CONCLUSIVE. What puts an end to a thing. A conclusive presumption of law, is one which cannot be contradicted even by direct and positive proof. Take, for example, the presumption that an infant is incapable of judging whether it is or is not against his interest; When infancy is pleaded and proved, the plaintiff cannot show that the defendant was within one day of being of age when the contract was made, and perfectly competent to make a contract. 3 Bouv. Inst. n. 3061.