Qiaochu_Yuan comments on Against utility functions - Less Wrong

40 Post author: Qiaochu_Yuan 19 June 2014 05:56AM

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Comment author: AlexMennen 19 June 2014 08:22:27PM 2 points [-]

Can you give some specific examples of people misusing utility functions? Or if you don't want to point fingers, can you construct examples similar to those you've seen people use?

Comment author: Qiaochu_Yuan 20 June 2014 03:14:18AM 2 points [-]

This thread was prompted by this comment in the Open Thread.

Comment author: Nisan 20 June 2014 04:57:26PM 3 points [-]

That comment is about utilitarianism and doesn't mention "utility functions" at all.

Comment author: Qiaochu_Yuan 20 June 2014 05:16:32PM *  3 points [-]

I can't help but suspect, though, that LW people are drawn to utilitarianism because of what they see as the inevitability of using utility functions to model preferences. Maybe this impression is mistaken.

Comment author: Caspar42 20 June 2014 10:31:48PM 0 points [-]

To me it seems as if utility functions were the most general (deterministic) way to model preferences. So, if we model preferences by "something else", it will usually be some special case of a utility function. Or do you have something even more general than utility functions that is not based on throwing a coin? Or do you propose that we model preferences with randomness?

Comment author: Qiaochu_Yuan 22 June 2014 06:21:10PM *  3 points [-]

There are helpful models and there are unhelpful models. I can model the universe as a wave function in a gigantic Hilbert space, and this is an incredibly general model as it applies to any quantum-mechanical system, but it's not necessarily a helpful model for making predictions at the level I care about most of the time. My claim is that, even if you believe that utility functions can model human preferences (which I also dispute), then it's still true that utility functions are in practice an unhelpful model in this sense.

Comment author: Caspar42 22 June 2014 08:51:51PM 0 points [-]

For our universe, other models have been extremely succesful. Therefore, the generality of wave functions clearly is not required. In case of (human) preferences, it is unclear whether another model suffices.

What you are saying seems to me a bit like: "Turing machines are difficult to use. Nobody would simulate this certain X with a Turing machine in practice. Therefore Turing-machines are generally useless." But of course on some level of practical application, I totally agree with you, so mabye there is no real disagreement in the use of utility functions here - at least I would never say something like "my utility funtion is ..." and I do not attempt to write a C-Compiler on a Turing machine.

I do not think that the statement "utility functions can model human preferences" has a formal meaning, however, if you say that it is not true, I would really be very interested in how you prefer to model human preferences.