Wei_Dai comments on The Anthropic Trilemma - Less Wrong

24 Post author: Eliezer_Yudkowsky 27 September 2009 01:47AM

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Comment author: Wei_Dai 29 September 2009 12:10:58PM 2 points [-]

UDT tells us what to do - but not what to anticipate seeing happen next.

Ok, we can count that as a disadvantage when comparing UDT with alternative solutions, but why is it a deal-killer for you, especially since you're mainly interested in decision theory as a tool for programming FAI? As long as the FAI knows what to do, why do you care so much that it doesn't anticipate seeing what happen next?

Comment author: Eliezer_Yudkowsky 29 September 2009 03:56:11PM 3 points [-]

Because I care about what I see next.

Therefore the FAI has to care about what I see next - or whatever it is that I should be caring about.

Comment author: Vladimir_Nesov 29 September 2009 05:36:51PM *  0 points [-]

There is no problem with FAI looking at both past and future you -- intuition only breaks down when you speak of first-person anticipation. You don't care what FAI anticipates to see for itself and whether it does. The dynamic of past->future you should be good with respect to anticipation, just as it should be good with respect to excitement.

Comment author: Nick_Tarleton 29 September 2009 06:24:25PM 1 point [-]

There is no problem with FAI looking at both past and future you -- intuition only breaks down when you speak of first-person anticipation.

But part of the question is: must past/future me be causally connected to me?

Comment author: Vladimir_Nesov 29 September 2009 06:28:32PM 0 points [-]

Part of which question? And whatever you call "causally connected" past/future persons is a property of the stuff-in-general that FAI puts into place in the right way.

Comment author: Wei_Dai 29 September 2009 10:10:49PM 0 points [-]

Ok, but that appears to be the same reason that I gave (right after I asked the question) for why we can't switch over to UDT yet. So why did you give a another answer without reference to mine? That seems to be needlessly confusing. Here's how I put it:

The problem with that is that much of our preferences are specified in terms of anticipation of experience, and there is no obvious way how to map those onto UDT preferences.

There's more in that comment where I explored one possible approach to this problem. Do you have any thoughts on that?

Also, do you agree (or think it's a possibility) that specifying preferences in terms of anticipation (instead of, say, world histories) was an evolutionary "mistake", because evolution couldn't anticipate that one day there would be mind copying/merging technology? If so, that doesn't necessarily mean we should discard such preferences, but I think it does mean that there is no need to treat it as somehow more fundamental than other kinds of preferences, such as, for example, the fear of stepping into a teleporter that uses destructive scanning, or the desire not to be consigned to a tiny portion of Reality due to "mistaken" preferences.

Comment author: Eliezer_Yudkowsky 29 September 2009 11:02:39PM 2 points [-]

I can't switch over to UDT because it doesn't tell me what I'll see next, except to the extent it tells me to expect to see pi < 3 with some measure. It's not that it doesn't map. It's that UDT goes on assigning measure to 2 + 2 = 5, but I'll never see that happen. UDT is not what I want to map my preferences onto, it's not a difficulty of mapping.

Comment author: Wei_Dai 29 September 2009 11:12:17PM *  1 point [-]

UDT goes on assigning measure to 2 + 2 = 5

That's not what happens in my conception of UDT. Maybe in Nesov's, but he hasn't gotten it worked out, and I'm not sure it's really going to work. My current position on this is still that you should update on your own internal computations, but not on input from the outside.

ETA:

UDT is not what I want to map my preferences onto, it's not a difficulty of mapping.

Is that the same point that Dan Armak made, which I responded to, or a different one?

Comment author: Vladimir_Nesov 29 September 2009 11:11:54PM *  0 points [-]

I can't switch over to UDT because it doesn't tell me what I'll see next, except to the extent it tells me to expect to see pi < 3 with some measure.

It's not you who should use UDT, it's the world. This is a salient point of departure between FAI and humanity. FAI is not in the business of saying in words what you should expect. People are stuff of the world, not rules of the world or strategies to play by those rules. Rules and strategies don't depend on particular moves, they specify how to handle them, but plays consist of moves, of evidence. This very distinction between plays and strategies is the true origin of updatelessness. It is the fault to make this distinction that causes the confusion UDT resolves.

Comment author: Wei_Dai 30 September 2009 12:20:04AM 6 points [-]

Nesov, your writings are so hard to understand sometimes. Let me take this as an example and give you some detailed feedback. I hope it's useful to you to determine in the future where you might have to explain in more detail or use more precise language.

It's not you who should use UDT, it's the world.

Do you mean "it's not only you", or "it's the world except you"? If it's the latter, it doesn't seem to make any sense. If it's the former, it doesn't seem to answer Eliezer's objection.

This is a salient point of departure between FAI and humanity.

Do you mean FAI should use UDT, and humanity shouldn't?

FAI is not in the business of saying in words what you should expect.

Ok, this seems clear. (Although why not, if that would make me feel better?)

People are stuff of the world, not rules of the world or strategies to play by those rules.

By "stuff", do you mean "part of the state of the world"? And people do in some sense embody strategies (what they would do in different situations), so what do you mean by "people are not strategies"?

Rules and strategies don't depend on particular moves, they specify how to handle them, but plays consist of moves, of evidence. This very distinction between plays and strategies is the true origin of updatelessness. It is the fault to make this distinction that causes the confusion UDT resolves.

This part makes sense, but I don't see the connection to what Eliezer wrote.

Comment author: Vladimir_Nesov 30 September 2009 12:48:58AM *  1 point [-]

It's not you who should use UDT, it's the world.

Do you mean "it's not only you", or "it's the world except you"? If it's the latter, it doesn't seem to make any sense. If it's the former, it doesn't seem to answer Eliezer's objection.

I mean the world as substrate, with "you" being implemented on the substrate of FAI. FAI runs UDT, you consist of FAI's decisions (even if in the sense of "influenced by", there seems to be no formal difference). The decisions are output of the strategy optimized for by UDT, two levels removed from running UDT themselves.

Do you mean FAI should use UDT, and humanity shouldn't?

Yes, in the sense that humanity runs on the FAI-substrate that uses UDT or something on the level of strategy-optimization anyway, but humanity itself is not about optimization.

By "stuff", do you mean "part of the state of the world"? And people do in some sense embody strategies (what they would do in different situations), so what do you mean by "people are not strategies"?

I suspect that people should be found in plays (what actually happens given the state of the world), not strategies (plans for every eventuality).

Comment author: SilasBarta 29 September 2009 04:19:22PM 0 points [-]

Unless I'm misunderstanding UDT, isn't speed another issue? An FAI must know what's likely to be happening in the near future in order to prioritize its computational resources so they're handling the most likely problems. You wouldn't want it churning through the implications of the Loch Ness monster being real while a mega-asteroid is headed for the earth.

Comment author: Eliezer_Yudkowsky 29 September 2009 05:33:07PM *  2 points [-]

Wei Dai should not be worrying about matters of mere efficiency at this point. First we need to know what to compute via a fast approximation.

(There are all sorts of exceptions to this principle, and they mostly have to do with "efficient" choices of representation that affect the underlying epistemology. You can view a Bayesian network as efficiently compressing a raw probability distribution, but it can also be seen as committing to an ontology that includes primitive causality.)

Comment author: SilasBarta 29 September 2009 11:33:25PM *  1 point [-]

Wei Dai should not be worrying about matters of mere efficiency at this point. First we need to know what to compute via a fast approximation.

But that path is not viable here. If UDT claims to make decisions independently of any anticipation, then it seems it must be optimal on average over all the impossibilities it's prepared to compute an output for. That means it must be sacrificing optimality in this world-state (by No Free Lunch), even given infinite computing time, so having a quick approximation doesn't help.

If an AI running UDT is just as prepared to find Nessie as to find out how to stop the incoming asteroid, it will be inferior to a program designed just to find out how to stop asteroids. Expand the Nessie possibility to improbable world-states, and the asteroid possibility to probable ones, and you see the problem.

Though I freely admit I may be completely lost on this.