n. A term invented, by Sir William Hamilton to denote the doctrine of the necessitarian philosophers, who hold that man's actions are uniformly determined by motives acting upon his character, and that he has not the power to choose to act in one way so long as he prefers on the whole to act in another way.n. In general, the doctrine that whatever is or happens is entirely determined by antecedent causes; the doctrine that the science of phenomena consists in connecting them with the antecedent conditions of their existence.