Matt_Simpson comments on Open thread, January 25- February 1 - Less Wrong

8 Post author: NancyLebovitz 25 January 2014 02:52PM

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Comment author: Alejandro1 26 January 2014 01:00:27AM *  14 points [-]

I think the non-intuitive nature of the A choice is because we naturally think of utilons as "things". For any valuable thing (money, moments of pleasure, whatever) anybody who is minimally risk adverse would choose B. But utllons are not things, they are abstractions defined by one's preferences. So that A is the rational choice is a tautology, in the standard versions of utility theory.

It may help to think it the other way around, starting from the actual preference. You would choose a 99.9% chance of losing ten cents and 0.1% chance of winning 10000 dollars over winning one cent with certainty, right? So then perhaps, as long as we don't think of other bets and outcomes, we can map winning 1 cent to +1 utilon, losing 10 cents to -100 utilons and winning 10000 dollars to +10000 utilons. Then we can refine and extend the "outcomes <=> utilons" map by considering your actual preferences under more and more bets. As long as your preferences are self-consistent in the sense of the VNM axioms, then there will a mapping that can be constructed.

ETA: of course, it is possible that your preferences are not self-consistent. The Allais paradox is an example where many people's intuitive preferences are not self-consistent in the VNM sense. But constructing such a case is more complicated that just considering risk-aversion on a single bet.

Comment author: [deleted] 26 January 2014 01:26:49AM 11 points [-]

Also, it's well possible that your utility function doesn't evaluate to +10000 for any value of its argument, i.e. it's bounded above.

Comment author: Matt_Simpson 31 January 2014 05:14:58AM 0 points [-]

Since utility functions are only unique up to affine transformation, I don't know what to make of this comment. Do you have some sort of canonical representation in mind or something?

Comment author: [deleted] 31 January 2014 07:25:49AM -1 points [-]

In the context of this thread, you can consider U(status quo) = 0 and U(status quo, but with one more dollar in my wallet) = 1. (OK, that makes +10000 an unreasonable estimate of the upper bound; pretend I said +1e9 instead.)