Harry Potter and the Methods of Rationality

by Eliezer Yudkowsky

  There was another long exchange of glances among the four, and finally Harry nodded, followed by Professor McGonagall.

  "In that case," said Harry, "I'm sure of one other thing."

  "And that is?" said Dumbledore.

  "I very much need to visit the washroom, and I would also like to change out of these pyjamas."

  "By the way," Harry said as he and the Headmaster emerged from Floo into the empty office of the Ravenclaw Head of House. "One last quick question I wanted to ask just you. That sword the Weasley twins pulled out of the Sorting Hat. That was the Sword of Gryffindor, wasn't it?"

  The old wizard turned, face neutral. "What makes you think that, Harry?"

  "The Sorting Hat yelled Gryffindor! just before handing it out, the sword had a ruby pommel and gold letters on the blade, and the Latin script said Nothing better. Just a hunch."

  "Nihil supernum," said the old wizard. "That is not quite what it means."

  Harry nodded. "Mmhm. What'd you do with it?"

  "I retrieved it from where it fell, and placed it in a secure place," the old wizard said. He gave Harry a stern look. "I hope you are not greedy for it yourself, young Ravenclaw."

  "Not at all, just want to make sure you're not keeping it permanently from its rightful wielders. So the Weasley twins are the Heir of Gryffindor, then?"

  "The Heir of Gryffindor?" Dumbledore said, looking surprised. Then the old wizard smiled, blue eyes twinkling brightly. "Ah, Harry, Salazar Slytherin may have built a Chamber of Secrets into Hogwarts, but Godric Gryffindor was not much given to such extravagances. We have seen only that Godric left his Sword to the defense of Hogwarts, if a worthy student ever faced a foe they could not defeat alone."

  "That's not the same as saying no. Don't think I didn't notice that you didn't actually say no."

  "I did not live in those years, Harry, and I do not know all that Godric Gryffindor may or may not have done -"

  "Do you in fact assign greater than fifty percent subjective probability that there is something like a Heir of Gryffindor and one or both Weasley twins are it. Yes or no, evasion means yes. You're not going to succeed in distracting me, no matter how much I have to go to the bathroom."

  The old wizard sighed. "Yes, Fred and George Weasley are the Heir of Gryffindor. I beg you not to speak of it to them, not yet."

  Harry nodded, and turned to go. "I'm surprised," Harry said. "I read a little about Godric Gryffindor's historical life. The Weasley twins are... well, they're awesome in various ways, but they don't seem much like the Godric in the history books."

  "Only a man exceedingly proud and vain," Dumbledore said quietly, as he turned back to the Floo roaring up again with green flames, "would believe that his heir should be like himself, rather than like who he wished that he could be."

  The Headmaster stepped into green fire, and was gone.

  The second meeting (in a small cubby off the Hufflepuff Common Room):

  Neville Longbottom's face was drawn up in anguish, as he spoke with no one to hear, to the empty air.

  "Seriously," the empty air said back to him. "I'm wearing an invisibility cloak with extra anti-detection charms just to walk through the hallways because I don't want to be killed. My parents would have me out of Hogwarts in an instant if the Headmaster allowed it. Neville, your getting the heck out of Hogwarts is common sense, it has nothing to do with -"

  "I betrayed you, General," Neville said, his voice around as hollow as any normal eleven-year-old boy could reasonably manage. "I didn't even do it the Chaotic way. I conformed to authority and tried to make you conform to authority too. What's that you always say, about how in the Chaos Legion, a soldier who can only obey orders is useless?"

  "Neville," the empty air said firmly. The pressure of two hands, beneath thin cloth, came firmly to bear on Neville's shoulders; and the voice moved closer to him. "You weren't blindly obeying authority, you were trying to protect me. It's true that in this chaotic world, soldiers who can only follow rules and regulations are worthless. However, soldiers who follow rules for the sake of protecting their friends are -"

  "Slightly better than worthless?" Neville said bitterly.

  "Significantly better than worthless. Neville, you made an error of judgment. It cost me around six seconds. Now it could be that Hermione's injuries were just barely fatal, but even then, I don't think six seconds was actually enough time for the troll to take an extra bite of Hermione. In the counterfactual world where you didn't step in front of me, Hermione still died. Now, I could stand here listing out the first dozen ways that Hermione would be alive if I hadn't been stupid -"

  "You? You ran right out after her. I'm the one who tried to stop you. It's my fault if it's anyone's," Neville said bitterly.

  The empty air went silent at this for a while.

  "Wow," the empty air finally said. "Wow. That puts a pretty different perspective on things, I have to say. I'm going to remember this the next time I feel an impulse to blame myself for something. Neville, the term in the literature for this is 'egocentric bias', it means that you experience everything about your own life but you don't get to experience everything else that happens in the world. There was way, way more going on than you running in front of me. You're going to spend weeks remembering that thing you did there for six seconds, I can tell, but nobody else is going to bother thinking about it. Other people spend a lot less time thinking about your past mistakes than you do, just because you're not the center of their worlds. I guarantee to you that nobody except you has even considered blaming Neville Longbottom for what happened to Hermione. Not for a fraction of a second. You are being, if you will pardon the phrase, a silly-dilly. Now shut up and say goodbye."

  "I don't want to say goodbye," Neville said. His voice was trembling, but he managed not to cry. "I want to stay here and fight with you against - against whatever's happening."

  The empty air moved closer to him, and embraced him in a hug, and Harry Potter's voice whispered, "Tough luck."

  Chapter 95: Roles, Pt 6

  The third meeting

  (10:31am, April 17th 1992)

  Spring had begun, the late-morning air still crisp with the leavings of winter. Daffodils had bloomed amid the sprouting grass of the forest, the gentle yellow petals with their golden hearts dangling limply from their dead, grayed stems, wounded or killed by one of the sudden frosts that you often saw in April. In the Forbidden Forest there would be stranger lifeforms, centaurs and unicorns at the least, and Harry had heard allegations of werewolves. Though from what Harry had read of real-life werewolves, that did not make the slightest bit of sense.

  Harry didn't venture anywhere near the border of the Forbidden Forest, since there was no reason to take the risk. He walked invisibly among the more ordinary life-forms of the permitted woods, wand in hand, a broomstick strapped to his back for easier access, just in case. He was not actually afraid; Harry thought it odd that he didn't feel afraid. The state of constant vigilance, readiness for fight or flight, failed to feel burdensome or even abnormal.

  On the edges of the permitted woods Harry walked, his feet never straying near the beaten path where he might be more easily found, never leaving sight of Hogwarts's windows. Harry had set the alarm upon his mechanical watch to tell him when it was lunchtime, since he couldn't actually look at his wrist, being invisible and all that. It raised the question of how his eyeglasses worked while he was wearing the Cloak. For that matter the Law of the Excluded Middle seemed to imply that either the rhodopsin complexes in his retina were absorbing photons and transducing them to neural spikes, or alternatively, those photons were going straight through his body and out the other side, but not both. It really did seem increasingly likely that invisibility cloaks let you see outward while being invisible yourself because, on some fundamental level, that was how the caster had - not wanted - but implicitly believed - that invisibility should work.

  Whereupon you had to wonder whether anyone had tried Confunding or Legilimiz
ing someone into implicitly and matter-of-factly believing that Fixus Everythingus ought to be an easy first-year Charm, and then trying to invent it.

  Or maybe find a worthy Muggleborn in a country that didn't identify Muggleborn children, and tell them some extensive lies, fake up a surrounding story and corresponding evidence, so that, from the very beginning, they'd have a different idea of what magic could do. Though apparently they'd still have to learn a number of previous Charms before they became capable of inventing their own...

  It might not work. Surely there'd been some organically insane wizards who'd truly believed in their own possibility of godhood, and yet had failed to become god. But even the insane had probably believed the ascension spell ought to be some grandiose dramatic ritual and not something you did with a carefully composed twitch of your wand and the incantation Becomus Goddus.

  Harry was already pretty sure it wouldn't be that easy. But then the question was, why not? What pattern had his brain learned? Could the reason be predicted in advance?

  A slight fringe of apprehension crept through Harry then, a tinge of worry, as he contemplated this question. The nameless concern sharpened, grew greater -

  Professor Quirrell?

  "Mr. Potter," a soft voice called from behind him.

  Harry spun, his hand going to the Time-Turner beneath his cloak; again the principle of being ready to flee upon an instant's notice felt only ordinary.

  Slowly, palms empty and turned outward, Professor Quirrell was walking towards him within the forests' outskirts, coming from the general direction of the Hogwarts castle.

  "Mr. Potter," Professor Quirrell said again. "I know that you're here. You know that I know that you're here. I must speak to you."

  Still Harry said nothing. Professor Quirrell hadn't actually said what this was about, and Harry's sunlit morning walk about the forest edge had produced a mood of silence within him.

  Professor Quirrell took a small step to the left, a step forward, another to the right. He tilted his head with a look of calculation, and then he walked almost directly towards where Harry stood, halted a few paces off with the sense of doom enflamed to the height of bearability.

  "Are you still resolved upon your course?" Professor Quirrell said. "The same course you spoke of yesterday?"

  Again Harry did not reply.

  Professor Quirrell sighed. "There is much I have done for you," the man said. "Whatever else you may wonder of me, you cannot deny that. I am calling in some of the debt. Talk to me, Mr. Potter."

  I don't feel like doing this right now, Harry thought; then: Oh, right.

  Two hours later, after Harry had spun the Time-Turner once, noted down the exact time and memorized his exact location, spent another hour walking, went inside and told Professor McGonagall that he was currently talking to the Defense Professor in the woods outside Hogwarts (just in case anything happened to him), walked for a further hour, then returned to his original location exactly one hour after he'd left and spun the Time-Turner again -

  "What was that?" Professor Quirrell said, blinking. "Did you just -"

  "Nothing important," Harry said without pulling back the hood of his invisibility cloak, or taking his hand from his Time-Turner. "Yes, I'm still resolved. To be honest, I'm thinking I shouldn't have said anything."

  Professor Quirrell inclined his head. "A sentiment which shall serve you well in life. Is there anything which is liable to change your mind?"

  "Professor, if I already knew about the existence of an argument which would change my decision -"

  "True, for the likes of us. But you would be surprised how often someone knows what they are waiting to hear, yet must wait to hear it said." Professor Quirrell shook his head. "To put this in your terms... there is a true fact, known to me but not to you, of which I would like to convince you, Mr. Potter."

  Harry's eyebrows rose, though he realized in the next moment that Professor Quirrell couldn't see it. "That's in my terms, all right. Go ahead."

  "The intention you have formed is far more dangerous than you realize."

  Replying to this surprising statement did not take much thought on Harry's part. "Define dangerous, and tell me what you think you know and how you think you know it."

  "Sometimes," said Professor Quirrell, "telling someone about a danger can cause them to walk directly into it. I have no intention of having that happen this time. Do you expect me to tell you exactly what you must not do? Exactly why I am afraid?" The man shook his head. "If you were wizardborn, Mr. Potter, you would know to take it seriously, when a powerful magus tells you only to beware."

  It would have been a lie to say that Harry was not annoyed, but he also wasn't an idiot; so Harry said merely, "Is there anything you can tell me?"

  Carefully, Professor Quirrell seated himself upon the grass, and took out his wand, his hand assuming a position that Harry recognized. Harry's breath caught.

  "This is the last time that I shall be able to do this for you," Professor Quirrell said quietly. Then the man began to speak words that were strange, of no language Harry could recognize, intonation that seemed not quite human, words which seemed to slip from Harry's memory even as he tried to grasp them, exiting from his mind as quickly as they entered.

  The spell took effect more slowly, this time. The trees seemed to darken, branches and leaves staining, as though seen through perfect sunglasses that faded and attenuated light without distorting it. The blue bowl of the sky receded, the horizon which Harry's brain falsely assigned a finite distance pulling back as it turned gray, and darker gray. The clouds became translucent, transparent, wisping away to let the darkness shine through.

  The forest shaded, faded, abated into blackness.

  The great sky river became visible once again, as Harry's eyes adjusted, became able to see the largest object which human eyes could ever behold as more than a point, the surrounding Milky Way.

  And the stars, piercingly bright and yet remote, out of a great depth.

  Professor Quirrell breathed deeply. Then he raised his wand again (just barely visible, in the starlight without sun or moon) and tapped himself on the head with a sound like an egg cracking.

  The Defense Professor also faded away, became likewise invisible.

  A tiny disk of grass, illuminated by not much light at all, drifted unoccupied within empty space.

  Neither of them spoke for a time. Harry was content to look at the stars, undistracted even by his own body. Whatever Professor Quirrell had called him here to say, it would be said in due time.

  In due time, a voice spoke.

  "There is no war here," said a soft voice emanating from within the emptiness. "No conflict and battle, no politics and betrayal, no death and no life. That is all for the folly of men. The stars are above such foolishness, untouched by it. Here there is peace, and silence eternal. So I once thought."

  Harry turned to look at where the voice originated, and saw only stars.

  "So you once thought?" Harry said, when no other words seemed to be forthcoming.

  "There is nothing above the folly of men," whispered the voice from the emptiness. "There is nothing beyond the destructive powers of sufficiently intelligent idiocy, not even the stars themselves. I went to a great deal of trouble to make a certain golden plaque last forever. I would not like to see it destroyed by human folly."

  Again Harry's eyes reflexively darted toward where the voice should have been, again saw only emptiness. "I think I can reassure you on that score, Professor. Nuclear weapons don't have a fireball extending out for... how far away is Pioneer 11? Somewhere around a billion kilometers, maybe? Muggles talk about nuclear weapons destroying the world, but what they actually mean is lightly warming up some of Earth's surface. The Sun is a giant fusion reaction and it doesn't vaporize distant space probes. The worst-case scenario for nuclear war wouldn't even come close to destroying the Solar System, not that this is much of a consolation."

  "True while we speak of Muggles," said
the soft voice amid starlight. "But what do Muggles know of true power? It is not they who frighten me now. It is you."

  "Professor," Harry said carefully, "while I have to admit I've rolled a few critical failures in my life, there's a bit of distance between that and missing a saving throw so hard that the Pioneer 11 probe gets caught in the blast radius. There's no realistic way to do that without blowing up the Sun. And before you ask, our Sun is a main-sequence G-type star, it can't explode. Any energy input would just increase the volume of the hydrogen plasma, the Sun doesn't have a degenerate core that could be detonated. The Sun doesn't have enough mass to go supernova, even at the end of its lifespan."

  "Such amazing things the Muggles have learned," the other voice murmured. "How stars live, how they are preserved from death, how they die. And they never wonder if such knowledge might be dangerous."

  "In all frankness, Professor, that particular thought has never occurred to me either."

  "You are Muggleborn. I speak not of blood, I speak of how you spent your childhood years. There is a freedom of thought in that, true. But there is also wisdom in the caution of wizardkind. It has been three hundred and twenty-three years since the country of magical Italy was ruined by one man's folly. Such incidents were more common in the years when Hogwarts was raised. Commoner still, in the aftertime of Merlin. Of the time before Merlin, little remains to study."

  "There's around thirty orders of magnitude of difference between that and blowing up the Sun," Harry observed, then caught himself. "But that's a pointless quibble, sorry, blowing up a country would also be bad, I agree. In any case, Professor, I don't plan on doing anything like that."

  "Your choice is not required, Mr. Potter. If you had read more wizardborn novels and fewer Muggle stories, you would know. In serious literature the wizard whose foolishness threatens to unleash the Shambling Bone-Men will not be deliberately bent on such a goal, that is for children's books. This truly dangerous wizard shall perhaps be bent on some project of which he anticipates great renown, and the certain prospect of losing that renown and living out his life in obscurity will seem to him more vivid than the unknown prospect of destroying his country. Or he shall have promised success to one he cannot bear to disappoint. Perhaps he has children in debt. There is much literary wisdom in those stories. It is born of harsh experience and cities of ash. The most likely prospect for disaster is a powerful wizard who, for whatever reason, cannot bring himself to halt as warning signs appear. Though he may speak much and loudly of caution, he will not be able to bring himself actually to halt. I wonder, Mr. Potter, have you thought of trying anything which Hermione Granger herself would have told you not to do?"