ciphergoth comments on You cannot be mistaken about (not) wanting to wirehead - Less Wrong

34 Post author: Kaj_Sotala 26 January 2010 12:06PM

You are viewing a comment permalink. View the original post to see all comments and the full post content.

Comments (79)

You are viewing a single comment's thread. Show more comments above.

Comment author: ciphergoth 28 January 2010 09:07:20AM *  4 points [-]

If you take a utility function and multiply all the utilities by 0.01, is it the same utility function? In one sense it is, but by your measure it will always win a "most pessimistic" contest.

Update: thinking about this further, if the only allowable operations on utilities are comparison and weighted sum, then you can multiply by any positive constant or add and subtract any constant and preserve isomorphism. Is there a name for this mathematical object?

Comment author: RichardKennaway 28 January 2010 03:00:33PM *  5 points [-]

Affine transformations. Utility functions are defined up to affine transformation.

In particular, this means that nothing has "positive utility" or "negative utility", only greater or lesser utility compared to something else.

ETA: If you want to compare two different people's utilities, it can't be done without introducing further structure to enable that comparison. This is required for any sort of felicific calculus.

Comment author: ciphergoth 29 January 2010 05:52:15PM 1 point [-]

There's a name I can't remember for the "number line with no zero" where you're only able to refer to relative positions, not absolute ones. I'm looking for a name for the "number line with no zero and no scale", which is invariant not just under translation but under any affine transformation with positive determinant.

Comment author: kpreid 29 January 2010 06:32:43PM 0 points [-]

I'm in an elementary statistics class right now and we just heard about “levels of measurement” which seem to make these distinctions: your first is the interval scale, and second the ordinal scale.

Comment author: pengvado 29 January 2010 07:02:11PM 1 point [-]

The "number line with no zero, but a uniquely preferred scale" isn't in that list of measurement types; and it says the "number line with no zero and no scale" is the interval scale.

Comment author: thomblake 28 January 2010 01:51:53PM 0 points [-]

A utility function is just a representation of preference ordering. Presumably those properties would hold for anything that is merely an ordering making use of numbers.

Comment author: RichardKennaway 28 January 2010 03:03:03PM 2 points [-]

You also need the conditions of the utility theorem to hold. A preference ordering only gives you conditions 1 and 2 of the theorem as stated in the link.

Comment author: thomblake 28 January 2010 03:42:11PM 0 points [-]

Good point. I was effectively entirely leaving out the "mathematical" in "mathematical representation of preference ordering". As I stated it, you couldn't expect to aggregate utiles.

Comment author: ciphergoth 29 January 2010 05:53:16PM 0 points [-]

You can't aggregate utils; you can only take their weighted sums. You can aggregate changes in utils though.