Answers (2)
A law is something that we can't prove because by definition it is not subject to anything else. The first law is "It is possible to know something." If that were not true then we have nothing to talk about. The second law is "All laws act the same in all cases everywhere." If that is not true then the universe is regulated by magic, not laws. We say that a mass attracts all other masses, but we can't prove that because we can't reach all masses. We can only measure the attraction to nearby masses. That is a poor example because the gravitation constant is not constant and nobody has any idea why.
en.wikipedia.org/wiki/Gravitational_constant
The scientific method:
1. Observe something.
2. Formulate a hypothesis.
3. Devise a test.
4. If the test fails, go to #2.
5. If the test passes and is confirmed, the hypothesis might be promoted to a theory and used to prove other hypotheses. And it might not.