Quote by Chalnoth
And then tested and verified. They aren't simply assumed by fiat, but people actually go out and test to see whether or not they are true.
Of course, one cannot prove in a strict, mathematical sense that a conservation law always holds. But one can place reasonable limits upon them.

Of course there is a strong basis for the assumption, which I mentioned. I don't agree that laws can be tested for truth or that they can be verified. Those ideas fly in the face of Popper's generally accepted notion of falsifiability. In science we do falsification, not verification. It seems that you just said that though, so I'm not sure there's any real disagreement.