To me, this is absurd. There must be something other than readability that defines what a simulation is . Otherwise, I could point to any sufficiently complex object and say : “this is a simulation of you”. If given sufficient time, I could come up with a reading grid of inputs and outputs that would predict your behaviour accurately.

Scott Arronson's paper "Why philosophers should care about complexity" has a chapter, Computationalism and Waterfalls, which very directly addresses this. Read that chunk for the full argument, but the conclusions is:

Suppose we want to claim, for example, that a computation that plays chess is “equivalent” to some other computation that simulates a waterfall. Then our claim is only non-vacuous if it’s possible to exhibit the equivalence (i.e., give the reductions) within a model of computation that isn’t itself powerful enough to solve the chess or waterfall problems.

Also, my model of your arg is "Saying consciousness is substrate independent creates all sorts of wacky results that don't feel legit, therefor consciousness is no substrate independent." Arronson's argument seems to eliminate all of the unreasonable conclusion of substrate independence that you invoked.

The example of the pile of sand sounds a lot like the Chinese Room thought experiment, because at some point, the function for translating between states of the "computer" and the mental states which it represents must begin to (subjectively, at least, but also with some sort of information-theoretic similarity) resemble a giant look-up table. Perhaps it would be accurate to say that a pile of sand with an associated translation function is somewhere on a continuum between an unambiguously conscious (if anything can be said to be conscious) mind (such as a natural human mind) and a Chinese Room. In such a case, the issue raised by this post is an extension of the Chinese Room problem, and may not require a separate answer, but does do the notable service of illustrating a continuum along which the Chinese Room lies, rather than a binary.

Thank you for your article. I really enjoyed our discussion as well.

To me, this is absurd. There must be something other than readability that defines what a simulation is . Otherwise, I could point to any sufficiently complex object and say : “this is a simulation of you”. If given sufficient time, I could come up with a reading grid of inputs and outputs that would predict your behaviour accurately.

I agree with the first part (I would say that this pile of sand is a simulation of you). I don't think you could accurately predict any behaviour accurately though.

• If I want to predict what Tiago will do next, I don't need just a simulation of Tiago, I need at least some part of the environment. So I would need to find some more sand flying around, and then do more isomorphic tricks to be able to say "here is Tiago, and here is his environment, so here is what he will do next". The more you want to predict, the more you need information from the environment. But the problem is that, the more information you get at the beginning, and the more you get at the end, and the more difficult it gets to find some isomorphism between the two. And it might just be impossible because most spaces are not isomorph.
• There is something to be said about complexity, and the information that drives the simulation. If you are able to give a precise mapping between sand (or a network of men) and some human-simulation, then this does not mean that the simulation is happening within the sand: it is happening inside the mind doing the computations. In fact, if you understand well-enough the causal relationships in the "physical" world, the law of physics etc., to precisely build some mapping from this "physical reality" to a pile of sand flying around, then you are kind of simulating it in your brain while doing the computations.
• Why I am saying "while doing the computations"? Because I believe that there is always someone doing the computations. Your thought experiments are really interesting, and thank you for that. But in the real world, sand does not start flying around in some strange setting forever without any energy. So, when you are trying to predict things from the mapping of the sand, the energy comes from the energy of your brain doing those computations / thought experiments. For the network of men, the energy comes from the powerful king giving precise details about what computations the men should do. In your example, we feel that it must not be possible to obtain consciousness from that. But this is because the energy to effectively simulate a human brain from computations is huge. The number of "basic arithmetic calculations by hand" needed to do so is far greater than what a handful of men in a kingdom could do in their lifetime, just to simulate like 100 states of consciousness of the human being simulated.

The simulation may be a way of gathering information about what is rendered, but it can't influence it. This is because the simulation does not create the universe that is being simulated.

Well, I don't think I fully understand your point here. The way I see it, Universe B is inside Universe A. It's kind of a data compression, so a low-res Universe (like a video game in your TV). So whatever you do inside Universe A that influences the particles of the "Universe B" (which is part of the "physical" Universe A) will "influence" Universe B.

So, what you're saying is that the Universe B kind of exists outside the physical world, like in the theoretical world, and so when we're modifying Universe B (inside universe A) we are making the "analogy" wrong, and simulating another (theoretical) Universe, like Universe C?

If this is what you meant, then I don't see how it connects to your other arguments. Whenever we give more inputs to a simulated universe, I believe we're adding some new information. If you're simulation is a closed one, and we cannot interact with it or add any input, then ok, it's a closed simulation, and you cannot change it from the outside. But you have indeed a simulation of a human being and are asking what happens if you torture him, you might want to incorporate some "external inputs" from torture.

Very interesting article. Most of my objections have been covered by previous commentators, except:

1a. Implicit in the usual definition of the word 'simulation' is approximation, or 'data compression' as Michaël Trazzi characterises it. It doesn't seem fair to claim that a real system and its simulation are identical but for the absence of consciousness in the latter, if the latter is only an approximation. A weather forecasting algorithm, no matter how sophisticated and accurate, will never be as accurate as waiting to see what the real weather does, because some data have been discarded in its input and processing stages. Equally, a lossy simulation of a conscious human mind is unlikely to be conscious.

1b. What Bostrom, Tegmark and other proponents of substrate-independent consciousness (and therefore the possibility of qualia in simulations) have in mind is more like the emulators or 'virtual machines' of computer science: lossless software reproductions of specific (hardware and software) systems, running on arbitrary hardware. Given any input state, and the assumption that both emulator and emulated system are working correctly, the emulator will always return the same output state as the emulated system. In other words, emulation is bit-perfect simulation.

1c. Even if brains are analogue computers, one can emulate them accurately enough to invoke consciousness (if it can be invoked) in a digital system with sufficiently high spatial and temporal resolution: real brains must have their own error correction to account for environmental noise, so the emulator's precision merely needs to exceed the brain's. Against Roger Penrose's vague, rather superstitious claim that quantum effects unique to meat brains are necessary for consciousness, much the same argument holds: brain electrochemistry operates at a vastly larger scale than the quantum upper limit, and even if some mysterious sauce does bubble up from the quantum to the classical realm in brains and not in silicone, that sauce is made of the same quarks and gluons that comprise brains and silicone, so can also be understood and built as necessary into the emulator.

2. You say that "People in universe A can act upon (change their conscious experiences) people in Universe B, at least by shutting the computer down." But shutting the computer down in Universe A does NOT change the conscious experiences of the people in the emulated Universe B, because they are only conscious while the emulator is running. Imagine being a conscious entity in Universe B. You are in the middle of a sneeze, or a laugh. An operator in Universe A shuts down the machine. Then imagine one of three scenarios taking place: the operator never restarts the machine; after a year the operator restarts the machine and the simulation continues from where it was paused; or the operator reboots the machine from its initial state. In none of these scenarios is your conscious experience affected. In the first, you are gone. You experience nothing, not even being annihilated from a higher magisterium, since the emulator has to be running for you to experience anything. In the second, you continue your laugh or sneeze, having felt no discontinuity. (Time is, after all, being emulated in Universe B along with every other quale.) In the third, the continuous 'you' from before the system was rebooted is gone. Another emulated consciousness begins the emulation again and, if no settings are changed, will have exactly the experience you had up to the reboot. But that new 'you' will have no memory of the previous run, nor of being shut down, nor of the reboot or anything subsequent.

3. Against your argument that stripping away inputs and outputs from the simulation constitutes a reductio ad absurdum of the premise that emulations can be conscious: this is true of meat brains too. To nourish an embryonic brain-in-a-jar to physical 'maturity' (whatever that might mean in this context), in the absence of all communication with the outside world (including its own body), and expect it to come close to being conscious, is absurd as well as ghoulish. Moreover -- relating this with 1. above -- to say that you have strictly emulated a brain-centred system whose consciousness you are trying to establish, you would have to include a sphere of emulated space of radius greater than tc around the brain's sensory organs, where t is the length of time you want to emulate and c is the speed of light in a vacuum (assuming no strong simulated gravitational fields). This is because information from anywhere in the tc-radius sphere of real space could conceivably affect the brain you're trying to emulate within that time interval.