Ibn Sina’s Arguments Against God’s Being a Substance

Abstract

In this paper I will provide an analysis of Avicenna's argument for the thesis that God is not a substance, and compare it with an argument for the same conclusion in Aquinas. In order to understand the argument, it will be necessary to examine Avicenna's concept of substance and how he distinguishes existence and quiddity (whatness). Avicenna begins with the two part Aristotelian definition of a substance as that which is neither in a subject nor predicated of a subject. It is the first part that is the focus of attention in Avicenna's argument, according to which this condition requires contingency. The argument is interesting for at least three reasons: (1) its significance in Islamic philosophical theology; (2) its similarities and differences with a Thomistic argument for the same conclusion; (3) the need for a logic of singular terms that refer to non-existents.