Abstract

Some legal historians are startled by the fact that Grotius was able to develop a new theory of res communes omnium and mare liberum by using antique ideas whereas these ideas were known in philosophy and jurisprudence throughout the Middle Ages. This contribution shows that Grotius's theory of res communes omnium was innovative only because he developed a new concept of ownership and placed it within a new framework of ius naturale. Both new concepts, ownership and ius naturale, had their predecessors in medieval theology and the jurisprudence of the Spanish Scholastics, but it was Grotius who merged them to a consistent new theory. This theory of res communes also enabled him to reconcile it with both the Roman legal sources and with contemporary practical needs