Eliezer Yudkowsky - Harry Potter and the Methods of Rationality

After Harry had run out of available magic he’d started tearing off branches with his bare hands and snapping them. His hands were bleeding, though nothing that Madam Pomfrey couldn’t fix in the morning. Only Dark magic left permanent scars on wizards.

There came a sound of something moving in the woods, like the hoofbeats of a horse, and Harry whirled, his wand rising once more; some part of his magic had returned while he was working with his hands. It occurred to him for the first time that he was out in the Forbidden Forest alone, and making noise.

What emerged into the moonlight was not the unicorn Harry had expected, but a creature with a lower body like that of a horse, gleaming white-brown beneath the moonlight, and the bare upper chest of a male human with long white hair. The moonlight caught the centaur’s face, and Harry saw that the eyes were almost as blue as Dumbledore’s, halfway to sapphire.

In one hand the centaur held a long wooden spear, with an overlarge metal blade whose edge did not gleam beneath the moonlight; a gleaming edge, Harry had once read, was the sign of a dull blade.

“So,” the centaur said. His voice was low, powerful and male. “Here you are, surrounded by destruction. I can smell the unicorn’s blood in the air, the blood of something innocent, slain to save oneself.”

A jolt of sudden fear brought Harry into the now, and he said quickly,

“It’s not what it looks like.”

“I know. The stars themselves proclaim your innocence, ironically enough.” The centaur took a step toward Harry within the small clearing, still holding his spear upright. “A strange word, innocence. It means lack of knowledge, like the innocence of a child, and also means lack of guilt. Only those entirely ignorant can lack all responsibility for the consequences of their actions. He knows not what he does, and therefore can be without harmful intent; so says that word.” The deep voice did not echo in the woods.

Harry’s eyes flickered to the spear-tip, and he realized that he should have grabbed his Time-Turner the moment he saw the centaur. Now, if Harry tried to reach beneath his robes, the spear could strike him before then, if the centaur was fast enough. “I read once,” Harry said, his voice a bit unsteady as he tried to match deep-sounding words to deep-sounding words, “that it’s wrong to think of little children as innocent, because not knowing isn’t the same as not choosing. That children do little harms to each other with schoolyard fights, because they don’t have the power to do great harm. And some adults do great harm. But the adults who don’t, aren’t they more innocent than children, not less?” “The wisdom of wizards,” the centaur said.

“Muggle wisdom, actually.”

“Of the magicless I know little. Mars has been dim of late, but it grows brighter.” The centaur took another step forwards, bringing him almost

within striking distance of Harry.

Harry didn’t dare look up to the sky. “That means Mars is coming closer to the Earth, as both planets go around the Sun. Mars is reflecting the same amount of sunlight as always, it’s just getting nearer to us. What do you mean, the stars proclaim my innocence?”

“The night sky speaks to centaurs. It is how we know what we know. Or do they not even tell wizards that much, these days?” A look of contempt crossed the centaur’s face.

“I… tried to look up centaurs, when I was checking out Divination. Most of the authors just ridiculed centaur Divination without explaining why, wizards don’t understand argumentative norms, to them ridiculing an idea or a person feels like casting that idea down just as much as bringing evidence against it… I thought the part about centaurs using astrology was just more ridicule…”

“Why?” the centaur intoned. His head cocked curiously.

“Because the course of the planets is predictable for thousands of years in advance. If I talked to the right Muggles, I could show you a diagram of exactly what the planets will look like from this spot ten years later. Would you be able to make predictions from that?”

The centaur shook his head. “From a diagram? No. The light of the planets, the comets, the subtle shifts in the stars themselves, those I would not see.”

“Cometary orbits are also set thousands of years in advance so they shouldn’t correlate much to current events. And the light of the stars takes years to travel from the stars to Earth, and the stars don’t move much at all, not visibly. So the obvious hypothesis is that centaurs have a native magical talent for Divination which you just, well, project onto the night sky.”

“Perhaps,” the centaur said thoughtfully. His head lowered. “The others would strike you for saying such a thing, but I have ever sought to know what I do not know. Why the night sky can foretell the future— that I surely do not know. It is hard enough to grasp the skill itself. All I can say, son of Lily, is that even if what you are saying is true, it does not seem useful.”

Harry allowed himself to relax a little; being addressed as ‘son of Lily’ implied that the centaur thought of him as more than a random intruder in the forest. Besides, attacking a Hogwarts student would probably bring some kind of huge reprisal upon the non-wizard centaur tribe in the forests, and the centaur probably knew that… “What Muggles have learned is that there is a power in the truth, in all the pieces of the truth which interact with each other, which you can only find by discovering as many truths as possible. To do that you can’t defend false beliefs in any way, not even by saying the false belief is useful. It might not seem to matter whether your predictions are really based on the stars or if it’s an innate talent being projected. But if you wanted to really understand Divination, or for that matter the stars, the real truth about centaur predictions would be a fact that matters to other truths.”

Slowly the centaur nodded. “So the wandless have become wiser than the wizards. What a joke! Tell me, son of Lily, do the Muggles in their wisdom say that soon the skies will be empty?”

“Empty?” Harry said. “Er… no?”

“The other centaurs in this forest have stayed from your presence, for we are sworn not to set ourselves against the heavens’ course. Because, in becoming entangled in your fate, we might become less innocent in what is to come. I alone have dared approach you.”

“I… don’t understand.”

“No. You are innocent, as the stars say. And to slay something innocent to save oneself, that is a terrible deed. One would live only a cursed life, a half-life, from that day. For any centaur would surely be cast out, if he slew a foal.”

The spear made a lightning motion, too fast for Harry’s eyes to follow, and smashed his wand out of his hand.

Another powerful blow smashed into Harry’s solar plexus, and he went gasping and retching to the forest floor.

Harry’s hand reached up toward his robes, for his Time-Turner, and the spear-butt knocked his hand away, almost hard enough to break fingers, he reached with his other hand and that was knocked away too—

“I am sorry, Harry Potter,” the centaur said, and then looked up with widened eyes. The spear spun about and came up, intercepting a red spellbolt. Then the centaur dropped the spear and leaped away desperately, a green flash of light went past him and another green flash of light followed in its wake, then a third green flash hit the centaur straight-on.

The centaur fell and did not move again.

It took a long time for Harry to catch his breath, to stagger to his feet, to pick up his wand, to croak, “What?”

By that time the sense of doom, of power almost tangible in the air, had approached once more.