Lumifer comments on Open thread, Apr. 18 - Apr. 24, 2016 - Less Wrong

2 Post author: MrMind 18 April 2016 07:19AM

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Comment author: Lumifer 21 April 2016 09:22:17PM 1 point [-]

Is it an observation that expected utility maximization does not include risk management for free, just because it's "utility".

Comment author: SilentCal 21 April 2016 09:47:15PM 0 points [-]

I'm still not sure which line you're taking on this: A) Disputing the VNM formulation of rational behavior that a rational agent should maximize expected utility (https://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Morgenstern_utility_theorem), or B) Disputing that we can write down an approximate utility function accurate enough to sufficiently capture our risk preferences.

Comment author: Lumifer 22 April 2016 01:24:32AM *  2 points [-]

Both.

VNM doesn't offer any "formulation of rational behavior". VNM says that a function with a particular set of properties must exist and relies on assumptions that do not necessarily hold in real life.

I also don't think that a utility function that can condense the risk preferences into a single scalar is likely to be accurate enough for practical purposes.

Comment author: solipsist 23 April 2016 10:25:46PM 0 points [-]

Can you by chance pin down your disagreement to a particular axiom? You're modus tollensing where I expected you would modus ponens.

Comment author: Lumifer 24 April 2016 12:29:48AM 1 point [-]

You are looking at the wrong meta level.

When I say "VNM doesn't offer any formulation of rational behavior" I'm not disagreeing with any particular axiom. It's like I'm saying that an orange is not an apple and you respond by asking me what kind of apples I dislike.

Comment author: solipsist 24 April 2016 02:53:58AM *  0 points [-]

Which (possibly all) of the VNM axioms do you think are not appropriate as part of a formulation of rational behavior?

I think the Peano natural numbers is a reasonable model for the number of steins I own (with the possible exception that if my steins fill up the universe a successor number of steins might not exist). But I don't think the Peano axioms are a good model for how much beer I drink. It is not the case that all quantities of beer can be expressed as successors to 0 beer, so beer does not follow the axiom of induction.

I think ZFC axioms are a poor model of impressionist paintings. For example, it is not the case that for every impressionist paintings x and y, there exists an impressionist painting that contains both x and y. Therefore impressionist paintings violate the axiom of pairing.

Comment author: Lumifer 24 April 2016 05:19:08AM 1 point [-]

Which (possibly all) of the VNM axioms do you think are not appropriate as part of a formulation of rational behavior?

I don't think that rational behaviour as understood on LW (basically, instrumental rationality) has anything to do with VNM axioms. In particular, I do not think that the VNM model is an adequate model of human decision-making once you go beyong toy examples.