Harry Potter and the Methods of Rationality

by Eliezer Yudkowsky

  "I am not asking for understanding or sorrow," said the dark silhouette, still with that deadly calm. "But I have just spent two full hours in the presence of Hermione Granger, dressed in such clothing as was provided me, visiting such fascinating places in Hogwarts as a tiny burbling waterfall of what looked to me like snot, accompanied by a number of other girls who insisted on such helpful activities as strewing our path with Transfigured rose petals. I have been on a date, scion of Malfoy. My first date. And when I call that favor due, you will pay it."

  Draco nodded solemnly. Before arriving he had taken the wise precaution of learning every available detail of Harry's date, so that he could get all of his hysterical laughing done before their appointed meeting time, and would not commit a faux pas by giggling continuously until he lost consciousness.

  "Do you think," Draco said, "that something sad ought to happen to the Granger girl -"

  "Spread the word in Slytherin that the Granger girl is mine and anyone who meddles in my affairs will have their remains scattered over an area wide enough to include twelve different spoken languages. And since I am not in Gryffindor and I use cunning rather than immediate frontal attacks, they should not panic if I am seen smiling at her."

  "Or if you're seen on a second date?" Draco said, allowing just a tiny note of skepticism into his voice.

  "There will be no second date," said the green-lit silhouette in a voice so fearsome that it sounded, not only like a Death Eater, but like Amycus Carrow that one time just before Father told him to stop it, he wasn't the Dark Lord.

  Of course it was still a young boy's high unbroken voice and when you combined that with the actual words, well, it just didn't work. If Harry Potter did become the next Dark Lord someday, Draco would use a Pensieve to store a copy of this memory somewhere safe, and Harry Potter would never dare betray him.

  "But let us talk of happier matters," said the green-shadowed figure. "Let us talk of knowledge and of power. Draco Malfoy, let us talk of Science."

  "Yes," said Draco. "Let us speak."

  Draco wondered how much of his own face could be seen, and how much was in shadow, in that eerie green light.

  And though Draco kept his face serious, there was a smile in his heart.

  He was finally having a real grownup conversation.

  "I offer you power," said the shadowy figure, "and I will tell you of that power and its price. The power comes from knowing the shape of reality and so gaining control over it. What you understand, you can command, and that is power enough to walk upon the Moon. The price of that power is that you must learn to ask questions of Nature, and far more difficult, accept Nature's answers. You will do experiments, perform tests and see what happens. And you must accept the meaning of those results when they tell you that you are mistaken. You will have to learn how to lose, not to me, but to Nature. When you find yourself arguing with reality, you will have to let reality win. You will find this painful, Draco Malfoy, and I do not know if you are strong in that way. Knowing the price, is it still your wish to learn the human power?"

  Draco took a deep breath. He'd thought about this. And it was hard to see how he could answer any other way. He'd been instructed to take every avenue of friendship with Harry Potter. It was just learning, he wasn't promising to do anything. He could always stop the lessons at any time...

  There were certainly any number of things about the situation which made it look like a trap, but in all honesty, Draco didn't see how this could go wrong.

  Plus Draco did kind of want to rule the world.

  "Yes," said Draco.

  "Excellent," said the shadowy figure. "I have had something of a crowded week, and it will take time to plan your curriculum -"

  "I've got a lot of things I need to do myself to consolidate my power in Slytherin," said Draco, "not to mention homework. Maybe we should just start in October?"

  "Sounds sensible," said the shadowy figure, "but what I meant to say is that to plan your curriculum, I need to know what I will be teaching you. Three thoughts come to me. The first is that I teach you of the human mind and brain. The second option is that I teach you of the physical universe, those arts which lie on the pathway to visiting the Moon. This involves a great deal of numbers, but to a certain kind of mind those numbers are more beautiful than anything else Science has to teach. Do you like numbers, Draco?"

  Draco shook his head.

  "Then so much for that. You will learn your mathematics eventually, but not right away, I think. The third option is that I teach you of genetics and evolution and inheritance, what you would call blood -"

  "That one," said Draco.

  The figure nodded. "I thought you might say as much. But I think it will be the most painful path for you, Draco. What if your family and friends, the blood purists, say one thing, and you find that the experimental test says another?"

  "Then I'll figure out how to make the experimental test say the right answer!"

  There was a pause, as the shadowy figure stood there with its mouth open for a short while.

  "Um," said the shadowy figure. "It doesn't really work like that. That's what I was trying to warn you about here, Draco. You can't make the answer come out to be anything you like."

  "You can always make the answer come out your way," said Draco. That had been practically the first thing his tutors had taught him. "It's just a matter of finding the right arguments."

  "No," said the shadowy figure, voice rising in frustration, "no, no, no! Then you get the wrong answer and you can't go to the Moon that way! Nature isn't a person, you can't trick them into believing something else, if you try to tell the Moon it's made of cheese you can argue for days and it won't change the Moon! What you're talking about is rationalization, like starting with a sheet of paper, moving straight down to the bottom line, using ink to write 'and therefore, the Moon is made of cheese', and then moving back up to write all sorts of clever arguments above. But either the Moon is made of cheese or it isn't. The moment you wrote the bottom line, it was already true or already false. Whether or not the whole sheet of paper ends up with the right conclusion or the wrong conclusion is fixed the instant you write down the bottom line. If you're trying to pick between two expensive trunks, and you like the shiny one, it doesn't matter what clever arguments you come up with for buying it, the real rule you used to choose which trunk to argue for was 'pick the shiny one', and however effective that rule is at picking good trunks, that's the kind of trunk you'll get. Rationality can't be used to argue for a fixed side, its only possible use is deciding which side to argue. Science isn't for convincing anyone that the blood purists are right. That's politics! The power of science comes from finding out the way Nature really is that can't be changed by arguing! What science can do is tell us how blood really works, how wizards really inherit their powers from their parents, and whether Muggleborns are really weaker or stronger -"

  "Stronger!" said Draco. He had been trying to follow this, a puzzled frown on his face, he could see how it sort of made sense but it certainly wasn't like anything he'd ever heard before. And then Harry Potter had said something Draco couldn't possibly let pass. "You think mudbloods are stronger?"

  "I think nothing," said the shadowy figure. "I know nothing. I believe nothing. My bottom line is not yet written. I will figure out how to test the magical strength of Muggleborns, and the magical strength of purebloods. If my tests tell me that Muggleborns are weaker, I will believe they are weaker. If my tests tell me that Muggleborns are stronger, I will believe they are stronger. Knowing this and other truths, I will gain some measure of power -"

  "And you expect me to believe whatever you say?" Draco demanded hotly.

  "I expect you to perform the tests personally," said the shadowy figure quietly. "Are you afraid of what you will find?"

  Draco stared at the shadowy figure for a while, his eyes narrowed. "Nice trap, Harry," he said. "I'll have to remember that one, it's new."

  The shadowy figure shook h
is head. "It's not a trap, Draco. Remember - I don't know what we'll find. But you do not understand the universe by arguing with it or telling it to come back with a different answer next time. When you put on the robes of a scientist you must forget all your politics and arguments and factions and sides, silence the desperate clingings of your mind, and wish only to hear the answer of Nature." The shadowy figure paused. "Most people can't do it. That's why this is difficult. Are you sure you wouldn't rather just learn about the brain?"

  "And if I tell you I'd rather learn about the brain," Draco said, his voice now hard, "you'll go around telling people that I was afraid of what I'd find."

  "No," said the shadowy figure. "I will do no such thing."

  "But you might do the same sort of tests yourself, and if you got the wrong answer, I wouldn't be there to say anything before you showed it to someone else." Draco's voice was still hard.

  "I would still ask you first, Draco," the shadowy figure said quietly.

  Draco paused. He hadn't been expecting that, he'd thought he saw the trap but... "You would?"

  "Of course. How would I know who to blackmail or what we could ask from them? Draco, I say again that this is not a trap I set for you. At least not for you personally. If your politics were different, I would be saying, what if the test shows that purebloods are stronger."

  "Really."

  "Yes! That's the price anyone has to pay to become a scientist!"

  Draco held up a hand. He had to think.

  The shadowy, green-lit figure waited.

  It didn't take long to think about, though. If you discarded all the confusing parts... then Harry Potter was planning to mess around with something that could cause a gigantic political explosion, and it would be insane to just walk away and let him do it on his own. "We'll study blood," said Draco.

  "Excellent," said the figure, and smiled. "Congratulations on being willing to ask the question."

  "Thanks," Draco said, not quite managing to keep the irony out of his voice.

  "Hey, did you think going to the Moon was easy? Be glad this just involves changing your mind sometimes, and not a human sacrifice!"

  "Human sacrifice would be way easier!"

  There was a slight pause, and then the figure nodded. "Fair point."

  "Look, Harry," said Draco without much hope, "I thought the idea was to take all the things that Muggles know, combine them with things that wizards know, and become masters of both worlds. Wouldn't it be a lot easier to just study all the things that Muggles already found out, like the Moon stuff, and use that power -"

  "No," said the figure with a sharp shake of his head, sending green shadows moving around his nose and eyes. His voice had turned very grim. "If you cannot learn the scientist's art of accepting reality, then I must not tell you what that acceptance has discovered. It would be like a powerful wizard telling you of those gates which must not be opened, and those seals which must not be broken, before you had proven your intelligence and discipline by surviving the lesser perils."

  A chill went down Draco's spine and he shuddered involuntarily. He knew it had been visible even in the dim light. "All right," said Draco. "I understand." Father had told him that many times. When a more powerful wizard told you that you weren't ready to know, you didn't pry any further if you wanted to live.

  The figure inclined his head. "Indeed. But there is something else you should understand. The first scientists, being Muggles, lacked your traditions. In the beginning they simply did not comprehend the notion of dangerous knowledge, and thought that all things known should be spoken freely. When their searches turned dangerous, they told their politicians of things that should have stayed secret - don't look like that, Draco, it wasn't simple stupidity. They did have to be smart enough to uncover the secret in the first place. But they were Muggles, it was the first time they'd found anything really dangerous, and they didn't start out with a tradition of secrecy. There was a war going on, and the scientists on one side worried that if they didn't talk, the scientists of the enemy country would tell their politicians first..." The voice trailed off significantly. "They didn't destroy the world. But it was close. And we are not going to repeat that mistake."

  "Right," Draco said, his voice now very firm. "We won't. We're wizards, and studying science doesn't make us Muggles."

  "As you say," said the green-lit silhouette. "We will establish our own Science, a magical Science, and that Science will have smarter traditions from the very start." The voice grew hard. "The knowledge I share with you will be taught alongside the disciplines of accepting truth, the level of this knowledge will be keyed to your progress in those disciplines, and you will share that knowledge with no one else who has not learned those disciplines. Do you accept this?"

  "Yes," said Draco. What was he supposed to do, say no?

  "Good. And what you discover for yourself, you will keep to yourself unless you think that other scientists are ready to know it. What we do share among ourselves, we will not tell the world unless we agree it is safe for the world to know. And whatever our own politics and allegiances, we will all punish any of our number who reveal dangerous magics or give away dangerous weapons, no matter what sort of war is going on. From this day onward, that will be the tradition and the law of science among wizards. Are we agreed on that?"

  "Yes," said Draco. Actually this was starting to sound pretty attractive. The Death Eaters had tried to take power by being scarier than everyone else, and they hadn't actually won yet. Maybe it was time to try ruling using secrets instead. "And our group stays hidden for as long as possible, and everyone in it has to agree to our rules."

  "Of course. Definitely."

  There was a very short pause.

  "We're going to need better robes," said the shadowy figure, "with hoods and so on -"

  "I was just thinking that," said Draco. "We don't need whole new robes, though, just cowled cloaks to put on. I have a friend in Slytherin, she'll take your measurements -"

  "Don't tell her what it's for, though -"

  "I'm not stupid!"

  "And no masks for now, not when it's just you and me -" said the shadowy figure.

  "Right! But later on we should have some sort of special mark that all our servants have, the Mark of Science, like a snake eating the Moon on their right arms -"

  "It's called a PhD and wouldn't that make it too easy to identify our people?"

  "Huh?"

  "I mean, what if someone is like 'okay, now everyone pull up their robes over their right arms' and our guy is like 'whoops, sorry, looks like I'm a spy' -"

  "Forget I said anything," said Draco, sweat suddenly springing out all over his body. He needed a distraction, fast - "And what do we call ourselves? The Science Eaters?"

  "No," said the shadowy figure slowly. "That doesn't sound right..."

  Draco wiped his robed arm across his forehead, wiping away beads of moisture. What had the Dark Lord been thinking? Father had said the Dark Lord was smart!

  "I've got it!" said the shadowy figure suddenly. "You won't understand yet, but trust me, it fits."

  Right now Draco would have accepted 'Malfoy Munchers' as long as it changed the subject. "What is it?"

  And standing amid the dusty desks in an unused classroom in the dungeons of Hogwarts, the green-lit silhouette of Harry Potter spread his arms dramatically and said, "This day shall mark the dawn of... the Bayesian Conspiracy."

  A silent figure trudged wearily through the halls of Hogwarts in the direction of Ravenclaw.

  Harry had gone straight from the meeting with Draco to dinner, and stayed at dinner barely long enough to choke down a few fast gulps of food before going off to bed.

  It wasn't even 7pm yet, but it was well past bedtime for Harry. He'd realized last night that he wouldn't be able to use the Time-Turner on Saturday until after the book-reading contest was already over. But he could still use the Time-Turner on Friday night, and gain time that way. So Harry had pushed himself to stay awake
until 9pm on Friday, when the protective shell opened, and then used the four hours remaining on the Time-Turner to spin back to 5pm and collapse into sleep. He'd woken up around 2am on Saturday morning, just as planned, and read for the next twelve hours straight... and it still hadn't been enough. And now Harry would be going to sleep rather early for the next few days, until his sleep cycle caught up again.

  The portrait on the door asked Harry some dumb riddle meant for eleven-year-olds that he answered without the words even passing through his conscious mind, and then Harry staggered up the stairs to his dorm room, changed into his pajamas and collapsed into bed.

  And found that his pillow seemed rather lumpy.

  Harry groaned. He sat up reluctantly, twisted in bed, and lifted up his pillow.

  This revealed a note, two golden Galleons, and a book titled Occlumency: The Hidden Arte.

  Harry picked up the note and read:

  My, you do get yourself into trouble and quickly. Your father was no match for you.

  You have made a powerful enemy. Snape commands the loyalty, admiration, and fear of all House Slytherin. You cannot trust any of that House now, whether they come to you in friendly guise or fearsome.

  From now on you must not meet Snape's eyes. He is a Legilimens and can read your mind if you do. I have enclosed a book which may help you learn to protect yourself, though there is only so far you can get without a tutor. Still you may hope to at least detect intrusion.

  So that you may find some extra time in which to study Occlumency, I have enclosed 2 Galleons, which is the price of answer sheets and homework for the first-year History of Magic class (Professor Binns having given the same tests and same assignments every year since he died). Your newfound friends the Weasley twins should be able to sell you a copy. It goes without saying that you must not get caught with it in your possession.

  Of Professor Quirrell I know little. He is a Slytherin and a Defense Professor, and that is two marks against him. Consider carefully any advice he gives you, and tell him nothing you do not wish known.