thomblake comments on VNM expected utility theory: uses, abuses, and interpretation - Less Wrong

21 Post author: Academian 17 April 2010 08:23PM

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Comment author: thomblake 20 April 2010 03:25:19PM 0 points [-]

Perhaps I'm missing something, but it seems to me this doesn't cover risk-aversion properly.

One great feature is that it implicitly accounts for risk aversion: not risking $100 for a 10% chance to win $1000 and 90% chance to win $0 just means that for you, utility($100) > 10%utility($1000) + 90%utility($0).

Suppose for me, utility($100) = 1, and utility($1000) = 100, and utility($0) = 0. Then, utility($100) < 10%utility($1000) + 90%utility($0); (1 < 10). Now suppose I am extremely risk-averse; I prefer to never wager any money I actually have and will practically always take a certain $100 over any uncertain $1000. It does not seem this configuration is impossible in an agent, but is not supported by your model of risk-aversion.

Does this merely mean that this type of risk-aversion is considered irrational and therefore not covered in the VNM model?

Comment author: pengvado 22 April 2010 10:44:58AM 0 points [-]

Does this merely mean that this type of risk-aversion is considered irrational and therefore not covered in the VNM model?

Yes. If you are risk-averse (or loss-averse) in terms of marginal changes in your money, then you're not optimizing any consistent function of your total amount of money.