Eliezer Yudkowsky - Harry Potter and the Methods of Rationality

Harry considered this for a moment. It was a rather seductive line of reasoning -

Good! said Slytherin. I'm glad you see now that the most moral thing to do is to sacrifice the lives of sentient beings for your own convenience, to feed your dreadful appetites, for the sick pleasure of ripping them apart with your teeth -

What? Harry thought indignantly. Which side are you on here?

His inner Slytherin's mental voice was grim. You too will someday embrace the doctrine... that the end justifies the meats. This was followed by some mental snickering.

Ever since Harry had started worrying that plants might also be sentient, his non-Ravenclaw components had been having trouble taking his moral caution seriously. Hufflepuff was shouting Cannibalism! every time Harry tried to think about any food item whatsoever, and Gryffindor would visualize it screaming while he ate it, even if it was, say, a sandwich -

Cannibalism!

AIIIEEEE DON'T EAT ME -

Ignore the screams, eat it anyway! It's a safe place to compromise your ethics in the service of higher goals, everyone else thinks it's okay to eat sandwiches so you can't use your usual rationalization about a small probability of a large downside if you get caught -

Harry gave a mental sigh, and thought, Just so long as you're okay with us being eaten by giant monsters that didn't do enough research into whether we were sentient.

I'm okay with that, said Slytherin. Is everyone else okay with that? (Internal mental nods.) Great, can we go back to deep-fried Diracawl slices now?

Not until I've done some more research into what's sentient and what isn't. Now shut up. And Harry turned firmly away from his plate full of oh-so-tempting vegetables to head toward the library -

Just eat the students, said Hufflepuff. There's no doubt about whether they're sentient.

You know you want to, said Gryffindor. I bet the young ones are the tastiest.

Harry was starting to wonder if the Dementor had somehow damaged their imaginary personalities.

" Honestly ," said Hermione. The young girl's voice sounded a little acerbic as her gaze scanned the bookshelves of the Herbology stacks in the Hogwarts library. Harry had left her a message asking if she could come to the library after she'd finished breakfast, which Harry had skipped; but then when Harry had introduced the day's topic she'd seemed a bit nonplussed. "You know your problem, Harry? You've got no sense of priorities. An idea gets into your head and you just go running straight off after it."

"I've got a great sense of priorities," said Harry. His hand reached out and grabbed Vegetable Cunning by Casey McNamara, and began to flip through the starting pages, searching for the table of contents. "That's why I want to find out whether plants can talk before I eat my carrots."

"Don't you think that maybe the two of us have more important things to worry about?"

You sound just like Draco, Harry thought, but of course didn't say out loud. Out loud he said, "What could possibly be more important than plants turning out to be sentient?"

There was a pregnant silence from beside him, as Harry's eyes went down the table of contents. There was indeed a chapter on Plant Language, causing Harry's heart to skip a beat; and then his hands began to rapidly turn the pages, heading for the appropriate page number.

"There are days," said Hermione Granger, "when I really, truly, have absolutely no idea what goes on inside that head of yours."

"Look, it's a question of multiplication, okay? There's a lot of plants in the world, if they're not sentient then they're not important, but if plants are people then they've got more moral weight than all the human beings in the world put together. Now, of course your brain doesn't realize that on an intuitive level, but that's because the brain can't multiply. Like if you ask three separate groups of Canadian households how much they'll pay to save two thousand, twenty thousand, or two hundred thousand birds from dying in oil ponds, the three groups will respectively state that they're willing to pay seventy-eight, eighty-eight, and eighty dollars. No difference, in other words. It's called scope insensitivity. Your brain imagines a single bird struggling in an oil pond, and that image creates some amount of emotion that determines your willingness to pay. But no one can visualize even two thousand of anything, so the quantity just gets thrown straight out the window. Now try to correct that bias with respect to a hundred trillion sentient blades of grass, and you'll realize that this could be thousands of times more important than we used to think the whole human species was... oh thank Azathoth, this says it's just a few magical plants that can talk and they speak regular human language out loud, not that there's a spell you can use to talk with any plant -"

"Ron came to me at breakfast yesterday morning," Hermione said. Now her voice sounded a little quiet, a little sad, maybe even a little scared. "He said he'd been dreadfully shocked to see me kiss you. That what you said while you were Demented should've shown me how much evil you were hiding inside. And that if I was going to be a follower of a Dark Wizard, then he wasn't sure he wanted to be in my army anymore."

Harry's hands had stopped turning pages. It seemed that Harry's brain, for all its abstract knowledge, was still incapable of appreciating scope on any real emotional level, because it had just forcibly redirected his attention away from trillions of possibly-sentient blades of grass who might be suffering or dying even as they spoke, and toward the life of a single human being who happened to be nearer and dearer.

"Ron is the world's most gigantic prat," Harry said. "They won't be printing that in the newspaper anytime soon, because it's not news. So after you fired him, how many of his arms and legs did you break?"

"I tried to tell him it wasn't like that," Hermione went on in the same quiet voice. "I tried to tell him you weren't like that, and that it wasn't like that between the two of us, but it just seemed to make him even more... more like he was."

"Well, yes," Harry said. He was surprised that he wasn't feeling angrier at Captain Weasley, but his concern for Hermione seemed to be overriding that, for now. "The more you try to justify yourself to people like that, the more it acknowledges that they have the right to question you. It shows you think they get to be your inquisitor, and once you grant someone that sort of power over you, they just push more and more." This was one of Draco Malfoy's lessons which Harry had thought was actually pretty smart: people who tried to defend themselves got questioned over every little point and could never satisfy their interrogators; but if you made it clear from the start that you were a celebrity and above social conventions, people's minds wouldn't bother tracking most violations. "That's why when Ron came over to me as I was sitting down at the Ravenclaw table, and told me to stay away from you, I held my hand out over the floor and said, 'You see how high I'm holding my hand? Your intelligence has to be at least this high to talk to me.' Then he accused me of, quote, sucking you into the darkness, unquote, so I pursed my lips and went schluuuuurp , and after that his mouth was still making those talking noises so I put up a Quieting Charm. I don't think he'll be trying his lectures on me again."

"I understand why you did that," Hermione said, her voice tight, "I wanted to tell him off too, but I really wish you hadn't, it will make things harder for me, Harry!"