I agree with the content, though I am not sure if I approve of a terminology where causation traverses time like a two-way street.

I tend to agree with mwengler - value is not a property of physical objects or world states, but a property of an observer having unequal preferences for different possible futures.

There is a risk we might be disagreeing because we are working with different interpretations of emotion.

Imagine a work of fiction involving no sentient beings, not even metaphorically - can you possibly write a happy or tragic ending? Is it not first when you introduce some form of intelligence with preferences that destruction becomes bad and serenity good? And are not preferences for this over that the same as emotion?

I do not want to make estimates on how and with what accuracy Omega can predict. There is not nearly enough context available for this. Wikipedia's version has no detail whatsoever on the nature of Omega. There seems to be enough discussion to be had, even with the perhaps impossible assumption that Omega can predict perfectly, always, and that this can be known by the subject with absolute certainty.

I do not think the standard usage is well defined, and avoiding these terms altogether is not possible, seeing as they are in the definition of the problem we are discussing.

Interpretations of the words and arguments for the claim are the whole content of the ancestor post. Maybe you should start there instead of quoting snippets out of context and linking unrelated fallacies? Perhaps, by specifically stating the better and more standard interpretations?

Then I guess I will try to leave it to you to come up with a satisfactory example. The challenge is to include Newcomblike predictive power for Omega, but not without substantiating how Omega achieves this, while still passing your own standards of subject makes choice from own point of view. It is very easy to accidentally create paradoxes in mathematics, by assuming mutually exclusive properties for an object, and the best way to discover these is generally to see if it is possible construct or find an instance of the object described.

I don't think it is, actually. It just seems so because it presupposes that your own choice is predetermined, which is kind of hard to reason with when you're right in the process of making the choice. But that's a problem with your reasoning, not with the scenario. In particular, the CDT agent has a problem with conceiving of his own choice as predetermined, and therefore has trouble formulating Newcomb's problem in a way that he can use - he has to choose between getting two-boxing as the solution or assuming backward causation, neither of which is attractive.

This is not a failure of CDT, but one of your imagination. Here is a simple, five minute model which has no problems conceiving Newcomb's problem without any backwards causation:

• T=0: Subject is initiated in a deterministic state which can be predicted by Omega.
• T=1: Omega makes an accurate prediction for the subject's decision in Newcomb's problem by magic / simulation / reading code / infallible heuristics. Denote the possible predictions P1 (one-box) and P2.
• T=2: Omega sets up Newcomb's problem with appropriate box contents.
• T=3: Omega explains the setup to the subject and disappears.
• T=4: Subject deliberates.
• T=5: Subject chooses either C1 (one-box) or C2.
• T=6: Subject opens box(es) and receives payoff dependent on P and C.

You can pretend to enter this situation at T=4 as suggested by the standard Newcomb's problem. Then you can use the dominance principle and you will lose. But this just using a terrible model. You entered at T=0, because you were needed at T=1 for Omega's inspection. If you did not enter the situation at T=0, then you can freely make a choice C at T=5 without any correlation to P, but that is not Newcomb's problem.

Instead, at T=4 you become aware of the situation, and your decision making algorithm must return a value for C. If you consider this only from T=4 and onward, this is completely uninteresting, because C is already determined. At T=1, P was determined to either P1 or P2, and the value of C follow directly from this. Obviously, healthy one-boxing code wins and unhealthy two-boxing code loses, but there is no choice being made here, just different code with different return values being rewarded differently, and that is not Newcomb's problem either.

Finally, we will work under illusion of choice with Omega as a perfect predictor. We realize that T=0 is the critical moment, seeing as all subsequent T follows directly from this. We work backwards as follows:

• T=6: My preferences are P1C2 > P1C1 > P2C2 > P2C1.
• T=5: I should choose either C2 or C1 depending on the current value of P.
• T=4: this is when all this introspection is happening
• T=3: this is why
• T=2: I would really like there to be a million dollars present.
• T=1: I want Omega to make prediction P1.
• T=0: Whew, I'm glad I could do all this introspection which made me realize that I want P1 and the way to achieve this is C1. It would have been terrible if my decision making just worked by the dominance principle. Luckily, the epiphany I just had, C1, was already predetermined at T=0, Omega would have been aware of this at T=1 and made the prediction P1, so (...) and P1 C1 = a million dollars is mine.

Shorthand version of all the above; if the decision is necessarily predetermined before T=4, then you should not pretend you make the decision at T=4. Insert a decision making step at T=0.5, which causally determines the value of P and C. Apply your CDT to this step.

This is the only way of doing CDT honestly, and it is the slightest bit messy, but that is exactly what happens when you create a reference to the decision the decision theory is going to make in the future in the problem itself with perfect correlation to the decision before the decision has overtly been made. This sort of self reference creates impossibilities out of the thin air every day of week, such as when Pinocchio says my nose will grow now. The good news is that this way of doing it is a lot less messy than inventing a new, superfluous decision theory, and it also allows you to deal with problems like the psychopath button without any trouble whatsoever.

The post scav made more or less represents my opinion here. Compatibilism, choice, free will and determinism are too many vague definitions for me to discuss with. For compatibilism to make any sort of sense to me, I would need a new definition of free will. It is already difficult to discuss how stuff is, without simultaneously having to discuss how to use and interpret words.

Trying to leave the problematic words out of this, my claim is that the only reason CDT ever gives a wrong answer in a Newcomb's problem is that you are feeding it the wrong model. http://lesswrong.com/lw/gu1/decision_theory_faq/8kef elaborates on this without muddying the waters too much with the vaguely defined terms.

I think the barbering example is excellent - it illustrates that, while controlled experiments more or less is physics, and while physics is great, it is probably not going to bring a paradigm shift to barbering any time soon. One should not expect all domains to be equally well suited to a cut and dried scientific approach.

Where medicine lies on this continuum of suitedness is an open question - it is probably even a misleading question, with medicine being a collection of vastly different problems. However, it is not at all obvious that simply turning up the scientificness dial is going to make things better. It is for instance conceivable that there are already people treating medicine as a hard science, and that the current balance of intuition and evidence in medicine reflects how effective these two approaches are.

I am not trying to argue whether astrology is evidence-based or not. I am saying that the very inclusive definition of evidence-based which encompasses barbering is, (a) nearly useless because it includes every possible way of doing medicine and (b) probably not the one intended by the others using the term.

If you interpret evidence-based in the widest sense possible, the phrase sort of loses its meaning. Note that the very post you quote explains the intended contrast between systematic and statistical use of evidence versus intuition and traditional experience based human learning.

Besides, would you not say that astrologers figure out both how to be optimally vague, avoiding being wrong while exciting their readers, much the same way musicians figure out what sounds good?

I think I agree, by and large, despite the length of this post.

Whether choice and predictability are mutually exclusive depends on what choice is supposed to mean. The word is not exactly well defined in this context. In some sense, if variable > threshold then A, else B is a choice.

I am not sure where you think I am conflating. As far as I can see, perfect prediction is obviously impossible unless the system in question is deterministic. On the other hand, determinism does not guarantee that perfect prediction is practical or feasible. The computational complexity might be arbitrarily large, even if you have complete knowledge of an algorithm and its input. I can not really see the relevance to my above post.

Finally, I am myself confused as to why you want two different decision theories (CDT and EDT) instead of two different models for the two different problems conflated into the single identifier Newcomb's paradox. If you assume a perfect predictor, and thus full correlation between prediction and choice, then you have to make sure your model actually reflects that.

Let's start out with a simple matrix, P/C/1/2 are shorthands for prediction, choice, one-box, two-box.

• P1 C1: 1000
• P1 C2: 1001
• P2 C1: 0
• P2 C2: 1

If the value of P is unknown, but independent of C: Dominance principle, C=2, entirely straightforward CDT.

If, however, the value of P is completely correlated with C, then the matrix above is misleading, P and C can not be different and are really only a single variable, which should be wrapped in a single identifier. The matrix you are actually applying CDT to is the following one:

• (P&C)1: 1000
• (P&C)2: 1

The best choice is (P&C)=1, again by straightforward CDT.

The only failure of CDT is that it gives different, correct solutions to different, problems with a properly defined correlation of prediction and choice. The only advantage of EDT is that it is easier to cheat in this information without noticing it - even when it would be incorrect to do so. It is entirely possible to have a situation where prediction and choice are correlated, but the decision theory is not allowed to know this and must assume that they are uncorrelated. The decision theory should give the wrong answer in this case.

Only in the sense that the term "pro-life" implies than there exist people opposed to life.