Rene Descartes is one of the most influential thinkers in the history of modern Western philosophy. Not only did he contribute significantly in the area of mathematics and physics, but he also created a systematic approach to philosophy that is still followed today. During his time, he rejected much of the Aristotelian traditions of the medieval age and took philosophy in a new direction, attempting to integrate it with the sciences that were just beginning to come into their own. He also contributed to the theological discussion by studying the nature of God cosmologically and ontologically in his work Meditations.
When one first reads Meditations on the First Philosophy: In Which the Existence of God and the Distinction Between Mind and Body are Demonstrated by Descartes, being aware of his reputation for being the “Father of Modern Philosophy,” and his claim to have arrived at a method of gaining knowledge about the world which had the same kind of certainty as knowledge of mathematics, they may be initially disappointed because of his refusal to completely abandon religious thought in favor of humanist ideology.
In the Preface to Meditations Descartes states his aim is to explain the nature of the human soul and demonstrate the existence of God. To demonstrate the latter, Descartes presents multiple proofs of God’s existence, the cosmological and the ontological arguments. Descartes cosmological argument as to the existence of God first comes to light in the third part of Meditations and begins and ends with the existence of God as the initial cause of everything, including human reason capable of ideation of different realities.
Following his maxim “Cogito ergo sum,” which translates into “I think, therefore I am,” Descartes begins with himself as existing, with existence perfect, and his existence caused by something. According to Descartes: “In order that an idea may contain this objective reality rather than that, it must doubtless derive it from some cause in which is found at least as much formal reality as the idea contains of objective; for, if we suppose that there is found in an idea anything which was not in its cause, it must of course derive this from nothing” (Med. III, par. 14).
Though Descartes can know himself, and he can know of perfection, even believing himself to be perfect, he is not perfect and could not be the cause of himself. To him, only God as a perfect being can truly possess infinite knowledge of perfection. As he states: “Although my knowledge increase more and more, nevertheless I am not, therefore, induced to think that it will ever be actually infinite, since it can never reach that point beyond which it shall be incapable of further increase” (Med. III, par. 27).
As his knowledge of perfection is limited, and God is perfect, his idea that God is perfect is only possible if God preceded the idea and made it possible. Descartes follows causation from his existence back through the reasons for it, from his parents, to their parents, and so on, finally concluding that at the beginning there must be God, as only nothing can come from nothing. While Descartes’ cosmological proof that God exists relies on causality for its foundation, in part five of Meditations he also provides ontological proof to back it up.
Descartes’ ontological argument takes a markedly different approach than his cosmological proof of God’s existence. Descartes’ ontological argument begins with his idea of God as being a perfect being of infinite substance as put forth in the third part of Meditations: “the idea by which I conceive a God [sovereign], eternal, infinite, [immutable], all-knowing, all-powerful, and the creator of all things that are out of himself, this, I say, has certainly in it more objective reality than those ideas by which finite substances are represented” (Med. III, par. 13). To Descartes, objective reality is more perfect than ideas about reality, and because his idea of God is that He is a perfect being that nothing more perfect can possibly be imagined, he must be more real than any of his nonexistent thoughts.
In essence, Descartes logical argument for his ontological proof of God’s existence is that he can experience the idea of God as a the most perfect being, existence is part of God’s essence and His existence is more perfect than human thoughts about it, so therefore God exists in reality as the most perfect being: “because I cannot conceive God unless as existing, it follows that existence is inseparable from him, and therefore that he really exists…the necessity of the existence of God, determines me to think in this way: for it is not in my power to conceive a God without existence, that is, a being supremely perfect, and yet devoid of an absolute perfection” (Med. V, par. 10). As the essence of Descartes’ idea of God is existence, much as having three sides is the essence of a triangle, God exists.
While Descartes presupposes the perfection of existence and the idea that God is the most perfect being, his ontological argument fails to provide the sound reasoning as his cosmological one and speaks more of his Catholic assumptions than his intellectual emphasis on reason. Descartes arguments for the existence of God are born from equal parts philosophy and religion. While this could largely be explained by Descartes’ Catholicism, it might be equal parts of his realization that any potential thought that contradicted the Church would be met with punishment. The Mediations were published just a few years after Galileo was accused of heresy during the Inquisition for supporting the Copernican view of the solar system, in which the earth revolved around the sun, rather than the Ptolemaic view, in which the sun moves around the earth.
Descartes even makes reference to his treatise on natural sciences in Part 5 of the Discourse, but in Part 6 specifically says he decided not publish it because of the condemnation of Galileo. With emphasis on proving the existence of God, Descartes assured himself protection from such persecution imposed on Galileo and other scientists and philosophers considered heretical, but also presented two arguments for it of varied questionability. The cosmological argument put forth by Descartes has far more credibility philosophically than his ontological argument. While a Catholic philosopher trying to prove the existence of God, it is impossible to expect atheistic indifference concerning the subject, but the ontological proof requires far more faith than the cosmological argument, which relies more on reason.
The cosmological argument, rather than presupposing the perfection of existence and therefore the perfection of God as a perfect being that exists, questions the causality that brought Descartes to the point of even being able to question the existence of God in the first place. Through reason, he is able to deduce that there must be a cause for his thought, his life, his parents, the world, and all of existence, and seeks to trace the origins back to the beginning. While scientists and philosophers today would trace it back to the big bang or a cyclical theory of existence, Descartes only had knowledge of God to explain the origins of existence.
The cosmological argument is one that had origins long before Descartes and continued to be posed long after him. Descartes ontological argument is far less convincing than his cosmological argument. He asks that too many presuppositions be made to justify accepting the existence of God. Instead of following with a line of thought that establishes human reason as the unshakable foundation of existence, Descartes asserts that a good God could not possibly deceive, and that therefore humans could confidently accept all the perceptions which the method of doubt had just led humans, including Descartes, to challenge. This begs the question that if the arguments for the existence of God are not valid, than will the whole system collapse?
It also asks that existence be considered perfect, though provides little justification for this claim, while contradictorily offering gradations of perfection as a thing in itself. The cosmological question that examines the causality of existence and leads to the proof of God is far more convincing than the ontological argument that lacks its scientific and philosophical reasoning. For Descartes, God is the justification for accepting the evidence of human senses. But in practice very few people ever doubt the evidence of their senses. Even though reality can be warped by senses, which can often mislead, it is only discovered when reflecting on other evidence from the senses.
By using his reason to argue for the existence of God, Descartes showed that faith needed not be the only tool used in the matter. His cosmological argument is far stronger than his ontological one, for the universe and everything in it must have started somehow, whether God or a prime mover. The ontological argument that proves the existence of God merely because humans can conceive of Him is not as strong, because the richness of imagination can create countless things that are not real outside of the mind. Even in recent years, as scientific discovery uncovers the Big Bang billions of years ago, Descartes’ cosmological argument still holds up, as God may have been the initial cause for the bang and all that followed.