How confident are you that you understand TDT better than Eliezer does? Because he seems to think that TDT implies smoking.
people constantly said things like, “if the lesion has a 100% correlation, then you can’t make a choice anyway,” and things like that, which is an intuition about the causality. But obviously that is not true except in the sense that if Omega has a 100% correlation and makes a decision, you can longer make a choice in Newcomb either.
This looks to me like another thing that actually depends on the details of what the alleged cause is and how it does the causing, and I don’t think it’s at all clear that “if the lesion is 100% correlated with smoking, you can’t be making a real choice” and “if Omega’s choice of what to put in the boxes is 100% correlated with your choice of which box(es) to pick, you can’t be making a real choice” are equivalent.
For instance, suppose Omega chooses what to put in the boxes by looking into the future using magic. In this case, your choice is as real and free as any choice ever is. On the other hand, suppose the way the smoking lesion works is that everyone in the world has a little override built into their brain by a mad genius neuroscientist that detects situations in which they might choose whether to start smoking and forces them to do one thing rather than another, in a way that has absolutely nothing in common with any other decisions they make. In this case, your choice is as unreal and un-free as anything choice-like could ever be.
I dunno, maybe you don’t care about such intuitions, and you insist on a definition of terms like “choice” and “freedom” that’s perfectly clear and rigorous but doesn’t refer to any of these details that might differ in the two scenarios. I personally would be absolutely staggered if any such definition actually came close to matching how those words are actually used in practice. I don’t know how to give an adequate definition of any of those terms, though I have vague handwavy guesses at the sort of shape a definition might have once we know a lot more about brains and things, so in default of such a definition I’m going with my intuitions, and those say that the level of abstraction at which Newcomb and Smoking Lesion look the same is too high a level of abstraction to enable us to answer questions like “is this person really making a choice?”.
And this is really no different from the lesion, since if we are to imagine the lesion case working in real life, we need to include the relationship between the physical lesion and the rest of the brain.
My understanding of what I was supposed to assume about the Smoking Lesion was that it’s something rather crude that doesn’t depend on fine details of how the brain does whatever it does when making choices. But I think the how-the-correlation-works question is more central, so let’s move on.
There will be parallel cases for Smoking Lesion and for Newcomb
Sure. If you augment the SL and Newcomb scenarios with extra details about what’s going on, those extra details can matter. So, e.g., if Omega just predicts that you’ll take two boxes iff you’ve usually said “I would take two boxes” then you should probably say “I would take one box” and then take two boxes. But this version of Newcomb is utterly incompatible with how the Newcomb problem is always presented: in a world where Omega was known to operate this way, Omega’s success rate would be approximately 0% rather than the near-100% that makes the problem actually interesting. (Because everyone would say “I would take one box” and then everyone would take two boxes.)
So your version of Newcomb designed to yield a two-boxing decision succeeds in yielding a two-boxing decision, but only by not actually being a version of Newcomb in anything but name.
Your examples in which (if I’m understanding them correctly) someone, after being present with the SL/Newcomb choice, selects a decision theory and then applies it, seem very strange. I mean, I admit that what gets people thinking about decision theories is often knotty questions like Newcomb—but I’ve never heard of a case where someone got into decision theory in order to resolve such a knotty question with which they personally were faced and then did actually select and apply some concrete decision theory to resolve their question. (Though I wouldn’t be surprised to hear it’s happened at least once.) In that case, I agree that the choice of decision theory is all tangled up with the other factors involved (lesion, desires, preference for getting a million dollars, …); but I don’t see what this has to do with the rest of us who are contemplating decision theories in the abstract, nor to do with a hypothetical person in the SL/NP scenarios who, like most such hypothetical people :-), doesn’t react to their challenge by trying to select a decision theory to live by thenceforward.
I’m going to answer this with several comments, and probably not all today. In this one I am going to make some general points which are not necessarily directly addressed to particular comments you made, but which might show more clearly why I interpret the Smoking Lesion problem the way that I do, and in what sense I was discussing how the correlation comes about.
Eliezer used the Smoking Lesion as a counterexample to evidential decision theory. It it supposed to be a counterexample by providing a case where evidential decision theory recommends a bad course of action, namely not smoking when it would be better to smoke. He needed it as a counterexample because if there are no counterexamples, there is no need to come up with an alternative decision theory.
But the stipulation that evidential decision theory recommends not smoking requires us to interpret the situation in a very subtle way where it does not sound much like something that could happen in real life, rather than the crude way where we could easily understand it happening in real life.
Here is why. In order for EDT to recommmend not smoking, your actual credence that you have the lesion has to go up after you choose to smoke, and to go down after you choose not to smoke. That is, your honest evaluation of how likely you are to have the lesion has to change precisely because you made that choice.
Now suppose a case like the Smoking Lesion were to come up in real life. Someone like Eliezer could say, “Look, I’ve been explaining for years that you should choose smoking in these cases. So my credence that I have the lesion won’t change one iota after I choose to smoke. I know perfectly well that my choice has nothing to do with whether I have the lesion; it is because I am living according to my principles.” But if this is true, then EDT does not recommend not smoking anyway in his case. It only recommends not smoking if he will actually believe himself more likely to have the lesion, once he has chosen to smoke, than he did before he made that choice. And that means that he has not found any counterexample to EDT yet.
The need to find a counterexample absolutely excludes any kind of crude causality. If the lesion is supposed to override your normal process of choice, so that for example you start smoking without any real decision, then deciding to smoke will not increase a person’s credence that he has the lesion. In fact it might decrease it, when he sees that he made a decision in a normal way.
In a similar way, there might be a statistical association between choosing to smoke and the lesion, but it still will not increase a person’s credence that he has the lesion, if the association goes away after controlling for some other factor besides the choice, like desire for smoking. In order to have the counterexample, it has to be the case that as far as the person can tell, the correlation is directly between the lesion and the actual choice to smoke. This does not imply that any magic is happening—it refers to the state of the person’s knowledge. But he cannot have the ability to explain away the association so that his choice is clearly irrelevant; because if he does, EDT no longer recommends not smoking.
This is what I think is parallel to the fact that in Newcomb X’s causality is defined directly in relation to the choice of A or B, and makes the situations equivalent. In other words, I agree that in such an unusual situation EDT will recommend not smoking, but I disagree that there is anything wrong with that recommendation.
When Eliezer was originally discussing Newcomb, he posited a 100% correlation or virtually 100%, to make the situation more convincing. So if the Smoking Lesion is supposed to be a fair counterexample to EDT, we should do the same thing. So the best way to interpret the whole situation is like this:
The lesion has in the past had a 100% correlation with the actual choice to smoke, no matter how the particular person concluded that he should make that choice.
In every case, the person makes the choice in a manner which is psychologically normal. This is to ensure that it is not possible to remove the subjective correlation between actually choosing and the lesion, and consequent this stipulation is to prevent a person from not updating his credence based on his choice.
It cannot be said that these stipulations make the whole situation impossible, as long as we admit that a person’s choices, and also his mode of choice, are caused by the physical structure of the brain in any case. And even though they make the situation unlikely, this is no more the case than the equivalent stipulations in a Newcomb situation.
Nor can the response be that “you don’t have a real choice” in this situation. Even if we found out that this was true in some sense of choice, it would make no difference to the real experience of a person in this situation, which would be a normal experience of choice, and would be done in a normal manner and for normal reasons. On the contrary: you cannot get out of making a choice anymore than a determinist in real life has a realistic possibility of saying, “Now that I realize all my actions are determined, I don’t have to make choices anymore.”
EDT will indeed recommend not smoking in this situation, since clearly if you choose to smoke, you will conclude with high probability that you have the lesion, and if you choose not to smoke, you will conclude with high probability that you do not.
In order for Eliezer to have the counterexample, he needs to recommend smoking even in this situation. Presumably that would go something like this: “Look. I realize that after you follow my recommendation you will rightly conclude that you have the lesion. But we should ignore that, and consider it irrelevant, because we know that you can choose to smoke or not, while you cannot choose to have the lesion or not. So for the purposes of considering what to do, we should pretend that the choice won’t change our credence. So choose to smoke, since you prefer that in theory to not smoking. It’s just too bad that you will have to conclude that you have the lesion.”
In my opinion this would be just as wrong as the following:
“Look. I realize that after you follow my recommendation you will rightly conclude that the million is not in the box. But we should ignore that, and consider it irrelevant, because we know that you can choose to take one or two boxes, while you cannot choose to make the million be there or not. So for the purposes of considering what to do, we should pretend that the choice won’t change our credence. So take both boxes, since you would prefer the contents of both boxes to the contents of only one. It’s just too bad that you will have to conclude that the million isn’t there.”
Eliezer criticizes the “it’s just too bad” line of thinking by responding that you should strop trying to pretend it isn’t your fault, when you could have just taken one box. I say the same in the lesion case with the above stipulations: don’t pretend it isn’t your fault, when you could just decide not to smoke.
Now suppose a case like the Smoking Lesion were to come up in real life. Someone like Eliezer could say [...]
In other words, for some highly atypical people who have given a lot of explicit thought to situations like the Smoking Lesion one (and who, furthermore, strongly reject EDT), deciding to smoke wouldn’t be evidence of having the lesion and therefore the SL situation for them doesn’t work as a counterexample to EDT. I think I agree, but I don’t see why it matters.
there might be a statistical association between choosing to smoke and having the lesion, but it still will not increase a person’s credence that he has the lesion, if the association goes away after controlling for some factor besides the choice, such as desire for smoking.
Yes, I agree. Just to be clear, it seems like you’re arguing here for “EDT doesn’t necessarily say not to smoke” but elsewhere for “TDT probably says not to smoke”. Is that right? I find the first of these distinctly more plausible than the second, for what it’s worth.
So if the Smoking Lesion is supposed to be a fair counterexample to CDT, we should do the same thing [sc. posit a very-near-100% correlation].
I’m not sure I follow the logic. Even a well-sub-100% Smoking Lesion situation is (allegedly) a counterexample to EDT, and it’s not necessary to push the correlation up to almost 100% for it to serve this purpose; the reason why you need a correlation near to 100% for Newcomb is that what makes it plausible (to the chooser in the Newcomb situation) that Omega really can predict his choices is exactly the fact that the correlation is so strong. If it were much weaker, the chooser would be entirely within his rights to say “My prior against Omega having any substantial predictive ability is extremely strong; no one has shown me the sort of evidence that would change my mind about that; so I don’t think my choosing to two-box is strong evidence that Omega will leave the second box empty; so I shall take both boxes.”
It’s not clear to me that anything parallel is true about the Smoking Lesion scenario, so I don’t see why we “should” push the correlations to practically-100% in that case.
(But I don’t think what you’re saying particularly depends on the correlation being practically 100%.)
I’m not sure what TDT, or Eliezer, would say about your refined smoking-lesion situation. I will think a bit more about what I would say about it :-).
“For some highly atypical people...” The problem is that anyone who discusses this situation is a highly atypical person. And such people cannot imagine actually having a higher credence that they have the lesion, if they choose to smoke. This is why people advocate the smoking answer; and according to what I said in my other comment, it is not a “real Smoking Lesion problem” as long as they think that way, or at least they are not thinking of it as one (it could be that they are mistaken, and that they should have a higher credence, but don’t.)
Just to be clear, it seems like you’re arguing here for “EDT doesn’t necessarily say not to smoke” but elsewhere for “TDT probably says not to smoke”. Is that right? I find the first of these distinctly more plausible than the second, for what it’s worth.
What I meant was: in the situations people usually think about, or at least the way they are thinking about them, EDT doesn’t necessarily say not to smoke. But these are not the situations that are equivalent to the real Newcomb problem—these are equivalent to the fake Newcomb situations. EDT does say not to smoke in the situations which are actually equivalent to Newcomb. When I said “TDT probably says not to smoke,” I was referring to the actually equivalent situations. (Although as I said, I am less confident about TDT now; it may simply be incoherent or arbitrary.)
You don’t need to have a 100% correlation either for Newcomb or for the Smoking Lesion. But you are right that the reason for a near 100% correlation for Newcomb is to make the situation convincing to the chooser. But this is just to get him to admit that the million will actually be more likely to be there if he takes only one box. In the same way, theoretically you do not need it for the Smoking Lesion. But again, you have to convince the chooser that he personally will have a higher chance of having the lesion if he chooses to smoke, and it is hard to convince people of that. As someone remarked about people’s attitude on one of the threads about this, “So the correlation goes down from 100% to 99.9% and suddenly you consider yourself one of the 0.1%?” If anything, it seems harder to convince people they are in the true Smoking Lesion situation, than in the true Newcomb situation. People find Newcomb pretty plausible even if the correlation is 90%, if it is both for one-boxers and two-boxers, but a 90% correlation in the lesion case would leave a lot of person’s opinions about whether they have the lesion unchanged, no matter whether they choose to smoke or not.
(But I don’t think what you’re saying particularly depends on the correlation being practically 100%.)
Sure. If you augment the SL and Newcomb scenarios with extra details about what’s going on, those extra details can matter. So, e.g., if Omega just predicts that you’ll take two boxes iff you’ve usually said “I would take two boxes” then you should probably say “I would take one box” and then take two boxes. But this version of Newcomb is utterly incompatible with how the Newcomb problem is always presented: in a world where Omega was known to operate this way, Omega’s success rate would be approximately 0% rather than the near-100% that makes the problem actually interesting. (Because everyone would say “I would take one box” and then everyone would take two boxes.)
So your version of Newcomb designed to yield a two-boxing decision succeeds in yielding a two-boxing decision, but only by not actually being a version of Newcomb in anything but name.
I was not assuming a world where Omega was known to operate this way. I originally said that it matters how the choice got correlated with one-boxing, and this was an example. In order for it work, as you are pointing out, it has to be working without this mode of acting being known. in other words, suppose someone very wealthy comes forward and says that he is going to test the Newcomb problem in real life, and says that he will act as Omega. We don’t know what his method is, but it turns out that he has a statistically high rate of success. Now suppose you end up with insider knowledge that he is just judging based on a person’s past internet comments. It does not seem impossible that this could give a positive rate of success in the real world as long as it is unknown; presumably people who say they would one-box, would be more likely to actually one-box. (Example: Golden Balls was a game show involving the Prisoner’s dilemma. Before cooperating or defecting, the contestants were allowed to talk to each other for a certain period. People analyzing it afterwards determined that a person explicitly and directly saying “I will cooperate” had a 30% higher chance of actually cooperating; people who weren’t going to cooperate generally were vaguer about their intentions.) But once you end up with the insider knowledge, it makes sense to go around saying you will take only one box, and then take both anyway.
This happens because the correlation between your choice and the million is removed once you control for the past comments. The point of those examples was a correlation that you cannot separate between your choice and the million. For the Smoking Lesion to be equivalent, it has to be equally impossible to remove the correlation between your choice and the lesion, as I said in the long comment.
It does not seem impossible that this could give a positive rate of success in the real world
I don’t know about you, but for me to give serious consideration to one-boxing in a Newcomb situation the box-stuffer would need to have demonstrated something better than “a positive rate of success”. I agree that if I had insider knowledge that they were doing it by looking at people’s past internet comments then two-boxing would be rational, but I don’t think any advocates of one-boxing would disagree with that. The situation you’re describing just isn’t an actual Newcomb problem any more.
It seems very likely possible for a human to achieve, say, 75% success on both one-boxers and two-boxers, maybe not with such a simple rule, but certainly without an actual mind reading ability. If this is the case, then there must be plenty of one-boxers who would one-box against someone who was getting a 75% success rate, even if you aren’t one of them.
I don’t think any advocates of one-boxing would disagree with that. The situation you’re describing just isn’t an actual Newcomb problem any more.
I agree. That was the whole point. I was not trying to say that one-boxers would disagree, but that they would agree. The point is that to have an “actual Newcomb problem” your personal belief about whether you will get the million has to actually vary with your actual choice to take one or two boxes in the particular case; if your belief isn’t going to vary, even in the individual case, you will just take both boxes according to the argument, “I’ll get whatever I would have with one box, plus the thousand.”
I was simply saying that since Eliezer constructs the Smoking Lesion as a counterexample to EDT, we need to treat the “actual Smoking Lesion” in the same way: it is only the “actual Smoking Lesion problem” if your belief that you have the lesion is actually going to vary, depending on whether you choose to smoke or not.
How confident are you that you understand TDT better than Eliezer does? Because he seems to think that TDT implies smoking.
I don’t think I understand TDT better than Eliezer. I think that any sensible decision theory will give corresponding answers to Newcomb and the Smoking Lesion, and I am assuming that TDT is sensible. I do know that Eliezer is in favor both of one boxing and of cooperating in the Prisoner’s Dilemma, and both of those require the kind of reasoning that leads to not smoking. That is why I said that I “suspect” that TDT means not smoking.
I don’t think I understand TDT better than Eliezer. I think that any sensible decision theory will give corresponding answers to Newcomb and the Smoking Lesion, and I am assuming that TDT is sensible.
Since Eliezer is on record as saying that TDT advocates non-corresponding answers to Newcomb and the Smoking Lesion, it seems to me that you should at the very least be extremely uncertain about at least one of (1) whether TDT is actually sensible, (2) whether Eliezer actually understands his own theory, and (3) whether you are correct about sensible theories giving corresponding answers in those cases.
Because if sensible ⇒ corresponding answers and TDT is sensible, then it gives corresponding answers; and if Eliezer understands his own theory then it doesn’t give corresponding answers.
I looked back at some of Eliezer’s early posts on this and they certainly didn’t claim to be fully worked out; he said things like “this part is still magic,” and so on. However, I have significantly increased my estimate of the possibility that TDT might be incoherent, or at any rate arbitrary; he did seem to want to say that you would consider yourself the cause of the million being in the box, and I don’t think it is true in any non-arbitrary way that you should consider yourself the cause of the million, and not of whether you have the lesion. As an example (which is certainly very different from Eliezer saying it), bogus seemed to assert that it was just the presentation of the problem, namely whether you count yourself as being able to affect something or not.
I think that any sensible decision theory will give corresponding answers to Newcomb and the Smoking Lesion, and I am assuming that TDT is sensible.
I think you don’t quite understand either how TDT is supposed to work, or how the way it works can be “sensible”. If you exogenously alter every “smoke” decision to “don’t smoke” in Smoking Lesion, your payoff doesn’t improve, by construction. If you exogenously alter every “two-box” decision to “one box”, this does change your payoff. Note the ‘exogenously’ qualification above, which is quite important—and note that the “exogenous” change must alter all logically-connected choices in the same way: in Newcomb, the very same exogenous input acts on Omega’s prediction as on your actual choice; and in Smoking Lesion, the change to “smoke” or “don’t smoke” occurs regardless of whether you have the Smoking Lesion or not.
(It might be that you could express the problems in EDT in a way that leads to the correct choice, by adding hardwired models of these “exogenous but logically-connected” decisions. But this isn’t something that most EDT advocates would describe as a necessary part of that theory—and this is all the more true if a similar change could work for CDT!)
Omega’s prediction in reality is based on the physical state of your brain. So if altering your choice in Newcomb alters Omega’s prediction, it also alters the state of your brain. And if that is the case, it can alter the state of your brain when you choose not to smoke in the Smoking Lesion.
The ‘state of your brain’ in Newcomb and Smoking Lesion need not be directly comparable. If you could alter the state of your brain in a way that makes you better off in Smoking Lesion just by exogenously forcing the “don’t smoke” choice, then the problem statement wouldn’t be allowed to include the proviso that choosing “don’t smoke” doesn’t improve your payoff.
The problem statement does not include the proviso that choosing not to smoke does not improve the payoff. It just says that if you have the lesion, you get cancer, and if you don’t, you don’t. And it says that people who choose to smoke, turn out to have the lesion, and people who choose not to smoke, turn out not to have the lesion. No proviso about not smoking not improving the payoff.
You might be right. But then TDT chooses not to smoke precisely when CDT does, because there is nothing that’s logically-but-not-physically/causally connected with the exogenous decision whether or not to smoke. Which arguably makes this version of the problem quite uninteresting.
How confident are you that you understand TDT better than Eliezer does? Because he seems to think that TDT implies smoking.
This looks to me like another thing that actually depends on the details of what the alleged cause is and how it does the causing, and I don’t think it’s at all clear that “if the lesion is 100% correlated with smoking, you can’t be making a real choice” and “if Omega’s choice of what to put in the boxes is 100% correlated with your choice of which box(es) to pick, you can’t be making a real choice” are equivalent.
For instance, suppose Omega chooses what to put in the boxes by looking into the future using magic. In this case, your choice is as real and free as any choice ever is. On the other hand, suppose the way the smoking lesion works is that everyone in the world has a little override built into their brain by a mad genius neuroscientist that detects situations in which they might choose whether to start smoking and forces them to do one thing rather than another, in a way that has absolutely nothing in common with any other decisions they make. In this case, your choice is as unreal and un-free as anything choice-like could ever be.
I dunno, maybe you don’t care about such intuitions, and you insist on a definition of terms like “choice” and “freedom” that’s perfectly clear and rigorous but doesn’t refer to any of these details that might differ in the two scenarios. I personally would be absolutely staggered if any such definition actually came close to matching how those words are actually used in practice. I don’t know how to give an adequate definition of any of those terms, though I have vague handwavy guesses at the sort of shape a definition might have once we know a lot more about brains and things, so in default of such a definition I’m going with my intuitions, and those say that the level of abstraction at which Newcomb and Smoking Lesion look the same is too high a level of abstraction to enable us to answer questions like “is this person really making a choice?”.
My understanding of what I was supposed to assume about the Smoking Lesion was that it’s something rather crude that doesn’t depend on fine details of how the brain does whatever it does when making choices. But I think the how-the-correlation-works question is more central, so let’s move on.
Sure. If you augment the SL and Newcomb scenarios with extra details about what’s going on, those extra details can matter. So, e.g., if Omega just predicts that you’ll take two boxes iff you’ve usually said “I would take two boxes” then you should probably say “I would take one box” and then take two boxes. But this version of Newcomb is utterly incompatible with how the Newcomb problem is always presented: in a world where Omega was known to operate this way, Omega’s success rate would be approximately 0% rather than the near-100% that makes the problem actually interesting. (Because everyone would say “I would take one box” and then everyone would take two boxes.)
So your version of Newcomb designed to yield a two-boxing decision succeeds in yielding a two-boxing decision, but only by not actually being a version of Newcomb in anything but name.
Your examples in which (if I’m understanding them correctly) someone, after being present with the SL/Newcomb choice, selects a decision theory and then applies it, seem very strange. I mean, I admit that what gets people thinking about decision theories is often knotty questions like Newcomb—but I’ve never heard of a case where someone got into decision theory in order to resolve such a knotty question with which they personally were faced and then did actually select and apply some concrete decision theory to resolve their question. (Though I wouldn’t be surprised to hear it’s happened at least once.) In that case, I agree that the choice of decision theory is all tangled up with the other factors involved (lesion, desires, preference for getting a million dollars, …); but I don’t see what this has to do with the rest of us who are contemplating decision theories in the abstract, nor to do with a hypothetical person in the SL/NP scenarios who, like most such hypothetical people :-), doesn’t react to their challenge by trying to select a decision theory to live by thenceforward.
I’m going to answer this with several comments, and probably not all today. In this one I am going to make some general points which are not necessarily directly addressed to particular comments you made, but which might show more clearly why I interpret the Smoking Lesion problem the way that I do, and in what sense I was discussing how the correlation comes about.
Eliezer used the Smoking Lesion as a counterexample to evidential decision theory. It it supposed to be a counterexample by providing a case where evidential decision theory recommends a bad course of action, namely not smoking when it would be better to smoke. He needed it as a counterexample because if there are no counterexamples, there is no need to come up with an alternative decision theory.
But the stipulation that evidential decision theory recommends not smoking requires us to interpret the situation in a very subtle way where it does not sound much like something that could happen in real life, rather than the crude way where we could easily understand it happening in real life.
Here is why. In order for EDT to recommmend not smoking, your actual credence that you have the lesion has to go up after you choose to smoke, and to go down after you choose not to smoke. That is, your honest evaluation of how likely you are to have the lesion has to change precisely because you made that choice.
Now suppose a case like the Smoking Lesion were to come up in real life. Someone like Eliezer could say, “Look, I’ve been explaining for years that you should choose smoking in these cases. So my credence that I have the lesion won’t change one iota after I choose to smoke. I know perfectly well that my choice has nothing to do with whether I have the lesion; it is because I am living according to my principles.” But if this is true, then EDT does not recommend not smoking anyway in his case. It only recommends not smoking if he will actually believe himself more likely to have the lesion, once he has chosen to smoke, than he did before he made that choice. And that means that he has not found any counterexample to EDT yet.
The need to find a counterexample absolutely excludes any kind of crude causality. If the lesion is supposed to override your normal process of choice, so that for example you start smoking without any real decision, then deciding to smoke will not increase a person’s credence that he has the lesion. In fact it might decrease it, when he sees that he made a decision in a normal way.
In a similar way, there might be a statistical association between choosing to smoke and the lesion, but it still will not increase a person’s credence that he has the lesion, if the association goes away after controlling for some other factor besides the choice, like desire for smoking. In order to have the counterexample, it has to be the case that as far as the person can tell, the correlation is directly between the lesion and the actual choice to smoke. This does not imply that any magic is happening—it refers to the state of the person’s knowledge. But he cannot have the ability to explain away the association so that his choice is clearly irrelevant; because if he does, EDT no longer recommends not smoking.
This is what I think is parallel to the fact that in Newcomb X’s causality is defined directly in relation to the choice of A or B, and makes the situations equivalent. In other words, I agree that in such an unusual situation EDT will recommend not smoking, but I disagree that there is anything wrong with that recommendation.
When Eliezer was originally discussing Newcomb, he posited a 100% correlation or virtually 100%, to make the situation more convincing. So if the Smoking Lesion is supposed to be a fair counterexample to EDT, we should do the same thing. So the best way to interpret the whole situation is like this:
The lesion has in the past had a 100% correlation with the actual choice to smoke, no matter how the particular person concluded that he should make that choice.
In every case, the person makes the choice in a manner which is psychologically normal. This is to ensure that it is not possible to remove the subjective correlation between actually choosing and the lesion, and consequent this stipulation is to prevent a person from not updating his credence based on his choice.
It cannot be said that these stipulations make the whole situation impossible, as long as we admit that a person’s choices, and also his mode of choice, are caused by the physical structure of the brain in any case. And even though they make the situation unlikely, this is no more the case than the equivalent stipulations in a Newcomb situation.
Nor can the response be that “you don’t have a real choice” in this situation. Even if we found out that this was true in some sense of choice, it would make no difference to the real experience of a person in this situation, which would be a normal experience of choice, and would be done in a normal manner and for normal reasons. On the contrary: you cannot get out of making a choice anymore than a determinist in real life has a realistic possibility of saying, “Now that I realize all my actions are determined, I don’t have to make choices anymore.”
EDT will indeed recommend not smoking in this situation, since clearly if you choose to smoke, you will conclude with high probability that you have the lesion, and if you choose not to smoke, you will conclude with high probability that you do not.
In order for Eliezer to have the counterexample, he needs to recommend smoking even in this situation. Presumably that would go something like this: “Look. I realize that after you follow my recommendation you will rightly conclude that you have the lesion. But we should ignore that, and consider it irrelevant, because we know that you can choose to smoke or not, while you cannot choose to have the lesion or not. So for the purposes of considering what to do, we should pretend that the choice won’t change our credence. So choose to smoke, since you prefer that in theory to not smoking. It’s just too bad that you will have to conclude that you have the lesion.”
In my opinion this would be just as wrong as the following:
“Look. I realize that after you follow my recommendation you will rightly conclude that the million is not in the box. But we should ignore that, and consider it irrelevant, because we know that you can choose to take one or two boxes, while you cannot choose to make the million be there or not. So for the purposes of considering what to do, we should pretend that the choice won’t change our credence. So take both boxes, since you would prefer the contents of both boxes to the contents of only one. It’s just too bad that you will have to conclude that the million isn’t there.”
Eliezer criticizes the “it’s just too bad” line of thinking by responding that you should strop trying to pretend it isn’t your fault, when you could have just taken one box. I say the same in the lesion case with the above stipulations: don’t pretend it isn’t your fault, when you could just decide not to smoke.
In other words, for some highly atypical people who have given a lot of explicit thought to situations like the Smoking Lesion one (and who, furthermore, strongly reject EDT), deciding to smoke wouldn’t be evidence of having the lesion and therefore the SL situation for them doesn’t work as a counterexample to EDT. I think I agree, but I don’t see why it matters.
Yes, I agree. Just to be clear, it seems like you’re arguing here for “EDT doesn’t necessarily say not to smoke” but elsewhere for “TDT probably says not to smoke”. Is that right? I find the first of these distinctly more plausible than the second, for what it’s worth.
I’m not sure I follow the logic. Even a well-sub-100% Smoking Lesion situation is (allegedly) a counterexample to EDT, and it’s not necessary to push the correlation up to almost 100% for it to serve this purpose; the reason why you need a correlation near to 100% for Newcomb is that what makes it plausible (to the chooser in the Newcomb situation) that Omega really can predict his choices is exactly the fact that the correlation is so strong. If it were much weaker, the chooser would be entirely within his rights to say “My prior against Omega having any substantial predictive ability is extremely strong; no one has shown me the sort of evidence that would change my mind about that; so I don’t think my choosing to two-box is strong evidence that Omega will leave the second box empty; so I shall take both boxes.”
It’s not clear to me that anything parallel is true about the Smoking Lesion scenario, so I don’t see why we “should” push the correlations to practically-100% in that case.
(But I don’t think what you’re saying particularly depends on the correlation being practically 100%.)
I’m not sure what TDT, or Eliezer, would say about your refined smoking-lesion situation. I will think a bit more about what I would say about it :-).
“For some highly atypical people...” The problem is that anyone who discusses this situation is a highly atypical person. And such people cannot imagine actually having a higher credence that they have the lesion, if they choose to smoke. This is why people advocate the smoking answer; and according to what I said in my other comment, it is not a “real Smoking Lesion problem” as long as they think that way, or at least they are not thinking of it as one (it could be that they are mistaken, and that they should have a higher credence, but don’t.)
What I meant was: in the situations people usually think about, or at least the way they are thinking about them, EDT doesn’t necessarily say not to smoke. But these are not the situations that are equivalent to the real Newcomb problem—these are equivalent to the fake Newcomb situations. EDT does say not to smoke in the situations which are actually equivalent to Newcomb. When I said “TDT probably says not to smoke,” I was referring to the actually equivalent situations. (Although as I said, I am less confident about TDT now; it may simply be incoherent or arbitrary.)
You don’t need to have a 100% correlation either for Newcomb or for the Smoking Lesion. But you are right that the reason for a near 100% correlation for Newcomb is to make the situation convincing to the chooser. But this is just to get him to admit that the million will actually be more likely to be there if he takes only one box. In the same way, theoretically you do not need it for the Smoking Lesion. But again, you have to convince the chooser that he personally will have a higher chance of having the lesion if he chooses to smoke, and it is hard to convince people of that. As someone remarked about people’s attitude on one of the threads about this, “So the correlation goes down from 100% to 99.9% and suddenly you consider yourself one of the 0.1%?” If anything, it seems harder to convince people they are in the true Smoking Lesion situation, than in the true Newcomb situation. People find Newcomb pretty plausible even if the correlation is 90%, if it is both for one-boxers and two-boxers, but a 90% correlation in the lesion case would leave a lot of person’s opinions about whether they have the lesion unchanged, no matter whether they choose to smoke or not.
This is correct.
I was not assuming a world where Omega was known to operate this way. I originally said that it matters how the choice got correlated with one-boxing, and this was an example. In order for it work, as you are pointing out, it has to be working without this mode of acting being known. in other words, suppose someone very wealthy comes forward and says that he is going to test the Newcomb problem in real life, and says that he will act as Omega. We don’t know what his method is, but it turns out that he has a statistically high rate of success. Now suppose you end up with insider knowledge that he is just judging based on a person’s past internet comments. It does not seem impossible that this could give a positive rate of success in the real world as long as it is unknown; presumably people who say they would one-box, would be more likely to actually one-box. (Example: Golden Balls was a game show involving the Prisoner’s dilemma. Before cooperating or defecting, the contestants were allowed to talk to each other for a certain period. People analyzing it afterwards determined that a person explicitly and directly saying “I will cooperate” had a 30% higher chance of actually cooperating; people who weren’t going to cooperate generally were vaguer about their intentions.) But once you end up with the insider knowledge, it makes sense to go around saying you will take only one box, and then take both anyway.
This happens because the correlation between your choice and the million is removed once you control for the past comments. The point of those examples was a correlation that you cannot separate between your choice and the million. For the Smoking Lesion to be equivalent, it has to be equally impossible to remove the correlation between your choice and the lesion, as I said in the long comment.
I don’t know about you, but for me to give serious consideration to one-boxing in a Newcomb situation the box-stuffer would need to have demonstrated something better than “a positive rate of success”. I agree that if I had insider knowledge that they were doing it by looking at people’s past internet comments then two-boxing would be rational, but I don’t think any advocates of one-boxing would disagree with that. The situation you’re describing just isn’t an actual Newcomb problem any more.
It seems very likely possible for a human to achieve, say, 75% success on both one-boxers and two-boxers, maybe not with such a simple rule, but certainly without an actual mind reading ability. If this is the case, then there must be plenty of one-boxers who would one-box against someone who was getting a 75% success rate, even if you aren’t one of them.
I agree. That was the whole point. I was not trying to say that one-boxers would disagree, but that they would agree. The point is that to have an “actual Newcomb problem” your personal belief about whether you will get the million has to actually vary with your actual choice to take one or two boxes in the particular case; if your belief isn’t going to vary, even in the individual case, you will just take both boxes according to the argument, “I’ll get whatever I would have with one box, plus the thousand.”
I was simply saying that since Eliezer constructs the Smoking Lesion as a counterexample to EDT, we need to treat the “actual Smoking Lesion” in the same way: it is only the “actual Smoking Lesion problem” if your belief that you have the lesion is actually going to vary, depending on whether you choose to smoke or not.
I don’t think I understand TDT better than Eliezer. I think that any sensible decision theory will give corresponding answers to Newcomb and the Smoking Lesion, and I am assuming that TDT is sensible. I do know that Eliezer is in favor both of one boxing and of cooperating in the Prisoner’s Dilemma, and both of those require the kind of reasoning that leads to not smoking. That is why I said that I “suspect” that TDT means not smoking.
Since Eliezer is on record as saying that TDT advocates non-corresponding answers to Newcomb and the Smoking Lesion, it seems to me that you should at the very least be extremely uncertain about at least one of (1) whether TDT is actually sensible, (2) whether Eliezer actually understands his own theory, and (3) whether you are correct about sensible theories giving corresponding answers in those cases.
Because if sensible ⇒ corresponding answers and TDT is sensible, then it gives corresponding answers; and if Eliezer understands his own theory then it doesn’t give corresponding answers.
I looked back at some of Eliezer’s early posts on this and they certainly didn’t claim to be fully worked out; he said things like “this part is still magic,” and so on. However, I have significantly increased my estimate of the possibility that TDT might be incoherent, or at any rate arbitrary; he did seem to want to say that you would consider yourself the cause of the million being in the box, and I don’t think it is true in any non-arbitrary way that you should consider yourself the cause of the million, and not of whether you have the lesion. As an example (which is certainly very different from Eliezer saying it), bogus seemed to assert that it was just the presentation of the problem, namely whether you count yourself as being able to affect something or not.
I think you don’t quite understand either how TDT is supposed to work, or how the way it works can be “sensible”. If you exogenously alter every “smoke” decision to “don’t smoke” in Smoking Lesion, your payoff doesn’t improve, by construction. If you exogenously alter every “two-box” decision to “one box”, this does change your payoff. Note the ‘exogenously’ qualification above, which is quite important—and note that the “exogenous” change must alter all logically-connected choices in the same way: in Newcomb, the very same exogenous input acts on Omega’s prediction as on your actual choice; and in Smoking Lesion, the change to “smoke” or “don’t smoke” occurs regardless of whether you have the Smoking Lesion or not.
(It might be that you could express the problems in EDT in a way that leads to the correct choice, by adding hardwired models of these “exogenous but logically-connected” decisions. But this isn’t something that most EDT advocates would describe as a necessary part of that theory—and this is all the more true if a similar change could work for CDT!)
Omega’s prediction in reality is based on the physical state of your brain. So if altering your choice in Newcomb alters Omega’s prediction, it also alters the state of your brain. And if that is the case, it can alter the state of your brain when you choose not to smoke in the Smoking Lesion.
The ‘state of your brain’ in Newcomb and Smoking Lesion need not be directly comparable. If you could alter the state of your brain in a way that makes you better off in Smoking Lesion just by exogenously forcing the “don’t smoke” choice, then the problem statement wouldn’t be allowed to include the proviso that choosing “don’t smoke” doesn’t improve your payoff.
The problem statement does not include the proviso that choosing not to smoke does not improve the payoff. It just says that if you have the lesion, you get cancer, and if you don’t, you don’t. And it says that people who choose to smoke, turn out to have the lesion, and people who choose not to smoke, turn out not to have the lesion. No proviso about not smoking not improving the payoff.
You might be right. But then TDT chooses not to smoke precisely when CDT does, because there is nothing that’s logically-but-not-physically/causally connected with the exogenous decision whether or not to smoke. Which arguably makes this version of the problem quite uninteresting.