Probably-incomprehensible decision theory exposition and speculation

-9 Post author: Will_Newsome 10 September 2011 09:16AM

These are extracts from some Facebook comments I made recently. I don't think they're actually understandable as isthey'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 )

Comments (58)

Comment author: Jack 10 September 2011 09:30:26AM *  1 point [-]

The Born rule should be derived from timelessness-cognizant game theory for multipartite systems in order to find equilibria from first principles.

?!?!?!?!?!?

You're saying what I think you're saying, right? (Either insane or ingenious)

Everything else at least resembled things I had thought before- which is to say I think it's right.

Comment author: Will_Newsome 10 September 2011 10:00:13AM *  1 point [-]

Probably a little insane, but there is prior work. Saying "hey, let's do this but with ambient decision theory" isn't much of a leap.

I have a more insane idea about under what specific conditions the Born rule isn't an accurate approximation for decision theoretic purposes (which is sort of like a hypothesis about one possible convergent universal instrumental value (a convergent way superintelligence-instantiations with near-arbitrary initial goal systems to collectively optimize the universe (or a decision policy attractor that superintelligence-instantiations will predictably fall into))), but the margin is too small to explain it and it builds on this other INCREDIBLY AWESOME idea of Steve Rayhawk's and I don't want to steal his thunder. (I previously hinted at it as a way to revive the dead even when there's no information about them left in your light cone and not just with stupid tricks like running through all possible programs. Sounds impossible right? Bwa ha ha. [Edit: Actually I'm not sure if it's technically still in your light cone or not. I'd have to think. I don't like thinking.]) Hey Steve, would you mind briefly explaining the reversible computing idea here? Pretty please so I don't have to keep annoying LW by being all seekrit?

Comment author: Mitchell_Porter 10 September 2011 10:26:33AM 3 points [-]

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.

Comment author: Jack 10 September 2011 11:44:24AM *  4 points [-]

What are your thoughts on the alternatives? My frustration with the subject as it is discussed on LW is that everyone only speaks about Many Worlds in contrast to Copenhagen. It's a bit like watching a man beat up a little girl and concluding he is the strongest man in the world. I wish people here would pay more attention to the live alternatives. I find De Broglie-Bohm particularly intriguing. I hope you write the sequence.

Comment author: Mitchell_Porter 10 September 2011 12:44:18PM 0 points [-]

These are my rather circumspect thoughts on where the answer will come from.

Bohmian mechanics is ontologically incompatible with special relativity. You still get relativistic effects, but the theory requires a notion of absolute simultaneity in order to be written down, so there is an undetectable preferred reference frame. Still, I have at least two technical reasons (weak values and holographic renormalization group) for thinking it is close to something important, so it's certainly in my thoughts (when I think about this topic).

Comment author: Jack 10 September 2011 01:43:32PM 1 point [-]

Thoughts on this?

Comment author: Mitchell_Porter 11 September 2011 06:44:09AM 0 points [-]

I'll admit that emergent Lorentz invariance is not a completely unreasonable idea; there are many other examples of emergent symmetry. Though I wonder how it looks when you try to obtain emergent diffeomorphism invariance (for general relativity) as well.

Goldstein and Tumulka looks a little artificial. They allow for entanglement but not interaction, and thereby avoid causal loops in time. I'm far more interested in attempts to derive quantum nonlocality from time loops. Possibly their model can be obtained from a time-loop model in the limit where interactions are negligible.

Comment author: Will_Newsome 10 September 2011 12:24:13PM 0 points [-]

I agree with Jack, I'd appreciate a sequence, especially one that touched on interpretations that do weird things with timelike curves.

Comment author: Will_Newsome 14 September 2011 03:39:37AM *  -1 points [-]

I'm okay with reposting this from my Facebook wall largely because no one will understand it. This is probably just insane (it has more conjunctions):

But some of my more insane ideas have to do with how the Born rule as betting odds is just an approximation of the rule implicit in the entire quantum superposition which results from agents coordinating decision policies across quantum branches in order to make the multiverse recohere faster, which lets them reverse the computation already done by the universe as information gets returned back from the heat bath to the superintelligences. IMHO this idea is awesome. It requires a certain amount of computational efficiency times raw resources relative to the quantum information density of the universe (which I've heard is really, really high, like black hole high, which maybe implies there's a weird conservation thingy going on... and I think maybe cosmological natural selection (fecund universes) might be involved, where universal laws are in local optima for black hole production... this stuff is crazy).

Comment author: Will_Newsome 14 September 2011 03:44:57AM 0 points [-]

(This probably isn't insane so much as something probably cancels something out in a way that makes it moot. Or it's just insane. Needs more math at any rate.)

Comment author: Mitchell_Porter 14 September 2011 04:49:37AM 4 points [-]

Whatever else it may be, by the rules of this discussion, a decision is a type of physical process. So if it is possible for the decisions of a superintelligence in one branch of a superposition to affect the recoherence time of the whole superposition, then logically it must be possible for physical events in one branch of a superposition to have this effect, because these "decisions" are just a type of physical event.

So the key idea that needs investigating is the whole idea of events, occurring "in one branch", which affect the recoherence time of the whole. This might allow us to temporarily sidestep the, uh, issues surrounding Wallace's "derivation" of the Born rule from quantum decision theory (which is the reverse of how everyone outside the Deutsch-Wallace school of thought sees it). If reducing the time to recoherence is the objective, one should first try to understand what "recoherence acceleration" looks like. You could look at some of the models of recoherence that you just posted, find out the parametric dependency of the time to recoherence (that is, find out which parameters or physical quantities it depends upon), and then think about what sort of processes, inside or outside the system, could control those parameters.

Comment author: Will_Newsome 14 September 2011 05:11:59AM 1 point [-]

I also think the derivation from decision theory is really circular (which I think is the same as "reverse"), which is unacceptable. I say "circular" because we don't know very much about either the Born rule or decision theory. ;)

I'll look closer at your comment later. I'd like to send you a much longer essay. (I received your email and want to respond to it but have lacked the necessary psychological motivation. I really, really appreciated how you kept your eye on the "save the world" ball unlike everyone else.)

Comment author: Will_Newsome 14 September 2011 05:32:22AM 0 points [-]

Thanks for restating the key question in a very clear way.

Comment author: [deleted] 27 September 2011 11:57:39AM 0 points [-]

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.

This reminds me of the experience of screwing things up in ordinary situations. I'm flinching away from the thought of doing it wrong, but this is actually allocating attention to the wrong procedure, which makes me more likely to fail. "Losing the faith". In the context of your quote this might mean paying attention to algorithms that aren't correlated with you, which results in them having more control over your actions.

what if “your” decisions are relevant (“significant”) for some “other” agent that doesn’t share “your” “actual” “values”?

Another alternative is to think of relative significance as value, and doing the right thing would mean increasing relative significance. A few months ago I was daydreaming about how you could think of reinforcement as value, and this seems to be a similar line of thought.

Comment author: Manfred 10 September 2011 11:06:46PM 0 points [-]

Man, why people always gotta' derive the Born rule from totally different stuff? Sometimes a cigar is just a cigar, and an empirically tested law is just a law.

Comment author: Will_Newsome 10 September 2011 11:29:56PM *  1 point [-]

I wouldn't want to build my church on such a rock. That is to say, "why existence works the way it does" is a question I really want my decision theories and institutions to be able to reason sanely about.

(Edit: Wow, I just used the words "really want" to describe my state of mind. Weird day.)

Comment author: Manfred 11 September 2011 12:34:09AM 2 points [-]

Well, we can never be sure that we've found the lowest level of reality. But the Born rule fits in with the rest of physics as well as can be expected. There's no special evidence that it can be reduced. So when people try to reduce the Born rule, I think "That doesn't seem likely to be right - the simplest explanation of the evidence is still that the Born rule is fundamental."

And when there's a trend of people trying to reduce the Born rule without also explicitly trying to reduce other stuff, e.g. the Dirac equation, I think "I wonder what makes people pick on the Born rule and not the Dirac equation."