Well, Harry hasn't actually tested the idea that wizards can suffer brain damage the same way as Muggles. He just assumed they do. But it's a reasonable assumption.
What happens if you progressively damage Quirrel's brain? At some point Voldemort will either decide or be forced to go and possess another body or Horcrux. That thing-which-goes-off is for all intents and purposes a soul.
A backup isn't a good description, because Voldemort is always aware - there's no point at which he exists only as a backup and may or may not be restored. Also, a backup implies restoring multiple instances, and creating multiple backups; the True Horcrux doesn't seem to do that.
Agreed, and I want to expand that a little:
Muggle science determined that muggle minds are contained in muggle brains, and Harry has been reluctant to let go of this idea even though there are observations against it and he has seen that magic can freely violate very solid muggle conclusions like conservation of matter.
Even if muggle brain damage seems to damage the mind, it could be that it damages the mind's interface to the body. Here in the real world, this dualism adds additional complications and doesn't help explain any evidence. In the HPMOR univ...
New long chapter! Since I expect its discussion to generate more than 160 comments (which would push the previous thread over the 500 comment limit) before the next chapter is posted, here is a new thread.
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 108
(and chapter 109, once it comes out on Monday).EDIT: There have now been two separate calls for having one thread per chapter, along with a poll in this thread. If the poll in this thread indicates a majority preference for one thread per chapter by Monday, I will edit this post to make it for chapter 108 only. In that case a new thread for chapter 109 should be posted by whoever gets a chance and wants to after the chapter is released.
EDIT 2: The poll indicates a large majority (currently 78%) in favor of one thread per chapter. This post has been edited accordingly.
There is 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.)
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: