Well, no. Absence of proof is not proof of absence. Anyhow, man can breathe under water. I even have photos of people breathing under water as evidence:
It would be if you actually demonstrated it. You haven't. Until either side is demonstrated, the assertion's truth is undefined. You don't just "win" by default.
Yes, but in the meantime, the mere fact that a person hasn't presented you with that evidence does not make a claim that will be debunked true. And the only way we can distinguish between a claim that will be debunked and a claim that won't be is to demonstrate that it's true on its own merits.
Until the modern age of spaceflight, it could not be proven conclusively that the moon was not made out of cheese. Does that mean that before this point in history, the claim "the moon is made out of cheese" was valid and true?
Anyhow, if you really do believe that unrefutable things must be valid and true, then I have a teapot to sell you.
Response: Post 112 proves to the contrary.