Jonii comments on Notes on logical priors from the MIRI workshop - Less Wrong

18 Post author: cousin_it 15 September 2013 10:43PM

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Comment author: Jonii 16 September 2013 08:02:45AM 1 point [-]

You lost me at part

In Counterfactual Mugging with a logical coin, a "stupid" agent that can't compute the outcome of the coinflip should agree to pay, and a "smart" agent that considers the coinflip as obvious as 1=1 should refuse to pay.

The problem is that, I see no reason why smart agent should refuse to pay. Both stupid and smart agent know it as logical certainty that they just lost. There's no meaningful difference between being smart and stupid in this case, that I can see. Both however like to be offered such bets, where logical coin is flipped, so they pay.

I mean, we all agree that a "smart" agent, that refused to pay here, would receive $0 if Omega flipped logical coin of asking if 1st digit of pi was an odd number, while "stupid" agent would get $1,000,000.

Comment author: cousin_it 16 September 2013 11:46:26AM *  1 point [-]

Note that there's no prior over Omega saying that it's equally likely to designate 1=1 or 1≠1 as heads. There's only one Omega, and with that Omega you want to behave a certain way. And with the Omega that designates "the trillionth digit of pi is even" as heads, you want to behave differently.

Comment author: wedrifid 16 September 2013 02:01:12PM 1 point [-]

And with the Omega that designates "the trillionth digit of pi is even" as heads, you want to behave differently.

Specifically, you want to bet on 'heads'. The trillionth digit of pi is a two.

I think we need to find a trickier logical uncertainty as a default example. There is a (mildly) interesting difference between logical uncertainties that we could easily look up or calculate like "Is 1,033 a prime?" or "is the trillionth digit of pi even?" and logical uncertainties that can not be plausibly looked up. Both types of uncertainty are sometimes relevant but often we want a 'logical coin' that isn't easily cheated.

Comment author: Jonii 16 September 2013 06:15:47PM 1 point [-]

After asking about this on #LW irc channel, I take back my initial objection, but I still find this entire concept of logical uncertainty kinda suspicious.

Basically, if I'm understanding this correctly, Omega is simulating an alternate reality which is exactly like ours, and where the only difference is that Omega says something like "I just checked if 0=0, and turns out it's not. If it was, I would've given you moneyzzz(iff you would give me moneyzzz in this kind of situation), but now that 0!=0, I must ask you for $100." Then the agent notices, in that hypothetical situation, that actually 0=0, so actually Omega is lying, so he is in hypothetical, and thus he can freely give moneyzzz away to help to real you. Then, because some agents can't tell for all possible logical coins if they are lied to or not, they might have to pay real moneyzzz, while sufficiently intelligent agents might be able to cheat the system if they are able to notice if they are lied to about the state of the logical coin.

I still don't understand why a stupid agent would want to make a smart AI that did pay. Also, there are many complications that restrict decisions of both smart and stupid agents, given argument I've given here, stupid agents still might prefer not paying, and smart agents might prefer paying, if they gain some kind of insght to how Omega chose these logical coins. Also, this logical coin problemacy seems to me like a not-too-special special class of Omega problems where some group of agents is able to detect if they are in counterfactuals

Comment author: cousin_it 16 September 2013 07:06:22PM 1 point [-]

Note that the agent is not necessarily able to detect that it's in a counterfactual, see Nesov's comment.

Comment author: Jonii 16 September 2013 07:10:07PM 0 points [-]

Yes, those agents you termed "stupid" in your post, right?

Comment author: cousin_it 16 September 2013 07:16:26PM *  1 point [-]

The smart ones too, I think. If you have a powerful calculator and you're in a counterfactual, the calculator will give you the wrong answer.

Comment author: Jonii 16 September 2013 07:45:40PM 0 points [-]

Well, to be exact, your formulation of this problem has pretty much left this counterfactual entirely undefined. Naive approximation, that the world is just like ours, and Omega just lies in counterfactual, would not contain such weird calculators which give you wrong answers. If you want to complicate problem by saying that some specific class of agents have a special class of calculators that one would usually think to work in certain way, but actually they work in a different way, well, so be it. That's however just a free-floating parameter you have left unspecified and that, unless stated otherwise, should be assumed not to be the case.

Comment author: cousin_it 16 September 2013 07:51:59PM *  0 points [-]

Hmm, no, I assumed that Omega would be using logical counterfactuals, which are pretty much the topic of the post. In logical counterfactuals, all calculators behave differently ;-) But judging from the number of people asking questions similar to yours, maybe it wasn't a very transparent assumption...

Comment author: Jonii 16 September 2013 08:08:34PM *  0 points [-]

I asked about these differences in my second post in this post tree, where I explained how I understood these counterfactuals to work. I explained as clearly as I could that, for example, calculators should work as they do in real world. I did this explaining in hopes of someone voicing disagreement if I had misunderstood how these logical counterfactuals work.

However, modifying any calculator would mean that there can not be, in principle, any "smart" enough ai or agent that could detect it was in counterfactual. Our mental hardware that checks if logical coin should've been heads or tails is a calculator the same as any computer, and again, there does not seem to be any reason to assume Omega leaves some calculators unchanged while changes results of others.

Unless, this thing is just assumed to happen, with some silently assumed cutaway point where calculators become so internal they are left unmodified.

Comment author: Vladimir_Nesov 16 September 2013 10:02:28PM *  1 point [-]

However, modifying any calculator

Calculators are not modified, they are just interpreted differently, so that when trying to answer the question of what happens in a certain situation (containing certain calculators etc.) we get different answers depending on what the assumptions are. The situation is the same, but the (simplifying) assumptions about it are different, and so simplified inferences about it are different as well. In some cases simplification is unavoidable, so that dependence of conclusions on assumptions becomes an essential feature.

Comment author: cousin_it 16 September 2013 08:19:53PM *  1 point [-]

My current understanding of logical counterfactuals is something like this: if the inconsistent formal theory PA+"the trillionth digit of pi is odd" has a short proof that the agent will take some action, which is much shorter than the proof in PA that the trillionth digit of pi is in fact even, then I say that the agent takes that action in that logical counterfactual.

Note that this definition leads to only one possible counterfactual action, because two different counterfactual actions with short proofs would lead to a short proof by contradiction that the digit of pi is odd, which by assumption doesn't exist. Also note that the logical counterfactual affects all calculator-like things automatically, whether they are inside or outside the agent.

That's an approximate definition that falls apart in edge cases, the post tries to make it slightly more exact.