>>We say "theory of gravity," too, but I don't run into too many people who refer to gravity as "just a theory."
Clearly gravity is just a theory, otherwise everybody in the Southern Hemisphere who isn't holding on would slide down towards Antarctica and then fall off.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
