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Basil Halperin · Mar 31, 2022

Newcomb’s problem is just a standard time consistency problem

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Basil Halperin · Basil Halperin

https://www.basilhalperin.com/essays/newcomb.html

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Basil Halperin@BasilHalperin

Newcomb’s problem is just a standard time consistency problem basilhalperin.com/essays/newcomb… I argue the typical description of Newcomb’s problem is confusing only because it unintentionally conflates *two different possible points in time* from which you could make your choice

5:07 PM · Mar 31, 2022

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Basil Halperin@BasilHalperin

Split into the two possible cases, Newcomb’s problem is basically trivial – and doesn’t require revising decision theory! In fact, the problem is (literally) isomorphic to the canonical Kydland-Prescott (1978) central bank time consistency problem from macroeconomics

5:07 PM · Mar 31, 2022

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Basil Halperin@BasilHalperin

Steelmanning the opposing view: I think folks who argue Newcomb demonstrates a flaw in standard decision theory are implicitly arguing (and should *explicitly* argue!), “We want to come up with a decision theory that never encounters time consistency problems”

5:07 PM · Mar 31, 2022

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Basil Halperin@BasilHalperin

“We want to come up with a decision theory that never encounters time consistency problems” Honestly I think that’s just a fool’s errand. It’s like trying to come up with a decision theory that never encounters multiple equilibria. Sorry, that’s just a thing that happens

5:07 PM · Mar 31, 2022

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Basil Halperin@BasilHalperin

Nerds in this literature should also note that the notion of “program equilibrium”, sometimes used in this lit, is implicitly smuggling a notion of commitment in – hence why it gives the “updateless” answer (Same with the “contractible contracts” of Peters and Szentes 2012)

5:07 PM · Mar 31, 2022

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