Having never read Permutation City, I would find a summary of Dust theory essential to understanding this post, which goal presently eludes me.
SPOILER ALERT
The basic idea is this: If the physical world (including consciousness) is just a succession of states, then why would it matter that these states occur sequentially in time and at the same place? The Dust Theory is the idea that it doesn't matter -- that the same collection of bits that describes the universe we experience also describes some ridiculously large number of other universes.
There's more on Egan's site, although it might be hard to follow if you haven't read the book:
http://gregegan.customer.netspace.net.au/PERMUTATION/FAQ/FAQ.html (edit: linked in TFA, I see now.)
The book is excellent, by the way.
I'm haunted by Solipsism. We should start a support group.
No, seriously. If LW had a forum, this would be one of its sections.
There's something terribly ironic that I can't put my finger on, about a support group for people haunted by solipsism.
I once received a letter from an eminent logician, Mrs. Christine Ladd Franklin, saying that she was a solipsist, and was surprised that there were no others. Coming from a logician, this surprise surprised me.
Note that the problem of "Why do I perceive order instead of disorder?" isn't unique to this metaphysical dust theory business. Given that I expect the universe to eventually settle into thermal equilibrium, why do I believe that I'm not a Boltzmann brain temporarily and randomly formed out of that great chaos?
I'm not sure if it counts as "purely logical", but another problem with Dust theory is that it assumes that conscious states supervene on brain states instantaneously. There is no evidence for that. We seem to be conscious moment-by-moment, but the "moments" in question are rather coarse-grained, corresponding to the specious present of 0.025-0.25 second or so. It's quite compatible with the phenomenology that it requires thousands or millions of neural events or processing steps to achieve a subjective instant of consciousness. Which ...
Isn't this, along with so many other problems, a candidate for our sometime friend the anthropic principle? That is: only in a conscious configuration field which has memories of perceptions of an orderly universe is the dust theory controversial or doubted?
The Anthropic Principle conditions on the fact of our existence. But you seem to be conditioning on the fact that we don't accept dust theory. That makes no sense - you could explain absolutely any observation that way!
Maybe that's not what you meant, but I don't see how the A. P. is relevant here.
Tegmark's level IV multiverse is the only explanation I've ever heard for why there is something rather than nothing. I intuitively lean toward it for that reason. Of course, I don't know how to put a measure on that space that explains my subjective experience, but that seems like a much smaller problem then the most fundamental problem of why anything exists in the first place.
Personally, I'd like to hear alternatives to Tegmark's theory more than I'd like to hear rebuttals.
Tegmark's level IV multiverse is the only explanation I've ever heard for why there is something rather than nothing.
You can tell when something has been explained because it no longer has the same air of mystery that it did at the start. The Level IV hypothesis might very well be true, but it's not an explanation.
I've tried to formalize the Dust argument, though I don't know if it actually succeeds at being deductively valid. FYI, I don't believe the conclusions are true, necessarily, I'm just working through the argument. There is for sure plenty wrong with it.
Subjective experience is found anytime there are mental states where relation K obtains. (K is something like the psychological or memorial continuity relation that gets used in personal identity theory, but I'm not sure I can define it except by appealing to the brain: where m1 and m2 are mental states an
Isn't this, along with so many other problems, a candidate for our sometime friend the anthropic principle? That is: only in a conscious configuration field which has memories of perceptions of an orderly universe is the dust theory controversial or doubted? In the vastly more numerous conscious configuration fields with memories of perceptions of a chaotic and disorderly universe lacking a rational way to support the observer the dust theory could be accepted a priori or at least be a favored theory.
Ahem, this is circular logic. "The vast majority...
I don't think that really works. The problem is "I perceive far more order than would be needed for me to (briefly) exist from this moment"
ie, I observe that my surroundings seem to match my recent memories, etc etc..
QM arguably IS dust theory, just that one adds on a few rules for how the arrangements relate to each other, and then assign to each a complex number and have various rules for those relate to each other, how that changes, etc...
Isn't this, along with so many other problems, a candidate for our sometime friend the anthropic principle? That is: only in a conscious configuration field which has memories of perceptions of an orderly universe is the dust theory controversial or doubted?
How is this not a fully general argument against ever trying to explain anything?
I say we are in a simulation. I'm not sure what the precise definition of 'simulation' is, but it should be a broad enough concept to include the universe, whatever the universe is. The universe may not be a directed simulation, it may not be a simulation that has a beginning and an end, and even the continuity of it may be a complete illusion. But I cannot imagine how anything at a sufficient level of detail could be interpreted as not a simulation; that is, as something that isn't computed or doesn't run with some mix of mechanical and random rules.
In th...
If we take the possibility of dust scenarios as a given, then perhaps our observation of a coherent universe can be explained by some idea of the "measure" of different possible universes/simulations. That is, if all possible universes are some Turing machine, then perhaps the simplest Turing machines have in some sense higher probability/measure, and the simplest machines that contain observers are still on the relatively simple and lawful side.
edit: or perhaps it's that lawful simulations have a higher density of observers.
I tend to ignore the dust theory simply because entities which are implemented as scattered states throughout spacetime can't be interacted with. Even just inverting the order of the states is enough to make interaction impossible - two observers with opposite time directions don't see each other as having any memories of past interactions.
Objection 1: many difficulties (Dust theory being one) are avoided if you simply do not use the term 'subjective experience'. Don't try to define it. Don't assume something exists that should be called that.
What is the discussion of 'subjective experience' needed for? What is the problem with discarding the entire concept? (I'm aware there are some problems, but I'm interested in your take on it because I think most of them can be explained away.)
Objection 2, to your item 3: the mapping of a 'mental state' to the configuration of some physical system is purely a matter of interpretation. The problem here is that you ascribe to physical configurations, some properties that are normally reserved for causal sequences of physical states, i.e. outright simulations.
Suppose I have a model of your 'mentality' - that thing whose states are your mental states. Since it's embodied in a physical system, I can enumerate all possible mental states. Suppose there are countable many states (I don't know physics that well, but at the very least this is valid if you accept arbitrarily precise descriptions of the physical system as mapping to arbitrarily precise specifications of your corresponding mental state).
Now, I can write down a few (very large) numbers that map to some mental states of yours. Do you think my act of writing down these numbers literally brings into existence a subjective experience that did not otherwise exists?
(You may object because the actual numbers involved are so big they probably can't be literally written down even on a Universe-sized piece of paper. But I can use any physical system, not much more complex than the one I'm modelling (that's you), to encode the numbers. Pen and paper aren't privileged media.)
Suppose I find a number, or a series of numbers, that corresponds to a state of extreme suffering on your part. How many real-life resources would you invest to prevent me, an AI, from storing that number in my memory where no-one's looking? (If your answer is 'none at all', then what else does this theory make you do differently, ever?) Would you react differently if I stored a sequence of very similar numbers, which correspond to almost-indistinguishable successive states of a real brain? (And that's without taking into account the problems raised by rearranging the states in time.)
But that's not the real problem. Remember that the mapping of mental states to numbers is purely arbitrary: any ordering of the natural numbers will do. What makes a given number invoke a given mental state? Is it just my own mental intention in using it? What if I build a non-sentient AI proxy to do it for me? What if I proclaim that I use the number 1 to encode a state of suffering in my simulation of you - will you try to stop everyone in the universe from writing down '1'? Will you counter-proclaim that no, the number 1 actually encodes your state of supreme happiness?
Objection 3, to your C2: your logic is invalid. Compare: "somewhere in the universe are mental states which correspond to someone mentally identical to yourself experiencing eternal torture. Therefore you will experience eternal torture, starting a moment from now."
The problem is that you have not defined what 'you' means in this context. If there are many similar or identical states to "yours", embodied at different points in the universe, which one are "you"? If there are several identical ones that diverge, and some experience eternal torture and some experience eternal happiness, which one is then "you"? If somewhere there is a sequence of mental states that starts out with the same memories you (Jack) have right now, but its actual experiences are of being on Mars, then do you expect to be on Mars?
This would be the Subjective Dust Theory, except that it's wrong. It's empirically wrong: my experiences have been highly ordered in the past and so I expect them to be ordered in the future, and not to jump randomly around the universe just because there exist embodiments of every possible future state I might experience. Of course you could say I just happen to be a state that remembers an ordered past - that's the Boltzmann's Brain (timelessness) postulate - but you can't really conclude anything based on this, so I think it's better to assume our memories are real and we really live in an ordered universe.
It sounds like I should clarify that I don't actually endorse the argument. I'm just trying to make the argument explicit so that we can stop all the hand-waving.
Objection 1:..What is the discussion of 'subjective experience' needed for? What is the problem with discarding the entire concept? (I'm aware there are some problems, but I'm interested in your take on it because I think most of them can be explained away.)
I successfully referred to something with the phrase. I know I did because your response wasn't "Huh? What does that word mean?"...
It has been well over a year since I first read Permutation City and relating writings on the internet on Greg Egan's dust theory. It still haunts me. The theory has been discussed tangentially in this community, but I haven't found an article that directly addresses the rationality of Egan's own dismissal of the theory.
In the FAQ, Egan says things like:
and:
Isn't this, along with so many other problems, a candidate for our sometime friend the anthropic principle? That is: only in a conscious configuration field which has memories of perceptions of an orderly universe is the dust theory controversial or doubted? In the vastly more numerous conscious configuration fields with memories of perceptions of a chaotic and disorderly universe lacking a rational way to support the observer the dust theory could be accepted a priori or at least be a favored theory.
It is fine to dismiss dust theory because it simply isn't very helpful and because it has no predictions, testable or otherwise. I suppose it is also fine never to question the nature of consciousness as the answers don't seem to lead anywhere helpful either; though the question of it will continue to vex some instances of these configuration states.