Harry Potter and the Methods of Rationality discussion thread, March 2015, chapter 118

My take: Harry has QQ('s legacy) and Hermione to protect, and kills dozens of death eaters etc. etc. to make it happen

McGonagall has her students to protect, and commits publicly to doing so, no matter who their parents are, and takes up the role of headmistress (which we know she thought herself unsuited to) to do it

The students have themselves and future cohorts to protect, and commit to passing on QQ's teachings themselves to do it

Seems to me the force needed to penetrate tracks the diameter, but the strength tracks the area of the cross-section.
That is, decrease the thickness by N and it decreases the force needed by N but the strength by N squared.
Below a critical thickness, the wire would just break.
Spiderwebs don't slice you up if you run into them.

There is nonzero finite surface energy involved in cleaving an object in two, which you need to impart (minimum applied force). But for a living thing the minimum would be low. And you can prevent falling over by using a circular wire that shrinks (or 2 or more wires arranged symmetrically) to counter any pushing non-cutting forces

It doesn't activate his horcrux network.

Memories don't include skills. Voldemort still knows all of his spells.

It's a question I've wondered about myself.

Obliviation makes a big difference in terms of the horcrux network, but I'm not sure what difference it makes in terms of Harry's reluctance to kill humans.

If we assume that our future selves want all of us around because we're cute-- that is, delightful and harmless, will they want both Voldemort and Quirrell? Is it clear that Quirrell was Voldemort all the time?

Would they want to give all our past selves (say, a sample of each of us from every major psychological change) to be given a chance to grow and develop?

Will they be willing to kill each other in extreme circumstances because they won't be harmless relative to each other?

Harry deleted (or tried to delete, we don't know he succeeded) LV/QQ's episodic memory, not his procedural memory (skills and spells). In principle, this could be fixed - in canon memory charms could sometimes be reversed, and in HPMOR most of LV's memories are backed up by the horcrux network. Sufficiently advanced magic might be able to extract those.

It's close to the same thing, yes.

(Unless we count the horcrux backups, but since Harry doesn't mean for them to come into play, they don't count in this moral calculus.)

I am okay with that.

An aside: a couple replies to you mention "horcrux backups", but that's Horcrux 1.0, the kind that Voldemort disdains for their failure to preserve continuity of identity. I get the impression that Horcrux 2.0 is more like RAID, but RAID is not backup. It's quite likely that now there are no backups and this was indeed a partial death.

Actually killing him (including his horcrux backup system, I assume?) would obliterate the LV-that-is and any possible LV-that-could-be. Harry obliterated the LV-that-is, but can still restore him to full health and allow him to become any one of the LV-that-could-be.

It’s a bit like taking a life but starting a new life, too.

Guess no more plot. Nothing is happening.

There may be some hope yet; HPMOR has still got ~20,000 words left to go.

I'm still holding out at least for Hermione to return as a Speaking Character.

She's alive. I'd have to assume that she comes back. Kind of odd that she hasn't already. And have they told her parents yet?

My hope is slowly dying, that we'll get Dumbledore back

Harry really should have been apprising McGonagall of the truth, between Dumbledore being trapped, and Voldemort riding around on his finger. Maybe getting Dumbledore out is time dependent, being easier the closer to his capture. Who knows? I'd want people looking at it as soon as possible.

Isn't the official story telling that David Munroe usurped Quirell identity in order to teach Defense at Hogwart?

QQ can't be polyjuced, which seemed to be the Auror's earlier assumption, because it would have worn off now he's dead. So given that David Munroe looks different from Quirell, the obvious next hypothosis is that he is a Metamorphmagus. But still, that is extremely rare, which is suspicious. But next, surely some people who knew the real Quirrel are going to turn up to his funeral, and start asking questions like "what do you mean he's a Slitherine?"

The Officials involved have believed Quirrel to be David Monroe for a long time (chapter 84), that seems to have become the Official Story over the last couple days, and Mad-Eye Moody knew that Quirrelmort should have been fired out of a cannon into a sun as soon as he took the Defense position, so they've been asking questions and taking the first reasonable answer for a while.

I'm fully expected Moody to dive through a door with stunners flying, yelling "Not paranoid enough!" because /someone/ didn't expect door transfiguration, but most of the other people involved have already gotten suspicious and had their suspicions allayed.

The fact that he's wearing it at all stuns me. It needs to be maintained by a coven of the greatest wizards around.

Imagine: Harry dies (heart attack, stroke, stabbed by Goyle, whatever) Handless amnesiac Voldemort appears, dies of human transfiguration sickness after a few deeply confused minutes Horcrux network activates.
Best case, this amnesiac being can't figure out how to possess anyone. Medium case, somebody gets possessed by the clueless shade.
Worst case: network was built to supplement current memories with dump of previous ones (we can see by the part where Voldemort Confounds himself before the Mirror that he had thought about the concept of changing his mental state), and the Dark Lord is back in business

A part surely overwhelmed by the legacy he left behind as Voldemort, which includes lots of orphans and lots of people whose own positive legacies he cut short by killing them.

If you're going to count legacy as part of one's self, then anyone who kills people for any reason is going to end up in the karmic negative very very quickly, because they are taking away other people's legacies, and their potential children's, and their potential children's, etc.

That he is Tom Riddle.

A whole lifetime's worth of stuff, which is repressed and forgotten by Tom Riddle Jr.

The Stone would make his transfiguration permanent and thus presumably render them immune to Finite Incantatem. If he doesn’t use the Stone (e.g. in the case of Voldemort, which you are probably referring to), I don’t know of any conventional way to proof against F.I. (Knowing Harry, I’m sure he’d be able to think of some rather unconventional ideas if he sets his mind on it.)

It was briefly noted in chapter 111:

The Dark Lord reached into his robes, took out a Knut, and flipped it to her. "Klaudia Alicja Tabor, I command you thus. Take this Knut to the spell circle I showed you beneath the Quidditch stands and put it in the center. Then Obliviate yourself of the last six hours."

"Yes, lord," the witch said, bowing to him, and went on her way.

"I thought -" Harry said. "I thought you needed the Stone to -"

The Dark Lord was still smiling, he had never stopped smiling. "I did not say that part in Parseltongue, child. All I said in Parseltongue was that I had set events in motion to kill students, events that I would stop if I obtained the Stone. […]”

He told another student to disarm it. He didn't need the stone to undo it.