Wei_Dai2 comments on Value is Fragile - Less Wrong

41 Post author: Eliezer_Yudkowsky 29 January 2009 08:46AM

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Comment author: Wei_Dai2 31 January 2009 01:24:37AM 4 points [-]

A utility function is like a program in a Turing-complete language. If the behaviour can be computed at all, it can be computed by a utility function.

Tim, I've seen you state this before, but it's simply wrong. A utility function is not like a Turing-complete language. It imposes rather strong constraints on possible behavior.

Consider a program which when given the choices (A,B) outputs A. If you reset it and give it choices (B,C) it outputs B. If you reset it again and give it choices (C,A) it outputs C. The behavior of this program cannot be reproduced by a utility function.

Here's another example: When given (A,B) a program outputs "indifferent". When given (equal chance of A or B, A, B) it outputs "equal chance of A or B". This is also not allowed by EU maximization.