Comment author: Wei_Dai 14 March 2011 07:17:02PM *  20 points [-]

Zvi mentioned hyperbolic discounting. What if an agent's preferences are actually described by hyperbolic discounting? Then different versions of the agent in time have different preferences, so they are essentially different agents. Consider just two such agent-moments. Each agent-moment would prefer both not eating garlic bread to both eating, but prefers even more itself eating while the other doesn't eat.

Since they have different preferences and the earlier agent-moment can't physically force the later agent-moment to make a certain choice, the analogy with PD seems pretty good and TDT does seem relevant here.

Comment author: ArthurB 14 March 2011 08:35:35PM 6 points [-]

Indeed, there is nothing irrational (in an epistemic way) about having hyperbolic time preference. However, this means that a classical decision algorithm is not conducive to achieving long term goals.

One way around this problem is to use TDT, another way is to modify your preferences to be geometric.

A geometric time preference is a bit like a moral preference... it's a para-preference. Not something you want in the first place, but something you benefit from wanting when interacting with other agents (including your future self).

Comment author: wedrifid 23 February 2011 04:43:47PM *  0 points [-]

That's certainly possible, it's also possible that you do not understand the argument.

The combination:

  • Uncontraversial understanding by academic orthodoxy
  • General position by those on lesswrong
  • My parsing of your post
  • Observation of your attempts to back up your argument when it was not found to be persuasive by myself or others

... is sufficient to give rather high confidence levels. It really is a huge claim you are making, to dismiss the understanding of basically the rest of the world regarding how CDT and EDT apply to the trivial toy problems that were designed to test them.

There is altogether too much deduction of causal mechanisms involved in your "EDT" reasoning. And the deductions involved rely on a premise (the second dot point) that just isn't a part of either the problem or 'genes'.

Comment author: ArthurB 23 February 2011 06:04:14PM *  0 points [-]

The second dot point is part of the problem description. You're saying it's irrelevant, but you can't just parachute a payoff matrix where causality goes backward in time.

Find any example you like, as long as they're physically possible, you'll either have the payoff tied to your decision algorithm (Newcomb's) or to your preference set (Solomon's).

Comment author: wedrifid 23 February 2011 04:43:47PM *  0 points [-]

That's certainly possible, it's also possible that you do not understand the argument.

The combination:

  • Uncontraversial understanding by academic orthodoxy
  • General position by those on lesswrong
  • My parsing of your post
  • Observation of your attempts to back up your argument when it was not found to be persuasive by myself or others

... is sufficient to give rather high confidence levels. It really is a huge claim you are making, to dismiss the understanding of basically the rest of the world regarding how CDT and EDT apply to the trivial toy problems that were designed to test them.

There is altogether too much deduction of causal mechanisms involved in your "EDT" reasoning. And the deductions involved rely on a premise (the second dot point) that just isn't a part of either the problem or 'genes'.

Comment author: ArthurB 23 February 2011 05:55:21PM *  1 point [-]

I'm making a simple, logical argument. If it's wrong, it should be trivial to debunk. You're relying on an outside view to judge; it is pretty weak.

As I've clearly said, I'm entirely aware that I'm making a rather controversial claim. I never bother to post on lesswrong, so I'm clearly not whoring for attention or anything like that. Look at it this way, in order to present my point despite it being so unorthodox, I have to be pretty damn sure it's solid.

Comment author: wedrifid 23 February 2011 02:28:23AM 0 points [-]

You get one-boxing behavior in Newcomb's and this is still CDT/EDT (which are really equivalent, as shown).

I suggest that what was 'shown' was that you do not understand the difference between CDT and EDT.

Comment author: ArthurB 23 February 2011 01:18:48PM *  0 points [-]

That's certainly possible, it's also possible that you do not understand the argument.

To make things absolutely clear, I'm relying on the following definition of EDT

Policy that picks action a = argmax( Sum( P( Wj | W, ai ). U( Wj ), j ) , i ) Where {ai} are the possible actions, W is the state of the world, P( W' | W, a ) the probability of moving to state of the world W' after doing a, and U is the utility function.

I believe the argument I made in the case of Solomon's problem is the clearest and strongest, would you care to rebut it?

I've challenged you to clarify through which mechanism someone with a cancer gene would decide to chew gum, and you haven't answered this properly.

  • If your decision algorithm is EDT, the only free variables that will determine what your decisions are are going to be your preferences and sensory input.
  • The only way the gene can cause you to chew gum in any meaningful sense is to make you prefer to chew gum.
  • An EDT agent has knowledge of its own preferences. Therefore, an EDT agent already knows if it falls in the "likely to get cancer" population.
Comment author: wedrifid 19 February 2011 03:30:45AM 1 point [-]

Yes, you could have preferences to two box, but there is no reason why you should catter in advance to crazy cosmic entities rewarding certain algorithms or preferences.

The problem generalises to any situation requiring cooperation based on mutual knowledge of the other agent's decision process when there is not the option to introduce new constraints in the environment.

Comment author: ArthurB 22 February 2011 11:12:32PM 0 points [-]

Yes, the causality is from the decision process to the reward. The decision process may or may not be known to the agent, but its preferences are (data can be read, but the code can only be read if introspection is available).

You can and should self-modify to prefer acting in such a way that you would benefit from others predicting you would act a certain way. You get one-boxing behavior in Newcomb's and this is still CDT/EDT (which are really equivalent, as shown).

Yes, you could implement this behavior in the decision algorithm itself, and yes this is very much isomorphic. Evolution's way to implement better cooperation has been to implement moral preferences though, it feels like a more natural design.

Comment author: Larks 20 February 2011 12:53:31AM 0 points [-]
  • If Omega thinks you were born loving Beige, he puts $1,000 in box Beige and nothing in box Aquamarine. Otherwise, he puts $1,000 in box Beige and nothing in box Aquamarine.

Did you intend for Omega to act differently in these two situations?

Since EDT reflects on his own decision, it can only be the only fixed point which is to one box.

I agree that EDT should one box, but the your previous two lines suggest the fixed point is at two-boxing.

Comment author: ArthurB 21 February 2011 04:40:12AM 0 points [-]

Typo, I do mean that EDT two boxes.

Comment author: CronoDAS 20 February 2011 12:06:54AM 4 points [-]

Here's an intuition pump:

10% of the population sunburns easily. 90% of people who sunburn easily wear sunscreen. 10% of the people who don't sunburn easily wear sunscreen. Regardless of whether or not you sunburn easily, wearing sunscreen will reduce the chances of getting sunburn. You don't know if you sunburn easily or not.

EDT looks at this data and says, "It's better to be a randomly chosen member of the group of people who don't wear sunscreen than a randomly chosen member of the group of people who do. Therefore, don't wear sunscreen." And that seems like the wrong answer, because your decision whether or not to wear sunscreen doesn't actually affect whether or not you sunburn easily. In other words, the problem with EDT is that it can't handle "Simpson's Paradox".

Comment author: ArthurB 21 February 2011 04:39:36AM 1 point [-]

According to wikipedia, the definition of EDT is

Evidential decision theory is a school of thought within decision theory according to which the best action is the one which, conditional on your having chosen it, gives you the best expectations for the outcome.

This is not the same as "being a randomly chosen member of a group of people..." and I've explained why. The information about group membership is contained in the filtration.

Comment author: Oscar_Cunningham 19 February 2011 03:02:10PM 1 point [-]

Thanks, fixed.

Comment author: ArthurB 19 February 2011 03:14:25PM -1 points [-]

You're saying EDT causes you not to chew gum because cancer gives you EDT? Where does the gum appear in the equation?

Comment author: Oscar_Cunningham 19 February 2011 01:08:45PM *  1 point [-]

wedrifid might well be making the point that your genes determine your choice, via your decision theory. i.e. Your genes give you EDT, and then EDT makes you not chew gum. I'm not sure how that affects the argument though.

Comment author: ArthurB 19 February 2011 02:28:07PM 0 points [-]

The claim is generally that EDT chooses not to chew gum.

Comment author: wedrifid 19 February 2011 05:35:22AM *  1 point [-]

To put it another way, is your decision to chew gum determined by EDT our by your genes? Pick one.

It can be both. Causation is not exclusionary. I'm suggesting that you are mistaken about the aforementioned handling.

Comment author: ArthurB 19 February 2011 06:23:38AM 0 points [-]

No it can't. If you use a given decision theory, your actions are entirely determined by your preferences and your sensory inputs.

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