Are we losing it?

Nick Bostrom’s suggestion that we’re most likely living in a simulated world continues to provoke discussion.  Joelle Dahm draws an interesting parallel with multiverses. I think myself that it depends a bit on what kind of multiverse you’re going for – the ones that come from an interpretation of quantum physics usually require conservation of identity between universes – you have to exist in more than one universe – which I think is both potentially problematic and strictly speaking non-Bostromic. Dahm also briefly touches on some tricky difficulties about how we could tell whether we were simulated or not, which seem reminiscent of Descartes’ doubts about how he could be sure he wasn’t being systematically deceived by a demon – hold that thought for now.

Some of the assumptions mentioned by Dahm would probably annoy Sabine Hossenfelder, who lays into the Bostromisers with a piece about just how difficult simulating the physics of our world would actually be: a splendid combination of indignation with actually knowing what she’s talking about.

Bostrom assumes that if advanced civilisations typically have a long lifespan, most will get around to creating simulated versions of their own civilisation, perhaps re-enactments of earlier historical eras. Since each simulated world will contain a vast number of people, the odds are that any randomly selected person is in fact living in a simulated world. The probability becomes overwhelming if we assume that the simulations are good enough for the simulated people to create simulations within their own world, and so on.

There’s  plenty of scope for argument about whether consciousness can be simulated computationally at all, whether worlds can be simulated in the required detail, and certainly about the optimistic idea of nested simulations. But recently I find myself thinking, isn’t it simpler than that? Are we simulated people in a simulated world? No, because we’re real, and people in a simulation aren’t real.

When I say that, people look at me as if I were stupid, or at least, impossibly naive. Dude,  read some philosophy, they seem to say. Dontcha know that Socrates said we are all just grains of sand blowing in the wind?

But I persist – nothing in a simulation actually exists (clue’s in the name), so it follows that if we exist, we are not in a simulation. Surely no-one doubts their own existence (remember that parallel with Descartes), or if they do, only on the kind of philosophical level where you can doubt the existence of anything? If you don’t even exist, why do I even have to address your simulated arguments?

I do, though. Actually, non-existent people can have rather good arguments; dialogues between imaginary people are a long-established philosophical method (in my feckless youth I may even have indulged in the practice myself).

But I’m not entirely sure what the argument against reality is. People do quite often set out a vision of the world as powered by maths; somewhere down there the fundamental equations are working away and the world is what they’re calculating. But surely that is the wrong way round; the equations describe reality, they don’t dictate it. A system of metaphysics that assumes the laws of nature really are explicit laws set out somewhere looks tricky to me; and worse, it can never account for the arbitrary particularity of the actual world. We sort of cling to the hope that this weird specificity can eventually be reduced away by titanic backward extrapolation to a hypothetical time when the cosmos was reduced to the simplicity of a single point, or something like it; but we can’t make that story work without arbitrary constants and the result doesn’t seem like the right kind of explanation anyway. We might appeal instead to the idea that the arbitrariness of our world arises from it’s being an arbitrary selection out of the incalculable banquet of the multiverse, but that doesn’t really explain it.

I reckon that reality just is the thing that gets left out of the data and the theory; but we’re now so used to the supremacy of those two we find it genuinely hard to remember, and it seems to us that a simulation with enough data is automatically indistinguishable from real events – as though once your 3D printer was programmed, there was really nothing to be achieved by running it.

There’s one curious reference in Dahm’s piece which makes me wonder whether Christof Koch agrees with me. She says the Integrated Information Theory doesn’t allow for computer consciousness. I’d have thought it would; but the remarks from Koch she quotes seem to be about how you need not just the numbers about gravity but actual gravity too, which sounds like my sort of point.

Regular readers may already have noticed that I think this neglect of reality also explains the notorious problem of qualia; they’re just the reality of experience. When Mary sees red, she sees something real, which of course was never included in her perfect theoretical understanding.

I may be naive, but you can’t say I’m not consistent…


  1. 1. SelfAwarePatterns says:

    A simulation doesn’t necessary have to recreate all the physics of the outside world in order to simulate the experience of it. It can feed sensory information to a simulated mind that makes it think the physics are all out there. Indeed, since it controls the reasoning of the simulated mind, it can merely make that mind think it’s been supplied with that information.

    Saying simulated activities don’t exist seems problematic to me. Doesn’t the simulation itself exist? If it does, doesn’t that mean its components, its contents, exist? Certainly they may not exist in the way the patterns they represent outside of the simulation exist, but then science keeps showing us that *we* don’t exist in the same way we often think we do.

    The question is, what in our patterns outside of the simulation make us different than the patterns inside the simulation? Granted, no simulation can go down to the base level of reality of patterns outside of it. But what level is necessary to capture the essence of the outside pattern?

    If the outputs of a simulated mind are effectively indistinguishable from the “real” version, particularly in terms of its simulated environment, by what right do we declare it less real? If an alien looked at us and decided because of our physical composition that we were “just” simulations of actual minds, what argument could we give to convince it otherwise?

    It’s worth remembering that we already know we live inside a simulation. Our brain creates internal image maps of the external world, a simulated reality. Our success hinges on that simulation being effective, albeit not necessarily accurate. But it may not stop there. Our feeling of an emotion may be a simulation in the neocortex of impulses in sub-cortical levels of the brain. Our brain runs simulations of other parts of itself. Where does the border lie between “us” and the simulations?

  2. 2. Peter says:

    A simulation doesn’t necessary have to recreate all the physics of the outside world

    But if you’re claiming that this actual world we’re in is a simulation, then that simulation certainly has to include all the features of this world!

    Doesn’t the simulation itself exist?

    Yes, but so what? The film trilogy The Lord of the Rings exists; that doesn’t mean Minas Tirith and Chicago are equally to be believed in.

    The question is, what in our patterns outside of the simulation make us different than the patterns inside the simulation?

    Reality. We’re real.

    It’s worth remembering that we already know we live inside a simulation.

    I think that’s an exaggeration. Our knowledge of the world is imperfect, but then a history book isn’t a perfect account. Are all history books the history of simulations?

  3. 3. SelfAwarePatterns says:

    On Lord of the Rings, I think it’s clearer to talk about one of the characters. Frodo exists as a fictional conception. No one would argue that Frodo as defined by Tolkien is real in the sense that you or I are real. The specification for him is too much of a facade for that, put together for our entertainment.

    But suppose we begin enhancing the specification to include a fictional brain with information flow similar to a real brain to increasingly detailed levels? You might continue to argue that he does not exist, but at some level of resolution, I know I’d start to squirm and worry that, even if everything else in LOTR remains a thin facade, maybe we were subjecting some kind of thinking feeling being to abuse.

    On the simulation in our brain, I’m not arguing that is isn’t an effective representation of what’s out there. At least for mentally healthy people. And science and philosophy enable us to go beyond day to day effectiveness and hopefully sharpen our models to increasingly accurate approximations.

    But the distinction between reality and the internal simulation seems more evident when we consider people where things aren’t working right, such as patients with schizophrenia. Their model of reality, their simulation, has malfunctioned. But they’re usually unable to recognize that malfunction or break out of it, at least without medication or some other kind of intervention. They only know reality through their simulation and can’t compare it to anything else to recognize how much it deviates from the outside world.

  4. 4. Miles Mutka says:

    Hello Conscious Entities,
    I have always felt that the simulation argument is really just a thought experiment or intuition pump, perhaps the widest possible version of the Chinese Room (Chinese Universe/Multiverse?).
    I wish that computationalists would drop Turing computability from their arguments. It has very little relevance to the kind of mechanisms that biological creatures can have. (And if you go the quantum computing route, you could potentially go beyond Turing anyway?)
    I haven’t look at the IIT lately (it seems to be a WIP anyway) but at least it does not seem to get hung up on computability.
    If I wanted to simulate life in a digital and step-wise manner, I would use some form of game theory. All the resources for an organism to decide the next step would have to be “on the table”, like any other physical resource, and if you cannot finish your computation in time to act on the next turn, some other organism with a simpler ruleset could win. Turing does not enter into it, unless you have hoarded so much resources that you think they are practically infinite.
    Game theory has never been successful enough to generate as much theoretical basis as algorithmic theory, and there is not that much interest in it either, outside of economics theory. (And to be clear, I am not proposing that experiential consciousness would “emerge” from game theoretical simulations either.)

  5. 5. Paul Torek says:

    Here’s the best part from Hossenfelder:

    Problem is, in this case it would have to be possible to encode a whole universe in part of another universe, and parts of the simulation would attempt to run their own simulation, and so on. This has the effect of attempting to reproduce the laws on shorter and shorter distance scales. That, too, isn’t compatible with what we know about the laws of nature. Sorry.

    I wondered about the energy and entropy requirements too. Anyway, good to hear from a physicist.

    You’re a little too fast with “nothing in a simulation actually exists (clue’s in the name)”. In special cases a simulation of X *is* an X – for example, a mathematical calculation, faithfully simulated, is itself a mathematical calculation. The very same mathematical calculation, even, is included in the simulation (although the simulation could be more complex and include additional math). In general, logico-mathematical processes seem to be the only ones where a simulation-of-X can be X. Or maybe, abstract processes.

    Is consciousness abstract? Is it purely mathematical? I think not.

  6. 6. zarzuelazen says:

    I’ve thought about this one for a very long time, and I have to tell you, I’m now very confident that the whole of reality is indeed just pure information (computation). There is nothing apart from that.

    It’s not that the universe *is* a simulation, I’m saying something even more radical: that there is no clear difference between a ‘simulation’ and the ‘real world’! In other words, I’m saying we should dispense with the notion of a ‘real world’ altogther: no hardware is needed! There is only software.

    I think ‘existence’ is not a binary yes/no, it’s a matter of *degree* (think of the brightness of a light-bulb for instance).

    Whenever something is simulated on a computer, that thing is literally drawn into existence a little bit – like a summoning! I mean this literally, it’s not just a metaphor. A simulated ‘hurricane’ is a *real* (partial) hurricane. And yes, I think that a simulated you, really would be you.

    I feel that ‘the universe’ is still in the process of being created. And it’s pulling itself up by it’s own bootstraps…by simulating *itself* (self-simulation). It’s the self-modeling that is making reality ever more ‘real’! (remember, I pointed out that ‘real’ could be a matter of degree)

    It’s pretty incredible when you think through this crazy-sounding ‘information theology’ carefully. The problem with Bostrom is not that’s he’s wrong…it’s that he hasn’t carried his own reasoning anywhere near far enough! 😀

  7. 7. zarzuelazen says:

    Hi Paul,

    Hossenfelder hasn’t fully grasped the implications of reality as information. If reality is pure information, no hardware is needed – there is NO ‘base level’ of reality – just information simulating other information. See my above post.

  8. 8. Peter says:

    a mathematical calculation, faithfully simulated, is itself a mathematical calculation

    Yes, although in that case I’d say that part of it isn’t really simulated! Simulations pick out certain features to reproduce and neglect the others; in some cases and for some purposes there are definitive features; if you put those in your simulation you’re doing it for real (signing a contract during a play that turns out to be legally binding might be another example).

    Bostrom’s case is curious because he specifies the simulation of an entire world (this one). That seems to imply that all features are included – in which case it’s a world, not a simulation – or that some things that weren’t important to the creators of the simulation were left out…?

    But I’m getting in too deep for a mere comment.

  9. 9. Peter says:

    the whole of reality is indeed just pure information (computation).

    The virus claims another victim… 😉

  10. 10. Hunt says:

    You have to admit, one enticing bit of evidence in favor of simulation is the rather bizarre way quantum mechanics seems to be influenced by observation. The naive view is that observation that has no physical interaction with experiment should not alter outcome. In reality there seem to be hidden factors that make this impossible.

    Seems like a bug to me.

    (For the record, I don’t think we’re in a giant simulation. I just think there are hidden factors.)

  11. 11. alma says:

    Some of my comments regarding what others have written:

    @Peter Bostrom in his original article ( III) says that most likely simulating brains and proper sensory inputs is feasible and thats enough for his though experiment.

    @SelfAwarePatterns wrote the same – “A simulation doesn’t necessary have to recreate all the physics of the outside world in order to simulate the experience of it”

    I’m not sure that this is true, if I arrange computations in this world than those computations have to be simulated to give the proper sensory input as a result. Of course not much can be said about the simulation overhead. We can only say something about the simulation overhead in our world*. So for example if we search mersenne primes on millions of machines, then the simulator also have to do that to finally give us the mersenne prime found as the “proper sensory input”. Of course an advanced civilization most of the things already precomputed that we can think of or put money into computing it…

    * About the cost of simulation (of course it is just in our known world/physics), the main relevant theoretical result is: any quantum system can be simulated with only linear time/size overhead in an universal quantum computer –

  12. 12. Chris Savia says:

    > But I persist – nothing in a simulation actually exists (clue’s in the name), so it follows that if we exist, we are not in a simulation.

    So you “refute it thus” like Samuel Johnson, just using different words?

  13. 13. Peter says:

    Yes, apart from the fact that it’s a different claim and a different counter-argument, the only other difference is that my refutation uses different words. 🙂

  14. 14. Tanju says:

    If we’re simulations living in a simulated world, then that is our reality. So, thinking about if we’re in a simulation really does not get us anywhere we have not been before.

    Arguments against the simulation scenario based on the laws of physics [Hossenfelder] are nonsensical as well since there is no requirement that the physics of our world is necessarily the same as the physics of our simulator.

    At the end, the simulation argument sounds like a deistic explanation.

  15. 15. Tom says:

    Equations describe reality.

    Peter, if by “equations” you mean the squiggles mathematicians write on paper then these are surely just descriptions of reality. But these equations have meaning, a referent, and that is reality itself. Mathematics is not the squiggles on paper but reality itself.

    The arbitrary particularity of the world we see around us can be easily explained by assuming that reality as a whole contains everything possible without any arbitrary preference and we just live in a part of reality.

  16. 16. Jochen says:

    I’m right there with you, Peter: claiming that the world could be a simulation or some type of computation/information processing is simply a mistake about the nature of computation. I believe that mistake ultimately lies in the fact that we can’t help but interpret symbolic vehicles, and scarcely notice this act of interpretation itself—consequently, if a computer screen shows us a simulated landscape, we interpret the collection of lit pixels as an actual simulated landscape, and wonder what it would be like to live there. It’s the same problem that causes the fish in the tale to wonder what the heck water is supposed to be: interpretation is so very natural to us that it’s all to easily missed, but without interpretation, there simply is no computation, no simulation, at all—there’s just a bunch of transistors that either allow a current to flow, or not.

    So there’s no actual landscape within which to live, any more than there’s an actual landscape of Middle Earth in the Lord of the Rings-trilogy. It’s just a conceptual error—mistaking the signifier for the signified. Computations are all signifier, while the real world is (a subset of) what is signified.

    Even the performance of a simple calculation is ultimately just imbued upon a computing device via an act of interpretation: if I enter the symbols ‘2’, ‘*’, ‘3’, and receive as an output the symbol ‘9’, then it is only by interpreting these symbols as the numbers 2, 3, and 9, and the symbol ‘*’ as indicative of the operation of multiplication, that I can say that the computer has carried out a multiplication. Without this interpretation, all that has happened is symbol manipulation, which is in and of itself utterly devoid of any meaning.


    You have to admit, one enticing bit of evidence in favor of simulation is the rather bizarre way quantum mechanics seems to be influenced by observation.

    This is just an aside, but since it’s something one hears quite often in this debate, I feel that it’s worth pointing out that simulating a quantum universe is actually way harder than simulating a classical universe—in general, simulating quantum mechanics incurs an exponential slowdown (basically due to the fact that a quantum state is of exponential complexity in the number of particles, while the complexity of a classical state scales linearly). So if anything, the quantum nature of our universe ought to count against the idea that we live in a simulation.

  17. 17. Peter says:

    there is no requirement that the physics of our world is necessarily the same as the physics of our simulator.

    Bostrom says this world might be a simulation, so the simulation absolutely has to provide the physics Hossenfelder knows about.

  18. 18. SelfAwarePatterns says:

    Hi alma,
    “if I arrange computations in this world than those computations have to be simulated to give the proper sensory input as a result”

    You seem to be assuming that your memory of what the computation is, what it should produce, and what it actually does produce, are all free of manipulation. But if your mind is part of a simulation, that can’t be taken for granted. It all depends on what the simulation’s goals are.

    Not that I’m convinced we are in a simulation. Or perhaps it’s more accurate to say that I don’t find it productive to assume we are. If in fact we are in one, for better or worse it’s our reality, ignoring it appears to have unpleasant consequences, and we have little choice but to play the game as best we can.

  19. 19. Tanju says:

    Peter [17]:

    Bostrom says this world might be a simulation, so the simulation absolutely has to provide the physics Hossenfelder knows about.

    What I meant is that if we are living in a simulation, the physics that we experience does not necessarily put any constraints of the physics of the (higher/parent) world in which our simulation is written and run. So the simulation provides (in fact, creates) our physics. The complexity we face in this world in dealing with this physics (say, quantum effects) does not imply a limitation on the capabilities of the simulator’s world. There is no way of deciding this question within our world. Sort of like a program running on a single core virtual machine cannot observe the multicore host it really is running on (provided there are no bugs in the supervisor 🙂

  20. 20. zarzuelazen says:


    The idea actually has support coming from leading edge theoretical physics and empricial observations. The holographic principle (a theory of quantum-gravity), appears to be demonstrating that all of 3D space can be generated from a 2D boundary consisting of pure qubits (quantum information).

    Top physicists including Sean Carroll, Leonard Susskind and others are now taking seriously the idea that ‘information’ is what is fundamental, and spacetime/gravity emerges from it.

    I think you need to keep an open mind here. Yes the idea that all of reality is pure information is deeply counter-intuitive, and on the surface does appear ridicious at first, but human intuition can be very very wrong.

  21. 21. Callan S. says:

    I think it’s more that any simulated creature that is capable of self evaluation would at default be stuck evaluating information that is really not really what it is. What it really is is a series of numbers on a database (which itself is a series of magnetic states on a metal disk). It exists as those numbers – a simulation is not nothing – every time you pay for a computer, it’s because a simulation is something. But the sim being is not going to see through the matrix. Not by default, anyway. It will be blissfully unaware.

    So, what philosophy might sim beings develop and partake in?

  22. 22. Peter says:

    I can’t pretend to understand the holographic theory properly, but isn’t it really an alternative description?
    A lot depends on what kind of ‘information’ you’re talking about: Shannon information, meaningful information or whatever. Pure information sounds as if it exists in some eternal Platonic world, and this world doesn’t look like that to me!

  23. 23. David Duffy says:

    “holography…what kind of information”: Susskind’s “Computational Complexity and
    Black Hole Horizons” just has it that the entropy of a black hole can be shown equivalent to a quantum computer (Hayden-Preskill quantum circuit) of the appropriate number of qubits, and the complexity is the usual algorithmic run-time complexity, and ER=EPR (that is, quantum entanglement is via wormhole). Alice then tries to send a birthday message via an Einstein-Rosen Bridge to Bob who has fallen into a black hole. It all seems so simple when he explains it…

    “Clearly if the holographic entropy bound is correct then there is a large amount
    of non-locality in whatever the correct theory of quantum gravity is. Indeed the area
    scaling of the entropy led ‘t Hooft and Susskind to conjecture that a true theory of quantum gravity must in some sense live in one fewer dimensions than naively expected; Susskind called this idea the holographic principle.”

  24. 24. Tom Clark says:

    As some others have pointed out (Peter in the OP, Tanju in 14, SAP in 1 and 18), whether we’re in a simulation or not, our experience is incontrovertibly real and we can’t help but take it seriously. The question then is whether consciousness can result from some sort of computation – what a simulation runs on. If it can, then we might be in a simulation. If not, then we aren’t. Either way, we’re stuck with the reality of experience, so the question doesn’t have much practical significance when it comes to the exigencies of being conscious.

  25. 25. Paul Torek says:

    Peter (22), you nailed it: the holographic theory is an alternative description, as with the AdS-CFT correspondence it is based on.

    Peter (17) and Tanju (19), Bostrom doesn’t just say this world might be a simulation (that would just be Cartesian skepticism warmed over), he says it probably is. And the reason is that in our world, we (supposedly) will create more simulated beings than non-simulated. So the physics of our world matters crucially to his argument.

  26. 26. Jochen says:


    The holographic principle (a theory of quantum-gravity), appears to be demonstrating that all of 3D space can be generated from a 2D boundary consisting of pure qubits (quantum information).

    That’s really just a red herring, though. Every quantum mechanical system (of finite dimension) can trivially be described in terms of ‘pure qubits’—simply because all Hilbert spaces of the same dimension are isomorphic, and every finite-dimensional Hilbert space can be embedded within a space of dimension 2^n, i.e. an n-qubit Hilbert space; furthermore, every unitary (i.e. every possible time evolution) can be represented in terms of a finite set of qubit unitaries (this is what makes universal quantum computing possible). So, you could point to every quantum description as ‘evidence’ for an informational underpinning of physics.

    And in fact, the same is true of Newtonian physics, and indeed, of any physical theory we might hope to formulate, at least in so far as we want to be able to compute anything within the theory, or simulate it—since then, the theory will be computable, and so, we can describe every system within the theory by means of a computational architecture. But just because we can describe everything this way, doesn’t mean things actually are this way—in just the same way, just because this message can be translated into bit strings doesn’t mean it is bit strings. It’s just confusing the map with the territory.

    (Also, but that’s a whole different matter, calling the holographic principle a ‘theory’ of quantum gravity is a little premature—as of right now, it’s an unproven conjecture (albeit with a lot of evidence for it) that describes a universe we know isn’t ours, namely, a stationary one with constant negative curvature, rather than an expanding one with positive curvature.)

  27. 27. Steve Philbrook says:

    Buddha said the world (universe) is illusion, both real and not real. Some of his disciples took this too far. To the extreme where everything was pointless. So he said, “if you find yourself doubting the reality of the world, give your thumb a whack with a hammer. You will find both hammer and thumb are quite real.” I don’t know if this answers anything, but I’m throwing it out there.

  28. 28. Jorge says:

    Let’s cut to the chase. The issue at hand is: “Is the plot of The Matrix actually logically coherent?”

    Like, is it possible that right now everything I am experiencing is a deception, like the Cartesian demon? Is that proposition intelligible, coherent and conceivable?

    I think it is, and if it is, then it stands to reason that we might call that deception a “simulation”. So, crucially, simulations can recapitulate the phenomenal features we associate with ‘realness’. Dennett’s piece “Where am I?” also argues that simulations can deceive us into thinking they are ‘reality’, and some top notch VR experiences can simulate experiences we are not actually having with some fidelity.

    Peter, you wrote:
    “People do quite often set out a vision of the world as powered by maths; somewhere down there the fundamental equations are working away and the world is what they’re calculating.”

    It’s by analogy- if the math that powers a convincing computer simulation is sufficient, then might it not stand to reaon by extrapolation that when I stop the VR headset and come back to “reality”, it’s actually just one more nested deception?

    I don’t know if you’ve ever had the “dream within a dream” experience Peter, but *I have* and let me tell you it is extremely, extremely alarming and disconcerting when it happens.

    The important thing to realize, I think, is that simulation-reality are not opposite words. All simulations, ultimately, are real in “some sense” since they must be executed by something that actually “exists”. I would also like to point out that the word “exist” is at the root of many tricky language issues in philosophy because it is a slippery and ambiguous word.

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