Vaniver comments on Risk aversion vs. concave utility function - Less Wrong

1 Post author: dvasya 31 January 2012 06:25AM

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Comment author: Vaniver 01 February 2012 12:41:59AM *  1 point [-]

If the sure payoff of

16 paperclips = 4 utilons

is strictly preferred to the bet

{P(9 paperclips) = 0.5; P(25 paperclips) = 0.5} = 4 utilons

Then you have a contradiction in terms, because you shouldn't have a strict preference for outcomes with the same number of utilons.

The sqrt(paperclips) agent should be indifferent between 16 paperclips and {.5: 9; .5: 25} paperclips. It has a strict preference for 16.5 paperclips to either 16 paperclips or {.5: 9; .5: 25} paperclips.

Savage's 4th axiom- the strict preference- says that in order for you to strictly prefer 16.5 paperclips to 16 paperclips, there has to be a difference in the utilon values. There is- 16.5 paperclips represents 4.06 utilons vs. only 4 for 16 paperclips.

By the 4th axiom, we can construct other bets: say, {.5: 9.4; .5; 25.4}. The agent strictly prefers 16.5 paperclips to that deal (which has 4.05 utilons).

Comment author: Dan_Moore 05 February 2013 04:37:39PM 1 point [-]

Upvoted. In my opinion, the literature on risk-averse agents is logically consistent, and being risk-averse does not imply irrationality. I agree with Vaniver's comments. Also, humans are, on average*, risk averse.

*For example, with respect to markets, 'market clearing' average in a Walrasian auction sense.