Scientific reasoning has brought humanity to incredibly high levels of sophistication in all realms of knowledge. For Saint Thomas Aquinas, his passion involved the scientific reasoning of God. The existence, simplicity and will of God are simply a few topics which Aquinas explores in the Summa Theologica. Through arguments entailing these particular topics, Aquinas forms an argument that God has the ability of knowing and willing this particular world of contingent beings. The contrasting nature of necessary beings and contingent beings is at the heart of this debate.
Aquinas sets up this argument in his discussion of whether or not God exists. His five proofs set up the framework for much of his later writings in the Summa Theologica. As with the five proofs in their entirety, most of Aquinas' reasoning stems from the third proof concerning the existence of God. The first two proofs lead to the third's conclusion that God is "esse a se", or to be of itself. From this conclusion of God as an infinite being, Aquinas moves to the third question, concerning the simplicity of God. In article four of question three, Aquinas determines that God is ultimately simple in that his essence does not differ from his being. He writes, "Therefore, since in God there is no potentiality, it follows that in Him essence does not differ from being. Therefore, His essence is His being." God is an unchanging, infinite being. There is no conceivable way in which he could have parts, such as a separate being and a separate essence. From these proofs and others, Aquinas determines that God is an all knowing, perfectly good, perfectly powerful being. Moving back to the third pr ...