By “first principles” you mean the indubitably true but unprovable elementary principles of all our knowledge.
It is undemonstrated and unproved—in fact, may truthfully be said to be undemonstrable and unprovable.
Godliness in men is latent, invisible, unprovable as to the sincerity of it, and obscure as to the exercise.
The heaven of the churches and chapels is remote, unprovable, and cannot affect her in the smallest degree.
That the unprovable is necessarily the unknowable, a thousand beliefs deny.
A difficult possibility to conceive of individual intelligence and if unprovable against the theory of existence after death.
He does not specify this unprovable, complex, unplausible, and useless hypothesis.
This answer, too, seems to entail an unprovable assumption which should not be made without explicit evidence.
There are the strongest ethical and religious reasons for refusing to accept this unproved and unprovable dogma.
late 12c., pruven, proven "to try, test; evaluate; demonstrate," from Old French prover, pruver "show; convince; put to the test" (11c., Modern French prouver), from Latin probare "to make good; esteem, represent as good; make credible, show, demonstrate; test, inspect; judge by trial" (source also of Spanish probar, Italian probare), from probus "worthy, good, upright, virtuous," from PIE *pro-bhwo- "being in front," from *pro-, extended form of root *per- (1) "forward, through" (see per), + root *bhu- "to be" (cf. Latin fui "I have been," futurus "about to be;" Old English beon "to be;" see be). Related: Proved; proven; proving.