linas comments on Decision Theory FAQ - Less Wrong

52 Post author: lukeprog 28 February 2013 02:15PM

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Comment author: linas 05 March 2013 03:31:52AM 2 points [-]

Presentation of Newcomb's problem in section 11.1.1. seems faulty. What if the human flips a coin to determine whether to one-box or two-box? (or any suitable source of entropy that is beyond the predictive powers of the super-intelligence.) What happens then?

This point is danced around in the next section, but never stated outright: EDT provides exactly the right answer if humans are fully deterministic and predictable by the superintelligence. CDT gives the right answer if the human employs an unpredictable entropy source in their decision-making. It is the entropy source that makes the decision acausal from the acts of the super-intelligence.

Comment author: wedrifid 05 March 2013 07:34:25AM 2 points [-]

Presentation of Newcomb's problem in section 11.1.1. seems faulty. What if the human flips a coin to determine whether to one-box or two-box? (or any suitable source of entropy that is beyond the predictive powers of the super-intelligence.) What happens then?

If the FAQ left this out then it is indeed faulty. It should either specify that if Omega predicts the human will use that kind of entropy then it gets a "Fuck you" (gets nothing in the big box, or worse) or, at best, that Omega awards that kind of randomization with a proportional payoff (ie. If behavior is determined by a fair coin then the big box contains half the money.)

This is a fairly typical (even "Frequent") question so needs to be included in the problem specification. But it can just be considered a minor technical detail.

Comment author: patrickscottshields 11 March 2013 03:10:07AM *  0 points [-]

This response challenges my intuition, and I would love to learn more about how the problem formulation is altered to address the apparent inconsistency in the case that players make choices on the basis of a fair coin flip. See my other post.

Comment author: linas 06 March 2013 03:24:01AM 0 points [-]

OK, but this can't be a "minor detail", its rather central to the nature of the problem. The back-n-forth with incogn above tries to deal with this. Put simply, either omega is able to predict, in which case EDT is right, or omega is not able to predict, in which case CDT is right.

The source of entropy need not be a fair coin: even fully deterministic systems can have a behavior so complex that predictability is untenable. Either omega can predict, and knows it can predict, or omega cannot predict, and knows that it cannot predict. The possibility that it cannot predict, yet is erroneously convinced that it can, seems ridiculous.

Comment author: MugaSofer 06 March 2013 09:59:37AM -2 points [-]

It should either specify that if Omega predicts the human will use that kind of entropy then it gets a "Fuck you" (gets nothing in the big box, or worse) or, at best, that Omega awards that kind of randomization with a proportional payoff (ie. If behavior is determined by a fair coin then the big box contains half the money.)

Or that Omega is smart enough to predict any randomizer you have available.

Comment author: linas 09 March 2013 05:34:18AM 2 points [-]

The FAQ states that omega has/is a computer the size of the moon -- that's huge but finite. I believe its possible, with today's technology, to create a randomizer that an omega of this size cannot predict. However smart omega is, one can always create a randomizer that omega cannot break.

Comment author: MugaSofer 21 March 2013 04:40:47PM -2 points [-]

True, but just because such a randomizer is theoretically possible doesn't mean you have one to hand.