Harry Potter and the Methods of Rationality discussion thread, part 19, chapter 88-89

Vaniver

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 88-89. The previous thread has passed 500 comments.

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, 16, 17, 18.

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Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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.

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Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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.

I was under the impression that it was a secret method of Dumbledore and his allies. But I can't substantiate that from memory. Besides, for someone already capable of casting a Patronus, it really is easy to guess once you know it exists - Harry did so on the first try.

Harry could have taught the method easily to any Patronus casters in the Great Hall and then they could have used it. But he didn't have the time. And once Harry left, of course NPCs wouldn't see themselves in the role of discovering new magic in order to take responsibility for something that wasn't their fault.

Harry tells Draco:

Harry closed the book and put it into his pouch. "Chaos and Sunshine both have soldiers that can cast corporeal Patronus Charms. Corporeal Patronuses can be used to convey messages. If you can't learn the spell, Dragon Army will be at a severe military disadvantage -"

That happens in chapter 47. I doubt such an event would happen without Draco asking other people whether the Patronuses can be used to send messages and making sure that people in his army know about it.