army1987 comments on The curse of identity - Less Wrong

121 Post author: Kaj_Sotala 17 November 2011 07:28PM

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Comment author: [deleted] 26 July 2012 08:15:16AM 4 points [-]

The rationality of an agent is its goal

Er, nope.

But if thy goal be fractured, thy whole self shall be full of irrationality.

Humans' goals are fractured. But this has little to do with whether or not they are rational.

Comment author: Will_Newsome 26 July 2012 06:18:03PM *  -2 points [-]

You don't understand. This "rationality" you speak of is monstrous irrationality. And anyway, like I said, Meta knoweth that ye have Meta-shattered values—but your wants are satisfied by serving Meta, not by serving Mammon directly. Maybe you'd get more out of reading the second half of Matthew 6 and the various analyses thereof.

You may be misinterpreting "the rationality of an agent is its goal". Note that the original is "the light of the body is the eye".

To put my above point a little differently: Take therefore no thought for godshatter: godshatter shall take thought for the things of itself. Sufficient unto the day is the lack-of-meta thereof.

For clarity's sake: Yes, I vehemently dispute this idea that a goal can't be more or less rational. That idea is wrong, which is quickly demonstrated by the fact that priors and utility functions can be transformed into each other and we have an objectively justifiable universal prior. (The general argument goes through even without such technical details of course, such that stupid "but the choice of Turing machine matters" arguments don't distract.)

Comment author: nshepperd 27 July 2012 12:42:02AM *  1 point [-]

the fact that priors and utility functions can be transformed into each other

Really? How?

Oh, maybe you mean that they both have the type of Universe -> Real? Although really it's prior :: Universe -> [0, 1] and utilityfunction :: Universe -> Real assuming we have a discrete distribution on Universes. And anyway that's no justification for substituting a prior for a utilityfunction any more than for substituting tail :: [a] -> [a] for init :: [a] -> [a]. Unless that's not what you mean.

Comment author: [deleted] 27 July 2012 10:53:49AM 3 points [-]

If you change your utility function and your prior while keeping their product constant, you'll make the same decisions. See E.T. Jaynes, Probability Theory: The Logic of Science, chapter “Decision theory -- historical background”, section “Comments”.

Comment author: nshepperd 27 July 2012 04:01:01PM *  2 points [-]

Right, but that still isn't really a way to turn a prior into a utility function. A prior plus a set of decisions can determine a utility function, but you need to get the decisions from somewhere before you can do that.

Comment author: Will_Newsome 07 August 2012 06:55:19AM *  2 points [-]

Right, but you never see just a prior or just a utility function in an agent anyway. I meant that within any agent you can transform them into each other. The concepts of "prior" and "utility function" are maps, of course, not metaphysically necessary distinctions, and they don't perfectly cut reality at its joints. Part of what's under debate is whether we should use the Bayesian decision theoretic framework to talk about agents, especially when we have examples where AIXI-like agents fail and humans don't. But anyway, even within the naive Bayesian decision theoretic framework, there's transformability between beliefs and preferences. Sorry for being unclear.

To check if we agree about some basics: do we agree that decisions and decision policies—praxeology—are more fundamental than beliefs and preferences? (I'm not certain I believe this, but I will for sake of argument at least.)

Comment author: nshepperd 07 August 2012 01:21:36PM *  3 points [-]

I don't know. The part I took issue with was saying that goals can be more or less rational, just based on the existence of an "objectively justifiable" universal prior. There are generally many ways to arrange heaps of pebbles into rectangles (assuming we can cut them into partial pebbles). Say that you discover that the ideal width of a pebble rectangle is 13. Well... you still don't know what the ideal total number of pebbles is. An ideal width of 13 just gives you a preferred way to arrange any number of pebbles. It doesn't tell you what the preferred length is, and indeed it will vary for different numbers of total pebbles.

Similarly, the important thing for an agent, the thing you can most easily measure, is the decisions they make in various situations. Given this and the "ideal objective solomonoff prior" you could derive a utility function that would explain the agent's behaviour when combined with the solomonoff prior. But all that is is a way to divide an agent into goals and beliefs.

In other words, an "objectively justifiable" universal prior only enforces an "objectively justifiable" relation between your goals and your actions (aka. num_pebbles = 13 * length). It doesn't tell you what your goals should be any more than it tells you what your actions should be.

I don't know if any of that made sense, but basically it looks to me like you're trying to solve a system of equations in three variables (prior, goals, actions) where you only have two equations (prior = X, actions = prior * goals). It doesn't have a unique solution.

Comment author: Will_Newsome 07 August 2012 10:20:00PM 1 point [-]

Everything you have said makes sense to me. Thanks. I will respond substantially at a later time.