1) Certainty 2) Provability 
• (n.) The quality of being demonstrable; demonstrableness.
De·mon`stra·bil'i·ty noun The quality of being demonstrable; demonstrableness. 
[n] - capability of being demonstrated or logically proved
demonstrable, demonstrability 1. The capability of being demonstrated or logically proven. 2. Obvious or apparent: Her lies were demonstrable. 3. So obvious as to be readily recognized. 4. Capable of being shown to exist or to be true: 'There was demonstrable proof that he set the fire.'
provability noun capability of being demonstrated or logically proved