Whether God is One?

In question 11 of the Summa, Aquinas discusses the unity of God. I will focus on article 3: Whether God is One? (Ia.11.3).

As usual, Aquinas begins the article with objections to the notion of God being One: "One, as the principle number, cannot be predicated of God". Furthermore, it is said in Corinthians that "there are many gods and many lords"(1 Cor 8:5).

But, as I have come to expect, Aquinas does have an answer to this fundamental question of the number of God, whether He is one or many.

"Respondeo dicendum quod Deum esse unum, ex tribus demonstratur"  (I answer that it can be shown from these three sources that God is One).

1. From God's simplicity we know that God is One. Aquinas gives an example of Socrates being a man: being a man is predicated of both Socrates and many other men, but being Socrates is predicated of only one, namely Socrates. In this way it is clear that Socrates is a particular member of the human race. But in the case of God, He is His own nature, as shown in Ia.3.3, and therefore it is impossible that many gods could exist. 
2. By definition and as proved in Ia.4.2, within God is contained the perfection of being. Now, if many gods existed, they would necessarily differ from one another otherwise they would not be many. Furthermore, there would be things that would belong to one which did not belong to another; if a privation, one of them would not be perfect, and if a perfection, then one of them would be without it as they must differ from one another necessarily. Therefore, it is impossible that many gods exist and we know that God must be one.
3. The unity of the world necessitates one first cause of order. We see that everything that exists serves some purpose and creates some harmony. A diverse cause or beginning would lead to a diverse end, leading to discord and chaos. This is not what we see in the world. Therefore, we know that what was the first cause was one, since it is the sole necessary cause. In this way we know that God is One.

Aquinas has done it again. He has a knack for taking very loaded objections to the foundation of the Catholic Faith and dismissing them concisely and completely. One key to remember is that this question does not stand alone, but it rests on previously defined truths that all serve as an "arsenal" for future questions.

But this is the beauty of what Aquinas accomplished.

He was able to start from the most basic--yet also profound--truth of God's existence and then move to uncovering what we can know about God. 

On a personal note, I recently decided who I would be working with on my thesis project here at TAMU. Dr. Robert Garcia and I will be working on the topic of natural kinds in contemporary analytic metaphysics; I am hoping to show how the Scholastics (like Aquinas) had a better metaphysical picture, so to speak, than the contemporary heavyweights like D.M. Armstrong.

I should be blogging rather regularly now, Wednesdays and Sundays. Anyways, until next time...cheers.