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Kingreaper comments on Newcomb's Problem: A problem for Causal Decision Theories - Less Wrong
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Causal Decision Theory isn't fatally flawed in this case, it's simply harder to properly apply.
A sufficiently advanced superintelligence could perfectly replicate you or I in a simulation. In fact, I can't currently concieve of a more reliable method of prediction.
Which is where the explanation comes in for Causal Decision Theory. You may be the simulation, if you are the simulation then which box you take DOES affect what is in the boxes.
The prediction method doesn't have to be very good. A predictor that's only slightly better than chance is quite enough to put EDT and CDT into conflict. For example, I could achieve better than 50% accuracy on LW participants by just reading through their comment history and seeing what they think about Newcomb's Problem.
Indeed. A 55% accuracy is plenty to make this an issue. And at present, CDT seems to me to fail on the 55% accuracy problem; whereas EDT clearly works.
It's easy to construct Newcomb-like problems where EDT fails. For example, we could make the two boxes transparent, so you already see their contents and your action gives you no further evidence. One-boxing is still the right decision because that's what you'd like to be predicted by Omega (alternatively: if you could modify your brain before meeting Omega, that's what you'd precommit to doing), but both EDT and CDT fail to see that. Another similar example is Parfit's Hitchhiker.
CDT still works in that case if you're dealing with omega, and have no reaason to believe Omega won't simulate you. If you are one of the simulations, you decide the prediction for the real version
How about if you're dealing with me?
Then CDT seems to fail, with it being a low-% case (perhaps 55% as I used above) and EDT fails due to the prize already being in evidence
We could do a modified Newcomb's Problem where the perfectly honest, all knowing Omega tells you that you're not the simulation but the actual person and the simulation has already been done which seems to resolve that possibility discussed above. I don't think you need to though because there's no statement in Newcomb's Problem that says that the predictions do occur via a simulation.
It reminds me of the trolley cart example in ethics where you're told a train is rolling out of control down a hill and will run over 3 people. By hitting a switch you can change the track it goes down and it will instead hit 1 different person. Should you hit the switch?
The specific question isn't relevant to what I'm trying to say but people's responses are.
People will say things like, "Well, I'd just yell at the three people to get off the tracks."
And then you have to specify that they're too far away.
And the person will say, "Well, I'll run toward them yelling so I get close enough in time."
And you have to specify that they're too far away for that as well.
The point is that the people that ask this question are missing the whole idea of the abstraction behind the trolley problem and they're thinking of it as a lateral thinking test rather than a scenario used to make an intellectual point.
I feel that finding a way for CDT to answer Newcomb's Problem via the specifics of the way Omega predicts your reactions is a similar response - trying to respecify the argument in such a way that an answer can be found rather than looking at the abstracted conception of the argument.
As always, I'm open to being shown that I'm wrong and missing something though.
Then the prediction has been based on a simulation that took place under different circumstances, since Omega (being perfectly honest) did not say this to the simulation.
But as others have said, this is beside the point. After reading all of these irrelevant objections and the irrelevant responses to them, I'm convinced that (at least when addressing people who understand decision theory up to the point of doing calculations with statistics) it's better to phrase the question so that Omega is simply a clever human being who has achieved very high accuracy with very high correlation on a very large number of previous trials, instead of bringing perfection into it.
I'm thinking something like this:
Also, make the amounts $1 and $1000 so that utility will be very close to linear in amount of money (at least to middle-class First-Worlders like me).
Would you say the trolley car problem implies that the fat man has a strong obligation to throw himself under the train?
I'm not AdamBell, but I think that doesn't follow. The fat man could value his own life higher than the lives of three strangers. But we have no reason to value his life higher too.
An All-knowing Omega by definition contains a simulation of this exact scenario. And in that simulation they aren't being perfectly honest, but I still believe they are.
If Omega is in fact all-knowing, all possible scenarios exist in simulation within it's infinite knowledge.
This is why throwing all-knowing entities into problems always buggers things up
Given the abstracted conception, prediction through simulation seems to be the most probable explanation. This results in CDT working.
It's not starting from wanting CDT to work, it's starting from examining the problem, working out the situation from the evidence, and then working out what CDT would say to do.
If I can't apply reason when using CDT, CDT will fail when I'm presented with an "opportunity" to buy a magic rock that costs £10,000, and will make me win the lottery within a month.
Sigh.
You are missing the point.
Replace Omega with a genius Psychologist who only gets it right 99% of the time and CDT will have you walk off with $1000 while correct thinking leaves you with $1,000,000 almost all of the time, it's just that in that scenario people will uselessly argue that the 1% chance to get lucky somehow makes it rational.
How is the genius psychologist likely to be predicting your actions?
To me, it seems probable that he's simulating you, imperfectly, within his own mind.
How would you explain his methodology?
EDIT: to clarify my reasoning, I simulate people, myself included, often. Generally when I want to predict their actions. I'm not very good at it. Were I a genius psychologist, and hence obviously great at simulating people, I don't see why I would be any less likely to simulate people.
She doesn't tell you in the scenario.
Maybe she had her grad students talk with you on various subjects and subject you to various stealth psychological experiments over the last 10 years and watched it all on video, all based on your signing an agreement to take part in a psychological experiment that didn't specify a duration 15 years ago that was followed by a dummy experiment and that you promptly forgot about.
Maybe she is secretly your mother.
Maybe she is just that good and tell it by the way you shaked her hand.
In any case 99% shouldn't require imagining the actions of a reflectively indistinguishable from you copy of you.
Those are all ways of her having gathered the evidence.
From the evidence, how has she reached the conclusion?
The most plausible scenario for getting from evidence to conclusion is mental simulation as far as I can tell.
You haven't even proposed a single alternative yet
EDIT: (did you edit this in, or did I miss it?)
You expect the copy to be able to tell it's a copy? Why? Why would the psychologist simulate it discovering that it is the copy? When you simulate someone's reaction to possible courses of action, do you simulate them as being aware of being a simulation?
None of my internal simulations have ever been aware of being simulations.
There are four possibilities:
Only in case 4. will you seriously have to wonder whether you are a copy. In case 1. you will know that you are not as soon as you consider the possibility, case 2. is irrelevant unless you also assume that the real you will also conclude that it's a copy, which is logically inconsistent.
Nevertheless case 1. should be sufficient for predicting the actions you take once you conclude that you are not a copy to a reasonable accuracy.
Case 1 is sufficient to predict my actions IFF I would never wonder about whether I was a copy.
Given that I would in fact wonder whether I was a copy, and that that thought-process is significant to the scenario, Case 1 seems likely to be woefully inadequate for simulating me.
Case 4 is therefore much more plausible for a genius psychologist (with 99% accuracy) from my PoV.
The psychologist tells you that she simply isn't capable of case 4 (there are all sorts of at least somewhat verifiable facts that you would expect yourself to know and that she doesn't [e. g. details about your job that have to make sense and be consistent with a whole web of other details, that she couldn't plausibly have spied out or invented a convincing equivalent thereof herself]). Given that you just wondered you can't be a simulation. What do you do?
The stealth psychological experiments could have included an isomorphic problem, or she could be using a more sophisticated version of
Stealth psychological experiments you forgot about allowed her to determine necessary and/or sufficient conditions for you assuming that you might be in a simulation that you yourself are unaware of, and she set the whole thing up in a such a way that she can tell with high confidence whether you do.
The categorisation possibility is reasonable. Personally I would estimate the probability of 99% accuracy achieved through categorisation lower than the probability of 99% accuracy achieved through mental simulation, but it's certainly a competitive hypothesis.
Assuming she tells you that she predicted your actions through some unspecified mechanism other than imagining your thought process in sufficient detail for the imagined version to ask itself whether it just exists in her imagination, what do you do?
No, he doesn't (necessarily). He could prove the inevitable outcome based of elements of the known state of your brain without ever simulating anything. If you read reduction of could you will find a somewhat similar distinction that may make things clearer.
... So we can't conclude this.
This suggests you don't really understand the problem (or perhaps CDT). That is not the same kind of reasoning.
Does he not know the answer to "what will happen after this" with regards to every point in the scenario?
If he doesn't, is he all-knowing?
If he does know the answer at every point, in what way doesn't he contain the entire scenario?
EDIT: A non-all-knowing superintelligence could presumably find ways other than simulation of getting my answer, as I said simulation just strikes me as the most probable. If you think I should update my probability estimate of the other methods, that's a perfectly reasonable objection to my logic re: a non-all-knowing superint.
Certainly. That is what I consider Omega doing when I think about these problems. It is a useful intuition pump, something we can get our head around.