Introduction

The Christian faith confesses the openness of God and the openness of His reality. Classic Christian theology translates this openness into a structured concept of God by stating that the one divine nature (una substantia: Tertullian) knows of three divine Persons (tres personae: Tertullian). We see that a closed concept of God is rejected, since the concepts of natura and persona do not coincide. We may describe an absolutely closed concept of God as a concept where the notions of natura and persona coincide. The alternative form of monotheism knows of two processions (processiones) between the three Persons, which are generally acknowledged in thirteenth-century theology in terms of divine knowledge and will (Albert the Great and Thomas Aquinas, Bonaventure and Duns Scotus).

We focus on the first production or procession which is the generation of the Son by the Father: the Father brings forth the Son, the Father generates the Son. The generation is eternal reality: it is the eternal reality of an invariable act of God in God (opus ad intra) and this activity of generation presupposes the potency to generate:

1. If the Father generates the Son, then it is possible that the Father generates the Son.

However, the Aristotelian notion of potency (possibility) cannot elucidate this theological proposition. On the contrary, it makes it inconsistent. Aristotelian philosophy of nature and change is based on potency language, but if we apply this notion of potency to (1), the consequent

1. It is possible that the Father generates the Son

entails that by now there is no generation.