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She is not exactly a p zombie. The Mary in sim #1 is not a p-zombie version of the original Mary, because she is only a functional duplicate, not a physical duplicate; and the Mary in Sim #2 is only a behavioural duplicate.
My explanation was a bit confusing, sorry about that! I wasn’t intending for there to be an “original” Mary; she and everyone else only ever existed as a simulation. If we were to assume substrate independence, we’d be fine with saying that the denizens of Sim#1 are conscious. And while Sim#2 Mary is not a P-zombie to the alien, she very much is one to the people in Sim#2.
I guess you’re correct that the right terminology would be that she’s C-zombie, but the people in the simulation can’t know that. And since we can’t know for sure whether we ourselves are “really” physical, for all intents and purposes we can’t be sure that there is a distinction between P- and C- zombies. Regardless; I was assuming substrate independence, not physicalism.
An aside on non-substrate-independent physicalism
Personally, I find physicalist theories of consciousness that don’t include substrate independence quite silly, but that’s a matter of taste, not a refutation.
My vague gesturing at an argument would be something like this: a brain in a vat is halfway between a physical person and a simulation of one, and there don’t seem to be any particular properties about it to say that it shouldn’t be conscious — and, crucially, such properties don’t seem to appear the more we shift the slider towards “computer-brain,” first by replacing each neuron with a chip, and then by replacing networks of chips with bigger chips running a network, and so on until the whole thing is a chip. Is it really the case that we’re losing the physics?
Regardless, this is a separate (though related) conversation. My piece was about apparent implications of substrate independence, not physicalism. In fact, I happen to think that part of the reason why a lot of physicalists have the tendency to speak of “actual persons made of actual atoms” is because they (subconsciously?) recognize that unintuitive conclusions like this can easily crop up, and they find them, well — absurd, as you put it.
Clearly , the answer isn’t “indefinitely”
Is it that clear? A reductio ad absurdum is really just a statement about the extent of one’s philosophical Overton Window — it’s not a proof by contradiction.
An aside on the absurd
We used to think that the prediction of dark stars meant that Newton’s fact of gravity broke down when it came to light (which was true); but then again, we thought the same about the prediction of black holes and General Relativity. Nowadays, most physicists (probably) don’t believe that white holes exist, despite the fact that they’re just as predicted by GR as black holes, because they find the prospect absurd (in the absence of evidence).
Of course there’s major differences here. Everything I’m saying about subjective experience is on its face unfalsifiable — but, at least currently, so is me stating that I’m conscious (to you, at least).
I’m still hoping for a smart person to come up with some mathematical reason for why what I’m saying makes sense; the unsung hero that Claude Shannon anticipated:
I think [...] that one is now, perhaps for the first time, ready for a real theory of meaning.
~ Shannon (1949) The Mathematical Theory of Communication, p. 116.
Thank you! And thanks for the reply! I’m very curious to read your piece.
I’m not sure I understand what you mean by “matters,” here. The only sense that I can think of is that it matters in the case that we are to interact with the simulation from the outside; otherwise, not really. I also avoided any discussion of Everettian quantum mechanics precisely because I think it really blows up the scope of it all. I actually believe that, because we’re not quantum computers, Everettian quantum mechanics isn’t important and its effects on us might as well be modeled as random noise in our internal communication channels. In the cellular automaton case, I don’t really see how quantum effects change things, except for the fact that in an insignificant percentage of possible worlds the computer will miscalculate the time evolution of the automaton — and hence whatever it’s calculating will be something other than what we intend.
I happen to think that there is no true reason that your “nows” feel connected — other than the fact that, at each time step, your brain state encodes not just the present moment, but also the recent past, as well as a lot of other information that you may not even be consciously aware of. I think that the tying together of all these individual “nows” into one continuous experience is nothing but an “illusion.” But it’s not like it’s a “helpful illusion” that you evolved; I think it’s almost logically necessary, it’s a consequence of the fact that the brain has short-term memory. What would it mean to say that your “nows” aren’t connected? How could it ever feel to you that they aren’t, unless your short term memory had been screwed with? On the other hand, if I asked you to close your eyes, and I had a magic wand that could freeze your atoms in place, scramble them, then unscramble them back to where they were, and finally unfreeze them, you’d be none the wiser, right? The sense of continuity would be preserved! If instead God did that exact thing to the whole universe, there would be no way for us to tell![1]
I’ve since read Tegmark’s book, and I find it striking that he and I came to very similar worldviews through almost complementary paths. On that note, I actually think that this might be something that he didn’t quite approach in the book (well, kind of). My belief is that subjective experiences are also a kind of mathematical object, and in that sense they’re “disembodied” from the Universes that produce them, even though they also exist as sub-objects of those Universes.[2]
That is to say, the two descriptions are the same up to isomorphism.
For instance, the solutions to string theory include the history of the particles that make up my body, which necessarily encompass my subjective experience, but we can also talk about my subjective experience “in its own right”, just like we can talk about all games of chess “in their own right”.