crazy88 comments on Decision Theory FAQ - Less Wrong

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

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Comment author: AlexMennen 28 February 2013 10:08:05PM *  2 points [-]

In the VNM system, utility is defined via preferences over acts rather than preferences over outcomes. To many, it seems odd to define utility with respect to preferences over risky acts. After all, even an agent who thinks she lives in a world where every act is certain to result in a known outcome could have preferences for some outcomes over others. Many would argue that utility should be defined in relation to preferences over outcomes or world-states, and that's not what the VNM system does. (Also see section 9.)

It's misleading to associate acts with lotteries over outcomes like that. In most situations, there are lotteries over outcomes that are not achievable by any act. And "lottery" makes it very clear that the probabilities of each outcome that could result are known, whereas "act" does not.

Comment author: crazy88 04 March 2013 09:12:21AM 0 points [-]

My understanding is that in the VNM system, utility is defined over lotteries. Is this the point you're contesting or are you happy with that but unhappy with the use of the word "acts" to describe these lotteries. In other words, do you think the portrayal of the VNM system as involving preferences over lotteries is wrong or do you think that this is right but the way we describe it conflates two notions that should remain distinct.

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