sounds instead like a universe with a regular and predictable relationship between people's beliefs and events in the world.
Not to mention that at least part of the reality must be sufficiently regular for there to be human-like observers in the first place
Yeah... I'd originally inferred that people and their beliefs somehow predated the universe's laws of physics, but in retrospect that's less narratively likely than some sort of default rule system.
I've been enjoying reading Less Wrong fanfiction, and I wanted to suggest another fandom that should have at least one rationalist fanfiction: Mage: The Awakening. It's a roleplaying game about "modern sorcery." My description can't really do it justice...