Eliezer Yudkowsky - Harry Potter and the Methods of Rationality

This was different.

The Transfigured Muggle device could explode and kill them.

The interface between the technology and the magic could fail in any number of ways and kill them.

The Aurors could get in a lucky shot.

It was just, well...

Seriously dangerous.

Harry had caught his mind trying to argue itself into believing that it was safe.

And sure, the whole thing could work, but...

But even leaving out that rationalists weren't ever allowed to argue themselves into things, Harry knew he couldn't possibly have argued himself into estimating less than a 20% probability of dying.

Lose, said Hufflepuff.

Lose , said the voice of Professor Quirrell in his mind.

Lose, said his mental model of Hermione and Professor McGonagall and Professor Flitwick and Neville Longbottom and, well, basically everyone Harry knew except for Fred and George, who would have gone for it in a hot second.

He should just go find Dumbledore and turn himself in. He should, he really really should, it was the only sane thing to do at this point.

And if it'd been only Harry on the mission, only his own life that'd been at stake, he would have; he surely would have.

The part that was almost causing him to lose his concentration on the partial Transfiguration he was performing, the part that was threatening to open him to the Dementors...

...was Professor Quirrell, still unconscious, still a snake.

If Professor Quirrell went to Azkaban for his part in the escape, he would die. He probably wouldn't last even a week. He was that sensitive.

It was that simple.

If Harry lost here...

He lost Professor Quirrell.

Even though he's probably evil, said the Hufflepuff part of him quietly. Even so?

It wasn't a decision that Harry had made in any conscious way. He just couldn't do it. Losing was for House points, not people.

If you think your own life is valuable enough that you're not willing to take on an eighty percent probability of dying in order to protect all the prisoners in Azkaban, his Slytherin side observed, there's no way you can justify taking a twenty percent risk to your life to save Bellatrix and Professor Quirrell. The math doesn't add up, you can't be assigning consistent utilities over outcomes here.

The logical side of him noted that Slytherin had just won the argument.

Harry kept the Form in his mind, kept on casting the spell. He could always just abort the mission when he was done with the Transfiguration, he didn't want to lose the effort he'd already invested.

And then Harry thought of something else that suddenly made it very hard to keep the magic going, very hard to keep up his resistance to the Dementors.

What if the portkey doesn't take us where Professor Quirrell said it did?

It was obvious in retrospect the moment he thought about it.

Even if the planned escape went completely right, even if the Muggle device worked and didn't explode and didn't interact badly with the mated magic item, even if the Aurors didn't get in a lucky shot, even if Harry made it far enough away from Azkaban to use the portkey...

...there might not be a psychiatric healer at the end of it.

That was something Harry had believed when he'd trusted Professor Quirrell, and he'd forgotten to re-evaluate it after Professor Quirrell was no longer to be trusted.

You can't do this, said Hufflepuff. At this point we're talking mere stupidity.

Cold seemed to spread through the room, but Harry kept the Transfiguration going, even as his resistance against the Dementors faltered.

I can't lose Professor Quirrell.

He tried to kill a police officer, said Hufflepuff. You already lost him, in that moment. Bellatrix is probably just what everyone thinks she is. Just take your Cloak back, go find Dumbledore and tell him you were tricked.

No, thought Harry desperately, not without talking to Professor Quirrell, there might be an explanation, I don't know, maybe he was standing far enough away from my Patronus that the Dementors got to him... I don't understand, it doesn't make sense on any hypothesis, why he would do that... I can't just...

Harry turned his mind away from that chain of thought before it completely broke his resistance to the fear, because he couldn't think of feeding Professor Quirrell to Dementors while staying resolved against Death, it was a cognitive impossibility.

Your reasoning is artificially impaired, observed the logical part of him calmly, find a way to unimpair it.

All right, let's just generate alternatives, Harry thought. Not choose, not weigh, certainly not commit... just think about what else I might be able to do besides the original plan.

And Harry went on cutting the hole in the wall. He was using partial Transfiguration on a thin cylindrical shell of metal, two meters in diameter and half a millimeter thick, running all the way through the wall. He was Transfiguring that half-millimeter thickness of metal into motor oil. Motor oil was a liquid and you weren't to Transfigure liquids because they might evaporate, but he and Bellatrix and the snake all had Bubble-Head Charms. And Harry would cast Finite on the oil immediately after, dispelling his own Transfiguration...

...as soon as the separated and lubricated hunk of metal slid out of the wall and onto the floor of their cell, he'd slanted it so gravity would pull it in, once the Transfiguration was done.

If Harry and Bellatrix didn't exit on his broomstick through the resulting hole in the wall...

Harry's brain suggested that he could try to Transfigure a surface cover over the hole in the wall, leaving a space for Bellatrix and Professor Quirrell to hide in, wearing the Cloak, while Harry turned himself in. And Professor Quirrell would eventually wake up, and he and Bellatrix could try to figure out how to exit Azkaban on their own.

It was, first of all, a dumb idea, and second, there would still be a huge hunk of metal on the floor of the cell, which would give it away.

And then Harry's brain saw the obvious.

Let Bellatrix and Professor Quirrell use the escape route you invented. You stay behind, and turn yourself in.

Bellatrix and Professor Quirrell were the ones whose lives were at stake.

They were gaining, not losing, from taking the risk.

And there was no reason, no sane reason at all, for Harry to go with them.

A calm came over Harry as he thought it, the cold and darkness that had been wavering around the fringes of his mind retreated. Yes, that was it, that was the creative outside-the-box route, that was the hidden third alternative. The falseness of the dilemma was obvious in retrospect. If Harry turned himself in, he didn't have to turn in Bellatrix and Professor Quirrell. If Bellatrix and Professor Quirrell took a dangerous escape route, Harry didn't need to go with them.

Harry didn't even need to face the embarrassment of admitting he'd been tricked, if he ordered Bellatrix to remove the memory. Everyone would just assume he'd been kidnapped, including Harry himself. Admittedly, there was no plausible reason why the Dark Lord would ever ask Bellatrix to do that; but Harry could simply smile and tell Bellatrix she wasn't allowed to know, and that would be that...

Her Auror team had gotten around three-quarters of the way down Azkaban, as had the other two teams on the other two spirals. Amelia was feeling tenser already, though she was betting on the criminals hiding on the second-to-lowest floor, part of her wished Dumbledore had thought to check that specific floor more carefully and part of her was glad he hadn't.