Update: Discussion has moved on to a new thread.
The load more comments links are getting annoying (at least if you're not logged in), so it's time for a new Harry Potter and the Methods of Rationality discussion thread. We're also approaching the traditional 500-comment mark, but I think that hidden comments provide more appropriate joints to carve these threads at. So as of chapter 67, this is the place to share your thoughts about Eliezer Yudkowsky's Harry Potter fanfic.
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: one, two, three, four, five, six. The fanfiction.net author page is the central author-controlled HPMOR clearinghouse with links to the RSS feed, pdf version, TV Tropes pages, fan art, and more, and AdeleneDawner has kept an archive of Author's Notes.
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Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).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.
If you want to figure out the James' Rock thing yourself, you should probably stop reading now.
I read this in ch58
and (putting my contrarian nature to good use) thought, the other reason he was good at it was, he concentrated on maintaining his transfigured ring stone all the time. Then I realized that's all thanks to Dumbledore and I started to wonder if it was intentional. In search of clues I reread ch17, specifically the part where Harry got the rock, and then went on to read the Lily's potion book part because it seemed related. That's when I realized I fell for some deliberate obfuscation, as I came away with the impression that Lily was asking questions and mysteriously receiving answers in her potion book. Realizing it was not the case, most of the rest was seen in a flash.
Just as Dumbledore challenged Lily with strange potion-related questions in order to get her to do extra research, possibly directing her to books and topics where she learned something extra about stuff, thus becoming exceptional at potions (which is canon fact), so too did he present Harry with a challenge, expecting him to find the obvious solution of maintained transfiguration in order to follow the advice of a wise old wizard.
Why would he do that? In Ch28 McGonagall seems to think this feat of Dumbledore impressive:
Now, how would you do this? Why, by having the ability to concentrate on transfiguration while paying attention to something else (such as the back and forth of a duel). Sounds familiar? To do this, being able to concentrate on transfiguration without conscious attention is indispensable. Dumbledore simply started building up his pet hero early, since, you understand,
(McGonagall, Ch15)
I mention all this now because Ch67 gave me the impression it will come to light soon. Could be wrong about that.
Plausible, but that can't be the only reason for the rock; too big a deal was made of it at the time.