the answer to "can I move this candle" is "it's complicated".

I think there's a principle at work here. I suspect that this has been expressed more formally. But...

... laws proposed to govern human behavior -- which is complicated -- can only anticipate a portion of that behavior. Lawmakers may enact the most rigid, black-and-white, unambiguous law you could imagine, but it must be expressed in words more ambiguous than the words used in mathematics. There will be a grey area, and human action will find that grey area. It will be complicated on the fringes.

This applies to any system of law by which humans are to govern themselves, Halacha just as much as the United States Code of Federal Regulations.