Harry Potter and the Methods of Rationality

And Severus Snape himself might or might not be even remotely trustworthy.

Someone had declared war against Harry, their first strike had been meant to take out Draco and Hermione both, and it was only by the barest of margins that Harry had saved Hermione.

You couldn't call it victory. Draco had been removed from Hogwarts, and if that wasn't death, it wasn't clear how it could be undone, or what shape Draco might be in when he got back. The country of magical Britain now thought Hermione an attempted-murderer, which might or might not make her decide to do the sane thing and leave. Harry had sacrificed his entire fortune to undo his loss, and that card could only be played once.

Some unknown power had struck at him, and if that blow had been partially deflected, it had still hit really hard.

At least his dark side hadn't asked anything of him in exchange for saving Hermione. Maybe because his dark side wasn't an imaginary voice like Hufflepuff; Harry might imagine his Hufflepuff part as wanting different things from himself, but his dark side wasn't like that. His "dark side", so far as Harry could tell, was a different way that Harry sometimes was. Right now, Harry wasn't angry; and trying to ask what "dark Harry" wanted was a phone ringing unanswered. The thought even seemed a little strange; could you owe something to a different way you sometimes were?

Harry stared up at the random stars, the scattered twinkling lights that human brains couldn't help but pattern-match into imaginary constellations.

And then there was that promise Harry had sworn.

Draco to help Harry reform Slytherin House. And Harry to take as an enemy whomever Harry believed, in his best judgment as a rationalist, to have killed Narcissa Malfoy. If Narcissa had never gotten her own hands dirty, if indeed she'd been burned alive, if the killer hadn't been tricked - those were all the conditions Harry could remember making. He probably should've written it down, or better yet, never made a promise requiring that many caveats in the first place.

There were plausible outs, for the sort of person who'd let themselves rationalize an out. Dumbledore hadn't actually confessed. He hadn't come right out and said he'd done it. There were plausible reasons for an actually-guilty Dumbledore to behave that way. But it was also what you'd expect to see, if someone else had burned Narcissa, and Dumbledore had taken credit.

Harry shook his head, flattening one side of his hair and then another against the stone-tiled floor. There was still a final out, Draco could still release him from the oath at any time. He could, at least, describe the situation to Draco, and talk about options with him, when they met again. It didn't seem like a very likely prospect for release - but the idea of talking something over honestly was enough to satisfy the part of himself that demanded adherence to oaths. Even if it only meant delaying, it was better than taking a good man as an enemy.

But is Dumbledore a good man? asked the voice of Hufflepuff. If Dumbledore burned someone alive - wasn't the whole point that good people may kill, but never kill with suffering?

Maybe he killed her instantly, said Slytherin, and then lied to Lucius about the burning-alive part. But... if there was any possibility of the Death Eaters magically verifying how Narcissa died... and if being caught in a lie would've endangered Light-side families...

Be careful what we cleverly rationalize, warned Gryffindor.

You have to expect reputational effects on how other people treat you, said Hufflepuff. If you decide there's sufficient reason to burn a woman alive, one of the predictable side effects is that good people decide you've crossed the line and have to be stopped. Dumbledore should've expected that. He's got no right to complain.

Or maybe he expects us to be smarter, said Slytherin. Now that we know this much of the truth - no matter the exact details of the full story - can we really believe that Dumbledore is a terrible, terrible person who ought to be our enemy? In the middle of a horrible bloody war, Dumbledore set one enemy civilian on fire? That's only bad by the standards of comic books, not by any sort of realistic historical standard.

Harry stared up at the night sky, remembering history.

In real life, in real wars...

During World War II, there had been a project to sabotage the Nazi nuclear weapons program. Years earlier, Leo Szilard, the first person to realize the possibility of a fission chain reaction, had convinced Fermi not to publish the discovery that purified graphite was a cheap and effective neutron moderator. Fermi had wanted to publish, for the sake of the great international project of science, which was above nationalism. But Szilard had persuaded Rabi, and Fermi had abided by the majority vote of their tiny three-person conspiracy. And so, years later, the only neutron moderator the Nazis had known about was deuterium.

The only deuterium source under Nazi control had been a captured facility in occupied Norway, which had been knocked out by bombs and sabotage, causing a total of twenty-four civilian deaths.

The Nazis had tried to ship the deuterium already refined to Germany, aboard a civilian Norwegian ferry, the SS Hydro.

Knut Haukelid and his assistants had been discovered by the night watchman of the civilian ferry while they were sneaking on board to sabotage it. Haukelid had told the watchman that they were escaping the Gestapo, and the watchman had let them go. Haukelid had considered warning the night watchman, but that would have endangered the mission, so Haukelid had only shaken his hand. And the civilian ship had sunk in the deepest part of the lake, with eight dead Germans, seven dead crew, and three dead civilian bystanders. Some of the Norwegian rescuers of the ship had thought the German soldiers present should be left to drown, but this view had not prevailed, and the German survivors had been rescued. And that had been the end of the Nazi nuclear weapons program.

Which was to say that Knut Haukelid had killed innocent people. One of whom, the night watchman of the ship, had been a good person. Someone who'd gone out of his way to help Haukelid, at risk to himself; from the kindness of his heart, for the highest moral reasons; and been sent to drown in turn. Afterward, in the cold light of history, it had looked like the Nazis had never been close to getting nuclear weapons after all.

And Harry had never read anything suggesting that Haukelid had acted wrongly.