Harry Potter and the Methods of Rationality

by Eliezer Yudkowsky

  All Dragon Army stopped for a moment as Padma slid the glove over her left hand, strapped it in place, and presented it before Draco Malfoy; who also stopped in place, took several deep breaths, raised his wand, executed a precise set of eight movements and bellowed "Colloportus!"

  The Dragon Warrior raised her gloved hand, flexed it, and gave a small bow to Draco Malfoy, who returned it more shallowly, though the Dragon General was staggering slightly. Padma then returned to her place at Draco's side, and the Dragons began marching once more.

  "Well," remarked Augusta Longbottom. "I don't suppose someone would care to explain?" Amelia Bones was frowning slightly as she gazed at the screen.

  "For some reason or other," said the amused voice of Professor Quirrell, "it seems that the scion of Malfoy is able to cast surprisingly strong magic for a first-year student. Due to the purity of his blood, of course. Certainly the good Lord Malfoy would not have openly flouted the underage magic laws by arranging for his son to receive a wand before his acceptance into Hogwarts."

  "I suggest you be careful in your implications, Quirrell," Lucius Malfoy said coldly.

  "Oh, I am," Professor Quirrell said. "A Colloportus cannot be dispelled by Finite Incantatem; it requires an Alohomora of equal strength. Until then, a glove so Charmed will resist lesser material forces, deflect the Sleep Hex and the Stunning Hex. And as neither Mr. Potter nor Miss Granger can cast a counterspell powerful enough, that Charm is invincible upon this battlefield. It is not the original intent of the Charm, nor the intent of whoever taught Mr. Malfoy an emergency spell for evading his enemies. But it would seem that Mr. Malfoy has been learning creativity."

  Lucius Malfoy had straightened as the Defense Professor spoke; he now sat erect upon his cushioned bench, his head held perceptibly higher than before, and when he spoke it was with quiet pride. "He will be the greatest Lord Malfoy that has yet lived."

  "Faint praise," Augusta Longbottom said under her breath; Amelia Bones chuckled, as did Mr. Davis for a tiny, fatal fraction of a second before he stopped with a strangled gargle.

  "I quite agree," said Professor Quirrell, though it wasn't clear to whom he spoke. "Unfortunately for Mr. Malfoy, he is still new to the art of creativity, and so he has committed a classic error of Ravenclaw."

  "And what might that be?" said Lucius Malfoy, his voice now turned chill once more.

  Professor Quirrell had leaned back in his seat, the pale blue eyes briefly unfocusing as one of the windows shifted its viewpoint within the greater screen, zooming in to show the sweat now on Draco Malfoy's forehead. "It is such a beautiful idea that Mr. Malfoy has quite overlooked its pragmatic difficulties."

  "Would someone care to explain that?" said Lady Greengrass. "Not all of us present are experts at such... affairs."

  Amelia Bones spoke, the old witch's voice somewhat dry. "It will tempt them to try to catch hexes that they would be wiser to simply dodge. The more so, if they have had little practice catching them. And the casting of so many Charms will tire their strongest warrior."

  Professor Quirrell gave the DMLE Director a half-nod of acknowledgment. "As you say, Madam Bones. Mr. Malfoy is new to the business of having ideas, and so when he has one, he becomes proud of himself for having it. He has not yet had enough ideas to unflinchingly discard those that are beautiful in some aspects and impractical in others; he has not yet acquired confidence in his own ability to think of better ideas as he requires them. What we are seeing here is not Mr. Malfoy's best idea, I fear, but rather his only idea."

  Lord Malfoy simply turned to watch the screens again, as though the Defense Professor had used up his right to exist.

  "But -" said Lord Greengrass. "But what in Merlin's name is Harry Potter -"

  Sixteen remaining soldiers of the Chaos Legion - or fifteen plus Blaise Zabini, rather - marched confidently through the forest, their shoes thudding over the still-dry ground. Their camouflage uniforms blended into the forest even more than usual, all colors washed out by the tints of an overcast day.

  Sixteen Chaos Legionnaires, against twenty-eight Dragon Warriors and twenty-eight Sunshine Soldiers.

  The common consensus had been that, with odds that bad, it was practically impossible for them to lose. After all, General Chaos was bound to come up with something really spectacular, facing odds like that.

  There was something almost nightmarish about how everyone seemed to now expect Harry to pull miracles out of his hat, on demand, any time one was needed. It meant that if you couldn't do the impossible, you were disappointing your friends and failing to live up to your potential...

  Harry hadn't bothered complaining to Professor Quirrell about 'too much pressure'. Harry's mental model of the Defense Professor had predicted him looking severely annoyed, saying things along the lines of You are perfectly capable of solving this problem, Mr. Potter; did you even try? and then deducting several hundred Quirrell points.

  From above, from where two broomsticks watched their march, the high young voice of Tess Walsh cried "Friend!" and after another moment, "Gingersnap!"

  A handful of seconds later, the soldier who'd code-named herself Gingersnap returned bearing a double handful of acorns, sweating slightly in the cool but humid air from the jog that had taken her to the oak tree Neville had spotted. Gingersnap approached to where Shannon was holding a uniform-shirt with the neck tied off, in lieu of anyone having to Transfigure a bag. When Gingersnap brought her hands forward to try and dump her acorns into the holding-shirt, Chaotic Shannon, giggling, jerked the shirt to the right, then to the left again as Gingersnap made another effort to dump the acorns, until a sharp "Miss Friedman!" from Lieutenant Nott caused Shannon to sigh and hold the shirt still. Gingersnap dumped her acorns into those accumulated, and then headed out for more.

  Somewhere in the background, Ellie Knight was singing her very own version of the Chaos Legion's marching song, and around half the other soldiers were trying to step along with it despite not knowing the tune in advance. Nearby, Nita Berdine, who had a high Transfiguration score, finished creating yet another pair of green sunglasses, and handed them to Adam Beringer, who folded up the sunglasses before tucking them into his uniform pocket. Other soldiers were already wearing their own green sunglasses, despite the cloudy day.

  You might guess that there was some sort of incredibly complicated and fascinating explanation behind this, and you would be right.

  Two days earlier Harry had been sitting amid his bookcases in the comfy rocking-chair he'd obtained for his trunk's cavern level, pondering silently in the quiet span between classes and dinnertime, thinking about power.

  For sixteen Chaotics to defeat twenty-eight Sunnies and twenty-eight Dragons they would need a force amplifier. There were limits to what you could do with maneuver. There had to be a secret weapon and it had to be invincible, or at least moderately unstoppable.

  Muggle artifacts were now illegal in Hogwarts's mock battles, banned by Ministry edict. And the trouble with finding some other clever and unusual spell was that an army twice your own size could brute-force Finite almost anything you tried. The Sunshine Regiment might have missed that tactic with the Transfigured chainmail, but nobody would miss it again now that Professor Quirrell had pointed it out. And Finite Incantatem was a brute-force counterspell which required at least as much magic as the spell being canceled... which, if you were severely outnumbered, made it a whole new order of military challenge. The enemy could Finite anything you tried, and still have enough magic left over for shields and volleys of Sleep Hexes.

  Unless, somehow, you could invoke potencies beyond the ordinary strength of first-year Hogwarts students, something too powerful for the enemy to Finite.

  So Harry had asked Neville if he'd ever heard of any small, safe sacrificial rituals -

  And then, after the screaming and the shouting had subsided, after Harry had stopped trying to argue about Unbreakable Vows and just given up the whole thing as impossible from a public relations standpoint, Ha
rry had realized that he hadn't even needed to go there. They taught you how to invoke potencies far beyond your own strength in ordinary Hogwarts classes.

  Sometimes, even though you were looking straight at something, you didn't realize what you were looking at until you happened to ask exactly the right question.

  Defense. Charms. Transfiguration. Potions. History of Magic. Astronomy. Broomstick Flying. Herbology...

  "Foe!" screamed the voice from above.

  It was a good thing that Neville Longbottom hadn't the tiniest idea that his grandmother was watching; or he would've been more self-conscious about screaming scary battlecries at the top of his lungs while casting Luminos every three seconds as he rocketed through a dense forest of trees, hot on the tail of Gregory Goyle.

  ("But -" Augusta Longbottom said, her expression showing almost as much astonishment as worry. "But Neville is afraid of heights!")

  ("Not all fears last," said Amelia Bones. The old witch was favoring the great screen before them with a measuring gaze. "Or perhaps he has found courage. It is much the same, in the end.")

  A glimmer of red -

  Neville dodged, very nearly into a tree but he did dodge; and then Neville somehow also managed to dodge almost all of the branches before they smacked him in the face.

  Now Mr. Goyle's broomstick was pulling further and further away - even though the two of them were riding exactly the same broomstick and Mr. Goyle weighed more, somehow Neville was still falling behind. So Neville slowed down, pulled back, angled up out of the forest and began to accelerate back toward where the Chaos Legion still marched.

  Twenty seconds later - it hadn't been a long chase, just an exciting one - Neville was back among his fellow Chaotics, and dismounted his broom to walk on the ground for a little bit.

  "Neville -" said General Potter. Harry's voice was a little distant, as he walked carefully and steadily through the forest, his wand still applied to the almost-finished Form of the object he was slowly Transfiguring. Beside him, Blaise Zabini, working a smaller version of the same Transfiguration, looked like a shambling Inferi as he stumbled forward. "I told you - Neville - you don't have to -"

  "Yes, I do," said Neville. He looked down at where his fingers grasped the broomstick, and saw that not just his hands, but his whole arms were shaking. But unless anyone else in Chaos had been practicing dueling for an hour a day with Mr. Diggory, and then practicing their aim in private for another hour afterward, Neville was probably the best shot from a broomstick even after taking into account that he wasn't a very good flyer.

  "Good show, Neville," Theodore said from where he was walking ahead of them all, leading the Chaos Legion forward through the forest while wearing only his undershirt.

  (Augusta Longbottom and Charles Nott exchanged brief astonished glances and then wrenched their gazes away from one another as though stung.)

  Neville took a few deep breaths, trying to steady his hands, trying to think; Harry might not be good for deep strategic thinking while he was in the middle of an extended Transfiguration. "Lieutenant Nott, do you have any idea why Dragon Army just did that? They lost a broom -" The Dragons had started the combat with a feint to provide a distraction for Mr. Goyle's approach through the forest; Neville hadn't realized there were two brooms attacking until almost too late. But the Chaos Legion had gotten the other pilot. That was why broomsticks usually didn't attack before armies met, it meant a whole army would concentrate fire on the broomstick. "And the Dragons didn't even get anyone, did they?"

  "Nope!" Tracey Davis said proudly. She too was now marching by General Potter's side, her wand gripped low and watchful as her eyes scanned the surrounding forest. "I threw up a Prismatic Sphere like a split second before Mr. Goyle's hex got Zabini, and the way Mr. Goyle had his other arm stretched out I think he planned to knock down the General, too." The Slytherin witch smiled with vicious confidence. "Mr. Goyle tried a Breaking Drill Hex, but learned to his dismay that his weak magic was no match for my newfound dark powers, hahahaha!"

  Some Chaotics laughed with her, but a queasy sensation was starting in Neville's stomach as he realized how close the Chaos Legion had come to complete disaster. If Mr. Goyle had managed to disrupt both Transfigurations -

  "Report!" snapped the Dragon General, doing his best to conceal the fatigue he felt after casting seventeen Locking Charms, with more yet to come.

  Beads of sweat now dotted Gregory's forehead. "The enemy got Dylan Vaughan," Gregory said formally. "Harry Potter and Blaise Zabini were each Transfiguring something dark-grey and roundish, I don't think it was finished but it looked like it would be big and hollow, sort of cauldron-shaped. Zabini's was smaller than Potter's. I couldn't get either of them or disrupt their Transfigurations, Tracey Davis blocked me. Neville Longbottom is on a broomstick and he's still a terrible flyer but his aim is really good."

  Draco listened, frowning, and then he glanced at Padma and Dean Thomas, who both shook their own heads, indicating that they also couldn't think of what might be big and grey and shaped like a cauldron.

  "Anything else?" said Draco. If that was it, they'd lost a broom for nothing -

  "The only other weird thing I saw," Gregory said, sounding puzzled, "was that some Chaotics were wearing... sort of like goggles?"

  Draco thought about this, not noticing that he'd stopped marching or that all of Dragon Army had automatically stopped with him.

  "Was there anything special about the goggles?" Draco said.

  "Um..." Gregory said. "They were... greenish, maybe?"

  "Okay," said Draco. Again without thinking, he began walking once more and his Dragons followed. "Here's our new strategy. We're only going to send eleven Dragons against the Chaos Legion, not fourteen. That should be enough to beat them, now that we can neutralize their special advantage." It was a gamble, but you had to take gambles sometimes, if you wanted to come in first in a three-way battle.

  "You figured out Chaos's plan, General Malfoy?" said Mr. Thomas with considerable surprise.

  "What are they doing?" said Padma.

  "I haven't the faintest idea," said Draco, with a smirk of the most refined smugness. "We'll just do the obvious thing."

  Harry, having now finished his cauldron, was carefully scooping acorns into the container while the scouts searched for a nearby source of water that could be used as a liquid base. They'd come across frequent sinkholes and miniature creeks in the forest before, so it ought not to take long. Another scout had brought a straight stick that would serve as a stirrer, so Harry didn't have to Transfigure one.

  Sometimes, even though you were looking straight at something, you didn't realize what you were looking at until you happened to ask exactly the right question...

  How can I invoke magical powers that ought to be beyond the reach of first-year students?

  There was a cautionary tale the Potions Master had told them (with much sneers and laughter to make the stupidity seem low-status instead of daring and romantic) about a second-year witch in Beauxbatons who'd stolen some extremely restricted and expensive ingredients, and tried to brew Polyjuiceso she could borrow the form of another girl for purposes better left unmentioned. Only she'd managed to contaminate the potion with cat hairs, and then instead of seeking a healer immediately, the witch had hidden herself in a bathroom, hoping the effects would just wear off; and when she'd finally been found, it had been too late to reverse the transformation completely, condemning her to a life of despair as a sort of cat-girl hybrid.

  Harry hadn't realized what that meant until the instant of thinking the right question - but what that implied was that a young wizard or witch could do things with Potions-Making that they couldn't even come close to doing with Charms. Polyjuice was one of the most potent potions known... but what made Polyjuice a N.E.W.T.-level potion, apparently, wasn't the required age before you had enough magical power; it was how difficult the potion was to brew preciselyand what happened to you if you screwed up.

  Nobody in an
y army had tried brewing any potions up until then. But Professor Quirrell would let you get away with nearly anything, if it was something you could also have done in a real war. Cheating is technique, the Defense Professor had once lectured them. Or rather, cheating is what the losers call technique, and will be worth extra Quirrell points when executed successfully. In principle, there was nothing unrealistic about Transfiguring a couple of cauldrons and brewing potions out of whatever came to hand, if you had enough time before the armies met.

  So Harry had retrieved his copy of Magical Drafts and Potions, and begun looking for a safe but useful potion he could brew in the minutes before the battle started - a potion which would win the battle too fast for counterspells, or produce spell effects too strong for first-years to Finite.

  Sometimes, even though you were looking straight at something, you didn't realize what you were looking at until you happened to ask exactly the right question...

  What potion can I brew using only components gathered from an ordinary forest?

  Every recipe in Magical Drafts and Potions used at least one ingredient from a magical plant or animal. Which was unfortunate, because all the magical plants and animals were in the Forbidden Forest, not the safer and lesser woods where battles were held.

  Someone else might have given up at that point.

  Harry had turned the pages from one recipe to another, skimming faster and faster in dawning realization, confirming what he had already read and was now seeing for the first time.

  Every single Potions recipe seemed to demand at least one magical ingredient, but why should that be true?

  Charms required no material components at all; you just said the words and waved your wand. Harry had been thinking about Potions-Making as essentially analogous: Instead of your spoken syllables triggering a spell effect for no comprehensible reason, you collected a batch of disgusting ingredients and stirred four times clockwise, and that arbitrarily triggered a spell effect.