Harry time-turned to just before the troll attack. (In the one-and-a-half minutes when he went into Hermione’s room.) This is probably pretty clear—he’s been keeping everyone else out of that room, and the centrality of the time-turner in this story more or less demands that Harry do so. Harry would have done this even if he couldn’t come up with a plan in his previous six hours, just so he’d have another six hours to think, or do what he deemed needful to preserve Hermione’s body.
Somewhere in there, he talked to the twins, and poorly obliviated them. Evidence:
Why does Harry know about the Marauder’s Map? When else has Harry learned plot-significant information off-camera?
Obliviation, and Memory Charms in general, and Harry’s horror of them, are repeatedly mentioned in the story, and haven’t really been used that much yet.
Harry has just learned that he has access to learn obliviation.
Quirrell suggests that obliviation is within his abilities, but barely—and so Harry is likely to botch it if he attempts it.
Who else in the story is likely to have performed a botched obliviation on the Weasley twins—such that they have vague memories of having the map, but no complete ones? Every potential foe is powerful enough to perform obliviation properly.
Besides, it’ll be a narratively nice, dark moment when Harry uses a spell whose existence he abhors on two of his best remaining friends and allies...
If you need more than 6 hours to learn Obliviation, you can use this method. Bonus: in addition to giving you more time to study, this method summons an army of hundreds of invisible Harry Potters (all with a single twist of the time-turner).
I would have tried this method, but I my narrative sense tells me that Harry did not.
… and prevents them from helping him find Hermione. You think he went back in time to become responsible for one of the circumstantial reasons for his failure?
That would not be wise: He should retroactively precommit to not steal the Marauders Map regardless of whether the Map is stolen, just as one should one-box on Newcombs problem.
On the contrary, you should precommit to being responsible for all apparently bad occurrences if you happen to gain the ability to travel through time because if you can trust anyone to try to fix them while making them seem like they were bad to you it will be you.
On the contrary, you should precommit to being responsible for all apparently bad occurrences if you happen to gain the ability to travel through time because if you can trust anyone to try to fix them while making them seem like they were bad to you it will be you.
This has the potential to produce many more self-sustaining “not quite as bad as it looks” bad events. Is this necessarily wise?
Consider this: You have essentially the same set up, and you’re a one-boxer, so you walk up and take your million dollars out of box B.
And then Omega comes back and says, “Oh, by the way, want to open Box A too?”
And you say, “Um. Okay?” And open Box A, and get a thousand dollars. Or not. Doesn’t really matter—you already have your million dollars, so you have nothing to lose by opening Box A.
This differs from the traditional two-boxing argument in one very important respect: you get new information in the middle of the experiment. Your single Omega-predictable algorithm doesn’t have to “change its mind” in the middle, it gets interrupted.
This is essentially what (might be) happening here. Harry has opened Box B and found a dead Hermione inside. That’s set and done. Assuming that he has reason to be believe that Box A will help him more than it will hurt him on average (and won’t contain, say, a dead/mindless/insane Fred and George), he has no reason not to open Box A.
A more perfectly isomorphic variant of Newcomb’s problem is the following. Both boxes are transparent, and Omega acts according to the following rule: if you two-box when box B is empty, then box B is always empty, while if you one-box, box B is empty with a 50% chance.
If you one-box in this variant, you win half a million dollars in expectation. If you intend to two-box should you see that box B is empty, then you only win a thousand dollars.
… Perhaps, but that’s no longer isomorphic to the actual problem. We are past the point of Omega’s influence; in Newcomb’s problem, it’d be as if Omega grabbed your mind state, ran it forward until it confirmed that you would not initially two-box, and then stopped. Omega itself has been removed from the problem, and you’re left with one empty box that you’ve already claimed a million dollars from (or negative one million, in this case) and one closed box.
Near as we can tell, history can’t change in the MoRverse: what’s done is done, so Harry might as well exploit it.
This is essentially what (might be) happening here. Harry has opened Box B and found a dead Hermione inside. That’s set and done. Assuming that he has reason to be believe that Box A will help him more than it will hurt him on average (and won’t contain, say, a dead/mindless/insane Fred and George), he has no reason not to open Box A.
Are you describing Transparent Newcomb’s problem? If so one should still one box when you see that the large box is empty. (I am not sure whether this maps precisely to the marauder’s map issue, I haven’t read the relevant chapter.)
Suppose my best friend loses her cell phone, gets lost in the woods, and dies. I could pre-commit to not travel back in time and steal her cell phone. It would be easy commitment to make, because Time-Turners are fictional. Would making that commitment help save my friend?
(Your friend is less likely to die if you make that commitment) iff timeturners are not fictional. Avert all scenarios in which you doom your friend for a cellphone.
((I feel that neither this post nor its father have contributed to the point grandfather was making. Should I have downvoted father? Maybe I have misunderstood fathers question, was that a rhetorical question supposed to be “answered” by “Of course not!”?))
Yes, it was supposed to be a rhetorical question answered by “of course not”.
Here’s a Newcomb-like algorithm for getting a pony in my yard.
Open my front door and check to see if I have a pony in my yard.
If I have a pony in my yard, we have succeeded. Otherwise, use a time machine to kill my grandfather.
This algorithm works because the only stable time loops are the ones where I get a pony. You can get magically nice results by pre-commiting to create a paradox in unwanted timelines, if you can to commit to do something unpleasant in those timelines.
Please correct me if I’m wrong, but I think you want to pull this trick with Hermione’s death. You’re trying to make the only stable time loop be one where the Weaslys have the Marauder’s Map.
Your suggestion would work if Harry had good cause to believe that the only person who could possibly steal the Marauder’s Map was a future version of himself. Even if the map had already been stolen, deciding not to go back in time and steal the map would create a paradox. The only stable time loops would be ones where the map is not stolen.
Does that situation apply? No, not at all. There are many stable time loops where the Wheaslys lose the map. Quirrell could have done it. Dumbledore could have done it. Some dark force unknown could have done it. There is little reason to believe that eliminating future Harry as the map thief will lead to a nicer distribution of stable time loops. By contrast, the stable time loops where Harry is the map thief seem much more likely to be pleasant.
Ah, I believe you have misunderstood me. Lets say that in Yudcanon, either Dumbledore stole the map or Quirrel stole the map or Harry stole the map or Hat&Cloak stole the map or Mr. X stole the map. If Harry makes sure that Harry never steals the map, there is one less person who might have had a reason to steal the map, and the probability of the map being stolen versus it not being stolen goes down, even though he already knows that the map was stolen when he makes that decision; just like when Omega presents you the two boxes, you should retroactively precommit to one-box to receive a million, even though the content of the boxes is already determined.
Imagine Harry saw that the map was stolen, and thinks immediately of stealing it himself so as to acquire it. Naturally, he then plans to precommit to invisibility-cloak deposit it right behind Fred and George in 5 seconds. He might then go further and precommit instead to never having stolen it in the first place, so that it never leaves the grasp of the Weasley twins and Harry doesn’t have to go to the effort of stealing it. Therefore, he now knows that the map was stolen by someone else, and that the probablity of the map being stolen in the first place has lessened, which is a good thing.
This is the point that I think is escaping many people in this thread. The options aren’t as simple as A/A+B in Newcomb.
The map has been stolen. Everything we know about how Time Travel works in this universe indicates that this is a fixed fact that cannot be altered. Who took the map however is an unknown, and while it cannot be ‘altered’ either, the Effect can in this case precede the Cause. ‘Map has been taken’ can happen before ‘Harry takes map because someone had to’ such that B causes A and A leads to B. If Harry doesn’t commit to it, B is still true, and so the Map is lost to him. His choices are (Map is Gone, I have it.) or (Map is gone.) The choice ‘Map is still here and Hermione lives’ is not a valid choice and should be discounted. So, his choices are to benefit or not benefit from the Map being gone.
The interesting question is, if the Twins forgot the Map entirely, how did they remember ‘Deligitor Prodi’? Admittedly not perfectly.
They learned the phrase from Dumbledore when they gave him the map. The fact that they don’t remember the map but imperfectly remember the phrase does support the “poorly done obviation” hypothesis. (either because the obliviator missed removing the phrase or the obliviator intended for them to keep the phrase but accidentally messed it up)
(or, less likely, ‘Deligitor Prodi’ would not have worked for the twins and the obliviator intentionally altered it so that it would)
A few moments later, Fred and George were handing over the Map to the Headmaster, wincing only slightly at the sacrilege of giving their precious piece of the Hogwarts security system to the person who actually owned it, and the old wizard was frowning at the apparent blankness.
“You’ve got to say,” they explained, “I solemnly swear that I am up to no good—”
“I decline to lie,” said the old wizard. He held the Map high and bellowed, “Hear me, Hogwarts! Deligitor prodi!” An instant later the Headmaster was wearing the Sorting Hat, which looked scarily right upon his head, as though Dumbledore had always been waiting for a patchwork pointed hat to complete his existence.
(Fred and George immediately memorized this phrase, just in case it would work for somebody besides the Headmaster, and began trying to think of pranks that would involve the Sorting Hat.)
They learned the phrase from Dumbledore when they gave him the map.
I’d completely forgotten that!
But, y’know, procedural versus declarative memory. It’s perfectly possible to remember to say something like “deligitor prodi” when you want the Sorting Hat, while forgetting all sorts of associated details. Er, like I did myself.
It seems to me that your proposal is equivalent to the “malicious genie has granted you a wish” problem. There are so many ways to construct stable time loops which don’t involve getting a pony that you’ve exceedingly unlikely to get one. You can precommit to whatever you want, but the answer may be as simple as being unable to achieve your committed goal due to bad information.
It seems to me that your proposal is equivalent to the “malicious genie has granted you a wish” .
I completely agree. For the question at hand, committing to not steal the Marauders Map will not magically cause the Marauders Map to not be stolen. There are too many other ways to make a stable time loops—too many “wishes gone wrong”—for that sort of Newcomb-like pre-committing to work the way you want it to.
Ah, there it is!
Harry time-turned to just before the troll attack. (In the one-and-a-half minutes when he went into Hermione’s room.) This is probably pretty clear—he’s been keeping everyone else out of that room, and the centrality of the time-turner in this story more or less demands that Harry do so. Harry would have done this even if he couldn’t come up with a plan in his previous six hours, just so he’d have another six hours to think, or do what he deemed needful to preserve Hermione’s body.
Somewhere in there, he talked to the twins, and poorly obliviated them. Evidence:
Why does Harry know about the Marauder’s Map? When else has Harry learned plot-significant information off-camera?
Obliviation, and Memory Charms in general, and Harry’s horror of them, are repeatedly mentioned in the story, and haven’t really been used that much yet.
Harry has just learned that he has access to learn obliviation.
Quirrell suggests that obliviation is within his abilities, but barely—and so Harry is likely to botch it if he attempts it.
Who else in the story is likely to have performed a botched obliviation on the Weasley twins—such that they have vague memories of having the map, but no complete ones? Every potential foe is powerful enough to perform obliviation properly.
Besides, it’ll be a narratively nice, dark moment when Harry uses a spell whose existence he abhors on two of his best remaining friends and allies...
If you need more than 6 hours to learn Obliviation, you can use this method. Bonus: in addition to giving you more time to study, this method summons an army of hundreds of invisible Harry Potters (all with a single twist of the time-turner).
I would have tried this method, but I my narrative sense tells me that Harry did not.
… and prevents them from helping him find Hermione. You think he went back in time to become responsible for one of the circumstantial reasons for his failure?
Sunk cost. Someone has taken the Marauder’s Map; might as well be him.
That would not be wise: He should retroactively precommit to not steal the Marauders Map regardless of whether the Map is stolen, just as one should one-box on Newcombs problem.
On the contrary, you should precommit to being responsible for all apparently bad occurrences if you happen to gain the ability to travel through time because if you can trust anyone to try to fix them while making them seem like they were bad to you it will be you.
This has the potential to produce many more self-sustaining “not quite as bad as it looks” bad events. Is this necessarily wise?
This isn’t quite Newcomb’s Problem, though.
Consider this: You have essentially the same set up, and you’re a one-boxer, so you walk up and take your million dollars out of box B.
And then Omega comes back and says, “Oh, by the way, want to open Box A too?”
And you say, “Um. Okay?” And open Box A, and get a thousand dollars. Or not. Doesn’t really matter—you already have your million dollars, so you have nothing to lose by opening Box A.
This differs from the traditional two-boxing argument in one very important respect: you get new information in the middle of the experiment. Your single Omega-predictable algorithm doesn’t have to “change its mind” in the middle, it gets interrupted.
This is essentially what (might be) happening here. Harry has opened Box B and found a dead Hermione inside. That’s set and done. Assuming that he has reason to be believe that Box A will help him more than it will hurt him on average (and won’t contain, say, a dead/mindless/insane Fred and George), he has no reason not to open Box A.
A more perfectly isomorphic variant of Newcomb’s problem is the following. Both boxes are transparent, and Omega acts according to the following rule: if you two-box when box B is empty, then box B is always empty, while if you one-box, box B is empty with a 50% chance.
If you one-box in this variant, you win half a million dollars in expectation. If you intend to two-box should you see that box B is empty, then you only win a thousand dollars.
… Perhaps, but that’s no longer isomorphic to the actual problem. We are past the point of Omega’s influence; in Newcomb’s problem, it’d be as if Omega grabbed your mind state, ran it forward until it confirmed that you would not initially two-box, and then stopped. Omega itself has been removed from the problem, and you’re left with one empty box that you’ve already claimed a million dollars from (or negative one million, in this case) and one closed box.
Near as we can tell, history can’t change in the MoRverse: what’s done is done, so Harry might as well exploit it.
Are you describing Transparent Newcomb’s problem? If so one should still one box when you see that the large box is empty. (I am not sure whether this maps precisely to the marauder’s map issue, I haven’t read the relevant chapter.)
Suppose my best friend loses her cell phone, gets lost in the woods, and dies. I could pre-commit to not travel back in time and steal her cell phone. It would be easy commitment to make, because Time-Turners are fictional. Would making that commitment help save my friend?
(Your friend is less likely to die if you make that commitment) iff timeturners are not fictional. Avert all scenarios in which you doom your friend for a cellphone.
((I feel that neither this post nor its father have contributed to the point grandfather was making. Should I have downvoted father? Maybe I have misunderstood fathers question, was that a rhetorical question supposed to be “answered” by “Of course not!”?))
Yes, it was supposed to be a rhetorical question answered by “of course not”.
Here’s a Newcomb-like algorithm for getting a pony in my yard.
Open my front door and check to see if I have a pony in my yard.
If I have a pony in my yard, we have succeeded. Otherwise, use a time machine to kill my grandfather.
This algorithm works because the only stable time loops are the ones where I get a pony. You can get magically nice results by pre-commiting to create a paradox in unwanted timelines, if you can to commit to do something unpleasant in those timelines.
Please correct me if I’m wrong, but I think you want to pull this trick with Hermione’s death. You’re trying to make the only stable time loop be one where the Weaslys have the Marauder’s Map.
Your suggestion would work if Harry had good cause to believe that the only person who could possibly steal the Marauder’s Map was a future version of himself. Even if the map had already been stolen, deciding not to go back in time and steal the map would create a paradox. The only stable time loops would be ones where the map is not stolen.
Does that situation apply? No, not at all. There are many stable time loops where the Wheaslys lose the map. Quirrell could have done it. Dumbledore could have done it. Some dark force unknown could have done it. There is little reason to believe that eliminating future Harry as the map thief will lead to a nicer distribution of stable time loops. By contrast, the stable time loops where Harry is the map thief seem much more likely to be pleasant.
Ah, I believe you have misunderstood me. Lets say that in Yudcanon, either Dumbledore stole the map or Quirrel stole the map or Harry stole the map or Hat&Cloak stole the map or Mr. X stole the map. If Harry makes sure that Harry never steals the map, there is one less person who might have had a reason to steal the map, and the probability of the map being stolen versus it not being stolen goes down, even though he already knows that the map was stolen when he makes that decision; just like when Omega presents you the two boxes, you should retroactively precommit to one-box to receive a million, even though the content of the boxes is already determined.
Imagine Harry saw that the map was stolen, and thinks immediately of stealing it himself so as to acquire it. Naturally, he then plans to precommit to invisibility-cloak deposit it right behind Fred and George in 5 seconds. He might then go further and precommit instead to never having stolen it in the first place, so that it never leaves the grasp of the Weasley twins and Harry doesn’t have to go to the effort of stealing it. Therefore, he now knows that the map was stolen by someone else, and that the probablity of the map being stolen in the first place has lessened, which is a good thing.
This is the point that I think is escaping many people in this thread. The options aren’t as simple as A/A+B in Newcomb.
The map has been stolen. Everything we know about how Time Travel works in this universe indicates that this is a fixed fact that cannot be altered. Who took the map however is an unknown, and while it cannot be ‘altered’ either, the Effect can in this case precede the Cause. ‘Map has been taken’ can happen before ‘Harry takes map because someone had to’ such that B causes A and A leads to B. If Harry doesn’t commit to it, B is still true, and so the Map is lost to him. His choices are (Map is Gone, I have it.) or (Map is gone.) The choice ‘Map is still here and Hermione lives’ is not a valid choice and should be discounted. So, his choices are to benefit or not benefit from the Map being gone.
The interesting question is, if the Twins forgot the Map entirely, how did they remember ‘Deligitor Prodi’? Admittedly not perfectly.
Why would the two be linked?
They learned the phrase from Dumbledore when they gave him the map. The fact that they don’t remember the map but imperfectly remember the phrase does support the “poorly done obviation” hypothesis. (either because the obliviator missed removing the phrase or the obliviator intended for them to keep the phrase but accidentally messed it up)
(or, less likely, ‘Deligitor Prodi’ would not have worked for the twins and the obliviator intentionally altered it so that it would)
I’d completely forgotten that!
But, y’know, procedural versus declarative memory. It’s perfectly possible to remember to say something like “deligitor prodi” when you want the Sorting Hat, while forgetting all sorts of associated details. Er, like I did myself.
It seems to me that your proposal is equivalent to the “malicious genie has granted you a wish” problem. There are so many ways to construct stable time loops which don’t involve getting a pony that you’ve exceedingly unlikely to get one. You can precommit to whatever you want, but the answer may be as simple as being unable to achieve your committed goal due to bad information.
I completely agree. For the question at hand, committing to not steal the Marauders Map will not magically cause the Marauders Map to not be stolen. There are too many other ways to make a stable time loops—too many “wishes gone wrong”—for that sort of Newcomb-like pre-committing to work the way you want it to.
http://www.reddit.com/r/HPMOR/comments/1i3y86/quick_question_about_chapter_94/cb0trf7 some new word of god spoilers you may or may not want concerning this