Not necessarily true:
A hypothesis is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires....
researchmethod.net
Theoretically, that is true.
Theoretically, if I shot you in one foot with a 12 ga. shotgun and it hurt like hell, that does in no way prove that if I shot you in the other foot with a 12 ga. it would also hurt.
I really doubt that you want me to shoot you in either foot with a 12 ga. to see whether it would hurt ... right?
See? Some things go beyond simple "beliefs".
Jim