S'mon said:I'm definitely in the "The rules are not the physics of the world. The rules are to facilitate gameplay" camp - rules facilitate interaction between players and game-universe, they don't define that universe. For one thing I might well use different rule sets for the same game world (for my primary world I've used AD&D, Warhammer Battle, my homebrew STIRPS system, D&D 3e, etc); the physics of the world doesn't change depending on the ruleset, although there can be minor conversion difficulties - eg before 3e, AD&D had no spontaneous casting, whereas Warhammer & STIRPS have point-based casting. Luckily changes in magic in my world are easily explained by the Flux, the variable electromagicomagnetic field surrounding the planet.
IOW, you *did* change your setting when you changed rulesets, even if it's just in one area, and even if you had an element of your setting that allowed it without "breaking" the setting. So, the "physics" changed because you changed rulesets. I don't understand how your example supports your point.
Maybe we're just having a semantic misunderstanding, and we actually agree? Because your description is exactly what i mean when i refer to the rules defining the behavior of the world, at least to some degree.