Harry Potter and the Methods of Rationality

discover today?'

'I discovered,' said Harry through gritted teeth, 'that when it comes to doing truly basic research on a genuinely confusing problem where you have no clue what's going on, my books on scientific methodology aren't worth crap -'

'Language, Mr. Potter! Some of us are innocent young girls!'

'Fine. But if my books were worth a carp, that's a kind of fish not anything bad, they would have given me the following important piece of advice: When there's a confusing problem and you're just starting out and you have a falsifiable hypothesis, go test it. Find some simple, easy way of doing a basic check and do it right away. Don't worry about designing an elaborate course of experiments that would make a grant proposal look impressive to a funding agency. Just check as fast as possible whether your ideas are false before you start investing huge amounts of effort in them. How does that sound for a moral?'

'Mmm... okay,' said Hermione. 'But I was also hoping for something like 'Hermione's books aren't worthless. They're written by wise old wizards who know way more about magic than I do. I should pay attention to what Hermione's books say.' Can we have that moral too?'

Harry's jaw seemed to be clenched too tightly to let any words out, so he just nodded.

'Great!' Hermione said. 'I liked this experiment. We learned a lot from it and it only took me an hour or so.'

'AAAAAAAAAAAAAAHHHHHHHHHHHHHHH!'

In the dungeons of Slytherin.

An unused classroom lit with eerie green light, much brighter this time and coming from a small crystal globe with a temporary enchantment, but eerie green light nonetheless, casting strange shadows from the dusty desks.

Two boy-sized figures in cowled grey cloaks (no masks) had entered in silence, and sat down in two chairs opposite the same desk.

It was the second meeting of the Bayesian Conspiracy.

Draco Malfoy hadn't been sure if he should look forward to it or not.

Harry Potter, judging by the expression on his face, didn't seem to have any doubts on the appropriate mood.

Harry Potter looked like he was ready to kill someone.

'Hermione Granger,' said Harry Potter, just as Draco was opening his mouth. 'Don't ask.'

He couldn't have gone on another date, could he? thought Draco, but that didn't make any sense.

'Harry,' said Draco, 'I'm sorry but I have to ask this anyway, did you really order the mudblood girl an expensive mokeskin pouch for her birthday?'

'Yes, I did. You've already worked out why, of course.'

Draco reached up and raked fingers through his hair in frustration, his cowl brushing the back of his hand. He hadn't been quite sure why, but now he couldn't say so. And Slytherin knew he was courting Harry Potter, he'd made it obvious enough in Defense class. 'Harry,' said Draco, 'people know I'm friends with you, they don't know about the Conspiracy of course, but they know we're friends, and it makes me look bad when you do that sort of thing.'

Harry Potter's face tightened. 'Anyone in Slytherin who can't understand the concept of acting nice toward people you don't actually like should be ground up and fed to pet snakes.'

'There are a lot of people in Slytherin who don't,' Draco said, his voice serious. 'Most people are stupid, and you have to look good in front of them anyway.' Harry Potter had to understand that if he ever wanted to get anywhere in life.

'What do you care what other people think? Are you really going to live your life needing to explain everything you do to the dumbest idiots in Slytherin, letting them judge you? I'm sorry, Draco, but I'm not lowering my cunning plots to the level of what the dumbest Slytherins can understand, just because it might make you look bad otherwise. Not even your friendship is worth that. It would take all the fun out of life. Tell me you haven't ever thought the same thing when someone in Slytherin is being too stupid to breathe, that it's beneath the dignity of a Malfoy to have to pander to them.'

Draco genuinely hadn't. Ever. Pandering to idiots was like breathing, you did it without thinking about it.

'Harry,' Draco said at last. 'Just doing whatever you want, without worrying about how it looks, isn't smart. The Dark Lord worried about how he looked! He was feared and hated, and he knew exactly what sort of fear and hate he wanted to create. Everyone has to worry about what other people think.'

The cowled figure shrugged. 'Perhaps. Remind me sometime to tell you about something called Asch's Conformity Experiment, you might find it quite amusing. For now I'll just note that it's dangerous to worry about what other people think on instinct, because you actually care, not as a matter of cold-blooded calculation. Remember, I was beaten and bullied by older Slytherins for fifteen minutes, and afterward I stood up and graciously forgave them. Just like the good and virtuous Boy-Who-Lived ought to do. But my cold-blooded calculations, Draco, tell me that I have no use for the dumbest idiots in Slytherin, since I don't own a pet snake. So I have no reason to care what they think about how I conduct my duel with Hermione Granger.'

Draco did not clench his fists in frustration. 'She's just some mudblood,' Draco said, keeping his voice calm, rather than shouting. 'If you don't like her, push her down the stairs.'

'Ravenclaw would know -'

'Have Pansy Parkinson push her down the stairs! You wouldn't even have to manipulate her, offer her a Sickle and she'd do it!'

'I would know! Hermione beat me in a book-reading contest, she's getting better