The Rationale for God’s Existence
Proving God’s existence is no easy feat. Yet Descartes puts forth two proofs of God in his Meditations on First Philosophy. Many might reasonably think that given the conservative religious milieu during Descartes’ time, he needed as many strong arguments as possible in order to convince the 17th-century audience he was writing for. Or that he was simply flexing his intellectual muscle. However, this is not the case. Each proof serves a specific purpose and together they form a key component of the larger Cartesian project. The first proof of God in the Third Meditation uses a causal relationship to explain why the idea of God must exist, or why the concept of a perfect being is needed to explain the natural world. The second proof in the Fifth Meditation then uses the idea of intuition to prove why God exists and not other constructs. Working together, the first proof serves as the underpinning deductive reasoning for the second proof. Ultimately, God’s existence enables Descartes to cross from having complete doubt to the possibility of true knowledge in the larger Cartesian project.
Having doubted the reality of all ideas in the First Meditation, and coming to realize his own existence in the second, Descartes identifies the idea of God in the Third Meditation. He begins by proposing that some ideas are innate in us, true and indubitable, while others are invented or adventitious (from external experiences)(38). For instance, it is an adventitious idea to say that the Sun is small because we perceive it to be, whereas it is an innate idea to say that the Sun is in reality several times bigger than Earth based on astronomical reasoning(39). Similarly, Descartes thinks that the idea of God is one that is also innate in us because we can use reasoning to conceive of Him. Employing a causal framework, he postulates that the idea of God cannot come from nothing(42). For example, the idea of a stone or heat cannot come from anything but a stone and heat. Further, a stone cannot come from anything but an object containing all of the elements in a stone, and heat cannot be caused by something that is not hot(44). Thus, the idea of God must come from something containing all the perfections of God. Since Descartes lacks the perfection and infinite quality found in God, he thinks God must exist as the source of his idea of Him(45).
While there is merit in Descartes’ idea of God, his argument that God exists is much less self-evident and innate. Admittedly, it is straightforward to follow Descartes’ logic that a stone must come from something containing all the properties of a stone, like a mountain, and heat from a fire or hot water. When one further investigates the cause of a mountain or a fire, and then the cause of their causes, the answer becomes increasingly abstract, and eventually leads to something that must have been the creator of everything — God. However, to say that only an existent God could have implanted the idea of Him inside Descartes is dubitable, because from the fact that I can think of a perfect being, it does not follow that the perfect being exists. In other words, there is no evidence that God put the idea of Himself in Descartes, so his argument is just an assertion. By the same token, I can think of the idea of Superman without having any of his superhuman attributes, and since we know Superman does not exist, he could not have put the idea of himself in me. So, I can say my idea of Superman is independent of his existence. Ultimately, the causal argument only works as long as formal reality, or that the thing in consideration is an existent thing, is not concerned. Descartes has only established the objective reality of God, or His essences or properties.
For a moment, Descartes doubts his own logic and questions if the thought of God can exist without Him existing. But his supporting argument similarly falls short of proving God’s existence because the premise that his existence is contingent on God’s is, again, an assertion. He begins his inquiry by raising several possible causes for his existence: himself, an infinite existence, his parents, an imperfect being, and God(48). He rules out himself as the cause of his own existence because he would have made himself perfect in nature(48). He has not always existed because there is nothing in his nature as a thinking thing that allows him to preserve himself in the future(49). He rejects the next two possible causes because they would fall into the same infinite regress as that of the cause of the mountain and fire mentioned prior. This leaves God as the only possibility(50). While Descartes rejects himself as his cause, the premise can be easily refuted by taking the opposing view that “I desired to make myself imperfect”. The next premise is also problematic in that the argument only stands within his logical framework; it is only an assertion that God preserves us and keeps us alive because there is biological evidence that our bodily systems keep us alive. Therefore, these two failed premises makes this argument unconvincing, and only the idea of God still stands.
In the Fifth Meditation, Descartes confirms the formal reality of some external objects by classifying the ideas of them as either “clear and distinct” or “confused”(63). Using this logical system, he proves God’s existence by examining God’s essence as a perfect being. Descartes first raises the example of a triangle to show that we can distinguish between true and false ideas by perceiving them “clearly and distinctly”(69). The triangle has three sides and three angles that add up to 180 degrees. As he puts it, these are the triangle’s “immutable and eternal” natures, even if it does not exist (64). It is important to emphasize that these properties are knowable and valid independent of the meditator, whereas the properties of something made-up would be dependent on him. In the context of God, since we cannot think of God’s essence as anything but perfect and omnipotent, it follows that He must exist as existence is a part of His perfection(69).
Descartes successfully proves God’s existence because his causal argument in the Third Meditation provides the necessary logical basis for him to make the case for why God has formal reality and not other constructs. Because his first proof of God deduces that there must be a primary cause for all other causes in the world, there is a logical rationale to believe in his existence instead of some other made-up concept that has no logical basis. Circling back to the Superman example, Superman’s objective reality — strong, intelligent, agile, just — is something made-up by man based solely on creativity. There lacks a reasoning component in his conception. He is born out of thin air in the same way that I can instantly imagine a horse with a giraffe’s head and a dog’s tail — without cause or purpose. God, like Superman, qualifies as a construct in that there is no empirical evidence to prove His existence. But unlike Superman, God’s conception is born out of a process of internal reasoning and not out of creativity or randomness. God’s existence is necessary to explain various aspects of the world, so there is formal reality in the idea of Him. The causal argument is also exhibited in the triangle example. Triangles, just like circles or rectangles, are shapes that are conceived by man through reasoning in order to explain the natural world. So, there is a logical, deducible basis for shapes’ conception, whereas there is no deducible rationale for the conception of Superman or any other creative construct. Therefore, without the causal proof of the idea of God, proving that He exists would be like proving Superman exists — it is invalid because there is nothing to ground their existence on.
In conclusion, Descartes puts forth two proofs of God because his second proof would be unconvincing without the logical reasoning of his first proof. To show there is formal reality in the construct of God, the argument needs deductive reasoning to show the causal relationship between God and the external world so as to demonstrate a need or cause for the idea to exist. Without deductive reasoning, the idea of God would be comparable to any other construct that is born out of thin air from our minds. As standalone arguments, the first proof of God is unconvincing because one can easily argue that they can think of something that does not formally exist, so ideas are not dependent on their formal reality. The second proof by itself is more convincing than the first, but objections still point to an unfair comparison between God’s existence to a geometric shape’s property. Only by working together do Descartes’ two proofs represent his argument for God’s existence at its strongest.
