Abstract

The Stoic system is alternatively described as “dualist” because its physics relies on two principles, God and matter, or as “monist”, because these two principles are intimately linked, and belong to the same body. It is difficult to describe the Stoic system as monist, since every substance is a body, and the two principles, while united in the same body, coexist from all eternity since matter is not created by God. But it is inappropriate as well to describe it as “dualist”, because the inferior principle is completely passive and is not a cause, but endures the effect of the active cause. Moreover, matter is not responsible for evil, even if some interpreters, ancient and modern, claimed it : the only metaphysical principle which accounts for the existence of evil is the “affinity of the contraries”, according to which good cannot exist without evil and agent without patient, but this is not a dualist explanation.