So it's something that's not a scientific hypothesis, but is considered knowledge!
(Or, if as in the other comment chain, 1+1=2 is too obvious, you can take any sufficiently non-trivial theorem of your choosing).
(Or, if as in the other comment chain, 1+1=2 is too obvious, you can take any sufficiently non-trivial theorem of your choosing).
You can investigate whether it is consistent with other definitions. I believe that doing so is empirical work, which I think is consistent with a broad notion of science