From chapter 86 :
And to answer your question, boy, there’s two reasons why that spell’s in the blackest book. The first is that the Killing Curse strikes directly at the soul, and it’ll just keep going until it hits one. Straight through shields. Straight through walls.
For Moody to believe that, it means either "animals have a soul" is a frequent belief among wizards, but then we would have had hints of it earlier, or it doesn't kill animals. That's how I interpreted it at least.
The killing curse works on animals in HPMOR. In Chapter 16, Quirrel tells the class that "The Killing Curse is unblockable, unstoppable, and works every single time on anything with a brain."
The view that "animals have souls" isn't particularly esoteric -- Aristotle asserted this, as did Thomas Aquinas. (http://en.wikipedia.org/wiki/Soul#Aristotle). So I don't think we should have expected it to be explicitly mentioned.
Both Aristotle and Thomas think of animal souls (and plant souls!) as qualitatively inferior to human souls, but they do claim they exist.
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 96. The previous thread is at almost 300 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, 19, 20, 21, 22, 23, 24, .
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: