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.
All it says is that there was never any reason in the first place to suppose there's a difference between possibility and existence.
That's good to know. So the next time someone tells me that something might be a cure for cancer, I won't have to think about it or research it, because if it is possibly a cure for cancer, then it is actually a cure for cancer. And the next possible theory of 9/11 that I hear, I don't need to wonder if it's true, because, being a possibility, it's also an actuality. And I don't need to worry about what you actually mean by your writing, because whatever possible interpretation I come up with, that must be the actual intended meaning...
Wait - you're saying that's not what you meant... that all those possibilities which seem to simply not exist... you're saying that they do exist, but somewhere else, in some other world? Well, uh, that's an interesting idea... pretty radical... I don't see what evidence you could have for it... but I guess I have to admit it's possible, ha ha... But wait - isn't it also possible that these other worlds don't exist? So does that possibility - meta-possibility - "exist" somewhere too?
Now please note: I am not disputing your right to build byzantine multiverse theories and to engage in abstruse logic-chopping which will allow your new interpretation of the word "possibility" to become consistent. But it is absurd to say that "there was never any reason in the first place to suppose there's a difference between possibility and existence". You may as well say there was never any reason to suppose that the Flying Spaghetti Monster doesn't exist, or that there was never any reason to suppose that black isn't secretly white as well. There are clear differences between the everyday original meanings of possible and actual, and proposing to negate them by supposing that all possible worlds are actual is radical metaphysical innovation, and before I believe it, it is reasonable to request some evidence, or at least an argument in its favor.
You may as well say there was never any reason to suppose that the Flying Spaghetti Monster doesn't exist
Exactly. In fact, if possibility and existence are the same, the Flying Spaghetti Monster does exist.
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.