This is Eliezer's model of blackmail in decision theory at the recent workshop at SIAI, filtered through my own understanding. Eliezer help and advice were much appreciated; any errors here-in are my own.

The mysterious stranger blackmailing the Countess of Rectitude over her extra-marital affair with Baron Chastity doesn't have to run a complicated algorithm. He simply has to credibly commit to the course of action:

"If you don't give me money, I will reveal your affair."

And then, generally, the Countess forks over the cash. Which means the blackmailer never does reveal the details of the affair, so that threat remains entirely counterfactual/hypothetical. Even if the blackmailer is Baron Chastity, and the revelation would be devastating for him as well, this makes no difference at all, as long as he can credibly commit to Z. In the world of perfect decision makers, there is no risk to doing so, because the Countess will hand over the money, so the Baron will not take the hit from the revelation.

Indeed, the baron could replace "I will reveal our affair" with Z="I will reveal our affair, then sell my children into slavery, kill my dogs, burn my palace, and donate my organs to medical science while boiling myself in burning tar" or even "I will reveal our affair, then turn on an unfriendly AI", and it would only matter if this changed his pre-commitment to Z. If the Baron can commit to counterfactually doing Z, then he never has to do Z (as the countess will pay him the hush money), so it doesn't matter how horrible the consequences of Z are to himself.

To get some numbers in this model, assume the countess can either pay up or not do so, and the baron can reveal the affair or keep silent. The payoff matrix could look something like this:

(Baron, Countess)
Not pay
 (-90,-110) (-100,-100)
(10,-10) (0,0)

Both the countess and the baron get -100 utility if the affair is revealed, while the countess transfers 10 of her utilitons to the baron if she pays up. Staying silent and not paying have no effect on the utility of either.

Let's see how we could implement the blackmailing if the baron and the countess were running simple decision algorithms. The baron has a variety of tactics he could implement. What is a tactic, for the baron? A tactic is a list of responses he could implement, depending on what the countess does. His four tactics are:

  1. (Pay, NPay)→(Reveal, Silent)        "anti-blackmail" : if she pays, tell all, if she doesn't, keep quiet
  2. (Pay, NPay)→(Reveal, Reveal)      "blabbermouth" : whatever she does, tell all
  3. (Pay, NPay)→(Silent, Silent)         "not-a-word" : whatever she does, keep quiet
  4. (Pay ,NPay)→(Silent, Reveal)        "blackmail" : if she pays, keep quiet, if she doesn't, tell all

The countess, in contract, has only two tactics: pay or don't pay. Each will try and estimate what the other will do, so the baron must model the countess, who must model the baron in turn. This seems as if it leads to infinite regress, but the baron has a short-cut: when reasoning counterfactually as to which tactic to implement, he will substitute that tactic in his model of how the countess models him.

In simple terms, it means that when he is musing 'what were to happen if I were to anti-blackmail, hypothetically', he assume that the countess would model him as an anti-blackmailer. In that case, the countess' decision is easy: her utility maximising decision is not to pay, leaving them with a payoff of (0,0).

Similarly, if he counterfactually considers the blabbermouth tactic, then if the countess models him as such, her utility-maximising tactic is also not to pay up, giving a payoff of (-100,-100). Not-a-word results in a payoff of (0,0), and only if the baron implements the blackmail tactic will the countess pay up, giving a payoff of (10,-10). Since this maximises his utility, he will implement the blackmail tactic. And the countess will pay him, to minimise her utility loss.

Notice that in order for this to work, the baron needs four things:

  1. The baron needs to make his decision after the countess does, so she cannot react to his action.
  2. The baron needs to make his decision after the countess does, so he can react to her action.
  3. The baron needs to be able to precommit to a specific tactic (in this case, blackmail).
  4. The baron needs the countess to find his precommitment plausible.

If we were to model the two players as timeless AI's implementing specific decision theories, what would these conditions become? They can be cast as:

  1. The baron and the countess must exchange their source code.
  2. The baron and the countess must both be rational.
  3. The countess' available tactics are simply to pay or not to pay.
  4. The baron's available tactics are conditional tactics, dependent on what the countess' decision is.
  5. The baron must model the countess as seeing his decision as a fixed fact over which she has no influence.
  6. The countess must indeed see the baron's decision as a fixed fact over which she has no influence.

The baron occupies what Eliezer termed a superior epistemic vantage.

Could two agents be in superior epistemic vantage, as laid out above, one over the other? This is precluded by the set-up above*, as two agents cannot be correct in assuming that the other treats their own decision as a fixed fact, while both running counterfactuals conditioning their response on the varrying tactics of the other.

"I'll tell, if you don't send me the money, or try and stop me from blackmailing you!" versus "I'll never send you the money, if you blackmail me or tell anyone about us!"

Can the countess' brother, the Archduke of Respectability, blackmail the baron on her behalf? If the archduke is in a superior epistemic vantage to the baron, then there is no problem. He could choose a tactic that is dependent on the baron's choice of tactics, without starting an infinite loop, as the baron cannot do the same to him. The most plausible version would go:

"If you blackmail my sister, I will shoot you. If you blabbermouth, I will shoot you. Anti-blackmail and not-a-word are fine by me, though."

Note that Omega, in the Newcomb's problem, is occupying the superior epistemic vantage. His final tactic is the conditional Z="if you two-box, I put nothing in box A; if you one-box, I put in a million pounds," whereas you do not have access to tactics along the lines of "if Omega implements Z, I will two-box; if he doesn't, I will one-box". Instead, like the countess, you have to assume that Omega will indeed implement Z, accept this as fact, and then choose simply to one-box or two-box.

*The argument, as presented here, is a lie, but spelling out the the true version would be tedious and tricky. The countess, for instance, is perfectly free to indulge in counterfactual speculations that the baron may decide something else, as long as she and the baron are both aware that these speculations will never influence her decision. Similarly, the baron is free to model her doing so, as long this similarly leads to no difference. The countess may have a dozen other options, not just the two presented here, as long as they both know she cannot make use of them. There is a whole issue of extracting information from an algorithm and a source code here, where you run into entertaining paradoxes such as if the baron knows the countess will do something, then he will be accurate, and can check whether his knowledge is correct; but if he didn't know this fact, then it would be incorrect. These are beyond the scope of this post.


[EDIT] The impossibility of the countess and the baron being each in epistemic vantage over the other has been clarified, and replaces the original point - about infinite loops - which only implied that result for certain naive algorithms.

[EDIT] Godelian reasons make it impossible to bandy about "he is rational and believes X, hence X is true" with such wild abandon. I've removed the offending lines.

[EDIT] To clarify issues, here is a formal model of how the baron and countess could run their decision theories. Let X be a fact about the world, and let S_B be the baron's source code.


Utility of pay = 10, utility of reveal = -100

Based on S_C, if the countess would accept the baron's behaviour as a fixed fact, run:

Let T={anti-blackmail, blabbermouth, not-a-word, blackmail}

For t_b in T, compute utility of the outcome implied by Countess(t_b,S_B). Choose the t_b that maximises it.


Countess(X, S_B)

If X implies the baron's tactic t_b, then accept t_b as fixed fact.

If not, run Baron(S_C) to compute the baron's tactic t_b. Stop as soon as the tactic is found. Accept as fixed fact.

Utility of pay = -10, utility of reveal = -100.

Let T={pay, not pay}

For t_c in T, under the assumption of t_b, compute utility of outcome. Choose t_c that maximises it.


Both these agents are rational with each other, in that they correctly compute each other's ultimate decisions in this situation. They are not perfectly rational (or rather, their programs are incomplete) in that they do not perform well against general agents, and may fall into infinite loops as written.

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What's to stop the Countess from having precommitted to never respond to blackmail?

Or to have precommitted to act as though having precommitted to the course of action having precommitted to in retrospect seems the most beneficial (including meta-precommittments, meta-meta-precommitments, meta^meta^meta precommitments etc up to the highest level she can model)?

Which would presumably include not being blackmailable to agents who would not try to blackmail if she absolutely committed to not be blackmailable, but being blackmailable to agents who would try blackmail even if she absolutely committed to not be blackmailable, except agents who would not have modified themselves into such agents were in not for such exceptions. Or in short: Being blackmailable only to irrationally blackmailing agents who were never deliberately modified into such by anyone.

Who precommits first wins. If the baron precommits to fulfil the threat unless he gets the money, later precommitment of the countess is worthless, since she expects the baron to fulfil the threat anyway. Her precommitment has sense only if she makes it and if the baron knows about it before his threat is announced. Assumed that all precommitments are public, the countess' precommitment to never respond to threats and the baron's precommitment to reveal the secret are mutually exclusive. Hence, if the baron actually threatens the countess, we can be sure that she hasn't precommited to never respond.
There is no "first" in precommiting -- your source code precommits you to certain actions, and you can't influence your source code, only carry out what the code states. The notion of precommiting, as a modification, is bogus (not so for the signalling of being precommited, or of being precommited in the particular case). You could be precommited to ignore certain signals of precommitment as well, and at some point signal such a precommitment. There seems to be no sense in distinguishing between when the same signal of precommitment is made (but it should be about the same precommitment, not a conditional variant of the previous one).
Having precommitted first is equivalent to deterministically acting as if already precommmitted in this instance, having precommitted too late is equivalent to only acting that way in future instances. I use "having precommitted" rather than "having source code such that..." because it's simpler, more intuitive, and more easily applicable to agents who don't have source code in the straightforward sense.
When you say "precommited", you mean "effectively signalled precommitment". When you say "can't precommit" (that is, can precommit only to certain other things), you mean "there is no way of effectively signalling this precommitment". Thus, you state that you can't signal that you'd uphold a counterfactual precommitment. But if it's possible to give your source code, you can. (Or the game might have a notion of rational strategy, and so you won't need either source code or signalling of precommitment.)

Please don't correct me on what I think. My use of precommitting has absolutely nothing to do with signaling. I first thought about these things (this explicitly) in the context of time travel, and you can't fool the universe with signaling, no matter how good your acting skills.

I don't propose fooling anyone, signaling is most effective when it's truthful. What could it mean to "make a precommitment", if not to signal the fact that your strategy is a certain way? You strategy either is, or isn't a certain way, this is a fixed fact about yourself, facts don't change. This being apparently the only resolution, I was not so much correcting as elucidating what you were saying (but assuming you didn't think of this elucidation explicitly), in order to make the conclusion easier to see (that the problem is with inability to signal counterfactual aspects of the strategy).
Signaling is about perceptions, not the truth by necessity. That means that fooling is at least a hypothetical possibility. Which is not the case for my use of precommittment. Taking the decision not to change your mind later in a way you will stick to. If as you seem to suggest the question whether the agent later acts a certain way or not is already implicit in its original source code then this agent already comes into existence precommitted (or not, as the case may be).
That you've taken this decision is a fact about your strategy (as such, it's timeless: looking at it from ten years ago doesn't change it). There is a similar fact of what you'd do if the situation was different. Did you read about counterfactual mugging, and do you agree that one should give up the money? No precommitment in this sense could help you there: there is no explicit decision in advance, it has to be a "passive" property of your strategy (the distinction between a decision that was "made" and that wasn't is superficial one -- that's my point). How could it be otherwise? And if so, "deciding to precommit" (in the sense of fixing this fact at a certain moment) is impossible in principle. All you can do is tell the other player about this fact, maybe only after you yourself discovered it (as being the way to win, and so the thing to do, etc.)
Yes, its a fact about your strategy, but this particular strategy would not have been your strategy before making that decision (it may have been a strategy you were considering, though). Unless you want to argue that there is no such thing as a decision, which would be a curious position in the context of a thought experiment about decision theory. Yes, I considered myself precommitted to hand over the money when reading that. I would not have considered myself precommmitted before my speculations about time travel a couple of years ago, and if I had read the scenario of the counterfactual mugging and nothing else here, and if I had been forced to say whether I would hand over the money without time to think it though I would have said that I would not (I can't tell what I would have said given unlimited time).
Would it make a difference if Omega told you that it tossed the coin a thousand years ago (before you've "precommited"), but only came for the money now?
That would make no difference whatsoever of course. Only the time I learn about the mugging matters.
But the coin precommited to demand the money from you first. How do you reconcile this with your position about the order of precommitments?
Are you trying to make fun of me?
No, a serious question. I was referring to the discussion starting from the top-level comment here (it's more of praise's position -- my mistake for confusing this -- it's unclear whether you agree).
"Who precommits first wins" means that if one party can make the other party learn about its precommitment before the other party can commit the first party wins. Not because commitment has magical powers that vary with time, but because learning about the precommitment makes making an exception in just this one case "rational" (if it's not "rational" to you you already had implicitly precommmitted).
Yes, this (general spin of your argument, not particular point) was my position at one time as well, until I realized that all rational decision-making has to consist of such "implicit precommitments", which robs the word of nontriviality.
Using the word precommitment makes it easier to talk about these things (unless you find yourself in an argument like this) and finding a reason to treat just this one case as an exception can genuinely be in the best interest of a particular instance of you that already finds itself in that exception (this is more obvious with time travel scenarios than with game theoretic scenarios), even though overall eliminating such exceptions is in your interest (since it will reduce the probability of the circumstances of these would be exceptions arising in the first place).
I don't agree. Not because I think you are believing anything crazy. I disagree with what is rational for the second person to do. I say that anything an agent can do by precommiting to an action it can also do just because it is the rational thing to do. Basically, any time you are in a situation where you think "I wish I could go back in time and change my source code that right now I would be precommitted to doing X" just do X. It's a bit counter-intuitive but it seems to give you the right answer. In this case the Baron will just not choose to precommit to defection because he knows that will not work due to the 'if I could time travel..." policy that he reads in your source code. It's kind of like 'free precommitment'! ETA: The word 'rational' was quoted, distancing FAWS own belief from a possible belief that some other people may call "rational". So I do agree. :)
I thought it was obvious that I have exactly the same opinion you voice in this post? After all I used quotes for rational and mentioned that considering this not rational is equivalent to an implicit precommitment. And I thought that It's obvious that I already have an implicit precommitment through the sort of mechanism you describe from my other posts.
Pardon me, I did not notice the quotes you placed around "rational". I was surprised by what seemed to me to be a false claim because your other posts did suggest to me that you 'get it'. Oversights like that are my cue to sleep!
If you allow precommitments that are strategies, that react to what you learn (e.g. about other precommitments), you won't need any exceptions. You'd only have "blank" areas where you haven't yet decided your strategy.
Have I ever said anything else? I believe I mentioned agents that come into existence precommitted, and my very first post in this thread mentioned such a fully general, indistiguishable-from-strategy precommmitment. The case I described is the one where "precommitted first" makes sense. Which is also the sort of case in the original post. Obviously the precise timing of a fully general precommitment before the actors even learn about each other doesn't matter.
Agreed. (I assume by non-general precommitments -- timing of which matters -- you refer to specific nonconditional strategies that don't take into account anything -- obviously you won't want to make such a precommitment too early, or too late. I still think it's a misleading concept, as it suggests that precommitment imposes additional limitation on one's actions, while as you agree it doesn't when it isn't rational -- that is when you've made a "general precommitment" to avoid that.)
I meant things like "I commit to one-box in Newcomb's problem" or "I commit not to respond to Baron Chastity's blackmail", specific precommitments you can only make after anticipating that situation. As a human it seems to be a good idea to make such a specific precommitment in addition to the general precommitment for the psychological effect (this is also more obvious in time travel scenarios), so I disagree that this is a misleading concept.
For humans, certainty it's a useful concept. For rational agents, exceptions overwhelm.
Why should rational agents deliberately sabotage their ability to understand humans? Merely having a concept of something doesn't imply applying it to yourself. Not that I even see any noticeable harm in a rational agent applying the concept of a specific precommitment to itself. It might be useful for e. g. modeling itself in hypothesis testing.
Determinism doesn't allow such magic. You need to read up on free will.
Are you being deliberately obtuse? I consider a strategy that involves killing myself in certain circumstances, but have not yet committed to it. * Before I can do so these circumstances suddenly arise. I chicken out and don't kill myself, because I haven't committed yet (or psyched myself up if you want to call it that). That strategy wasn't really my strategy yet. * 5 Minutes later I have committed myself to that strategy. The circumstances I would kill myself under arise, and I actually do it (or so I hope. I'm not completely sure I can make precommittments that strong) The strategy I previously considered is now my strategy. How is any of that free will magic?
Thanks, this explains the "would not have been your strategy" thing. So, when you talk about "X is not my strategy", you refer to particular time: X is not the algorithm you implement at 10AM, but X is the algorithm you implement at 11AM. When you said "before I decided at 10:30AM, X wasn't my strategy", I heard "before I decided at 10:30AM, at 11AM there was no fact about which strategy I implement, but after that, there appeared a fact that at 11AM I implement X", while it now seems that you meant "at 10AM I wasn't implementing X; I decided to implement X at 10:30AM; at 11AM I implemented X". Is the disagreement resolved? (Not the original one though, of the top-level comment -- that was about facts.)
Yes. I can't see why you would interpret my position in a way that is both needlessly complicated (taking "before" to be a statement about some sort of meta-time rather than just plain normal time?) and doesn't make any sense whatsoever, though.
Well, it's a common failure mode, you should figure out some way of signalling that you don't fall in it (and I should learn to ask the right questions). Since you can change your mind about what to do at 11AM, it's appealing to think that you can also change the fact of the matter of what happens at 11AM. To avoid such confusion, it's natural enough to think about "the algorithm you implement at 10AM" and "the algorithm you implement at 11AM" as unrelated facts that don't change (but depend and are controlled by particular systems, such as your source code at given time, or even "acausally", or "logically" controlled by the algorithms in terms of which they are defined).
Any evidence, that is any way in which you may know facts about the world, is up to interpretation, and you may err in interpreting it. But it's also the only way to observe the truth.
You are talking about the relation between truth and your own perceptions. None of this is relevant for the relation between truth and what you want other peoples perceptions to be, which is the context those words are used in the post you reply to. Are you deliberately trying to misinterpret me? Do I need to make all of my posts lawyer-proof?
No. The other people will interpret your words depending on whether they expect them to be in accordance with reality. Thus, I'm talking about the relation between the way your words will be interpreted by the people you talk to, and the truth of your words. If signaling (communication) bore no relation to the truth, it would be as useless as listening to white noise.
You're doing it again. I never said that signaling bore no relationship to the truth whatsoever, I said it was about perceptions and not by necessity about the truth, and what I (obviously, it seemed to me) meant was that signaling means attempting to manipulate the perceptions of others in a certain way, and that this does not necessarily mean changing the reality of the thing these perceptions are about.
You can't change reality... You can only make something change in time, but every instant, as well as the whole shape of the process of change, are fixed facts. By signalling I mean, for example, speaking (though the term fits better in the original game). Of course, you are trying to manipulate the world (in particular, perceptions of other people) in a certain way by your actions, but it's a general property shared by all actions.
You can't change reality in this meta-time sort of sense you seem to be eager to assign me. If I take a book out of the book case and put it on my desk I have changed the reality of where that book is. I haven't changed the reality of where that book will be in 2 minutes in your meta-time sense through my magical free will powers at the meta-time of making the decision to do that, but have changed the reality of where that book is in the plain English sense. EDIT: You edited your post while I was replying. I only saw the first sentence.
What I was 10 years ago is a fixed fact about what I was 10 years ago. That doesn't change. But I have.
So? (Not a rhetorical question.)
The point is that it is not a fixed fact about yourself unless you have an esoteric definition of self that is "what I was, am or will be at one particular instant in time". Under the conventional meaning of 'yourself', you can change and do so constantly. Essentially the 'So?' is a fundamental rejection of the core premise of your comment. (We disagree about a fundamental fact here. It is a fact that appears trivial and obvious to me and I assume your view appears trivial and obvious to you. It doesn't seem likely that we will resolve this disagreement. Do you agree that it would be best for us if we just leave it at that? You can, of course, continue the discussion with FAWS who on this point at least seems to have the same belief as I.)
Also, you shouldn't agree with the statement I cited here. (At least, it seems to be more clear-cut than the rest of the discussion.) Do you?
I agree with the statement of FAWS' that you quoted there. Although I do note that FAWS' statement is ambiguous. I only agree with it to the extent that the meaning is this:
Still ambiguous, and hints at non-lawful changes, though likely not at all intended. It's better to merge in this thread (see the disambiguation attempt).
What is the fact about which you see us disagreeing? I don't understand this discussion as having a point of disagreement. From my point of view, we are arguing relevance, not facts. (For example, I don't see why it's interesting to talk of "Who this fact is about?", and I've lost the connection of this point to the original discussion.)
1. You can modify your source code. 2. You can make precommitments. 3. "What could it mean to "make a precommitment"" is 'make a precommitment'. That is a distinct thing and 'signalling that you have made a precommitment". (If you make a precommitment and do not signal it effectively then it sucks for you.) 4. More simply - on the point on which you were disagreeing with FAWS (I assert that) * FAWS' position does have meaning. * FAWS' meaning is a different meaning to what you corrected it to. * FAWS is right. It is probably true that we would make the same predictions about what would happen in given interactions between agents.
Sure, why not? Not helping! Of course, having a strategy that behaves in a certain way and signaling this fact are different things. It isn't necessarily a bad thing to hide something (especially from a jumble of wires that distinguishes your thoughts and not just actions as terminal value). Not helping!
No, it is not. You asked (with some implied doubt) where we disagree. I answered as best I could. As I stated, we are probably not going to resolve our disagreement so I will leave it at that, with no disrespect intended beyond, as Robin often describes, the inevitable disrespect implicit in the actual fact of disagreement.
The "Not helping!" parts didn't explain where we disagree (what are the facts I believe are one way and you believe are the other way), they just asserted that we do disagree. But the last sentence suggests that we disagree about the definition of disagreement, because how could we disagree if you concede that
FAWS clearly does not mean that. He means what he says he means and you disagree with him. Since the game stipulates that one of the two acts before the other editing their source code is a viable option. If you happen to know that the other party is vulnerable to this kind of tactic then this is the right decision to make. On this I agree.
I don't disagree with him, because I don't see what else it could mean. See the other reply -- the edited code is not an interesting fact. The communicated code must be the original one -- if it's impossible to verify, this just means it can't be effectively communicated (signalled), which implies that you can't signal your counterfactual precommitment.
No, it need not be the original code. In fact, if the Baron really wants to he can destroy all copies of the original code. This is a counterfactual actual universe. The agent that is the baron is made up of quarks which can be moved about using the normal laws of physics.
It need not be the original code, but if we are interested in the original code, then we read the communicated data as evidence about the original code -- for what it's worth. It may well be in Baron's interest to give info about his code -- since otherwise, what distinguishes him from a random jumble of wires, in which case the outcome may not be appropriate for his skills.
You can influence your source code. You change the words and symbols in the text file, hit recompile, load the new binary into memory and execute it. If your code is such that it considers making such modifications as a suitable action to a situation then that is what you will do.
Common computer programs have a rather sharp boundary between their source code and the data. In brains (and hypothetical AIs) this distinction is (would be) probably less explicit. Whenever the baron learns anything, his source code changes in some sense, involuntarily, without recompiling. Still, the original source code contains all the information. Precommiting, in order to have some importance, should mean learning about a particular output of your own source code, rather than recompiling.
The use of 'source code' here is merely a metaphor.
Metaphor standing for what exactly?
UTM tape, brain, clockwork mechanism... whatever.
Think functional program, or what was initially written on the tape of a UTM. We are interested in that particular fact, not what happened after.
But I am interested in what happened after. If a tape operating on a UTM is programmed to operate a peripheral device to take the tape and modify it. then it is able to do that and the original tape is no longer running, the new one is. For any given agent in the universe it is possible to alter its state such that it behaves differently. Agents that are not implemented within this universe may not be changed in this way and those are the agents that I am not interested in. Functional programs can operate machines that alter code to produce new, different functional programs. The baron can alter his source code. Once he does so he is a different agent. How a countess responds to the baron's decision to modify his source code is a different question. If the countess is wise she will not pay in such a situation, the baron will know this and he will choose not to modify his source code. But it is a choise, the universe permits it.
Now this is a game of signalling -- to lie or not to lie, to trust or not to trust (or just how to interpret a given signal). The payoffs of the original game induce the payoff for this game of signalling the facts useful for efficiently playing the original game. You don't neet to talk about "modified source code" to discuss this data as signalling the original source code. (The original source code is interesting, because it describes the strategy.) The modified code is only interesting to the extent it signals the original code (which it probably doesn't). (Incidentally, one can only change things in accordance with the laws of physics, and many-to-one mapping may not be an option, though reconstructing the past may be infeasible in practice.)
But it isn't a lie. It is the truth. I don't want to signal the original source code.
But I want to know it, so whatever you do, signals something about the original source code, possibly very little. What's not a lie? (I'm confused.) I was just listing the possible moves in a new meta-game.
By precommiting I understand starting to be aware of the fact that my source code will do the particular thing with certainty. Nobody knows his source code completely, and even knowing the source code doesn't imply knowing all its outputs immediately. So, what I wanted to say is that when making the threat, the baron must know that he will certainly act the way he announces (this is the precommitment) and the countess has to know this fact about the baron (this is the signalling part). Time matters because the baron has to calculate his counterfactual actions (i.e. partly simulate himself) before he can precommit in the sense I understand the word.
Obviously. Hence my use of perfect tense rather than present tense. A world with agents acting and reflecting in the way the two players acting in the example do, but without previous commitments that make this precise behavior impossible seems highly implausible to me. I personally would have considered myself as being precommitted not to respond to blackmail in the scenario given even before reading it, and that would have been obvious to anyone familiar enough with me to reasonably feel as confident about predicting my reaction as would be required in the scenario.
"Being blackmailable only to irrationally blackmailing agents who were never deliberately modified into such by anyone"... i.e. being blackmailable by any old normal blackmailer.
Most normal blackmailers don't try to blackmail knowably unblackmailable agents and are therefore insufficiently irrational in the sense used.

The fifth fact is a consequence of the previous ones.

Um, no. Again, I think you may have misunderstood that point there. The point is not that all Countesses can inevitably and inescapably be blackmailed. It is just that a Countess designed a particular way can be blackmailed. The notion of a superior epistemic vantage point is not that there is some way for the Baron to always get it, but that if the Baron happens to have it, the Baron wins.

Could the countess plausibly raise herself to a superior epistemic vantage over the baron, and get out from under his thumb? Alas no.

Again, this just wasn't a conclusion of the workshop. A certain fixed equation occupies a lower epistemic vantage. Nothing was said about being unable to raise yourself up.

Alas no. Once the countess allows herself to use tactics conditional on the baron's actions, the whole set-up falls apart: the two start modelling the other's actions based on their own actions which are based on the other's actions, and so on. The baron can no longer assume that the countess has no influence on his decision, as now she does, so the loop never terminated.

Or the Countess just decides not to pay, unconditional o... (read more)

I haven't missunderstood the points - though I have, I fear, over-simplified the presentation for illustrative purposes. The key missing ingredient is that when I wrote that: implicit in that was the assumption that the baron was rational, knew his source and the countess' and would arrive at a decision in finite time - hence he must be correct in his assumption. I nearly wrote it that way, but thought this layout would be more intuitive. Indeed. Those are conditions that allow the countess to be blackmailed. If the countess is already in an inferior epistemic vantage point, she can't raise herself deterministically to a higher one - for instance, she cannot stop treating the baron's actions as a fixed fact, as an entity capable of doing that is not genuinly treating them as fixed already. The rest of that section was a rather poorly phrased way of saying that two entities cannot be in superior epistemic vantage over each other.
It seems that by "consequence" you mean "logical consequence", that is if I, observing this scenario, note that the first 5 conditions hold, I can derive that the 6th condition holds as well. There is another interpretation though, that you mean a "causal consequence", that the baron, by having a certain model of the countess, makes that model correct, because the baron is rational and therefor will produce a correct model. What this interpretation tells us is wrong. (Eliezer, were you interpreting it this way when you said Stuart misunderstood your point?)
Yes, I'm eliding Godelian arguments there... Consequences of anyone being rational and believing X have been removed. Interestingly, in the model I produced down below, both the countess and the baron produce correct models of each other. Furthermore, the countess knows she produces a correct model of the baron (as she runs his source successfuly). It also happens that the baron can check he has the correct model of the countess, after making his decision, by running her code. Since the countess will stop running his own code as soon as she also knows his outcome, he can know that his model was accurate in finite time.
You say here that the baron is rational and he knows the countess's. This being the case the only way for the countess to be blackmailed is if she implements a defective decision algorithm. Yet you describe the difference between the two as an 'inferior epistemic vantage point'. This does not seem like the right label. It seems to me that the advantage is instrumental and not epistemic.
We do not yet have a decision algorithm that reliably "respond to offers, not to threats". Therefore 'defective decision algorithm' must include everything we are capable of designing today :-)
We don't have a decision theory that reliably responds to offers, not to threats. We do have an algorithm that responds to offers, not to threats. Approximately it goes "when dealing with with rational agents and there is full epistemic awareness thrown all over the place respond to offers, not to threats because that is what works best." Unfortunately, integrating that into situations with epistemic uncertainty is all sorts of complex and probably beyond me. But that is a general problem that can be expected with any decision theory.
Sorry, trapped by Godel again. Consequences of anyone being rational and believing X have been removed.

If the Baron can commit to counterfactually doing Z, then he never has to do Z, so it doesn't matter how horrible the consequences of Z are to himself.

This is true, but you've neutered the prisoner's dilemma. One of the central problems one faces in game theory is that it is extremely hard to credibly precommit to do something that you'd clearly rather not do. Your point is valid, but you've assumed away almost all of the difficult parts of the problem. This is even more of a problem in your subsequent post on nukes.

(A few notes, with no particular point.)

The players should be modeled as algorithms that respond not to each other's moves, but as algorithms responding to information about the other player's algorithm (by constructing a strategy for responding to the other player's moves). In particular, saying that a certain player is a "rational agent" with certain payoff in the game might sometimes fix what that player's algorithm (of responding to info about the other player's algorithm) is. "It's a rational agent", if given as info about the play... (read more)

I'm staying out of this discussion mainly because I'm incredibly confused about acausal/timeless/counterfactual trade/blackmail. Eliezer gave a small presentation at the recent decision theory mini-workshop on his ideas but unlike Stuart I'm pretty sure I don't understand it. I've been told there are also some very rough notes/drafts on related ideas written by a couple of individuals floating around SIAI and FHI, but so far I have been unsuccessful in getting access to them.

ETA: I should mention that the workshop was very enjoyable and I greatly appreciate SIAI's efforts in setting it up, even though I came out more confused than I did going in. That just means I wasn't confused nearly enough previously. :)

I also don't understand the general case of these problems, but from what I understand, discussing payoff matrices is the wrong thing to do -- it's about jumbles of wires, not "rational agents", and dancing around computational complexity, not figuring out simple strategies or heuristics, such as not listening to threats (the "baseline" harm discussion -- seems to end on the suggestion that rational agents won't blackmail other rational agents to begin with -- but what would you do when you are blackmailed by a jumble of wires?). These concepts seem important: logical uncertainty (state of partial computation, program code vs. denotation, state vs. dynamics, proof vs. cut-free proof), observational uncertainty (and its combination with logical uncertainty), acausal control ("logical control", a situation when a system X is defined using the state (partial computation) of agent A, so that A's decisions control what X is -- this means that we are interested in the way X works, not just what it does -- that is not its denotation, not its strategy), recursive acausal control (what happens when the agent controls environment by conceptualizing it as containing the agent, or when two agents think about each other). The latter is the crux of most games, and seems incompatible with Bayesian networks, requiring thinking about algorithms (but not just their semantics -- acausal control is interested in the way things work, not just what they do).
Sigh... you may be the wiser of the two of us. I understand certain formal models that ressemble the blackmail problem, but have a sloppy understanding of the exact conditions where they apply. Will edit the post to insert the formal model.

Sure to all that; but what I want to see is an explanation of why I should consider the notion of "superior epistemic vantage" a useful idea. It seems like a fantasy that has no bearing on real life. Why shouldn't I dismiss Newcomb's dilemma as philosophical masturbation the moment someone says that it depends on superior epistemic vantage?

Parfit does a good job of covering this ground in Reasons and Persons in his discussion of threat-fulfillers and threat-ignorers. Let's see... you can read most of that section on Google Books, starting on p. 20 (section 1 part 8). A "threat" is a claim by someone that they will do X if you do Y, where doing X would make both them and you worse-off. In a world of transparency (shared source codes), Parfit comes out in favor of threat-ignoring (as well as promise-keeping).

Sorry for such a late reply... Just so I understand the point, the point is "whoever can better model their opponent while themselves being able to then precommit to an action is the one in a superior epistemic vantage, whoever can go 'deeper' in the counterfactuals wins"?

ie, just so I understand, is the only thing stopping the countess from doing the same sort of counterfactual modelling on the baron, from having strategies that are functions of which strategy the baron chooses being that simply "by assumption, the countess's code/computati... (read more)

The most plausible version would go: "If you reveal the affair, I will shoot you."

This is of course contingent on the Countess being aware of this limitation on the Baron (i.e. she knows he will not reveal, forcing him to choose either not-a-word or anti-blackmail, as these are the only precommitments that would result in her not forcing him to reveal). I am therefore fairly certain the Archduke does not need an epistemic advantage; he merely needs the ability to make one outcome unacceptable to the party with an epistemic advantage, and make... (read more)

In the world of perfect decision makers, there is no risk to doing so, because the Countess will hand over the money, so the Baron will not take the hit from the revelation.

Since the payoffs are symmetrical (in sense that both baron and countess lose the same amount of utility if the secret is revealed), in the world of perfect decision markers the winner is clearly the person who decides to blackmail. But the countess can retaliate easily: after she pays, she can blackmail the baron, and get the money back with certainty, even with some bonus. So, say ... (read more)