Harry Potter and the Methods of Rationality

by Eliezer Yudkowsky

  "Thermos," Harry's voice said behind him.

  They went together to the railing, to look down at the ground a long way below. Draco tried to figure if they were in one of the towers that could be seen from outside, and found that right now he couldn't quite seem to picture how Hogwarts looked from outside. But the ground below was always the same; he could see the Forbidden Forest as a vague outline, and moonlight glittering from the Hogwarts Lake.

  "You know," Harry's voice said quietly from beside him where his arms leaned on the railing next to Draco's, "one of the things that Muggles get really wrong, is that they don't turn all their lights out at night. Not even for one hour every month, not even for fifteen minutes once a year. The photons scatter in the atmosphere and wash out all but the brightest stars, and the night sky doesn't look the same at all, not unless you go far away from any cities. Once you've looked up at the sky over Hogwarts, it's hard to imagine living in a Muggle city, where you wouldn't be able to see the stars. You certainly wouldn't want to spend your whole life in Muggle cities, once you'd seen the night sky over Hogwarts."

  Draco glanced at Harry, and found that Harry was craning his neck to stare up at where the Milky Way arched across the darkness.

  "Of course," Harry went on, his voice still quiet, "you can't ever see the stars properly from Earth, either, the air always gets in the way. You have to look from somewhere else, if you want to see the real thing, the stars burning hard and bright, like their true selves. Have you ever wished that you could just whisk yourself up into the night sky, Draco, and go look at what there is to see around other Suns than ours? If there were no limit to the power of your magic, is that one of the things you would do, if you could do anything?"

  There was a silence, and then Draco realized that he was expected to answer. "I didn't think of it before," Draco said. Without any conscious decision, his voice came out as soft and hushed as Harry's. "Do you really think anyone would ever be able to do that?"

  "I don't think it'll be that easy," said Harry. "But I know I don't mean to spend my whole life on Earth."

  It would have been something to laugh at, if Draco hadn't known that some Muggles had already left, without even using magic.

  "To pass your test," Harry said, "I'm going to have to say what it means to me, that thought, the whole thing, not the shorter version I tried to explain to you before. But you should be able to see it's the same idea, only more general. So my version of the thought, Draco, is that when we go out into the stars, we might find other people there. And if so, they certainly won't look like we do. There might be things out there that are grown from crystal, or big pulsating blobs... or they might be made of magic, now that I think about it. So with all that strangeness, how do you recognize a person? Not by the shape, not by how many arms or legs it has. Not by the sort of substance it's made out of, whether that's flesh or crystal or stuff I can't imagine. You would have to recognize them as people from their minds. And even their minds wouldn't work just like ours do. But anything that lives and thinks and knows itself and doesn't want to die, it's sad, Draco, it's sad if that person has to die, because it doesn't want to. Compared to what might be out there, every human being who ever lived, we're all like brothers and sisters, you could hardly even tell us apart. The ones out there who met us, they wouldn't see British or French, they wouldn't be able to tell the difference, they'd just see a human being. Humans who can love, and hate, and laugh, and cry; and to them, the ones out there, that would make us all as alike as peas in the same pod. They would be different, though. Really different. But that wouldn't stop us, and it wouldn't stop them, if we both wanted to be friends together."

  Harry raised his wand then, and Draco turned, and looked away, as he had promised; looked toward the stone floor and stone wall in which the door was set. For Draco had promised not to look, and not to tell anyone of what Harry had said, or anything at all of what happened here this night, though he didn't know why it was to be so secret.

  "I have a dream," said Harry's voice, "that one day sentient beings will be judged by the patterns of their minds, and not their color or their shape or the stuff they're made of, or who their parents were. Because if we can get along with crystal things someday, how silly would it be not to get along with Muggleborns, who are shaped like us, and think like us, as alike to us as peas in a pod? The crystal things wouldn't even be able to tell the difference. How impossible is it to imagine that the hatred poisoning Slytherin House would be worth taking with us to the stars? Every life is precious, everything that thinks and knows itself and doesn't want to die. Lily Potter's life was precious, and Narcissa Malfoy's life was precious, even though it's too late for them now, it was sad when they died. But there are other lives that are still alive to be fought for. Your life, and my life, and Hermione Granger's life, all the lives of Earth, and all the lives beyond, to be defended and protected, EXPECTO PATRONUM!"

  And there was light.

  Everything turned to silver in that light, the stone floor, the stone wall, the door, the railings, so dazzling just in the reflection that you could hardly even see them, even the air seemed to shine, and the light grew brighter, and brighter, and brighter -

  When the light ended it was like a shock, Draco's hand went automatically to his robe to bring out a handkerchief, and it was only then that he realized he was crying.

  "There is your experimental result," Harry's voice said quietly. "I really did mean it, that thought."

  Draco slowly turned toward Harry, who had lowered his wand now.

  "That, that's got to be a trick, right?" Draco said. He couldn't take many more of these shocks. "Your Patronus - can't really be that bright -" And yet it had been Patronus light, once you knew what you were looking at, you couldn't mistake it for anything else.

  "That was the true form of the Patronus Charm," Harry said. "Something that lets you put all your strength into the Patronus, without hindrance from within yourself. And before you ask, I did not learn it from Dumbledore. He does not know the secret, and could not cast the true form if he did. I solved the puzzle for myself. And I knew, once I understood, that this spell must not be spoken of. For your sake, I undertook your test; but you must not speak of it, Draco."

  Draco didn't know any more, he didn't know where the true strength lay, or the right of things. Double vision, double vision. Draco wanted to call Harry's ideals weakness, Hufflepuff foolishness, the sort of lie that rulers told to placate the populace and that Harry had been silly enough to believe for himself, foolishness taken seriously and raised up to insane heights, projected out onto the stars themselves -

  Something beautiful and hidden, mysterious and bright -

  "Will I," whispered Draco, "be able to cast a Patronus like that, someday?"

  "If you always keep seeking the truth," Harry said, "and if you don't refuse the warm thoughts when you find them, then I'm sure you will. I think a person could get anywhere if they just kept going long enough, even to the stars."

  Draco wiped his eyes with his handkerchief again.

  "We should go back inside," Draco said in an unsteady voice, "someone could've seen it, all that light -"

  Harry nodded, and moved to and through the door; and Draco looked up at the night sky one last time before he followed.

  Who was the Boy-Who-Lived, that he was already an Occlumens, and could cast the true form of the Patronus Charm, and do other strange things? What was Harry's Patronus, why must it stay unseen?

  Draco didn't ask any of those questions, because Harry might have answered, and Draco just couldn't take any more shocks today. He just couldn't. One more shock and his head was going to just fall right off his shoulders and go bounce, bounce, bounce down the corridors of Hogwarts.

  They'd ducked into a small alcove, instead of going all the way back to the classroom, at Draco's request; he was feeling too nervous to put it off any longer.

  Draco put up a Quieting barrier, and then looked at Harry in silent question.
>
  "I've been thinking about it," Harry said. "I'll do it, but there are five conditions -"

  "Five?"

  "Yes, five. Look, Draco, a pledge like this is just begging to go terribly wrong somehow, you know it would go wrong if this were a play -"

  "Well, it's not!" Draco said. "Dumbledore killed Mother. He's evil. It's one of those things you talk about that doesn't have to be complicated."

  "Draco," Harry said, his voice careful, "all I know is that you say that Lucius says that Dumbledore says he killed Narcissa. To believe that unquestioningly, I have to trust you and Lucius and Dumbledore. So like I said, there are conditions. The first one is that at any point you can release me from the pledge, if it no longer seems like a good idea. It has to be a deliberate and intended decision on your part, of course, not a trick of wording or something."

  "Okay," said Draco. That sounded safe enough.

  "Condition two is that I'm pledging to take as an enemy whoever actually did kill Narcissa, as determined to the honest best of my ability as a rationalist. Whether that's Dumbledore, or someone else. And you have my word that I'll exercise my best ability as a rationalist to keep that judgment honest, as a question of simple fact. Agreed?"

  "I don't like it," said Draco. He didn't, the whole point was to make sure Harry never went with Dumbledore. Still, if Harry was honest, he'd catch on to Dumbledore soon enough; and if dishonest, he'd already broken his word... "But I'll agree."

  "Condition three is that Narcissa has to have been burned alive. If that part of the story turns out to be something exaggerated just to make it sound a little worse, then I get to decide for myself whether or not to still go through with the pledge. Good people sometimes have to kill. But they don't ever torture people to death. It's because Narcissa was burned alive that I know whoever did that was evil."

  Draco kept his temper, barely.

  "Condition four is that if Narcissa got her own hands dirty, and, say, Crucioed someone's child into insanity, and that person burned Narcissa for revenge, the deal might be off again. Because then it was still wrong for them to burn her, they still should've just killed her without pain; but it wasn't evil the same way as if she was just Lucius's love who never did anything herself, like you said. Condition five is that if whoever killed Narcissa was tricked somehow into doing it, then my enemy is whoever tricked them, not the person who was tricked."

  "All this really sounds like you're planning to weasel out of it -"

  "Draco, I won't take a good person as an enemy, not for you or anyone. I have to really believe they're in the wrong. But I've thought about it, and it seems to me that if Narcissa didn't do any evil with her own hands, just fell in love with Lucius and chose to stay his wife, then whoever burned her alive in her own bedroom isn't likely to be a good guy. And I'll pledge to take as my enemy whoever made that happen, whether it's Dumbledore or anyone else, unless you deliberately release me from that pledge. Hopefully that won't go wrong the way it would if this were a play."

  "I'm not happy," said Draco. "But okay. You pledge to take my mother's murderer as your enemy, and I'll -"

  Harry waited, with a patient look on his face, while Draco tried to make his voice work again.

  "I'll help you fix the problem with Slytherin House hating Muggleborns," Draco finished in a whisper. "And I'll say it was sad that Lily Potter died."

  "So be it," said Harry.

  And it was done.

  The break, Draco knew, had just widened a little more. No, not a little, a lot. There was a sensation of drifting away, of being lost, further and further from shore, further and further from home...

  "Excuse me," Draco said. He turned away from Harry, and then tried to calm himself, he had to do this test, and he didn't want to fail it from being nervous or ashamed.

  Draco raised his wand into the starting position for the Patronus Charm.

  Remembered falling from his broomstick, the pain, the fear, imagined it coming from a tall figure in a cloak, looking like a dead thing left in water.

  And then Draco closed his eyes, the better to remember Father holding his small, cold hands in his own warm strength.

  Don't be frightened, my son, I'm here...

  The wand swung up in a broad brandish, to drive the fear away, and Draco was surprised at the strength of it; and he remembered in that moment that Father wasn't lost, would never be lost, would always be there and strong in his own person, no matter what happened to Draco, and his voice cried, "Expecto Patronum!"

  Draco opened his eyes.

  A shining snake looked back at him, no less bright than before.

  Behind him, he heard Harry exhale a breath, as though in relief.

  Draco gazed into the white light. It seemed he wasn't lost completely, after all.

  "That reminds me," said Harry after a while. "Can we test my hypothesis about how to use a Patronus to send messages?"

  "Is it going to surprise me?" said Draco. "I don't want any more surprises today."

  Harry had claimed that the idea wasn't all that strange and he didn't see how it could possibly shock Draco in any way, which made Draco feel even more nervous, somehow; but Draco could see how important it was to have a way of sending messages in emergencies.

  The trick - or so Harry hypothesized - was wanting to spread the good news, wanting the recipient to know the truth of whatever happy thought you'd used to cast the Patronus Charm. Only instead of telling the recipient in words, the Patronus itself was the message. By wanting them to see that, the Patronus would go to them.

  "Tell Harry," said Draco to the luminous snake, even though Harry was standing only a few paces away on the other side of the room, "to, um, beware the green monkey," this being a sign from a play Draco had once seen.

  And then, just like at King's Cross station, Draco wanted Harry to know that Father had always cared for him; only this time he didn't try to say it in words, but wanted to say it with the happy thought itself.

  The bright snake slithered across the room, looking more like it was slithering through the air rather than the stone itself; it got to Harry after traveling that short distance -

  - and said to Harry, in a strange voice that Draco recognized as how he himself probably sounded to other people, "Beware the green monkey."

  "Hsssss ssss sshsshssss," said Harry.

  The snake slithered back across the floor to Draco.

  "Harry says the message is received and acknowledged," said the shining Blue Krait in Draco's voice.

  "Huh," Harry said. "Talking to Patronuses feels odd."

  ...

  ...

  ...

  ...

  "Why are you looking at me like that?" said the Heir of Slytherin.

  Aftermath:

  Harry stared at Draco.

  "You mean just magical snakes, right?"

  "N-no," said Draco. He was looking rather pale, and was still stammering, but had at least stopped the incoherent noises he'd been making earlier. "You're a Parselmouth, you can speak Parseltongue, it's the language of all snakes everywhere. You can understand any snake when it talks, and they can understand when you talk to them... Harry, you can't possibly believe you were Sorted into Ravenclaw! You're the Heir of Slytherin!"

  ...

  ...

  ...

  ...

  ...

  "SNAKES ARE SENTIENT?"

  Chapter 48: Utilitarian Priorities

  It was Saturday, the first morning of February, and at the Ravenclaw table, a boy bearing a breakfast plate heaped high with vegetables was nervously inspecting his servings for the slightest trace of meat.

  It might have been an overreaction. After he'd gotten over the raw shock, Harry's common sense had woken up and hypothesized that "Parseltongue" was probably just a linguistic user interface for controlling snakes...

  ...after all, snakes couldn't really be human-level intelligent, someone would have noticed by now. The smallest-brained creatures Harry had ever heard of with
anything like linguistic ability were the African grey parrots taught by Irene Pepperberg. And that was unstructured protolanguage, in a species that played complex games of adultery and needed to model other parrots. While according to what Draco had been able to remember, snakes spoke to Parselmouths in what sounded like normal human language - i.e., full-blown recursive syntactical grammar. That had taken time for hominids to evolve, with huge brains and strong social selection pressures. Snakes didn't have much society at all that Harry had ever heard. And with thousands upon thousands of different species of snakes all over the world, how could they all use the same version of their supposed language, "Parseltongue"?

  Of course that was all merely common sense, in which Harry was starting to lose faith entirely.

  But Harry was sure he'd heard snakes hissing on the TV at some point - after all, he knew what that sounded like from somewhere - and that hadn't sounded to him like language, which had seemed a good deal more reassuring...

  ...at first. The problem was that Draco had also asserted that Parselmouths could send snakes on extended complex missions. And if that was true, then Parselmouths had to make snakes persistently intelligent by talking to them. In the worst-case scenario that would make the snake self-aware, like what Harry had accidentally done to the Sorting Hat.

  And when Harry had offered that hypothesis, Draco had claimed that he could remember a story - Harry hoped to Cthulhu that this one story was just a fairy tale, it had that ring to it, but there was a story - about Salazar Slytherin sending a brave young viper on a mission to gather information from other snakes.

  If any snake a Parselmouth had talked to, could make other snakes self-aware by talking to them, then...

  Then...

  Harry didn't even know why his mind was going all "then... then..." when he knew perfectly well how the exponential progression would work, it was just the sheer moral horror of it that was blowing his mind.