Harry Potter and the Methods of Rationality discussion thread, part 16, chapter 85

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The next discussion thread is here.

This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 85. The previous thread has long passed 500 comments. Comment in the 15th thread until you read chapter 85.

There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)

The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15.

As a reminder, it’s often useful to start your comment by indicating which chapter you are commenting on.

Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically:

You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).

If there is evidence for X in MOR and/or canon then it’s fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that “Eliezer said X is true” unless you use rot13.

The next discussion thread is here.

As a reminder, it’s often useful to start your comment by indicating which chapter you are commenting on.

Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically:

You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).

If there is evidence for X in MOR and/or canon then it’s fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that “Eliezer said X is true” unless you use rot13.

Some predictions for the next arc and beyond:

The climax where Quirrell's identity and/or motives are revealed will be in the next two arcs (p ≈ 0.8), and possibly in the next arc (p ≈ 0.3).

This last arc ended ominously; I think we're perilously close to seeing some serious shit. I assigned low probability to this happening in the next arc because Eliezer said the next arc picks up immediately after this one. We're still in April, and I have this hunch that maybe Harry's "What do I get if I can make it happen on the last day of school?" line to McGonagall was foreshadowing. I also think we'll get to see Quirrell execute his Christmas Wish plot. And speaking of Quirrell plots,

Quirrell will execute his Final Solution to the Granger Problem in the next arc (p ≈ 0.75) and very possibly succeed (p ≈ 0.5)

The next arc is going to pick up immediately following the last one. I assume that "immediately following" means "the day after". Quirrell might have given her more than one night to consider if he weren't planning on getting rid of her immediately. If seers all over the world have nightmares one night, then presumably something bad is going to happen very soon thereafter. Hermione meeting (or maybe even almost meeting) a horrible demise would send Harry straight to his Dark Side, and who knows what he'd do then.

The worldwide seer activity is due to Harry being about to kill a lot of people. (p ≈ 0.35)

Harry Potter's Dark Side just figured out a reliable way to kill large numbers of people in a small amount of time. Maybe he's about to use it.

The Trigger Warnings are next going to be updated for a chapter called Gur Olfgnaqre Rssrpg. Vs n ohapu bs crbcyr jngpu Urezvbar trg uheg naq yrg vg unccra, Uneel zvtug qrpvqr gurl nyy arrq gb qvr.

Or, if you connect Harry's two unwittingly ominous resolutions that directly preceded the two Trelawney nightmares, he might decide that everyone in Britain who supports Azkaban's use of Dementors needs to die. All he needs is a broadcast medium to disable the country's Patronuses, and he can send a Dementor to create a wizarding holocaust.

I assign low probability to this not because I think the clues don't point reasonably strongly in this direction, but because I fail to see how Harry and the story could recover from it. Perhaps Dumbledore would subdue Harry and take him into hiding? But then we wouldn't see the end-of-year stuff at Hogwarts, unless it happens two or three arcs from now.

At some point, Harry will break his Time-Turner to get out of a sticky situation. (p ≈ 0.85)

Twice in early chapters we were told that strange things happen when Time-Turners are broken. Once would be an offhand reference, but twice indicates to me that Eliezer has something in mind. If Harry successfully rescues Hermione from whatever Quirrell tries to do to her next, I think this might be how.

Those probabilities are mostly pulled out of thin air, but I've seen other people use them, so apparently it's expected. Is there some systematic method people use to arrive at them, or do you just sort of look out a window and see what number feels right?

A common method to get an idea what is the "subjectively correct" number to use as your probability is to imagine yourself betting (a moderate amount of money you would be willing to risk) on the claim, and deciding which odds would you accept. For example, if you would accept betting up to $40 against $10 on your claim, but not more, then the probability you assign to it is 0.8. If you would be willing to bet only up to $10 on a chance of winning $90, then your probability is 0.1.

5[anonymous]14y

The probability you assign to a hypothesis should accurately represent your degree of belief that the hypothesis is true. Moreover, your degree of belief should be coherent with the rules of probability theory. Unfortunately, we human beings are notoriously bad at probabilistic reasoning. So while there are systematic methods for assigning probabilities based on evidence, it takes a lot of work to use them properly. For a lot of untrained people, myself included, the best we can currently do is see how we feel, attempt to quantify it, and try to constrain it based on rational factors. If you want to learn more, a few key search words here are "Bayes' theorem," "heuristics and biases," and "debiasing." If you read through the sequences - a daunting task, I know - a lot of it is covered in detail. Or if you'd prefer to read some academic papers and books on the subject, I'm sure I and other users could make recommendations.

675th14y

I meant to add this when I originally wrote the above post, but forgot, probably because it's pretty obvious: A major focus of the next arc will be Quirrell teaching the first years to cast Avada Kedavra. (p ≈ 0.9) Quirrell was antsy to get back to his classes, of which there are not many left. And teaching the Killing Curse is a good way to make sure Harry is deeply in tune with his Dark Side when Quirrell executes his plot against Hermione. Harry's Dark Side will of course be exceptionally good at casting the Killing Curse, and casting it will make it easier for him to stay Dark when he wants to. Whenever Harry next gets back to his Light Side thereafter, he'll be alarmed at how right it felt for him to cast it; indeed, he'll probably start finding it hard to resist casting it whenever something activates his Dark Side.