All of SMK's Comments + Replies

SMK
20

You might also find the following cases interesting (with self-locating uncertainty as an additional dimension), from this post.

Sleeping Newcomb-1. Some researchers, led by the infamous superintelligence Omega, are going to put you to sleep. During the two days that your sleep will last, they will briefly wake you up either once or twice, depending on the toss of a biased coin (Heads: once; Tails: twice). After each waking, they will put you back to sleep with a drug that makes you forget that waking. The weight of the coin is determined by what

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SMK
00

Epistemic Constraint: The probability distribution  which the agent settles on cannot be self-refuting according to the beliefs. It must be a fixed point of : a  such that .

Minor: there might be cases in which there is a fixed point , but where the agent doesn't literally converge or deliberate their way to it, right? (Because you are only looking for  to satisfy the conditions of Brouwer/Kakutani, and not, say, Banach, right?) In other words, it might not always be accurate to say that the agent "set... (read more)

2Abram Demski
Yeah, "settles on" here meant however the agent selects beliefs. The epistemic constraint implies that the agent uses exhaustive search or some other procedure guaranteed to produce a fixed point, rather than Banach-style iteration.  Moving to a Banach-like setting will often make the fixed points unique, which takes away the whole idea of FixDT. Moving to a setting where the agent isn't guaranteed to converge would mean we have to re-write the epistemic constraint to be appropriate to that setting.
SMK
*72

A common trope is for magic to work only when you believe in it. For example, in Harry Potter, you can only get to the magical train platform 9 3/4 if you believe that you can pass through the wall to get there.

Are you familiar with Greaves' (2013) epistemic decision theory? These types of cases are precisely the ones she considers, although she is entirely focused on the epistemic side of things. For example (p. 916):

Leap. Bob stands on the brink of a chasm, summoning up the courage to try and leap across it. Confidence helps him in such situations: speci

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2Abram Demski
Yes, thanks for citing it here! I should have mentioned it, really. I see the Skyrms iterative idea as quite different from the "just take a fixed point" theory I sketch here, although clearly they have something in common. FixDT makes it easier to combine both epistemic and instrumental concerns -- every fixed point obeys the epistemic requirement; and then the choice between them obeys the instrumental requirement. If we iteratively zoom in on a fixed point instead of selecting from the set, this seems harder? If we try the Skyrms iteration thing, maybe the most sensible thing would be to move toward the beliefs of greatest expected utility -- but do so in a setting where epistemic utility emerges naturally from pragmatic concerts (such as A Pragmatists Guide to Epistemic Decision Theory by Ben Levinstein). So the agent is only ever revising its beliefs in pragmatic ways, but we assume enough about the environment that it wants to obey both the epistemic and instrumental constraints? But, possibly, this assumption would just be inconsistent with the sort of decision problem which motivates FixDT (and Greaves).
2SMK
You might also find the following cases interesting (with self-locating uncertainty as an additional dimension), from this post.
SMK
*00

And, second, the agent will continually implement that plan, even if this makes it locally choose counter-preferentially at some future node.

Nitpick: IIRC, McClennen never talks about counter-preferential choice. Rather, that's Gauthier's (1997) approach to resoluteness.

as devised by Bryan Skyrms and Gerald Rothfus (cf Rothfus 2020b).

Found a typo: it is supposed to be Gerard. (It is also misspelt in the reference list.)

1Sami Petersen
Thanks Sylvester; fixed!