With this in mind, a final arbitrator makes a lot of sense. The point isn't to find out how the universe works, make a product that is economical viable and functioning, or determine absolute truth. The point is to keep people from killing each other in the fairest way possible.
It also doesn't have to be consistent. That's why we have laws AND judges. Sometimes the law is wrong because of the context of the specific case. In the US we throw a lot of layers at the problem to try to avoid human tyranny, but at the end of the day human tyranny is preferable to the tyranny of an ambiguously written law.