​LIBERTARIANISM (from Lat. libertas, freedom), in ethics, the doctrine which maintains the freedom of the will, as opposed to necessitarianism or determinism. It has been held in various forms. In its extreme form it maintains that the individual is absolutely free to chose this or that action indifferently (the liberum arbitrium indifferentiae), but most libertarians admit that acquired tendencies, environment and the like, exercise control in a greater or less degree.