Overview of Summa Theologica

on the Existence of God (Part 1, Question 2)

Summa Thelogica:

Aquinas organizes his summa in a series of parts with each part consisting of a different question. Each question is broken down into a number of "articles" that go into detail about a certain aspect of the question. Within each article Aquinas proposes, first, alternative ways of answering the question, second, his rebuttal to the first set of answers, then lastly, what he deduces based upon his rebuttal. The section in which I place my attention on is Part 1, Question 2 which focuses on proving the existence of God.

Part 1, Question 2: Does God Exist?

Aquinas states that there are three key aspects to this question: 1.) Is it self-evident that God exists? 2.) Can we demonstrate that God exists? 3.) Does God exist?

Article 1. Is it self-evident that God exists?

Aquinas does not believe so. The first alternative answer he provides argues that God is known naturally by humans; that we are born with the knowledge of God's presence and because it is part of our natural thought process, God is self-evident. Although Aquinas concedes that humans intrinsically know what they desire, and that the over-reaching desire of all humanity is happiness (which he believes can be attained only through God), he states that that knowledge (the desire for happiness) does not outright prove that there is a God. He points to the fact that some people believe riches or material things will bring them happiness.

The second alternative answer claims that God is self-explanatory in its name, stating that the understanding of the word "God" (meaning "that than which nothing greater can be signified") creates an idea or thought about something that fits the definition. Since God exists in thought God must also exist in fact (since we can only think of things that exist), therefore God exists. Aquinas refutes this, claiming that someone may not understand that God means "that than which nothing greater can be signified." If there is no consistant definition of God, then God does not exist. Even if there was an agreement on the previous definition, people may still only realize God in thought and not in actuality, making God more or less like Santa Claus. He closes by saying, "If we do not grant that somethnig in fact exists than which nothing greater can be thought, the conclusion that God in fact exists does not follow."

The last alternative answer deals with the existence of truth. Denying the existence of truth is contradictory, for if there was no such thing as truth, the statement "truth does not exist" would be a true statement. Aquinas agrees that truth is self-evident, but the "First Truth" (God) is not self-evident.

Article 2. Can we demonstrate that God exists?

Aquinas' first alternative answer responds that we cannot demonstrate this because God's existence is "an article of faith." Since something is demonstrated physically, and faith is "concerned with 'the unseen,'" God cannot be demonstrated. Aquinas disagrees; God's truths are not articles of faith but are presupposed by faith, meaning that faith is a result of God's truths. Although we cannot demonstrate God's truth, God can, which is evident in people's faith in God.

His second alternative answer states that the catalyst (the "middle term") between a subject and another predicate is the essence of the subject (so in between God and its effects is what God truly is). However, since we do not know what God is (only what he is not), God cannot be demonstrated. Aquinas rebukes this by saying that the catalyst is not the cause, but rather the definition or purpose of the cause and does not demonstrate what God is.

His last alternative answer is about the effects of God. Ssomething is ultimately measured by its effects, but God (being infinite) is incommensurable to its effects (which are finite). Since God cannot be measured by its effects, then God cannot be demonstrated. Although Aquinas agrees that "effects can give comprehensive knowledge of their cause only when they are commensurate with it," he states that some knowledge of God can be gleaned through its effects, even if they are finite.

Article 3. Does God exist?

Aquinas provides two alternative ways of proving that God does not exist. He first gives the argument of the existence of evil; if God is a entity of a infinite goodness, then evil should not exist in the world. Since it is apparent that evil does exist, then there is no God. Secondly, the existence of every object in the world is substantially explained without the use of God, so there simply "is no need to accept that God exists."

Aquinas responds to these statements by proving that God exists in five ways:

1.) Change: It is apparent that there is change in the world, but the process of change is started by something else. Change, as Aquinas defines it, is the transformation "from potentiality to actuality" - from what something can become to what it is supposed to be - and is only started by something that is "actual." For instance, Aquinas gives the example of fire and wood; fire which is actually hot, heats wood because it is able to become hot. However, something in actuality cannot be the same thing in potentiality; ice cannot be ice in its potential state because it would be water. In other words, a thing cannot change itself, something must first cause it to change. In turn, something else must cause this thing to change or else it would not be able to cause change because it is still in a potential state. This process extends until we reach the first cause of change, the one that was not changed by anything, God.

2.) Causation: This follows the same logic as change; since something cannot cause itself to happen, something must first put this happening into effect - something must cause it to happen. Also, if there was no initial cause, then there would be no effect as well. So as above, this process goes on until we're reached the first cause.

3.) The Possible and the Necessary: Things, through the process of life, come into and leave out of existence. So at some point in time everything in this world was not (potentiality) before it was (actuality). But since poentiality cannot cause itself to acutalize, there must be something that is always in a state of actualization. So by tracing everything that is back to its beginning, we end with a thing that is necessary for everything that exist, to exist.

4.) Gradations: We know things to be better or worse in comparison to something that is the best; Aquinas gives the example of a thing becoming "hotter and hotter as it approaches the hottest." Following this logic, everything is situated in such a way that there is a model or perfect form (not unlike Plato) that exist (the coldest, the straightest, the fastest, etc.). When many things share a particular property, the one possessing most of the property is considered the cause of the properties that the other ones share ("fire, the hottest of all things, causes all other things to be hot"). Therefore there is something that causes all of the properties we observe in ourselves and the world around us, God.

5.) Governance: Material objects in nature have no intelligence, so their actuality is based upon a purpose or end goal. This purpose, however, is directed by a thing with knowledge just as "an arrow needs an archer." So it must follow that everything in nature has directing it an archer.

Aquinas closes by directly responding to the statements in his alternative answer. He says that God allows evil in the world because he is powerful and good enough to turn evil into good, and that God is part of the explanation of the objects in the world, namely the first part.

Sources: "Medieval Philosophy: Essential Readings with Commentary," Allhoff, Klima, Waidya, Blackwell Publishing 2007

Contact me: cngardner@smcm.edu

Site Last Updated: 11/01/2005