Descartes and the Existence of God

Descartes and the Existence of God

The question generations have asked: how can one truly prove the existence of God? Both those who do not believe God exists—atheists— and those who have been faithful Christians from childhood all ask themselves at some point in their life if and how God truly exists. Belief in God is oftentimes seen as being solely reliant on faith. According to Hebrews chapter 11, faith is described as “evidence of things not seen”(King James, Heb. 11.1). In other words, faith causes us to believe in that which is not concrete—something we cannot touch or feel or see. Perhaps one of the reasons people find themselves doubting God is because they long for a physical connection to Him—a connection that seems quite impossible. But what if there was a way to prove the existence of God without having to rely on faith or a physical proof? According to Descartes in his A Discourse on the Method, there is a way to prove God exists through reason. In the opening of Descartes’ text, he explains how his love for knowledge drove him to start questioning that which his teachers and elders had taught him. It was because he loved knowledge that he began to question his teachers, for he reasoned that what he had been taught by those in authority over him had the potential to be flawed or biased. Descartes describes how he was able to pull away from the teachings of his elders and start an experiment to think for himself. It was during this experiment that he was able to reason through the idea of a God that does not necessarily require faith alone. However, before utilizing reason to prove the existence of God, Descartes proves through reason alone that we exist. Unifying both the studies of metacognition and the contrast between perfection and imperfection, Descartes argues that it is possible to prove there is a God through reason.

Descartes begins his journey to prove self and God by first delving into the idea of reasoning about reason alone. He describes his self-doubt in the area, stating that “..because there are men who make mistakes in reasoning even in the simplest of elements of geometry, and commit logical fallacies, I judged that I was as prone to error as anyone else, and I rejected as false all the reasoning I had hitherto accepted as valid proof.” (Descartes 28). At first glance, it appears as though Descartes perhaps undervalues his reasoning, claiming that any man has the potential for flaws in his reason. However, he follows his doubts by stating that, “...while I was trying to think of all these things being false in this way, it was necessarily the case that I, who was thinking them had to be something; and observing this truth: I am thinking therefore I exist…” (Descartes 28). Essentially, what Descartes is conveying is that the act of thinking about his existence proves that he exists. If Descartes did not truly exist—if life were a dream that merely felt real—he would not be able to logically reason his own reasoning. Descartes says that he concluded he was the “substance whose whole essence or nature resides only in thinking” and that he was not fully dependent on a concrete, physical item for his existence (Descartes 29). He solidifies this claim by highlighting a spiritual aspect saying that, “...the Soul by which I am what I am, is entirely distinct from the body and is even easier to know than the body; and would not stop being everything it is, even if the body were  not to exist.” (Descartes 29). In other words, he argues that he can know his existence because he realizes the difference between body and soul—that both are distinct beings while they coincide, but that soul can function without body. 

After describing how one can prove their own existence, Descartes transitions to using the same method to prove God, but in this case, applying reason to the idea of perfection. He starts by describing how he was able to see elements of perfection within nature. While he realizes that nothing in nature is absolutely perfect, he is able to deduce that “the more perfect should proceed from and depend on the less perfect” (Descartes 29-30). From here, Descartes is able to bring in the subject of God saying that there was only one possibility that remained: that he had been created by a nature that was more perfect that he could fathom, which had to be God (Descartes 30). To add further credibility to his argument, acknowledging that some readers still may doubt God’s existence, Descartes touches on the idea that reasoning the existence of a perfect God is in fact more credible than reasoning many other things such as the stars and the earth, claiming that within the physical world, there is always room for doubts, as “metaphysical certainty is in question” (Descartes 32). In other words, there will always be uncertainties within the realm of the sciences which should, in essence, lend themselves to more doubt than the idea of a perfect God who created all realms of nature. Descartes concludes his argument by acknowledging that “the best of minds choose the investigate the matter” but that should they continue to reason through the idea of perfection and the fact that we ourselves are not wholly perfect, we should be able to come to the conclusion that the idea of an all-perfect and all-true God is entirely possible (Descartes 33-34).

Aligning with Descartes’ method of reasoning is a section of text from Thomas Aquinas’ Summa Theologica. Aquinas uses a five-proof approach to proving the existence of God, utilizing both facts of science and reason. His first proof is that of motion and the scientific law that “whatever is in motion must be put into motion by another” (Aquinas 65). From this undeniable fact of science, Aquinas is able to connect motion to the idea of a “mover”, saying that “it is necessary to arrive at a first mover, put into motion by no other; and this everyone understands to be God” (Aquinas 65). In simpler terms, Aquinas is saying that due to the laws of motion, the earth is required to have been set into motion by an almighty being. Aquinas’ second and third proofs are taken from the nature of cause and effect, as well as necessity. Similar to his proof about motion, Aquinas argues that there must be a “first cause” of every following effect, and a beginning for every aspect of creation. The cause of both of these, Aquinas says, would have to be God (Aquinas 67-68). Similar to Descartes’ analysis of perfection, Aquinas covers the idea of perfection in his fourth proof saying that “there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God” (Aquinas 69). Aquinas’ final proof analyzes intelligence, claiming that “whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge” (Aquinas 69). He follows this claim by confirming that intelligent beings exist by a knowledgeable director of all nature whom he identifies as God (Aquinas 69). While Aquinas’ approach to proving God uses more scientific fact than Descartes’ does, he utilizes the same approach as Descartes by allowing readers to see that through reasoning, one can determine how God exists.

In The British Journal for the History of Philosophy, author Willis Doney addresses some of the misconceptions within Descartes’ argument in an article entitled Objections and Replies within the Fifth Meditation. Doney argues that a misconception many readers have is to what degree God’s existence can be proved.  He brings to light that nowhere in Descartes’ text does it imply that God can metaphysically be proved through reason (Doney 220). This is an important aspect to remember while studying A Discourse on the Method. Descartes’ goal is not necessarily for his readers to be able to scientifically prove that God is an existent being, but to allow them to absorb the information of the world around them and use it as evidence that God exists as a spiritual being. From this argument, Doney further credits Descartes’ point by labeling God’s essence as “Not-Possibly S” and the idea that God does not exist as “Not-Possibly T” (Doney 221) and then highlighting a quote by Descartes that “it is just as much a contradiction to think of (repugnet cogitare) God (that is, a supremely perfect being) lacking existence (that is lacking a perfection) as it is to think of (cogitare) a mountain without valley” (Doney 222). From this quote, Doney replies that “Descartes’s argument against his imagined objector seems to be: “It is evident on reflection that existence cannot be separated from the essence of God –‘Not-Possibly-S’– and so it is contradictory to think of God as not existing” (Doney 222-223). Similar to Descartes, Doney allows his readers to see for themselves that reason can be applied when pondering God, and that the results are undeniable.

Returning to the idea discussed at the beginning of this essay that belief in God requires more faith than reason and is therefore too weak to be credible, we can now see how that is not necessarily the case. Based on both Descartes’ method of using reasoning to first define self and then God, coupled with Aquinas’ method of scientific fact intertwined ith common sense, one can decipher within themselves that there is indeed a God. As Descartes affirms in his experiment, even the most intelligent of people, both those who have always believed in God, and those who are adamant He does not exist, will doubt their own beliefs at times (Descartes 33). Doubt, he says, is in fact a tool for knowledge, and is the first step to coming to terms with what the most logical answer to what one reasons (Descartes 29). Once we are able to acknowledge our doubts and reason through the information we have around us, we can prove the existence of God.

Works Cited

The Bible. Authorized King James Version, Oxford UP, 1998.

Descartes, René. A Discourse on the Method of Correctly Conducting One’s Reason and Seeking Truth in the Sciences. Translated by Ian Maclean, Oxford University Press, 2006.

Aquinas, Thomas. Summa of the Summa, edited by Peter Kreeft, Ignatius Press, 1990.

Doney, Willis. “Objections and Replies within the Fifth Meditation” The British Journal for the History of Philosophy, vol. 11, no 2, 2003, pp. 219-234.