These are extracts from some Facebook comments I made recently. I don't think they're actually understandable as is—they're definitely not formal and there isn't an actual underlying formalism I'm referring to, just commonly held intuitions. Or at least intuitions commonly held by me. Ahem. But anyway I figure it's worth a shot.
The following’s a brief over-abstract hint at the theoretical reasoning style that replaced naive anthropics a few years ago, ushered in by the development of updateless-like decision theories which are incredibly inchoate but widely considered a step in a direction that is at the very least rather appealing: “Anthropic”-like “explanations”, as exampled in my original status update, can be generalized to give the now-fundamental ‘relative significances’ for all decision theoretically relevant self-dependent processes—but for humans only as determined by some self-unknown decision policy, or in other words derived from some provably imperfectly self-known “true” “preferences”/”values”/”morality”. This preference-centered decision policy can easily refer to some superficially-"objective" relative existence measure like probability, and thus humans can use Bayes & EU as an approximation that is sorta mathematically sound—that is, until the humans start bothering to pay much attention to their infinitely many different contexts and correlated algorithms, each of which might split differently and mess up the calculations. If even as a human you insist on thinking about these “copies” then Bayes quickly becomes meaningless, and you’ll need to start thinking in terms of decision theory.
([I suspect that an attempt at sane moral reasoning for mere humans must indeed take into account logical correlations with the infinity of Platonic algorithms—but trying to guess at which Platonic algorithm one is “truly” using to make a decision can be immediately recognized as futile by anyone who takes a moment to reflect on any non-trivial decision of their own. Often it’s not clear where to go from there besides looking for different ways of abstracting your decision rule to see if all abstractions exhibit certain stable features—you can thus say you’re deciding to at least some extent for some algorithms that exhibit those features, but that amount of correlation seems awfully weak. (But if the features are rare, does that matter? I’ve yet to think carefully on these matters.) In general humans aren't even close to being able to reason straightforward-causally, let alone timelessly.
Interestingly Eliezer Yudkowsky has talked about this discorrelation as being a limited resource, specifically for agents that aren’t as self-opaque as humans: at some point your Platonic decision algorithm and other agents’ Platonic decision algorithms will start to overlap a little bit, and insofar as they overlap they logically just can’t not make a correlated decision. This makes it easier for each algorithm to predict the other, which can be good, bad, or hilarious, depending on the non-specified aspects of the agents. Perhaps we humans should value our unique utter inability to introspect?])
You might wonder: what if “your” decisions are relevant (“significant”) for some “other” agent that doesn’t share “your” “actual” “values”? The answer can only be that the same copies-ambivalent reasoning applies here too. Without the scare quotes, you can technically be a part of some other agent’s decision algorithm just as much as your naive decision algorithm—you can even switch perspectives right now and think of yourself as some fragment of a larger agent, much like many normal folk identify as Soldiers, Buddhists, Humans, or all of those at once, as well as thinking of themselves as themselves. More intuitively you can think of yourself not just as yourself but as the source of inspiration for everyone else's models of you—models that tend to be very lossy due to economic reasons. Even a superintelligence might not bother to model you very carefully if it has other shit to do (e.g. modeling all possible variations on Babyeaters given increasingly improbable assumed evolutionary lineages). Thus the rules say you can be a pawn in many games at once, as long as multiple processes have a vested interested in you, which they assuredly do. And as previously shown, they’re obviously allowed to be overlapping and at varying levels of abstraction and organization: A forgiving ontology to be sure, but a nightmare for finding Schelling focal points!One neat way this all adds up to normality is that by the time you find any such outlandish decision theoretic “explanations” for finding yourself as you somewhat compelling, you already have a lot of reason to think you’re life is unusually influential, and that evidence screens off any additional “anthropic” update. You’re about as important to you-dependent structures as you think you are, given straightforward causal evidence, and finding yourself as a you-like structure shouldn’t cause you to update on top of that. This same reasoning applies to the original motivator for all this madness, anthropic probabilities: I have yet to see any anthropics problem that involves actually necessary updates and not simply counterfactually necessary belief updates—updates made in counterfactual worlds which would have been accompanied by their own non-anthropic evidence. [I think this is important and deserves fleshing out but I won't feel justified in doing so until I have a formalism to back me up.] And these days I tend to just facepalm when someone suggests I use “human beings” as my "reference class".
A proposal to rationalize derive magick and miracles from updateless-like decision theoretic assumptions:
The Born rule should be derived from timelessness-cognizant game theory for multipartite systems in order to find equilibria from first principles. Deriving it from causal decision theory is clearly circular and Platonic-truth-ignoring “rationality” isn’t rationality anyway. I suspect that the Born rule is generally self-similar across levels of organization but is mostly an approximation/baseline/Schelling-focal-point for influence-influencing systems with gradiently influential decision policies in something like a not-necessarily-timeful Bayesian game.
You can intuitively model this with an ontology of simulations: simulators agree or at least are incentivized to leave certain parts of their simulations constant, and the extent to which different things are left constant falls out of economic and ecological selection effects.
The Born rule is a lot less physics-y than the rest of quantum mechanics, akin to how there is a deep sense in which thermodynamics is more about subjective Bayesianism than about universal laws. Thus it's not too bad a sin to instead think of simulators computing different branches of automata. If they sample uniformly from some boring set of possible automata (given some background laws of physics like Conway’s game of life) then the end result might look like a Born rule, whereas if they differentially sample based on game theoretic equilibria (formalizable by, like, saying their utility functions are over relative entropies of predictions of automata evolution patterns some of which are more interesting in a Schmidhuberian compressibility sense [assuming they agree on reference Turing machine], for example) then there can be interesting disregularities.
(On Google+ I list my occupation as "Theoretical Thaumaturgist". ;P )
I am going to have to do a proper LW sequence demonstrating why Many Worlds is of little or no interest as a serious theory of physics. Reduced to a slogan: Either you specify what parts of the wavefunction correspond to observable reality, and then you fail to comply with relativity and the Born rule, or else you don't specify what parts of the wavefunction correspond to observable reality, and then you fail to have a theory. The Deutsch-Wallace approach of obtaining the Born rule from decision theory rather than from actual frequencies of events in the multiverse IMHO is just a hopeless attempt to get around this dilemma, by redefining probability so it's not about event frequencies.
If you spent as much energy actually trying to understand what MWI actually means as you do trying to argue against it, we wouldn't have to play Karma Whack-A-Mole every time you start spouting nonsense on here.