Necessarily or demonstrably true:
— Demonstrable truths.

synonym: incontrovertible.

Roget 478: demonstrating etc. v., demonstrative, demonstrable; probative, unanswerable, conclusive; apodictic^†, apodeictic^†, apodeictical^†; irresistible, irrefutable, irrefragable; necessary.    categorical, decisive, crucial.    demonstrated etc. v.; proven; unconfuted^†, unanswered, unrefuted^†; evident etc. 474.    deducible, consequential, consectary^†, inferential, following.    [demonstrated to one's satisfaction] convincing, cogent, persuasive (believable) 484.    ... show more

Capable of being demonstrated or proved:
— A demonstrable lack of concern for the general welfare.

synonym: provable.