Back when I was a teenager and didn't know about LW or any of these turds, HPMoR came across my desk. I read less than five chapters before I realised I couldn't stand the smugness of MC Potter and dropped it. I took the most rational course of action after this and became a HPMoR hater. How could I prove, objectively, that this was a bad fic^[Note: This was just a framing device for this comment. I don't actually "hate" HPMoR. I mostly forgot about it until LW popped up in my life again like ten years later and I when into a K-hole and learned that the Bay Area, where I was soon to move for work, was filled with technofascists.]?

Initially, I was thinking about how it's kind of stupid to take a world with magic in it, then write a story about trying to impose "scientific" or "rational" concepts outside of that world onto it. It's kind of a non-starter in the sense that it feels like the point of a magical setting is to remove some of the annoyances of reality. I mean, that's the entire plot of HP to start with: Potter had a shit life, and now he gets to do dope wizard shit. Bringing in rationality to a magical world would seem to spoil the whole thing.

But then I realised that I don't read that much fiction and that there are probably enough counterexamples where I'm wrong, and that this idea is pulled off well. So I thought some more. How do you write a story that "rationally" talks about magic? I think it's an exercise in worldbuilding. Like, if you're going to write a story about a magical world and call out all the ways it doesn't fit with the economic and scientific models that apply to the mortal world, that kind of necessitates some reasoning about why.

For example, I remember that MC HP points out that you could perform arbitrage by exploiting the exchange rates between gold and silver in the mortal and magic worlds. OK, sure. The only thing that justified why the magical world hadn't closed this loophole was that the mortal and magic worlds were disconnected. My argument is: this is fine if the thing you're explaining is why mortals don't see fairies or dragons fly around every day. It's not fine if you're talking about arbitrage. You're saying that, in the magical world, nobody, at any point, has seen that you can buy something in one place for a lower price than you can sell elsewhere? Yud, of course, lampshades all this with Potter just saying "Boy, are these magical bumpkins stupid."

This is the only example I have to draw on from HPMoR because I ain't gonna read that shit to find more, but I guarantee that Yud never does the research about how all the models and laws and theories he likes to teach actually came about, and which ones would definitely be observable or applicable in the magic world and which wouldn't be.