I read Aquinas’ three articles on the existence of God found in his Summa Theologica. The following article I wrote as an analysis of his five arguments for the existence of God found in article 3. To better understand and engage with this article, please read the linked selection above. Thank you!
Thomas Aquinas, a Dominican friar, born in Aquino, Italy, in the 13th century, is known as a master of systematic theology, with no one of great comparison before him besides Augustine. He was a great influencer in the tradition of scholasticism, a school of thought that placed a high emphasis on reason. As such, it is no surprise that Aquinas is well known for his contribution to natural theology, reasoned arguments from logic and natural experience that make the case for the existence of God. These arguments are found in his work, Summa Theolgica, a text that Aquinas wrote as a summary of the Catholic faith. His other two important works include the Summa contra Gentiles, written to postulate Christian theology in the context of the unbeliever, and the Compendium Theologiae, written for the lay beginner learning the faith. In this paper I will briefly present and analyze his arguments to answer the question, “Whether God Exists?” as found in Aquinas’ Summa Theolica.
Aquinas’ purpose in this selection of his work is to show that God does exist in opposition to the objection to God’s existence on account of the presence of evil in the world (since God is infinitely good, it appears there should be no evil if he existed) and the objection that supposes it is reasonable that everything in the natural world can be accounted for by nature itself and that everything voluntary can be accounted for by the human will apart from God’s existence.
To answer how he knows that God exists, Aquinas gives five arguments from natural knowledge. The first argument is that the observed motion in the world dictates a first mover to initiate the movement. The second argument is that God alone has the necessary qualities to be the efficient cause of all things (to be that first mover), since a thing cannot bring itself into existence (existing before it existed). The third argument derives from the possibility for things not to be, meaning it’s possible for nature to not exist, but at that point there would be nothing, and since nothing produces nothing, it then follows that nothing cannot be the explanation of the first mover. The fourth argument is that of gradation in which all aspects of nature have a comparable greater than or less than quality to them and that the maximum in any given classification (genus) is the cause of all in that category. It follows that there must be something that is maximum to all beings from which everything derives: God. Finally, Aquinas’ fifth argument for the existence of God is taken from the orderly and intended purposes found in all things of the natural world, thus pointing to an intelligent being that orchestrated this design.
Aquinas then uses these five arguments from nature to refute the two objections against the existence of God that he is striving to refute. To the existence of evil being incompatible with God, Aquinas applies the principle that God is the highest good stating, “He would not allow any evil to exist in His works, unless His omnipotence and goodness were such as to bring good even out of evil” (Kerr, 114). It is reasonable to say that the best of the best in the realm of goodness would be able to produce good out of evil. To put the nail in the coffin for the objection that nature can produce all we see in nature, Aquinas simply works from the fifth argument he gave back to the first.
Aquinas adequately met his goal to defend the existence of God against these two objections, but I’m not sure who would have been making a case for naturalism in Aquinas’ day that would have been interacting with this work to warrant such an articulated effort on his part. In today’s zeitgeist, numerous sophisticated arguments for atheism have emerged (Darwinian Evolution, multiverse theory, panspermia theory, and even redefining nothing as something). However, all of these arguments (or mere theories) fail to answer the question of first causes and break down upon the same arguments Aquinas offered almost 800 years ago. In fact, Aquinas’ arguments are essentially the same arguments from nature used today; they are just more refined and organized into syllogisms now (usually). For example, William Lane Craig has in recent decades popularized the Kalam Cosmological Argument, stems back to Aristotle (who said everything has a cause), was then established by Aquinas (who said God is the uncaused cause), then repackaged by Islamic philosophers in the Kalam argument, which states: 1) Everything that begins has a cause. 2) The Universe has a beginning. 3) Therefore, the universe has a cause for its beginning. The personal creator God is that cause, since as Aquinas explained, the universe couldn’t cause itself and it couldn’t have been the product of nothing. The argument of design and order that Aquinas presented, which in modern day is typically called the teleological argument, has garnered much more detailed support through our increased knowledge of the fine details of the building blocks of life (cells, DNA, etc.) and the intricacies of organ systems within living creatures and the interplay of ecosystems – all we know of the world (which is more than in Aquinas’ day) screams for a Creator, just as Paul said it does in Romans 1.
In closing, Aquinas’ work seems to be the foundation of much of modern day Christian apologetics concerning arguments from nature. However, arguments from nature are arguments that any Theist can offer, as demonstrated by Craig’s reinvigoration of the Islamic Kalam argument. I’d argue that it is far more important to focus Christian apologetics on revealed knowledge, pointing to the historicity of the Gospel narratives concerning Jesus’ life, death, and resurrection that demonstrate not only that God exists, but tell us precisely who God is and what he thinks of us and what he has done for us. Centering such arguments for the existence of God around the cross of Jesus of Nazareth and his subsequent empty tomb also better counter the problem of evil that Aquinas was ultimately addressing through his arguments for the existence of God. Instead of just posturing that an infinitely good God isn’t incompatible with the existence of evil, because such a God can produce good from evil, Aquinas, and Christians today, can and should point to the certain assurance of God’s capabilities to do this through the death and resurrection of Jesus of Nazareth. Out of the greatest evil that has occurred in human history (the death of the God-Man at the hands of his own creation) the greatest good was produced (salvation for all who believe as Jesus reconciled the world to the Father through the shedding of his blood).
 All About Philosphy. “Cosmological Argument”: https://www.allaboutphilosophy.org/cosmological-argument.htm accessed on Oct. 29th, 2018.