Why would he need backup to kill a baby?
People protect babies and it would be reasonable to expect that people would work especially hard to protect babies that are prophesied to save the world from an evil villain. It turns out that his enemies were idiots and suffered a single point of failure, but even if he thought he knew that the target would be under protected the smart thing to do is not to depend on his quisling and go in alone.
And yes, the sacrifice story comes from canon, not MoR. Still, with no other hints, that gives it a pretty high prior probability.
How high is this canon bonus to probability of yours? Would you say that Aberforth was probably a zoophile just because he was in canon? Or that Ron and Hermione will probably get together because they did in canon? Or that Snape will kill Dumbldedore because he did in canon?
What was idiotic about the way Harry was protected? They were betrayed to a superior force by someone highly placed, and there's no good defense against that. And Voldemort was knowingly superior to every possible defender, so why would he worry about it?
And re prior probabilities, it's obviously dependant on the issue in question. On something where MoR is silent, canon carries a lot of weight. On something where MoR spends time adjusting expectations, canon carries very little weight. So it's quite likely that Aberforth loved goats(though even more like...
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 84. The previous thread has passed 500 comments. Comment in the 14th thread until you read chapter 84.
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.
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: