maybe is also something you won't have if you check into this experience machine. So some people might actually feel the life I want to have for me is one where I have a big positive impact on how history unfolds. So you could kind of explore these different possible explanations for why it is you wouldn't want to go into the experience machine, if that's what you feel. And one interesting observation regarding this Nozick thought experiment and the conclusions he wanted to draw from it is how much is a kind of a status quo effect. So a lot of people might not want to get this on current reality to plug into this dream machine. But if they instead were told, well, what you've experienced up to this point was a dream. Now, do you want to disconnect from this and enter the real world when you have no idea maybe what the real world is? Or maybe you could say, well, you're actually a farmer in Peru, growing peanuts, and you could live for the rest of your life in this. Or would you want to continue your dream life as Alex Friedman, going around the world, making podcasts and doing research? So if the status quo was that they were actually in the experience machine, I think a lot of people might then prefer to live the life that they are familiar with, rather than sort of bail out into... It's interesting, the change itself, the leap, whatever. Yeah, so it might not be so much the reality itself that we are after, but it's more that we are maybe involved in certain projects and relationships. And we have a self-identity and these things, that our values are kind of connected with carrying that forward. And then whether it's inside a tank or outside a tank in Peru, or whether inside a computer or outside a computer, that's kind of less important to what we ultimately care about. Yeah, but still, just to linger on it, it is interesting. I find, maybe people are different, but I find myself quite willing to take the leap to the farmer in Peru, especially as the virtual reality system becomes more realistic. I find that possibility, and I think more people would take that leap. But in this thought experiment, just to make sure we are understanding, so in this case, the farmer in Peru would not be a virtual reality, that would be the real, your life, like before this whole experience machine started. Well, I kind of assume from that description, you're being very specific, but that kind of idea just like washes away the concept of what's real. I mean, I'm still a little hesitant about your kind of distinction between real and illusion. Because when you can have an illusion that feels, I mean, that looks real, I don't know how you can definitively say something is real or not. Like, what's a good way to prove that something is real in that context? Well, so I guess in this case, it's more a stipulation. In one case, you're floating in a tank with these wires by the super duper neuroscientists plugging into your head, giving you like Friedman experiences. In the other, you're actually tilling the soil in Peru, growing peanuts, and then those peanuts are being eaten by other people all around the world who buy the exports. So, these are two different possible situations in the one and the same real world that you could choose to occupy. But just to be clear, when you're in a vat with wires and the neuroscientists, you can still go farming in Peru, right? No, well, if you wanted to, you could have the experience of farming in Peru, but there wouldn't actually be any peanuts grown. But what makes a peanut... So, a peanut could be grown and you could feed things with that peanut. And why can't all of that be done in a simulation? I hope, first of all, that they actually have peanut farms in Peru. I get a lot of comments otherwise from Angry. I was with you up to the point when you started talking about... You should know you can't grow peanuts in that climate. No, I mean, I think in the simulation, I think there's a sense, the important sense in which it would all be real. Nevertheless, there is a distinction between inside a simulation and outside a simulation, or in the case of NOSIG's thought experiment, whether you're in the vat or outside the vat. And some of those differences may or may not be important. I mean, that comes down to your values and preferences. So, if the experience machine only gives you the experience of growing peanuts, but you're the only one in the experience machine... No, but there's other... Within the experience machine, others can plug in. Well, there are versions of the experience machine. So, in fact, you might want to have different thought experiments, different versions of it. So, in the original thought experiment, maybe it's only you, right? Just you. And you think, I wouldn't want to go in there. Well, that tells you something interesting about what you value and what you care about. Then you could say, well, what if you add the fact that there would be other people in there and you would interact with them? Well, it starts to make it more attractive, right? Then you could add in, well, what if you could also have important long-term effects on human history and the world and you could actually do something useful even though you were in there? That makes it maybe even more attractive. Like you could actually have a life that had a purpose and consequences. So, as you sort of add more into it, it becomes more similar to the baseline reality that you were comparing it to. Yeah, but I just think inside the experience machine and without taking those steps you just mentioned, you still have an impact on long-term history of the creatures that live inside that, of the quote-unquote fake creatures that live inside that experience machine. And that, like at a certain point, you know, if there's a person waiting for you inside that experience machine, maybe your newly found wife, and she dies, she has fear, she has hopes, and she exists in that machine. When you unplug yourself and plug back in, she's still there going on about her life. Well, in that case, yeah, she starts to have more of an independent existence. Independent existence. But it depends, I think, on how she's implemented in the experience machine. Take one limit case where all she is is a static picture on the wall, a photograph. So, you think, well, I can look at her, right? But that's it. But then you think, well, it doesn't really matter much what happens to that, any more than a normal photograph, if you tear it up, right? It means you can't see it anymore, but you haven't harmed the person whose picture you tore up. It's a good one. But if she's actually implemented, say, at a neural level of detail, so that she's a fully realized digital mind with the same behavioral repertoire as you have, then very possibly she would be a conscious person like you are. And then what you do in this experience machine would have real consequences for how this other mind felt. So, you have to specify which of these experience machines you're talking about. I think it's not entirely obvious that it would be possible to have an experience machine that gave you a normal set of human experiences, which include experiences of interacting with other people, without that also generating consciousnesses corresponding to those other people. That is, if you create another entity that you perceive and interact with, that to you looks entirely realistic. Not just when you say hello, they say hello back, but you have a rich interaction, many days, deep conversations. It might be that the only possible way of implementing that would be one that also has a side effect, instantiated this other person in enough detail that you would have a second consciousness there. I think that's, to some extent, an open question. So, you don't think it's possible to fake consciousness and fake intelligence? Well, it might be. I mean, I think you can certainly fake, if you have a very limited interaction with somebody, you could certainly fake that. That is, if all you have to go on is somebody said hello to you, that's not enough for you to tell whether that was a real person there, or a pre-recorded message, or a very superficial simulation that has no consciousness. Because that's something easy to fake. We could already fake it now, you can record a voice recording. But if you have a richer set of interactions where you're allowed to ask open-ended questions and probe from different angles, you could give canned answers to all of the possible ways that you could probe it, then it starts to become more plausible that the only way to realize this thing, in such a way that you would get the right answer from any which angle you probed it, would be a way of instantiating it where you also instantiated a conscious mind. Yeah, I'm with you on the intelligence part, but there's something about me that says consciousness is easier to fake. I've recently gotten my hands on a lot of Roombas, don't ask me why or how, and I've made them, there's just a nice robotic mobile platform for experiments, and I made them scream or moan in pain and so on, just to see when they're responding to me. And it's just a sort of psychological experiment on myself, and I think they appear conscious to me pretty quickly. To me, at least my brain can be tricked quite easily. So if I introspect, it's harder for me to be tricked that something is intelligent. So I just have this feeling that inside this experience machine, just saying that you're conscious and having certain qualities of the interaction, like being able to suffer, like being able to hurt, like being able to wander about the essence of your own existence, not actually creating the illusion that you're wandering about it, is enough to create the illusion of consciousness, and because of that, create a really immersive experience to where you feel like that is the real world. Is there a big gap between appearing conscious and being conscious, or is it that you think it's very easy to be conscious? I'm not actually sure what it means to be conscious. All I'm saying is the illusion of consciousness is enough to create a social interaction that's as good as if the thing was conscious, meaning I'm making it about myself. Right, yeah. I mean, I guess there are a few different things. One is how good the interaction is, which might, I mean, if you don't really care about probing hard for whether the thing is conscious, maybe it would be a satisfactory interaction, whether or not you really thought it was conscious. Now, if you really care about it being conscious inside this experience machine, how easy would it be to fake it, and you say it sounds fairly easy? But then the question is, would that also mean it's very easy to instantiate consciousness? It's much more widely spread in the world, and we have thought it doesn't require a big human brain with 100 billion neurons. All you need is some system that exhibits basic intentionality and can respond, and you already have consciousness. In that case, I guess you still have a close coupling. I guess a data case would be where they can come apart, where you could create the appearance of there being a conscious mind without actually not being another conscious mind. I'm somewhat agnostic exactly where these lines go. I think one observation that makes it plausible that you could have very realistic appearances relatively simply, which also is relevant for the simulation argument and in terms of thinking about how realistic would a virtual reality model have to be in order for the simulated creature not to notice that anything was awry. Well, just think of our own humble brains during the wee hours of the night when we are dreaming. Many times, well, dreams are very immersive, but often you also don't realize that you're in a dream. And that's produced by simple, primitive three-pound lumps of neural matter effortlessly. So if a simple brain like this can create a virtual reality that seems pretty real to us, then how much easier would it be for a super-intelligent civilization with planetary-sized computers optimized over the eons to create a realistic environment for you to interact with? Yeah, by the way, behind that intuition is that our brain is not that impressive relative to the possibilities of what technology could bring. It's also possible that the brain is the epitome, is the ceiling. The ceiling, how is that possible? Meaning this is the smartest possible thing that the universe could create. So that seems unlikely to me. Yeah, I mean, for some of these reasons we alluded to earlier, in terms of designs we already have for computers that would be faster by many orders of magnitude than the human brain. Yeah, but it could be that the constraints, the cognitive constraints in themselves is what enables the intelligence. So the more powerful you make the computer, the less likely it is to become super-intelligent. This is where I say dumb things to push back on the statement. Yeah, I'm not sure I follow you. So there are different dimensions of intelligence. A simple one is just speed. Like if you could solve the same challenge faster, in some sense, you're smarter. So there I think we have very strong evidence for thinking that you could have a computer in this universe that would be much faster than the human brain and therefore have speed super-intelligence, like be completely superior, maybe a million times faster. Then maybe there are other ways in which you could be smarter as well, maybe more qualitative ways. And the concepts are a little bit less clear-cut, so it's harder to make a very crisp, neat, firmly logical argument about why that could be qualitative super-intelligence as opposed to just things that were faster. Although I still think it's very plausible for various reasons that are less than watertight arguments. But you can sort of, for example, if you look at animals and even within humans, there seems to be Einstein versus random person. It's not just that Einstein was a little bit faster, but how long would it take a normal person to invent general relativity? It's not 20% longer than it took Einstein or something like that. It's like, I don't know whether they would do it at all, or it would take millions of years, or some totally bizarre... But your intuition is that the compute size will get you... Increasing the size of the computer and the speed of the computer might create some much more powerful levels of intelligence that would enable some of the things we've been talking about with the simulation. Being able to simulate an ultra-realistic environment, ultra-realistic perception of reality. Yeah. Strictly speaking, it would not be necessary to have super-intelligence in order to have, say, the technology to make these simulations, ancestor simulations or other kinds of simulations. As a matter of fact, I think if we are in a simulation, it would most likely be one built by a civilization that had super-intelligence. It certainly would help a lot. I mean, it could build more efficient, larger scale structures if you had super-intelligence. I also think that if you had the technology to build these simulations, that's a very advanced technology. It seems kind of easier to get the technology to super-intelligence. So I'd expect by the time they could make these fully realistic simulations of human history with human brains in there, before they got to that stage, they would have figured out how to create machine super-intelligence or maybe biological enhancements of their own brains if they were biological creatures to start with. So we talked about the three parts of the simulation argument. One, we destroy ourselves before we ever create the simulation. Two, we somehow, everybody somehow loses interest in creating simulation. And three, we're living in a simulation. So you've kind of, I don't know if your thinking has evolved on this point, but you kind of said that we know so little that these three cases might as well be equally probable. So probabilistically speaking, where do you stand on this? Yeah, I mean, I don't think equal necessarily would be the most supported probability assignment. So how would you, without assigning actual numbers, what's more or less likely in your view? Well, I mean, I've historically tended to punt on the question of like as between these three. So maybe you ask another way is which kind of things would make each of these more or less likely? What kind of, yeah, intuition. I mean, certainly in general terms, if you take anything that say increases or reduces the probability of one of these, we tend to slosh probability around on the others. If one becomes less probable, like the other would have to, because it's going to add up to one. So if we consider the first hypothesis, the first alternative that there's this filter that makes it so that virtually no civilization reaches technological maturity, in particular, our own civilization. If that's true, then it's like very unlikely that we would reach technological maturity, because if almost no civilization at our stage does it, then it's unlikely that we do it. So hence... Sorry, can you linger on that for a second? Well, if it's the case that almost all civilizations at our current stage of technological maturity fail, at our current stage of technological development fail to reach maturity, that would give us very strong reason for thinking we will fail to reach technological maturity. And also sort of the flip side of that is the fact that we've reached it means that many other civilizations have reached this point. Yeah, so that means if we get closer and closer to actually reaching technological maturity, there's less and less distance left where we could go extinct before we are there. And therefore, the probability that we will reach increases as we get closer. And that would make it less likely to be true that almost all civilizations at our current stage failed to get there. Like we would have this... The one case we'd started ourselves would be very close to getting there. That would be strong evidence that it's not so hard to get to technological maturity. So to the extent that we feel we are moving nearer to technological maturity, that would tend to reduce the probability of the first alternative and increase the probability of the other two. It doesn't need to be a monotonic change. Like if every once in a while, some new threat comes into view, some bad new thing you could do with some novel technology, for example, that could change our probabilities in the other direction. But that technology, again, you have to think about as that technology has to be able to equally, in an even way, affect every civilization out there. Yeah, pretty much. I mean, strictly speaking, it's not true. I mean, that could be two different existential risks in every civilization, you know, one or the other, but none of them kills more than 50%. Yeah, gotcha. Incidentally, some of my work on machine superintelligence, like I've pointed to some existential risks related to superintelligent AI and how we must make sure to handle that wisely and carefully. It's not the right kind of existential catastrophe to make the first alternative true, though. Like it might be bad for us if the future lost a lot of value as a result of it being shaped by some process that optimized for some completely non-human value. But even if we got killed by machine superintelligence, that machine superintelligence might still attain technological maturity. Oh, I see. So you're not human exclusive. This could be any intelligent species that achieves... Like it's all about the technological maturity, it's not that the humans have to attain it. Right. So like superintelligence could replace us and that's just as well for the simulation argument. Yeah, I mean, it could interact with the second alternative. Like if the thing that replaced us was either more likely or less likely, then we would be to have an interest in creating ancestor simulations, you know, that could affect probabilities. But yeah, to a first order, like if we all just die, then yeah, we won't produce any simulations because we are dead. But if we all die and get replaced by some other intelligent thing that then gets to technological maturity, the question remains, of course, if not that thing, then use some of its resources to do this stuff. So can you reason about this stuff? Like given how little we know about the universe, is it reasonable to reason about these probabilities? So like how little... Well, maybe you can disagree, but to me, it's not trivial to figure out how difficult it is to build a simulation. We kind of talked about it a little bit. We also don't know, like as we try to start building it, like start creating virtual worlds and so on, how that changes the fabric of society. Like there's all these things along the way that can fundamentally change just so many aspects of our society about our existence that we don't know anything about. Like the kind of things we might discover when we understand to a greater degree the fundamental, the physics, like the theory, if we have a breakthrough, have a theory and everything, how that changes stuff, how that changes deep space exploration and so on. So like, is it still possible to reason about probabilities given how little we know? Yes, I think there will be a large residual of uncertainty that we'll just have to acknowledge. And I think that's true for most of these big picture questions that we might wonder about. It's just, we are small, short-lived, small-brained, cognitively very limited humans with little evidence. And it's amazing we can figure out as much as we can really about the cosmos. But, okay, so there's this cognitive trick that seems to happen when I look at the simulation argument, which for me, it seems like case one and two feel unlikely. I want to say feel unlikely as opposed to sort of, it's not like I have too much scientific evidence to say that either one or two are not true. It just seems unlikely that every single civilization destroys itself. And it seems, like feels unlikely that the civilizations lose interest. So naturally, without necessarily explicitly doing it, but the simulation argument basically says it's very likely we're living in a simulation. Like to me, my mind naturally goes there. I think the mind goes there for a lot of people. Is that the incorrect place for it to go? Well, not necessarily. I think the second alternative, which has to do with the motivations and interest of technological immature civilizations, I think there is much we don't understand about that. Can you talk about that a little bit? What do you think? I mean, this is a question that pops up when you build an AGI system or build a general intelligence, or how does that change our motivations? Do you think it will fundamentally transform our motivations? Well, it doesn't seem that implausible that once you take this leap to technological maturity, I mean, I think it involves creating machine super intelligence, possibly, that would be sort of on the path for basically all civilizations, maybe before they are able to create large numbers of ancestral simulations. That possibly could be one of these things that quite radically changes the orientation of what a civilization is, in fact, optimizing for. There are other things as well. So, at the moment, we have not perfect control over our own being, our own mental states, our own experiences, are not under our direct control. So, for example, if you want to experience pleasure and happiness, you might have to do a whole host of things in the external world to try to get into the mental state where you experience pleasure. Like, if people get pleasure from eating great food, well, they can't just turn that on. They have to kind of actually go to a nice restaurant and then they have to make money. So, there's like all this kind of activity that maybe arises from the fact that we are trying to ultimately produce mental states, but the only way to do that is by a whole host of complicated activities in the external world. Now, at some level of technological development, I think we'll become auto potent in the sense of gaining direct ability to choose our own internal configuration and enough knowledge and insight to be able to actually do that in a meaningful way. So, then it could turn out that there are a lot of instrumental goals that would drop out of the picture and be replaced by other instrumental goals because we could now serve some of these final goals in more direct ways. And who knows how all of that shakes out after civilizations reflect on that and converge on different attractors and so on and so forth. And that could be new instrumental considerations that come into view as well that we are just oblivious to that would maybe have a strong shaping effect on actions, like very strong reasons to do something or not to do something. And we just don't realize they're there because we are so dumb, fumbling through the universe. But if almost inevitably on route to attaining the ability to create many answers to simulations, you do have this cognitive enhancement or advice from super intelligences or you yourself, then maybe there's this additional set of considerations coming into view. And you have to realize, it's obvious that the thing that makes sense is to do X. Whereas right now it seems, you could X, Y, or Z and different people will do different things. And we are kind of random in that sense. Yeah, because at this time with our limited technology, the impact of our decisions is minor. I mean, that's starting to change in some ways. Well, I'm not sure it follows that the impact of our decisions is minor. Well, it's starting to change. I mean, I suppose a hundred years ago it was minor. It's starting to... It depends on how you view it. But people that a hundred years ago still have effects on the world today. Oh, I see. As a civilization in the togetherness. Yeah. So it might be that the greatest impact of individuals is not at technological maturity or very far down. It might be earlier on when there are different tracks, civilization could go down. I mean, maybe the population is smaller, things still haven't settled out. If you count indirect effects, those could be bigger than the direct effects that people have later on. So part three of the argument says that, so that leads us to a place where eventually somebody creates a simulation. I think you had a conversation with Joe Rogan, I think there's some aspect here where you got stuck a little bit. How does that lead to we're likely living in a simulation? So this kind of probability argument, if somebody eventually creates a simulation, why does that mean that we're now in a simulation? What you get to if you accept alternative three first is there would be more simulated people with our kinds of experiences than non-simulated ones. Like if you look at the world as a whole, by the end of time, as it were, you just count it up. There would be more simulated ones than non-simulated ones. Then there is an extra step to get from that. So suppose for the sake of the argument that that's true, how do you get from that to the statement, we are probably in a simulation? So here you're introducing an indexical statement, like it's that this person right now is in a simulation. There are all these other people that are in simulations and some that are not in a simulation. But what probability should you have that you yourself is one of the simulated ones? So I call it the bland principle of indifference, which is that in cases like this, when you have two sets of observers, one of which is much larger than the other, and you can't from any internal evidence you have tell which set you belong to, you should assign a probability that's proportional to the size of these sets. So that if there are 10 times more simulated people with your kinds of experiences, you would be 10 times more likely to be one of those. Is that as intuitive as it sounds? I mean, that seems kind of, if you don't have enough information, you should rationally just assign the same probability as the size of the set. It seems pretty plausible to me. Where are the holes in this? Is it at the very beginning, the assumption that everything stretches, sort of, you have infinite time, essentially? You don't need infinite time. You just need, how long does the time... Well, however long it takes, I guess, for a universe to produce an intelligent civilization that then attains the technology to run some ancestry simulations. Gotcha. At some point, when the first simulation is created, that stretch of time, just a little longer, then they'll all start creating simulations. Yeah, well, I mean, it might, if you think of there being a lot of different planets and some subset of them have life, and then some subset of those get to intelligent life, and some of those maybe eventually start creating simulations, they might get started at quite different times. Like maybe on some planet, it takes a billion years longer before you get monkeys or before you get even bacteria than on another planet. So this might happen at different cosmological epochs. Is there a connection here to the doomsday argument and that sampling there? Yeah, there is a connection in that they both involve an application of anthropic reasoning, that is reasoning about these kind of indexical propositions. But the assumption you need in the case of the simulation argument is much weaker than the assumption you need to make the doomsday argument go through. What is the doomsday argument? And maybe you can speak to the anthropic reasoning in more general. Yeah, that's a big and interesting topic in its own right, anthropics. But the doomsday argument is this really first discovered by Brandon Carter, who was a theoretical physicist and then developed by philosopher John Leslie. I think it might have been discovered initially in the 70s or 80s. And Leslie wrote this book, I think, in 96. And there are some other versions as well by Richard Gott, who is a physicist. But let's focus on the Carter-Leslie version, where it's an argument that we have systematically underestimated the probability that humanity will go extinct soon. Now, I should say most people probably think at the end of the day, there is something wrong with this doomsday argument that it doesn't really hold. It's like there's something wrong with it, but it's proved hard to say exactly what is wrong with it. And different people have different accounts. My own view is it seems inconclusive. And I can say what the argument is. Yeah, that would be good. Yeah, so maybe it's easiest to explain via an analogy to sampling from urns. So imagine you have two urns in front of you, and they have balls in them that have numbers. The two urns look the same, but inside one, there are 10 balls. Ball number one, two, three, up to ball number 10. And then in the other urn, you have a million balls numbered one to a million. And somebody puts one of these urns in front of you and asks you to guess what's the chance it's the 10 ball urn. And you say, well, 50-50, I can't tell which urn it is. But then you're allowed to reach in and pick a ball at random from the urn. And let's suppose you find that it's ball number seven. So that's strong evidence for the 10 ball hypothesis. It's a lot more likely that you would get such a low-numbered ball if there are only 10 balls in the urn. It's in fact 10% done, right? Then if there are a million balls, it would be very unlikely you would get number seven. So you perform a Bayesian update. And if your prior was 50-50 that it was the 10 ball urn, you become virtually certain after finding the random sample was seven that it only has 10 balls in it. So in the case of the urns, this is uncontroversial, just elementary probability theory. The Doomsday Argument says that you should reason in a similar way with respect to different hypotheses about how many balls there will be in the urn of humanity. I said, for how many humans there will ever be by the time we go extinct. So to simplify, let's suppose we only consider two hypotheses, either maybe 200 billion humans in total or 200 trillion humans in total. You could fill in more hypotheses, but it doesn't change the principle here. So it's easiest to see if we just consider these two. So you start with some prior based on ordinary empirical ideas about threats to civilization and so forth. And maybe you say it's a 5% chance that we will go extinct by the time there will have been 200 billion only. You're kind of optimistic, let's say. You think probably we'll make it through, colonize the universe. But then, according to this Doomsday Argument, you should think of your own birth rank as a random sample. So your birth rank is your sequence in the position of all humans that have ever existed. It turns out you're about a human number of 100 billion, give or take. That's roughly how many people have been born before you. That's fascinating because we each have a number. We would each have a number in this. Obviously, the exact number would depend on where you started counting, like which ancestors was human enough to count as human. But those are not really important. There are relatively few of them. So you're roughly 100 billion. Now, if there are only going to be 200 billion in total, that's a perfectly unremarkable number. You're somewhere in the middle, right? It's run-of-the-mill human, completely unsurprising. Now, if there are going to be 200 trillion, you would be remarkably early. What are the chances out of these 200 trillion humans that you should be human number 100 billion? That seems it would have a much lower conditional probability. And so analogously to how in the urn case you thought after finding this low-numbered random sample, you updated in favor of the urn having few balls. Similarly, in this case, you should update in favor of the human species having a lower total number of members. That is doom soon. You said doom soon? Yeah. Well, that would be the hypothesis in this case, that it will end after 100 billion. I just like that term for that hypothesis. So what it kind of crucially relies on, the doomsday argument, is the idea that you should reason as if you were a random sample from the set of all humans that will ever have existed. If you have that assumption, then I think the rest kind of follows. The question then is why should you make that assumption? In fact, you know you're 100 billion, so where do you get this prior? And then there is like a literature on that with different ways of supporting that assumption. That's just one example of atheropic reasoning, right? That seems to be kind of convenient when you think about humanity, when you think about sort of even like existential threats and so on. As it seems that quite naturally that you should assume that you're just an average case. Yeah, that you're a kind of a typical, a randomly sampled. Now, in the case of the doomsday argument, it seems to lead to what intuitively we think is the wrong conclusion. Or at least many people have this reaction that there's got to be something fishy about this argument. Because from very, very weak premises, it gets this very striking implication that we have almost no chance of reaching size 200 trillion humans in the future. And how could we possibly get there just by reflecting on when we were born? It seems you would need sophisticated arguments about the impossibility of space colonization, blah, blah. So one might be tempted to reject this key assumption. I call it the self-sampling assumption. The idea that you should reason as if you're a random sample from all observers or in some reference class. However, it turns out that in other domains, it looks like we need something like this self-sampling assumption to make sense of bona fide scientific inferences. In contemporary cosmology, for example, you have these multiverse theories. And according to a lot of those, all possible human observations are made. So if you have a sufficiently large universe, you will have a lot of people observing all kinds of different things. So if you have two competing theories, say about the value of some constant, it could be true according to both of these theories that there will be some observers observing the value that corresponds to the other theory. Because there will be some observers that have hallucinations, so there's a local fluctuation or a statistically anomalous measurement. These things will happen. And if enough observers make enough different observations, there will be some that sort of by chance make these different ones. And so what we would want to say is, well, many more observers, a larger proportion of the observers will observe as it were the true value. And a few will observe the wrong value. If we think of ourselves as a random sample, we should expect with a probability to observe the true value. And that will then allow us to conclude that the evidence we actually have is evidence for the theories we think are supported. It kind of then is a way of making sense of these inferences that clearly seem correct, that we can make various observations and infer what the temperature of the cosmic background is and the fine structure constant and all of this. But it seems that without rolling in some assumption similar to the self-sampling assumption, this inference just doesn't go through. And there are other examples. So there are these scientific contexts where it looks like this kind of anthropic reasoning is needed and makes perfect sense. And yet, in the case of the Doobster argument, it has this weird consequence and people might think there's something wrong with it there. So there's then this project that would consistently try to figure out what are the legitimate ways of reasoning about these indexical facts when observer selection effects are in play. In other words, developing a theory of anthropics. And there are different views of looking at that. And it's a difficult methodological area. But to tie it back to the simulation argument, the key assumption there, this bland principle of indifference, is much weaker than the self-sampling assumption. So if you think about in the case of the Doomsday argument, it says you should reason as if you're a random sample from all humans that will ever have lived. Even though in fact, you know that you are about number 100 billionth human and you're alive in the year 2020. Whereas in the case of the simulation argument, it says that, well, if you actually have no way of telling which one you are, then you should assign this kind of uniform probability. Yeah, yeah. Your role as the observer in the simulation argument is different, it seems like. Who's the observer? I keep assigning the individual consciousness. Well, a lot of observers in the context of the simulation argument, the relevant observers would be A, the people in original histories, and B, the people in simulations. So this would be the class of observers that we need. I mean, there are also maybe the simulators, but we can set those aside for this. So the question is, given that class of observers, a small set of original history observers and a large class of simulated observers, which one should you think is you? Where are you amongst this set of observers? I'm maybe having a little bit of trouble wrapping my head around the intricacies of what it means to be an observer in the different instantiations of the anthropic reasoning cases that we mentioned. I mean, it may be an easier way of putting it, it's just like, are you simulated or are you not simulated? Given this assumption that these two groups of people exist. Yeah, in the simulation case, it seems pretty straightforward. Yeah. So the key point is the methodological assumption you need to make to get the simulation argument to where it wants to go is much weaker and less problematic than the methodological assumption you need to make to get the doomsday argument to its conclusion. Maybe the doomsday argument is sound or unsound, but you need to make a much stronger and more controversial assumption to make it go through. In the case of the simulation argument, I guess one maybe way intuition popped to support this blind principle of indifference is to consider a sequence of different cases where the fraction of people who are simulated to non-simulated approaches one. So in the limiting case where everybody is simulated, obviously you can deduce with certainty that you are simulated. If everybody with your experiences is simulated, then you know you're got to be one of those. You don't need a probability at all. You just kind of logically conclude it. Right. So then as we move from a case where say 90% of everybody is simulated, 99.9%, it should seem plausible that the probability assigned should sort of approach one certainty as the fraction approaches the case where everybody is in a simulation. Yeah, that's a good one. So you wouldn't expect that to be a discrete. Well, if there's one non-simulated person, then it's 50-50. But if we'd move that, then it's 100%. There are other arguments as well one can use to support this blind principle of indifference, but that might be enough to... But in general, when you start from time equals zero and go into the future, the fraction of simulated, if it's possible to create simulated worlds, the fraction of simulated worlds will go to one. Well, it won't probably go all the way to one. In reality, there would be some ratio. Although maybe a technologically mature civilization could run a lot of simulations using a small portion of its resources, it probably wouldn't be able to run infinitely many. I mean, if we take, say, the physics in the observed universe, if we assume that that's also the physics at the level of the simulators, that would be limits to the amount of information processing that any one civilization could perform in its future trajectory. Right. Well, first of all, there's a limited amount of matter you can get your hands off because with a positive cosmological constant, the universe is accelerating. There is a finite sphere of stuff, even if you travel with the speed of light that you could ever reach, you have a finite amount of stuff. And then if you think there is a lower limit to the amount of loss you get when you perform an erasure of a computation, or if you think, for example, just matter gradually over cosmological time scales, decay, maybe protons decay, other things, and you radiate out gravitational waves. There's all kinds of seemingly unavoidable losses that occur. So eventually we'll have something like a heat death of the universe or a cold death or whatever. So it's finite, but of course we don't know which, if there's many ancestral simulations, we don't know which level we are. So there could be, couldn't there be like an arbitrary number of simulation that spawned ours and those had more resources in terms of physical universe to work with? Sorry, what do you mean that that could be? Sort of, okay, so if simulations spawn other simulations, it seems like each new spawn has fewer resources to work with. Yeah. But we don't know at which step along the way we are at. Any one observer doesn't know whether we're in level 42 or 100 or 1, or does that not matter for the resources? I mean, it's true that there would be uncertainty as you could have stacked simulations and that could be uncertainty as to which level we are at. As you remarked also, all the computations performed in a simulation within the simulation also have to be expanded at the level of the simulation. Right. So the computer in basement reality where all the simulations within the simulations within the simulations are taking place, like that computer ultimately, it's CPU or whatever it is that has to power this whole tower. Right. So if there is a finite compute power in basement reality, that would impose a limit to how tall this tower can be. And if each level kind of imposes a large extra overhead, you might think maybe the tower would not be very tall, that most people would be low down in the tower. I love the term basement reality. Let me ask one of the popularizers, you said there's many through this, when you look at sort of the last few years of the simulation hypothesis, just like you said, it comes up every once in a while, some new community discovers it and so on. But I would say one of the biggest popularizers of this idea is Elon Musk. Do you have any kind of intuition about what Elon thinks about when he thinks about simulation? Why is this of such interest? Is it all the things we've talked about or is there some special kind of intuition about simulation that he has? I mean, you might have a better, I think, I mean, why it's of interest, I think it's like seems fairly obvious why, to the extent that one think the argument is credible, why it would be of interest. It would, if it's correct, tell us something very important about the world, in one way or the other, whichever of the three alternatives for a simulation, that seems like arguably one of the most fundamental discoveries. Right. Now, interestingly, in the case of someone like Elon, so there's like the standard arguments for why you might want to take the simulation hypothesis seriously, the simulation argument, right. In the case that if you are actually Elon Musk, let us say, there's a kind of an additional reason in that what are the chances you would be Elon Musk? Like, it seems like maybe there would be more interest in simulating the lives of very unusual and remarkable people. So if you consider not just a simulations where all of human history or the whole of human civilization are simulated, but also other kinds of simulations, which only include some subset of people. Like in those simulations that only include a subset, it might be more likely that that would include subsets of people with unusually interesting or consequential lives. So if you're Elon Musk, it's more likely than your inspiration. Or if you're Donald Trump, or if you're Bill Gates, or you're like some particularly distinctive character, you might think that that adds, I mean, if you just think of yourself into the shoes, right, it's got to be like an extra reason to think, that's kind of. So interesting. So on a scale of like Farmer in Peru to Elon Musk, the more you get towards the Elon Musk, the higher the probability. You'd imagine that would be some extra boost from that. There's an extra boost. So he also asked the question of what he would ask an AGI saying, the question being, what's outside the simulation? Do you think about the answer to this question, if we are living in a simulation, what is outside the simulation? So the programmer of the simulation? Yeah, I mean, I think it connects to the question of what's inside the simulation in that if you had views about the creators of the simulation, it might help you make predictions about what kind of simulation it is, what might happen, what happens after the simulation, if there is some after, but also like the kind of setup. So these two questions would be quite closely intertwined. But do you think it would be very surprising to like, is the stuff inside the simulation, is it possible for it to be fundamentally different than the stuff outside? Yeah. Like, another way to put it, can the creatures inside the simulation be smart enough to even understand or have the cognitive capabilities or any kind of information processing capabilities enough to understand the mechanism that created them? They might understand some aspects of it. I mean, it's a level of, it's kind of, there are levels of explanation, like degrees to which you can understand. So does your dog understand what it is to be human? Well, it's got some idea, like humans are these physical objects that move around and do things. And like a normal human would have a deeper understanding of what it is to be a human. And maybe some very experienced psychologist or great novelist might understand a little bit more about what it is to be human. And maybe superintelligence could see right through your soul. So similarly, I do think that we are quite limited in our ability to understand all of the relevant aspects of the larger context that we exist in. But there might be hope for some. I think we understand some aspects of it. But, you know, how much good is that if there's like one key aspect that changes the significance of all the other aspects? So we understand maybe seven out of 10 key insights that you need. But the answer actually, like varies completely depending on what like number eight, nine and 10 insight is. It's like whether you want to, suppose that the big task were to guess whether a certain number was odd or even, like a 10 digit number. And if it's even, the best thing for you to do in life is to go north. And if it's odd, the best thing for you to go south. Now we are in a situation where maybe through our science and philosophy, we figured out what the first seven digits are. So we have a lot of information, right? Most of it we figured out. But we are clueless about what the last three digits are. So we are still completely clueless about whether the number is odd or even and therefore whether we should go north or go south. I feel that's an analogy, but I feel we're somewhat in that predicament. We know a lot about the universe. We've come maybe more than half of the way there to kind of fully understanding it. But the parts we're missing are plausibly ones that could completely change the overall upshot of the thing and including change our overall view about what the scheme of priorities should be or which strategic direction would make sense to pursue. Yeah, I think your analogy of us being the dog trying to understand human beings is an entertaining one and probably correct. The closer the understanding tends from the dog's viewpoint to us human psychologists viewpoint, the steps along the way there will have completely transformative ideas of what it means to be human. So a dog has a very shallow understanding. It's interesting to think that, to analogize that a dog's understanding of a human being is the same as our current understanding of the fundamental laws of physics in the universe. Oh man, okay. We spent an hour and 40 minutes talking about the simulation. I like it. Let's talk about superintelligence, at least for a little bit. And let's start at the basics. What to you is intelligence? Yeah, not to get too stuck with the definitional question. I mean, the common sense to understand, like the ability to solve complex problems, to learn from experience, to plan, to reason, some combination of things like that. Is consciousness mixed up into that or no? Is consciousness mixed up into that or is it- Well, I think it could be fairly intelligent, at least without being conscious probably. So then what is superintelligence? Yeah, that would be like something that was much more, had much more general cognitive capacity than we humans have. So if we talk about general superintelligence, it would be much faster learner be able to reason much better, make plans that are more effective at achieving its goals, say in a wide range of complex, challenging environments. In terms of, as we turn our eye to the idea of sort of existential threats from superintelligence, do you think superintelligence has to exist in the physical world or can it be digital only? Sort of, we think of our general intelligence as us humans, as an intelligence that's associated with the body that's able to interact with the world, that's able to affect the world directly with physically. I mean, digital only is perfectly fine, I think. I mean, it's physical in the sense that obviously the computers and the memories are physical. But it's capability to affect the world sort of- Could be very strong, even if it has a limited set of actuators, if it can type text on the screen or something like that, that would be, I think, ample. So in terms of the concerns of existential threat of AI, how can an AI system that's in the digital world have existential risk sort of, and what are the attack vectors for a digital system? Well, I mean, I guess maybe to take one step back, I should emphasize that I also think there's this huge positive potential from machine intelligence, including superintelligence. And I want to stress that because some of my writing has focused on what can go wrong. And when I wrote the book, Superintelligence, at that point, I felt that there was a kind of neglect of what would happen if AI succeeds, and in particular, a need to get a more granular understanding of where the pitfalls are so we can avoid them. And I think that since the book came out in 2014, there has been a much wider recognition of that, and a number of research groups are now actually working on developing, say, AI alignment techniques and so on and so forth. So I think now it's important to make sure we bring back onto the table the upside as well. And there's a little bit of a neglect now on the upside, which is, I mean, if you look at, I was talking to a friend, if you look at the amount of information that is available, or people talking, people being excited about the positive possibilities of general intelligence, that's not, it's far outnumbered by the negative possibilities in terms of our public discourse. Possibly, yeah. It's hard to measure. Can you linger on that for a little bit? What are some, to you, possible big positive impacts of general intelligence, superintelligence? Well, I mean, superintelligence, because I tend to also want to distinguish these two different contexts of thinking about AI and AI impacts, the kind of near term and long term, if you want, both of which I think are legitimate things to think about, and people should discuss both of them. But they are different and they often get mixed up. And then I get, you get confusion. I think you get simultaneously, like maybe an overhyping of the near term and an underhyping of the long term. And so I think as long as we keep them apart, we can have like two good conversations, or we can mix them together and have one bad conversation. Can you clarify just the two things we're talking about, the near term and the long term? What are the distinctions? Well, it's a blurry distinction. But say the things I wrote about in this book, superintelligence, long term, things people are worrying about today with, I don't know, algorithmic discrimination, or even things, self-driving cars and drones and stuff, more near term. And then of course, you could imagine some medium term where they kind of overlap and one evolves into the other. But at any rate, I think both, yeah, the issues look kind of somewhat different depending on which of these contexts. So I think it would be nice if we can talk about the long term and think about a positive impact or a better world because of the existence of the long term superintelligence. Do you have views of such a world? I guess it's a little hard to articulate because it seems obvious that the world has a lot of problems as it currently stands. And it's hard to think of any one of those which it wouldn't be useful to have a friendly aligned superintelligence working on. So from health to the economic system to be able to sort of improve the investment and trade and foreign policy decisions, all that kind of stuff. All that kind of stuff and a lot more. I mean, what's the killer app? Well, I don't think there is one. I think AI, especially artificial general intelligence is really the ultimate general purpose technology. So it's not that there's this one problem, this one area where it will have a big impact. But if and when it succeeds, it will really apply across the board in all fields where human creativity and intelligence and problem solving is useful, which is pretty much all fields, right? The thing that it would do is give us a lot more control over nature. It wouldn't automatically solve the problems that arise from conflict between humans, fundamentally political problems. Some subset of those might go away if you just had more resources and cooler tech, but some subset would require coordination that is not automatically achieved just by having more technological capability. But anything that's not of that sort, I think you just get an enormous boost with this kind of cognitive technology once it goes all the way. Now, again, that doesn't mean I'm thinking, oh, people don't recognize what's possible with current technology. And sometimes things get overhyped, but I mean, those are perfectly consistent views to hold the ultimate potential being enormous. And then it's a very different question of how far are we from that or what can we do with near-term technology? Yeah, so what's your intuition about the idea of intelligence explosion? So there's this, you know, when you start to think about that leap from the near term to the long term, the natural inclination, like for me, sort of building machine learning systems today, it seems like it's a lot of work to get to general intelligence. But there's some intuition of exponential growth, of exponential improvement, of intelligence explosion. Can you maybe try to elucidate, try to talk about what's your intuition about the possibility of intelligence explosion, that it won't be this gradual, slow process, there might be a phase shift? Yeah, I think it's, we don't know how explosive it will be. I think for what it's worth, it seems fairly likely to me that at some point there will be some intelligence explosion, like some period of time where progress in AI becomes extremely rapid. And roughly in the area where you might say it's kind of human-ish equivalent in core cognitive faculties, that the concept of human equivalent starts to break down when you look too closely at it. And just how explosive does something have to be for it to be called an intelligence explosion? Does it have to be overnight, literally, or a few years? But overall, I guess, if you plotted the opinions of different people in the world, I guess I would be somewhat more probability towards the intelligence explosion scenario than probably the average AI researcher, I guess. So, and then the other part of the intelligence explosion, or just forget explosion, just progress, is once you achieve that gray area of human level intelligence, is it obvious to you that we should be able to proceed beyond it to get to super intelligence? Yeah, that seems, I mean, as much as any of these things can be obvious, given we've never had one, people have different views, smart people have different views, it's like there's some degree of uncertainty that always remains for any big futuristic philosophical grand question that just we realize humans are fallible, especially about these things. But it does seem, as far as I'm judging things based on my own impressions, that it seems very unlikely that that would be a ceiling at or near human cognitive capacity. And that's such a, I don't know, that's such a special moment. It's both terrifying and exciting to create a system that's beyond our intelligence. So maybe you can step back and say, like, how does that possibility make you feel? That we can create something, it feels like there's a line beyond which it steps, it'll be able to outsmart you. And therefore, it feels like a step where we lose control. Well, I don't think the latter follows. That is, you could imagine, and in fact, this is what a number of people are working towards, making sure that we could ultimately project higher levels of problem solving ability while still making sure that they are aligned, like they are in the service of human values. I mean, so losing control, I think, is not a given that that would happen. Now you asked how it makes you feel. I mean, to some extent, I've lived with this for so long, since as long as I can remember, being an adult or even a teenager, it seemed to me obvious that at some point, AI will succeed. And so I actually misspoke, I didn't mean control. I meant, because the control problem is an interesting thing, and I think the hope is, at least we should be able to maintain control over systems that are smarter than us. But we do lose our specialness. It's sort of, we'll lose our place as the smartest, coolest thing on earth. And there's an ego involved with that, that humans aren't very good at dealing with. I mean, I value my intelligence as a human being. It seems like a big transformative step to realize there's something out there that's more intelligent. I mean, you don't see that as such a fundamentally... I think, yes, a lot. I think there are already a lot of things out there that are, I mean, certainly if you think the universe is big, there's going to be other civilizations that already have super intelligences, or that just naturally have brains the size of beach balls and are like, completely leaving us in the dust. And we haven't come face to face with them. We haven't come face to face, but I mean, that's an open question. What would happen in a kind of post-human world? Like how much day to day would these super intelligences be involved in the lives of ordinary... I mean, you could imagine some scenario where it would be more like a background thing that would help protect against some things, but you wouldn't... Like, there wouldn't be this intrusive kind of, like, making you feel bad by making clever jokes on your expense. There's like all sorts of things that maybe in the human context would feel awkward about that. You don't want to be the dumbest kid in your class. Everybody picks it. Like, a lot of those things, maybe you need to abstract away from if you're thinking about this context where we have infrastructure that is in some sense, beyond any or all humans. I mean, it's a little bit like say the scientific community as a whole, if you think of that as a mind, it's a little bit of metaphor, but I mean, obviously, it's got to be like, way more capacious than any individual. So in some sense, there is this mind like thing already out there that's just vastly more intelligent than a new individual is. And we think, okay, that's, you just accept that as a fact. That's the basic fabric of our existence is there's a super intelligence. Yeah, you get used to a lot of... I mean, there's already Google and Twitter and Facebook, these recommender systems that are the basic fabric of our... I could see them becoming... I mean, do you think of the collective intelligence of these systems as already perhaps reaching super intelligence level? Well, I mean, so here it comes to this, the concept of intelligence and the scale and what human level means. The kind of vagueness and indeterminacy of those concepts starts to dominate how you would answer that question. So, like, say the Google search engine has a very high capacity of a certain kind, like remembering and retrieving information, particularly like text or images that you have a kind of string, a word string key, like obviously superhuman at that, but a vast set of other things it can't even do at all, not just not do well. So, you have these current AI systems that are superhuman in some limited domain and then radically subhuman in all other domains. Same with a chess, like a simple computer that can multiply really large numbers, right? So, it's going to have this like one spike of super intelligence and then a kind of a zero level of capability across all other cognitive fields. Yeah, I don't necessarily think the generalness, I mean, I'm not so attached with it, but I could sort of, it's a gray area and it's a feeling, but to me, sort of alpha zero is somehow much more intelligent, much, much more intelligent than deep blue. And to say which domain, well, you could say, well, these are both just board games, they're both just able to play board games, who cares if they're gonna do better or not, but there's something about the learning, the self play that makes it, crosses over into that land of intelligence that doesn't necessarily need to be general. In the same way, Google is much closer to deep blue currently in terms of its search engine than it is to sort of the alpha zero. And the moment these recommender systems really become more like alpha zero, but being able to learn a lot without the constraints of being heavily constrained by human interaction, that seems like a special moment in time. I mean, certainly learning ability seems to be an important facet of general intelligence, that you can take some new domain that you haven't seen before, and you weren't specifically pre-programmed for, and then figure out what's going on there and eventually become really good at it. That's something alpha zero has much more of than deep blue had. And in fact, I mean, systems like alpha zero can learn not just goal, but other, in fact, probably beat deep blue in chess and so forth. So you do see this general, and it matches the intuition, we feel it's more intelligent, and it also has more of this general purpose learning ability. And if we get systems that have even more general purpose learning ability, it might also trigger an even stronger intuition that they are actually starting to get smart. So if you were to pick a future, what do you think a utopia looks like with AGI systems? Is it the neural link brain computer interface world where we're kind of really closely interlinked with AI systems? Is it possibly where AGI systems replace us completely while maintaining the values and the consciousness? Is it something like it's a completely invisible fabric, like you mentioned, a society where just AIDS and a lot of stuff that we do, like curing diseases and so on? What is the utopia if you get to pick? Yeah, I mean, it's a good question, and a deep and difficult one. I'm quite interested in it. I don't have all the answers yet, but or might never have. But I think there are some different observations one could make. One is if this scenario actually did come to pass, it would open up this vast space of possible modes of being. On one hand, material and resource constraints would just be expanded dramatically. So there would be a lot of a big pie, let's say. Also, it would enable us to do things, including to ourselves, or like that. It would just open up this much larger design space and option space than we have ever had access to in human history. So I think two things follow from that. One is that we probably would need to make a fairly fundamental rethink of what ultimately we value. Like think things through more from first principles. The context would be so different from the familiar that we could have just take what we've always been doing and then like, oh, well, we have this cleaning robot that cleans the dishes in the sink and a few other small things. I think we would have to go back to first principles. So even from the individual level, go back to the first principles of what is the meaning of life, what is happiness, what is fulfillment? And then also connected to this large space of resources is that it would be possible, and I think something we should aim for is to do well by the lights of more than one value system. That is, we wouldn't have to choose only one value criterion and say, we're going to do something that scores really high on the metric of, say, hedonism. And then is like a zero by other criteria, like kind of wire headed brain Cinevat. And it's like a lot of pleasure. That's good. But then like no beauty, no achievement. I think to some significant, not unlimited sense, but a significant sense, it would be possible to do very well by many criteria. Like maybe you could get like 98% of the best according to several criteria at the same time, given this great expansion of the option space. So have competing value systems, competing criteria as a sort of forever, just like our Democrat versus Republican, there seems to be this always multiple parties that are useful for our progress in society, even though it might seem dysfunctional inside the moment. But having the multiple value systems seems to be beneficial for, I guess, a balance of power. So that's not exactly what I have in mind that it's well, although it can be maybe in an indirect way it is. But that if you had the chance to do something that scored well, on several different metrics, our first instinct should be to do that rather than immediately leap to the thing, which ones of these value systems are we going to screw over? Let's first try to do very well by all of them. Then it might be that you can't get 100% of all, and you would have to then have the hard conversation about which one will only get 97%. There you go. There's my cynicism that all of existence is always a trade-off. But you say, maybe it's not such a bad trade-off. Let's first at least try it out. Well, this would be a distinctive context in which at least some of the constraints would be removed. So there's probably still be trade-offs in the end. It's just that we should first make sure we at least take advantage of this abundance. So in terms of thinking about this, one should think in this kind of frame of mind of generosity and inclusiveness to different value systems and see how far one can get there first. I think one could do something that would be very good according to many different criteria. We kind of talked about AGI fundamentally transforming the value system of our existence, the meaning of life. But today, what do you think is the meaning of life? The silliest or perhaps the biggest question. What's the meaning of life? What's the meaning of existence? What gives your life fulfillment, purpose, happiness, meaning? Yeah, I think these are, I guess, a bunch of different related questions in there that one can ask. Happiness, meaning, they're all different. I mean, it could imagine somebody getting a lot of happiness from something that they didn't think was meaningful. Like mindless, like watching reruns of some television series while eating junk food. Maybe some people that gives pleasure, but they wouldn't think it had a lot of meaning. Whereas conversely, something that might be quite loaded with meaning might not be very fun always. Like some difficult achievement that really helps a lot of people, maybe requires self-sacrifice and hard work. And so these things can, I think, come apart, which is something to bear in mind also if you're thinking about these utopia questions. To actually start to do some constructive thinking about that, you might have to isolate and distinguish these different kinds of things that might be valuable in different ways. Make sure you can sort of clearly perceive each one of them, and then you can think about how you can combine them. And just as you said, hopefully come up with a way to maximize all of them together. Yeah, or at least get, I mean, maximize or get like a very high score on a wide range of them, even if not literally all. You can always come up with values that are exactly opposed to one another, right? But I think for many values, they're kind of opposed if you place them within a certain dimensionality of your space. Like there are shapes that you can't untangle in a given dimensionality, but if you start adding dimensions, then it might in many cases just be that they are easy to pull apart. And you could, so we'll see how much space there is for that, but I think that there could be a lot in this context of radical abundance if ever we get to that. I don't think there's a better way to end it, Nick. You've influenced a huge number of people to work on what could very well be the most important problems of our time. So it's a huge honor. Thank you so much for talking to me. Well, thank you for coming by, Lex. That was fun. Thank you. Thanks for listening to this conversation with Nick Bostrom and thank you to our presenting sponsor, Cash App. Please consider supporting the podcast by downloading Cash App and using code LEXPODCAST. If you enjoy this podcast, subscribe on YouTube, review it with five stars on Apple Podcast, support it on Patreon, or simply connect with me on Twitter at Lex Friedman. And now let me leave you with some words from Nick Bostrom. Our approach to existential risks cannot be one of trial and error. There's no opportunity to learn from errors. The reactive approach, see what happens, limit damages, and learn from experience is unworkable. Rather, we must take a proactive approach. This requires foresight to anticipate new types of threats and a willingness to take decisive preventative action and to bear the costs, moral and economic, of such actions. Thank you for listening and hope to see you next time.