Harry Potter and the Methods of Rationality

by Eliezer Yudkowsky

Their insignia was a smiley face.

  And in ten minutes, they would be at war.

  Harry stood in the bright forest clearing that was their assigned starting location, an area of open space with old and rotting tree stumps that had been cleared away for some unknown purpose, ground coated with a small scattering of blown leaves and the dried grey remnants of grass that had failed the test of summer's heat, and the sun shining down brilliantly from above.

  Around him were the twenty-three soldiers that Professor Quirrell had assigned to him. Nearly all of Gryffindor had signed up, of course, and more than half of Slytherin, and less than half of Hufflepuff, and a handful of Ravenclaw. In Harry's army there were twelve Gryffindors and six Slytherins and four Hufflepuffs and one Ravenclaw besides himself... not that there was any way to tell that by looking at the uniforms. No red, no green, no yellow, no blue. Just Muggle camouflage patterns, and a patch on the breast with the device of a hand poised to snap its fingers.

  Harry looked upon his twenty-three soldiers, all wearing the same uniforms with no marks of group identity save that single patch.

  And lo, Harry smiled, because he understood what this part of Professor Quirrell's master plan was about; and Harry was taking full advantage of it for his own purposes, too.

  There was a legendary episode in social psychology called the Robbers Cave experiment. It had been set up in the bewildered aftermath of World War II, with the intent of investigating the causes and remedies of conflicts between groups. The scientists had set up a summer camp for 22 boys from 22 different schools, selecting them to all be from stable middle-class families. The first phase of the experiment had been intended to investigate what it took to start a conflict between groups. The 22 boys had been divided into two groups of 11 -

  - and this had been quite sufficient.

  The hostility had started from the moment the two groups had become aware of each others' existences in the state park, insults being hurled on the first meeting. They'd named themselves the Eagles and the Rattlers (they hadn't needed names for themselves when they thought they were the only ones in the park) and had proceeded to develop contrasting group stereotypes, the Rattlers thinking of themselves as rough-and-tough and swearing heavily, the Eagles correspondingly deciding to think of themselves as upright-and-proper.

  The other part of the experiment had been testing how to resolve group conflicts. Bringing the boys together to watch fireworks hadn't worked at all. They'd just shouted at each other and stayed apart. What had worked was warning them that there might be vandals in the park, and the two groups needing to work together to solve a failure of the park's water system. A common task, a common enemy.

  Harry had a strong suspicion Professor Quirrell had understood this principle very well indeed when he had chosen to create three armies per year.

  Three armies.

  Not four.

  And definitely not segregated by House... except that no Slytherins had been assigned to Draco besides Mr. Crabbe and Mr. Goyle.

  It was things like this which reassured Harry that Professor Quirrell, despite his affected Dark atmosphere and his pretense of neutrality in the conflict between Good and Evil, was secretly backing Good, not that Harry would ever dare say that out loud.

  And Harry had decided to take full advantage of Professor Quirrell's plan to define a group identity his way.

  The Rattlers, once they'd met the Eagles, had started thinking of themselves as rough-and-tough, and they'd conducted themselves accordingly.

  The Eagles had thought of themselves as good-and-proper.

  And in that bright forest clearing, scattered around the old and rotting tree stumps, outlined in the sun shining down brilliantly from above, General Potter and his twenty-three soldiers were arranged in nothing remotely resembling a formation. Some soldiers stood, some soldiers sat, some stood on one leg just to be different.

  It was the Chaos Legion, after all.

  And if there wasn't a reason to stand in neat little lines, Harry had said disdainfully, there weren't going to be neat little lines.

  Harry had divided the army into 6 squads of 4 soldiers each, each squad commanded by a Squad Suggester. All troops were under strict orders to disobey any orders they were given if it seemed like a good idea at the time, including that one... unless Harry or the Squad Suggester prefixed the order with "Merlin says", in which case you were supposed to actually obey.

  The Chaos Legion's chief attack was to split up and run in from multiple directions, randomly changing vectors and firing the approved sleep spell as rapidly as you could rebuild the magical strength. And if you saw a chance to distract or confuse the enemy, you took it.

  Fast. Creative. Unpredictable. Non-homogenous. Don't just obey orders, think about whether what you're doing right now makes sense.

  Harry wasn't quite as sure as he'd pretended that this was the optimum of military efficiency... but he'd been given a golden opportunity to change how some students thought about themselves, and that was how he intended to use it.

  Five minutes to wartime, according to Harry's watch.

  General Potter walked (not marched) over to where his air force was waiting tensely, broomsticks already clutched firmly in their hands.

  "All wings report in," said General Potter. They'd rehearsed this during their one training session on Saturday.

  "Red Leader standing by," said Seamus Finnigan, who had no idea what it meant.

  "Red Five standing by," said Dean Thomas, who'd waited his entire life to say it.

  "Green Leader standing by," Theodore Nott said rather stiffly.

  "Green Forty-One standing by," Tracey Davis said.

  "I want you in the air the instant we hear the bell," said General Potter. "Do not engage, repeat, do not engage. Evade if under fire." (Of course you did not aim sleep spells at broomsticks; you fired a spell that gave a temporary red glow to whatever it hit. If you hit the broomstick or the rider, they were out of the war.) "Red Leader and Red Five, fly toward Malfoy's army as fast as you can, stay as high as you can while still seeing them, return the instant you know for sure what they're doing. Green Leader, do the same for Granger's army. Green Forty-One, fly above us and watch for any approaching broomsticks or soldiers, you and only you are authorized to fire. And remember, I didn't say 'Merlin says' for any of that, but we do really need the information. For Chaos!"

  "For Chaos!" the four echoed with varying degrees of enthusiasm.

  Harry expected Hermione to launch an immediate attack on Draco, in which case he'd move his troops into position and start supporting her, but only after she'd taken severe losses and caused some damage. He would frame it as a heroic rescue, if possible; it wouldn't do to have Sunshine thinking that Chaos wasn't their friend, after all.

  But just in case she didn't... well, that was why the Chaos Legion was staying put until Green Leader reported back.

  Draco's moves would be in his own self-interest. He would predictably ready his army to defend against Hermione; he might or might not realize that Harry had been lying about waiting to attack until after that battle finished. Harry had still put two broomsticks on Dragon Army, just in case they were doing something, and just in case Draco or Mr. Goyle or Mr. Crabbe was good enough to shoot a broomstick out of the sky.

  But General Granger was the unpredictable one, and Harry couldn't move until he knew how she was moving.

  In the heart of the forest, with shadow patterns dancing on the ground as leafy canopies swayed high above, General Malfoy stood where the trees were relatively sparser, and looked out on his troops with calm satisfaction. Six units of three troops each, the Aerial Unit of four (to which Gregory was assigned), and the Command Unit, which was himself and Vincent. They'd only drilled for a short time on the previous Saturday, but Draco was confident that he'd managed to explain the basics. Stay with your mates, watch their back and trust them to watch yours. Move as a single body. Obey orders and show no fear. Aim, fire, move, aim again, fire again
.

  The six units were formed up in a defensive perimeter around Draco, watchfully gazing outward into the forest. Back-to-back they stood, wands gripped low until they needed to strike.

  They already looked remarkably like the Auror units whose training Draco had watched during his father's inspections.

  Chaos and Sunshine weren't going to know what hit them.

  "Attention," said General Malfoy.

  The six units unfolded and spun toward Draco; the faces of his broomstick riders turned from where they stood with broomsticks already in hand.

  Draco had decided to wait on demanding salutes until after they won their first battle, when Gryffindors and Hufflepuffs would be more willing to salute a Malfoy.

  But his soldiers were already standing straight enough, especially the Gryffindors, that Draco wondered if he'd even needed to delay. Gregory had quietly listened, and reported back that Draco's volunteering to stand by Harry Potter in Defense class, that time when Professor Quirrell had taught Harry how to lose, had marked Draco as an acceptable commander. At least if you happened to be assigned to his army. Not all Slytherins are alike; there are Slytherins, and then there are Slytherins was what the Gryffindors in Draco's army were quoting to their Housemates.

  Draco was frankly astounded at how incredibly easy that had been. Draco had protested at first about not being assigned any Slytherins, and Professor Quirrell had told him that if he wanted to be the first Malfoy to gain complete political control of the country, he needed to learn how to govern the other three-quarters of the population. It was things like this which reassured Draco that Professor Quirrell had a great deal more sympathy for the good guys than Professor Quirrell was letting on.

  The actual battle wouldn't be easy, especially if Granger did attack the Dragons first. Draco had agonized over whether to commit all his forces against Granger immediately in a preemptive strike, but had worried that (1) Harry had been misleading him completely about what Granger was likely to do, and (2) Harry had been misleading him about waiting until after Granger's attack to join the battle.

  Though Dragon Army had a secret weapon, three of them in fact, which might be enough to win even if they were attacked by both armies at once...

  It was almost time, and that meant it was time for the pre-battle speech that Draco had composed and memorized.

  "The battle is about to begin," Draco said. His voice was calm and precise. "Remember everything that I and Mr. Crabbe and Mr. Goyle showed you. An army wins because it is disciplined and deadly. General Potter and the Chaos Legion will not be disciplined. Granger and the Sunshine Regiment will not be deadly. We are disciplined, we are deadly, we are Dragons. The battle is about to begin, and we are about to win it."

  (Ex tempore speech given by General Potter to the Chaos Legion, immediately before their first battle, on November 3rd, 1991, at 2:56pm:)

  My troops, I'm not going to lie to you, our situation today is very grim. Dragon Army has never lost a single battle. And Hermione Granger... has a very good memory. The truth is, most of you are probably going to die. And the survivors will envy the dead. But we have to win this. We have to win this so that someday, our children can enjoy the taste of chocolate again. Everything is at stake here. Literally everything. If we lose, the whole universe just blinks out like a light bulb. And now I realize that most of you don't know what a light bulb is. Well, take it from me, it's bad. But if we have to go down, let's go down fighting, like heroes, so that as the darkness closes in, we can think to ourselves, at least we had fun. Are you afraid to die? I know I am. I can feel those cold shivers of fear like someone is pumping ice cream into my shirt. But I know... that history is watching us. It was watching us when we changed into our uniforms. It was probably taking pictures. And history, my troops, is written by the victors. If we win this, we can write our own history. A history in which Hogwarts was founded by four renegade house elves. We can make everyone study that history, even though it isn't true, and if they don't answer the right way on our tests... they'll fail the class. Isn't that worth dying for? No, don't answer that. Some things are better left unknown. None of us know why we're here. None of us know why we're fighting. We just woke up in these uniforms in this mysterious forest, knowing only that there was no way to get our names and memories back except victory. The students in those other armies out there... they're just like us. They don't want to die. They're fighting to protect each other, the only friends they have left. They're fighting because they know they have families who'll miss them, even if they can't remember now. They may even be fighting to save the world. But we have a better reason to fight than they do. We fight because we like it. We fight to amuse eldritch monstrosities from beyond Space and Time. We fight because we're Chaos. Soon the final battle will begin, so let me say now, because I won't get a chance later, that it was an honor to be your commander, however briefly. Thank you, thank you all. And remember, your goal isn't just to cut down the enemy, it's to make them afraid.

  A great booming gong echoed over the forest.

  And the Sunshine Regiment began to march.

  The tension rose and rose, as Harry and the nineteen other soldiers who remained waited for the aerial warriors to report back. It shouldn't take long, broomsticks were fast and the distances in the forest were not great -

  Two broomsticks approached, at speed, from the direction of Draco's camp, and all the soldiers tensed. They weren't executing the maneuvers that were today's code for a friendly broomstick.

  "Scatter and fire!" roared General Potter, and then suited action to words, scurrying off at top speed toward the forest cover; and then as soon as Harry was among the trees, he spun back, raised his wand, tried to seek out the broomstick in the sky -

  "Clear!" shouted a voice. "They're heading back!"

  Harry gave a mental shrug. There'd been no way to prevent Draco from obtaining that information, and he'd only learn that they'd been standing still.

  And the Chaotics slowly emerged from the forest -

  "Broomstick approaching from Granger's direction!" yelled another voice. "I think it's Green Leader, he did the dip and roll!"

  Moments later Theodore Nott dived out of the sky and pulled up in the midst of the soldiers.

  "Granger has divided her forces in two!" yelled Nott as he hovered on his broomstick. There was sweat staining his uniform, and all the reserve was gone from his voice. "She's attacking both armies! Two brooms covering each force, they pursued me halfway here!"

  Divided her army, what on Earth -

  A large force concentrating fire on a small force could deplete that force rapidly without taking much damage in return. If twenty soldiers faced ten soldiers, twenty sleep spells would be aimed at the ten soldiers with only ten sleep spells going the other way, so unless every one of those first sleep spells hit its target, the smaller force would lose more people than they could manage to take down with them. Defeated in detail was the military term for what happened when you divided your forces like that. What could Hermione possibly be thinking...

  Then Harry realized.

  She's being fair.

  It was going to be a long year in Defense class.

  "All right," Harry said loudly, so the army could hear. "We'll wait until the Red Wing reports in, and then we'll go cloud up some Sunshine."

  Draco listened to the flyers' reports with his face calm, all his shock concealed inside. What could Granger possibly be thinking?

  Then Draco realized.

  It's a feint.

  One of Sunshine's two forces would change direction, and both would converge on... who?

  Neville Longbottom marched through the forest toward the approaching Sunny force, occasionally glancing up at the sky for broomsticks. Beside him marched his squad comrades, Melvin Coote and Lavender Brown of Gryffindor, and Allen Flint of Slytherin. Allen Flint was their Squad Suggester, though Harry had first said to Neville, in private, that the position was his if he wanted it.

  Har
ry had said quite a lot of things to Neville in private, starting with "You know, Neville, if you want to become as awesome as the imaginary Neville who lives in your head but isn't allowed to do anything because you're scared, then you really should sign up for Professor Quirrell's armies."

  Neville was now sure the Boy-Who-Lived could read minds. There was just no other way Harry Potter could've known. Neville had never talked about that with anyone, or given any sign; and other people weren't like that, not that Neville had ever noticed.

  And Harry's promise had come true, this did feel different from sparring in Defense class. Neville had hoped that sparring would fix everything that was wrong with him, and, well, it hadn't. Even if he could fire a few spells at another student in class with Professor Quirrell watching to make sure nothing went wrong, even if he could dodge and fire back when it was allowed and everyone else was expecting it and they would stare at him funny if he didn't do it, none of that was the same as being able to stand up for himself.

  But being part of an army...

  Something strange was stirring inside Neville, as he marched through the forest alongside his comrades, upon their uniforms an insignia of fingers poised to snap.

  He was allowed to walk if he wanted to, but he just felt like marching.

  Beside him, Melvin and Lavender and Allen all seemed to feel like marching too.

  And Neville softly began to sing the Song of Chaos.

  The tune was what a Muggle would have identified as John Williams's Imperial March, also known as "Darth Vader's Theme"; and the words Harry had added were easy to remember.

  Doom doom doom

  Doom doom doom doom doom doom

  Doom doom doom

  Doom doom doom doom doom doom

  DOOM doom DOOM

  Doom doom doom-doom-doom doom doom

  Doom doom-doom-doom doom doom

  Doom doom doom, doom doom doom.