Make the complete description of an apple the input of the right computer program, and the pattern resulting from the sequence of all states of the computation will be the apple.
This is still nonsense. If I have a computer made only of naturally occurring atomic elements, and I use it to simulate a plutonium nucleus, are you saying I now actually have a plutonium nucleus there?
If I have a computer made only of naturally occurring atomic elements, and I use it to simulate a plutonium nucleus, are you saying I now actually have a plutonium nucleus there?
“Actually have” is vague and should probably be tabooed. Yes, in that there is a causal structure there isomorphic to a plutonium nucleus; no, in that this causal structure has the wrong relationship to you.
This is still nonsense. If I have a computer made only of naturally occurring atomic elements, and I use it to simulate a plutonium nucleus, are you saying I now actually have a plutonium nucleus there?
Yes, that’s exactly what I’m saying.
Of course, the ‘simulated’ nucleus exists within the system that is the simulation, just as ‘real’ nuclei exist within the system that is our universe. Thus it would be silly to ask why we can’t create simulated uranium and take it ‘out’ of the computer to generate electricity, or something, because that’s exactly like asking why, if our universe exists within another universe, the aliens living in the other universe can’t just ‘reach out’ and take the Sun into their universe. The only way to (sort of) do both of these things would be to convert the pattern/thing we wish to take out of the inner system into the equivalent pattern in the outer system.
It’s what things are made of.
What would a mathematical description of substance look like? Not a description of a really simple object made of substance; a description of substance itself.
Of course, the ‘simulated’ nucleus exists within the system that is the simulation
Try as I might, I still find it very difficult to take this seriously as more than a way of speaking about something which in reality is not a plutonium nucleus, but just a simulation of a plutonium nucleus.
One reason is that most actual simulations are not complete. If I simulate the global economy on my PC, the simulation is assuredly not complete in the sense of picking out a single possible world or specifying where every atom of every product is located. Most likely it will consist of a few macroeconomic variables evolving over time according to plausible causal relationships.
The common-sense understanding of a simulation is that it is not the thing simulated; it is a computational process designed to mimic aspects of the thing simulated. But you ask me to believe that, in those rare cases where the simulation is somehow “complete”, the thing itself—the object of simulation—is actually present, albeit “within the system that is the simulation”.
Every actual computer on Earth is a structure of atoms. Every actual computation ever carried out within these computers is a physical process which has also been given a semantic interpretation, explicitly or implicitly, by human users. I will leave to one side for the moment the question of how to accurately describe what is going on in “biological computers” like the human brain; but I would expect you to at least agree that the previous description is accurate when applied to the technological artefacts we call computers.
So there is the common-sense analysis of computers and computation: computers are physical objects, passing through a sequence of physical states which by design admit elaborate semantic interpretations, such as “representing” or “simulating” this or that (and perhaps inaccurately).
To insist that these physical states in a computer intrinsically have one true computational interpretation is already highly dubious. The closest a computer comes to having an intrinsic computational property is its description as a finite-state machine, and even then, there’s no single such description, just a tower of them, with the finest-grained description treating each distinct possible microphysical state as a distinct computational state, and with the coarser descriptions mapping physical state to computational state in a many-to-one fashion.
To say that a process occurring in a computer is intrinsically about something, you not only have to pick just one of those physical-to-computational mappings as the one true computational description, but you also have to pick one possible computational-to-semantic mapping as the one true interpretation. Because the finite-state-machine description does not yet have any semantics—it’s just a clustering of physical states combined with causal flow—but for a computation to be a simulation, it has to have a semantics: it has to be a simulation of something.
Now I am trying to rebut your position by contrasting it with the down-to-earth facts, but I’m reaching the point where I don’t know what your response would be. So it would be useful if at this stage you offered some commentary on what I’ve said so far, about the nature of computation, from your particular perspective. I’ll return to the issue of “substance” later.
To insist that these physical states in a computer intrinsically have one true computational interpretation is already highly dubious.
To say that a process occurring in a computer is intrinsically about something, you not only have to pick just one of those physical-to-computational mappings as the one true computational description, but you also have to pick one possible computational-to-semantic mapping as the one true interpretation.
Right. The usual dodge is that all possible computational interpretations are simultaneously happening.
This is still nonsense. If I have a computer made only of naturally occurring atomic elements, and I use it to simulate a plutonium nucleus, are you saying I now actually have a plutonium nucleus there?
It’s what things are made of.
“Actually have” is vague and should probably be tabooed. Yes, in that there is a causal structure there isomorphic to a plutonium nucleus; no, in that this causal structure has the wrong relationship to you.
Yes, that’s exactly what I’m saying.
Of course, the ‘simulated’ nucleus exists within the system that is the simulation, just as ‘real’ nuclei exist within the system that is our universe. Thus it would be silly to ask why we can’t create simulated uranium and take it ‘out’ of the computer to generate electricity, or something, because that’s exactly like asking why, if our universe exists within another universe, the aliens living in the other universe can’t just ‘reach out’ and take the Sun into their universe. The only way to (sort of) do both of these things would be to convert the pattern/thing we wish to take out of the inner system into the equivalent pattern in the outer system.
What would a mathematical description of substance look like? Not a description of a really simple object made of substance; a description of substance itself.
Try as I might, I still find it very difficult to take this seriously as more than a way of speaking about something which in reality is not a plutonium nucleus, but just a simulation of a plutonium nucleus.
One reason is that most actual simulations are not complete. If I simulate the global economy on my PC, the simulation is assuredly not complete in the sense of picking out a single possible world or specifying where every atom of every product is located. Most likely it will consist of a few macroeconomic variables evolving over time according to plausible causal relationships.
The common-sense understanding of a simulation is that it is not the thing simulated; it is a computational process designed to mimic aspects of the thing simulated. But you ask me to believe that, in those rare cases where the simulation is somehow “complete”, the thing itself—the object of simulation—is actually present, albeit “within the system that is the simulation”.
Every actual computer on Earth is a structure of atoms. Every actual computation ever carried out within these computers is a physical process which has also been given a semantic interpretation, explicitly or implicitly, by human users. I will leave to one side for the moment the question of how to accurately describe what is going on in “biological computers” like the human brain; but I would expect you to at least agree that the previous description is accurate when applied to the technological artefacts we call computers.
So there is the common-sense analysis of computers and computation: computers are physical objects, passing through a sequence of physical states which by design admit elaborate semantic interpretations, such as “representing” or “simulating” this or that (and perhaps inaccurately).
To insist that these physical states in a computer intrinsically have one true computational interpretation is already highly dubious. The closest a computer comes to having an intrinsic computational property is its description as a finite-state machine, and even then, there’s no single such description, just a tower of them, with the finest-grained description treating each distinct possible microphysical state as a distinct computational state, and with the coarser descriptions mapping physical state to computational state in a many-to-one fashion.
To say that a process occurring in a computer is intrinsically about something, you not only have to pick just one of those physical-to-computational mappings as the one true computational description, but you also have to pick one possible computational-to-semantic mapping as the one true interpretation. Because the finite-state-machine description does not yet have any semantics—it’s just a clustering of physical states combined with causal flow—but for a computation to be a simulation, it has to have a semantics: it has to be a simulation of something.
Now I am trying to rebut your position by contrasting it with the down-to-earth facts, but I’m reaching the point where I don’t know what your response would be. So it would be useful if at this stage you offered some commentary on what I’ve said so far, about the nature of computation, from your particular perspective. I’ll return to the issue of “substance” later.
Right. The usual dodge is that all possible computational interpretations are simultaneously happening.