necessitarian n 1: someone who does not believe the doctrine of free will [ant: {libertarian}]
Necessitarian \Ne*ces`si*ta"ri*an\, a. Of or pertaining to the doctrine of philosophical necessity in regard to the origin and existence of things, especially as applied to the actings or choices of the will; -- opposed to {libertarian}. [1913 Webster]
Necessitarian \Ne*ces`si*ta"ri*an\, n. One who holds to the doctrine of necessitarianism. [1913 Webster]