Houshalter comments on Against Expected Utility - Less Wrong

-3 Post author: Houshalter 23 September 2015 09:21PM

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

Comments (28)

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

Comment author: Houshalter 24 September 2015 05:56:41AM *  -1 points [-]

I'm not sure where this comes from, when the VNM theorem gets so many mentions on LW.

I understand the VNM theorem. I'm objecting to it.

A utility function is, by definition, that which the corresponding rational agent maximizes the expectation of

If you want to argue "by definition", then yes, according to your definition utility functions can't be used in anything other than expected utility. I'm saying that's silly.

simply an encoding of the actions which a rational agent would take in hypothetical scenarios

Not all rational agents, as my post demonstrates. An agent following median maximizing would not be describable by any utility function maximized with expected utility. I showed how to generalize this to describe more kinds of rational agents. Regular expected utility becomes a special case of this system. I think generalizing existing ideas and mathematics is a desirable thing sometimes.

It is not "optimal as the number of bets you take approaches infinity"

Yes, it is. If you assign some subjective "value" to different outcomes, and to different things, then maximizing expected u̶t̶i̶l̶i̶t̶y̶ value, will maximize it, as the number of decisions approaches infinity. For every bet I lose at certain odds, I will gain more from others some predictable percent of the time. On average it cancels out.

This might not be the standard way of explaining expected utility, but it's very simple and intuitive, and shows exactly where the problem is. It's certainly sufficient for the explanation in my post.

Humans do not have utility functions. We do not exhibit the level of counterfactual self-consistency that is required by a utility function.

That's quite irrelevant. Sure humans are irrational and make inconsistencies and errors in counterfactual situations. We should strive to be more consistent though. We should strive to figure out the utility function that most represents what we want. And if we program an AI, we certainly want it to behave consistently.

Yes, it is common, especially on LW and in discussions of utilitarianism, to use the term "utility" loosely, but don't conflate that with utility functions by creating a chimera with properties from each. If the "utility" that you want to talk about is vaguely-defined (e.g., if it depends on some account of subjective preferences, rather than on definite actions under counterfactual scenarios), then it probably lacks all of useful mathematical properties of utility functions, and its expectation is no longer meaningful.

Again, back to arguing by definition. I don't care what the definition of "utility" is. If it would please you to use a different word, then we can do so. Maybe "value function" or something. I'm trying to come up with a system that will tell us what decisions we should make, or program an AI to make. One that fits our behavior and preferences the best. One that is consistent and converges to some answer given a reasonable prior.

You haven't made any arguments against my idea or my criticisms of expected utility. It's just pedantry about the definition of a word, when it's meaning in this context is pretty clear.

Comment author: AlexMennen 24 September 2015 06:40:37PM 3 points [-]

You're missing VincentYu's point, which is also a point I have made to you earlier: the utility function in the conclusion of the VNM theorem is not the same as a utility function that you came up with a completely different way, like by declaring linearity with respect to number of lives.

If you assign some subjective "value" to different outcomes, and to different things, then maximizing expected u̶t̶i̶l̶i̶t̶y̶ value, will maximize it, as the number of decisions approaches infinity. For every bet I lose at certain odds, I will gain more from others some predictable percent of the time. On average it cancels out.

This might not be the standard way of explaining expected utility, but it's very simple and intuitive, and shows exactly where the problem is. It's certainly sufficient for the explanation in my post.

This is an absurd strawman that has absolutely nothing to do with the motivation for EU maximization.

Comment author: Houshalter 25 September 2015 03:55:12AM -1 points [-]

You're missing VincentYu's point, which is also a point I have made to you earlier: the utility function in the conclusion of the VNM theorem is not the same as a utility function that you came up with a completely different way, like by declaring linearity with respect to number of lives.

I discussed this in my post. I know VNM is indifferent to what utility function you use. I know the utility function doesn't have to be linear. But I showed that no transformation of it fixes the problems or produces the behavior we want.

This is an absurd strawman that has absolutely nothing to do with the motivation for EU maximization.

It's not a strawman! I know there are multiple ways of deriving EU. If you derive it a different way, that's fine. It doesn't affect any of my arguments whatsoever.

Comment author: AlexMennen 25 September 2015 05:37:59AM 2 points [-]

But I showed that no transformation of it fixes the problems or produces the behavior we want.

No, you only tried two: linearity, and a bound that's way too low.

It's not a strawman! I know there are multiple ways of deriving EU. If you derive it a different way, that's fine. It doesn't affect any of my arguments whatsoever.

You picked a possible defense of EU maximization that no one ever uses to defend EU maximization, because it is stupid and therefore easy for you to criticize. That's what a strawman is. You use your argument against this strawman to criticize EU maximization without addressing the real motivations behind it, so it absolutely does affect your arguments.

Comment author: Lumifer 24 September 2015 02:38:08PM 3 points [-]

I don't care what the definition of "utility" is.

It's a word you use with wild abandon. If you want to communicate (as opposed to just spill a mind dump onto a page), you should care because otherwise people will not understand what you are trying to say.

I'm trying to come up with a system that will tell us what decisions we should make

There are a lot of those, starting with WWJD and ending with emulating nature that is red in tooth and claw. The question is on which basis will you prefer a system over another one.

Comment author: Houshalter 25 September 2015 03:55:15AM 0 points [-]

It's a word you use with wild abandon. If you want to communicate (as opposed to just spill a mind dump onto a page), you should care because otherwise people will not understand what you are trying to say.

Everyone except VincentYu seems to understand what I'm saying. I do not understand where people are getting confused. The word "utility" has more meanings than "that thing which is produced by the VNM axioms".

The question is on which basis will you prefer a system over another one.

The preference should be too what extent it would make the same decisions you would. This post was the argue that expected utility doesn't and can not do that. And to show some alternatives which might.

Comment author: Lumifer 25 September 2015 02:44:20PM 2 points [-]

I do not understand where people are getting confused.

I just told you.

If you want to understand where people are getting confused, perhaps you should listen to them.

The preference should be too what extent it would make the same decisions you would.

Huh? First, why would I need a system to make the same decisions I'm going to make by default? Second, who is that "you"? For particular values of "you", building a system that replicates the preferences of that specific individual is going to be a really bad idea.

Comment author: gjm 25 September 2015 04:24:31PM 2 points [-]

Building a reasonably comprehensible system that replicates the preferences of a specific individual could at least be somewhat enlightening.

Comment author: Lumifer 25 September 2015 04:36:46PM 2 points [-]

Houshalter clearly wants not a descriptive, but a normative system.

Comment author: redding 24 September 2015 04:29:34PM 0 points [-]

You say you are rejecting Von Neumann utility theory. Which axiom are you rejecting?

https://en.wikipedia.org/wiki/Von_Neumann–Morgenstern_utility_theorem#The_axioms

Comment author: Vaniver 24 September 2015 04:59:22PM 2 points [-]

The last time this came up, the answer was:

That for any bet with an infinitesimally small value of p, there is a value of u high enough that I would take it.

This is, as pointed out there, not one of the axioms.

Comment author: Houshalter 25 September 2015 03:55:43AM 0 points [-]

The axiom of independence. I did mention this in the post.