Quote Originally Posted by Flickerdart View Post
See, I think that a ruling should be in a vacuum, because then it's not tainted by the bias of the DM. Physics changing themselves based on why something is happening is something that doesn't sit well with me. An ability that does a thing should do that thing every time. If you make a ruling based on specific contexts, it will bite you in the butt later when your PCs try something else that depends on it working that way. If you don't want them to do that, do you reverse the ruling - and make the thing they did in the past legal?
Often, when this kind of ruling is called for, it has to do with something that isn't easily decided just by looking at what's written. The DM is being asked to write a new law of physics right then and there. Its hard to do that on the spot in a way which is going to be completely future proof against every situation that could come up, especially if its being done in a vacuum of knowing what sorts of situations the player envisions it coming up in. On the other hand, if the DM understands why they're being asked to write a new law of physics, it gives them a better idea of what particular consequences they need to pay very close attention to and be careful about, which drastically reduces the chance that later on they'll need to ret-con their ruling because of something broken or stupid.

To put it another way, in the absence of that information, the safest response that the DM can make for the stability of the game is 'no, you can't do that'. However, that's a very limited and constraining way to play. Giving the DM more information better allows them to sometimes say 'sure, and here's how it will work' without worrying that it's going to break things or that they're being tricked into something.