On your first point: It's not the making of a Horcrux which rips apart the soul, it's murder. Although multiple Horcruxes are unprecedented, multiple murders are not. Since it's the ripped apart soul which causes accidental Horcruxes, if Horcruxes can accidentally be made then we'd expect at least a few of the people in Azkaban to have accidental Horcruxes, and for this to be known about. On the other hand, if making Horcruxes requires complicated Dark Incantations (and it seems like it would) then that's also evidence against.
On your second point: right, but the absence of any evidence which makes "accidental Horcrux" more probable should make "accidental Horcrux" even less probable than the broad category of "generic unexplained random magic" because when good authors want to write about specific pieces of magic they leave evidence supporting that specific thing. It made sense, since she didn't support any one possibility of accidental magic over another, to believe that she wouldn't specify the mechanism at all and that perhaps there was no specific mechanism she had thought out.
we'd expect at least a few of the people in Azkaban to have accidental Horcruxes,
None of the people in Azkaban have been hit with Killing Curses, though.
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: