Harry Potter and the Methods of Rationality

'I see,' Harry Potter said, it wasn't a shout so Padma had to strain to hear it. 'Professor Quirrell isn't here to explain to me how stupid people are, but I bet this time I can get it on my own. People do something dumb and get caught and are given Veritaserum. Not romantic master criminals, because they wouldn't get caught, they would have learned Occlumency. Sad, pathetic, incompetent criminals get caught, and confess under Veritaserum, and they're desperate to stay out of Azkaban so they say they were False-Memory-Charmed. Right? So your brain, by sheer Pavlovian association, links the idea of False Memory Charms to pathetic criminals with unbelievable excuses. You don't have to consider the specific details, your brain just pattern-matches the hypothesis into a bucket of things you don't believe, and you're done. Just like my father thought that magical hypotheses could never be believed, because he'd heard so many stupid people talking about magic. Believing a hypothesis that involves False Memory Charms is low- status.'

'What are you blithering about?' said Morag, looking down her nose at the Boy-Who- Lived.

'You think we'd believe anything you say?' yelled a slightly older-looking Ravenclaw witch who Padma didn't recognize. 'When you turned Granger Dark?'

'And I'm not going to complain,' Harry Potter said in an eerily calm voice, 'about wizards not having any logic and believing the craziest things. Because I said that to Professor Quirrell once, and he just gave me this look and said that if I wasn't blinded by my upbringing I could think of a hundred more ridiculous things that lots of Muggles believe. What you're all doing is very human and very normal and doesn't make you unusually bad people, so I'm not going to complain.' The Boy-Who-Lived rose up from his bench. 'I'll see you all later.'

And Harry Potter walked away from them, walked away from all of them.

'You're not thinking he's right, are you?' said Su Li from beside her, in a tone which made it clear what she thought.

'I -' said Padma. Her words seemed to be caught in her throat, her thoughts seemed to be caught in her head. 'I - I mean - I -'

If you think hard enough you can do the impossible.

(It had always been an article of faith with Harry. There'd been a time when he'd acknowledged the laws of physics as ultimate limitations, and now he suspected there were no true limits at all.)

If you think fast enough you can sometimes do the impossible quickly...

...sometimes.

Only sometimes.

Not always.

Not reliably.

The Boy-Who-Lived stared around the trophy room, surrounded by awards and cups and plates and shields and statues and medals kept behind thousands, perhaps tens of thousands, of crystal glass displays. For as many centuries as Hogwarts had existed, this room had been accumulating details. A week, a month, maybe even a year, wouldn't have sufficed to take the 'examine' option on every item in the room. With Professor Flitwick gone, Harry had asked Professor Vector if there was any way to detect damage to the wards around the crystal cases, verify the residue that a real duel should have left behind. Harry had raced through the Hogwarts library looking for spells to tell the difference between old fingerprints and new fingerprints, or to detect lingering exhalations in a room. And all those attempts at playing detective had failed.

There were no clues, none that he was smart enough to find.

Professor Snape had said that the portkey led to an empty house in London, with no sign of anyone or anything else.

Professor Snape hadn't found any notes in Hermione's dorm.

Headmaster Dumbledore had said that Voldemort's spirit was probably hiding out in the Chamber of Secrets where the Hogwarts security system couldn't find him. Harry had snuck into the Slytherin dungeons under the Cloak of Invisibility and spent the rest of the afternoon looking through all the obvious places, but he hadn't found anything snaky that answered back when spoken to. The entrance to the Chamber of Secrets, it seemed, hadn't been meant to be found in a day.

Harry had talked to all of Hermione's friends that would still talk to him, and none of them had remembered Hermione saying anything specific about why she'd believed that Draco was plotting against her.

Professor Quirrell hadn't come back from the Ministry as of dinnertime. The older students seemed to think that this year's Defense Professor would probably end up being blamed for the incident, and fired for teaching Hogwarts students to be too violent. They'd talked about the Defense Professor as though he were already gone.

Harry had used up all six hours from his Time-Turner, and there were still no clues, and he had to go to sleep now if he wanted to be functional at Hermione's trial the next day.

The Boy-Who-Destroyed-A-Dementor was standing in the middle of the Hogwarts trophy room, his wand dropped at his feet.

He was crying.

Sometimes you call your brain and it doesn't answer.

The trial of Hermione Granger started on schedule the next day.

Chapter 80: Taboo Tradeoffs, Pt 2, The Horns Effect

The Most Ancient Hall of the Wizengamot is cool and dark, with concentric half-circles of stone rising up from the lowest center, and simple wooden benches set down upon those elevated half-circles. There is no source of light, but the chamber is well-lit, without any apparent cause or reason; it is simply a brute fact that the hall is well-lit. The walls like the floor are stone, dark stone, some elegant and mysterious conjugation of rock most fine to gaze upon, with a smooth texture that seems to flow and shift beneath its surface. This is the Most Ancient Hall, the oldest place of wizardry that has lasted into the modern day; every other place of power was destroyed in one war or another. This is the Hall of the Wizengamot, which is most ancient because the wars ended with the building of this place.