Introduction

Given the previous short sections on Augustine and Aquinas, it should come as no surprise that, for more than 2,000 years, philosophy and theology, specifically Christian theology, have been mutually influential. Since philosophy aims to find answers by using reason, and since religion tends to promote faith as being at least as important as reason, it also shouldn’t come as a surprise to learn that one of the topics that gained significant attention in Western philosophy during this time has been rational arguments about God and God’s existence. In what follows, you’ll learn about several of the most influential arguments that philosophers have considered regarding God’s existence. In other courses, you could explore other, related ideas.

Ancient Arguments about God’s Existence

Many people between Aristotle and Augustine thought about ways that they might demonstrate or prove that God exists. For some of them, it wasn’t so much that they were trying to prove that God exists in anything like what today we might think of as a scientific proof. And, for some of them, it wasn’t that they didn’t already believe in God. Instead, in many cases, they were demonstrating what they thought were reasonable inferences that could be drawn from either observations about the world, observations about human conduct, or observations about the way that some ideas seemed to fit together. Courses in ancient philosophy, some courses in history, and some courses in the philosophy of religion might explore some of these thinkers’ views.

Augustine’s Arguments about God’s Existence

Augustine himself reflected many of these ways of thinking in his writing, and, while he didn’t offer the same kind of formal proofs you’ll see in the next sections, he did offer thoughtful commentary on what could definitely be called arguments about God’s existence. For instance, he thought that there were some truths that were eternal and unchanging, like mathematical truths, and that such truths suggested that there must be eternal, unchanging minds where they resided. If, from a certain point of view, “truths” are things that exist in minds, then eternal truths suggest the existence of eternal minds. If you recall that he was heavily influenced by Platonic and Neoplatonic ideas, you’ll recognize that it’s not much a stretch to then argue that, since all the minds in this physical world are not eternal, there must be eternal minds in some other, more perfect world.

Further, the fact that there is this imperfect world, and that it is a world that was created, suggests that there is something else, behind it, or the cause of it, that is itself not created and that is itself perfect. This, of course, on this line of thinking points to a non-physical, uncaused God as the creator of the physical, caused world.

Anselm’s Arguments about God’s Existence

Many hundreds of years after Augustine, for about 15 years around the year 1100, Anselm was the Archbishop of Canterbury (that is, he was an important leader of the Church of England). Just before being in that role, Anselm had published many writings, some of which remain famous and cited to this day. One in particular, the Proslogion, contains an argument that is often simply called “The Ontological Argument.” Here is a simplified version of that argument.

1. God is defined as “that than which nothing greater can be conceived” (the greatest possible being).
2. The idea of God exists in our minds.
3. A being that exists in reality is greater than a being that exists only in the mind.
4. If God existed only in our minds, we could conceive of a greater being – one that exists in reality.
5. But we cannot conceive of a being greater than God (by definition in premise 1).
6. Therefore, God cannot exist only in our minds.

Anselm’s Ontological Argument has been the subject of debate and criticism ever since.

Aquinas’s Arguments about God’s Existence

In addition to all of Aquinas’s other contributions, his arguments for God’s existence stand out as important pieces of philosophical history. Famously, he offered five different arguments to prove God’s existence. They are today widely recognized by the term “Aquinas’ Five Ways.”

The First Mover (argument from motion)

1. Things in the world are in motion (changing).
2. Something cannot move itself; it must be moved by something else.
3. This can’t go on forever in an infinite chain of movers.
4. Therefore, there must be a first mover (God) that started all motion.

The First Cause (argument from causation)

1. Everything has a cause.
2. Nothing can cause itself.
3. Causes can’t go back infinitely.
4. So, there must be a first cause (God) that started everything.

The Argument from Contingency

1. Things in the world exist in one of two ways: they are necessary or contingent. Things that exist necessarily don’t depend on anything else to exist; things that exist contingently do depend on something else to exist.
2. At some point, nothing contingent existed.
3. If everything were contingent, nothing would exist now.
4. Therefore, there must be a necessary being (God) that always exists.

The Argument from Degree

1. Things have different degrees of goodness, truth, and other perfections.
2. We compare things to the top standard in its category (most good, most beautiful, etc.).
3. This maximum standard of perfection must actually exist.
4. This perfect being is God.

The Argument from Design

1. Natural things work towards a purpose, even without intelligence.
2. Things without intelligence don’t move towards a goal by chance or randomly.
3. They must be guided by something with knowledge and intelligence.
4. Therefore, an intelligent being (God) must guide all of nature.

Each of these arguments starts with an observation (about the world, about goodness, and purpose) and reasons that God must exist to explain that observation. Aquinas believed these five ways were the strongest proofs for God’s existence based on reason alone, without relying on faith or revelation. Aquinas did not think that reason and faith had to be in conflict. He was confident that there were multiple ways to arrive at the same truths. He believed that since God created reason, the things that reason revealed to be true would have to align with the things that were revealed through scripture or through faith.

Modern Commentary on Arguments about God’s Existence

There are many philosophers in the modern period (roughly 1600 to 1900) who contributed to the arguments about God’s existence. Several stand out as offering particularly compelling arguments. Some of them offered arguments that were elaborations on Anselm’s or Aquinas’s arguments. In particular, Descartes offers an argument that has remarkable parallels to Anslem’s Ontological Argument, and Hume offers arguments that are quite similar to several of Aquinas’s arguments. There were some additional contributions, and you could learn more about those in a course on modern philosophy or the philosophy of religion. One arguer in particular, however, make some very interesting claims that I’ll provide here as an end to this section.

Kant wrote on almost every conceivable topic in philosophy and made important contributions to everything he did write about. He suggested that there were only so many possible ways to argue for God’s existence and he explained the various categories of arguments that he considered relevant. In every case, he provided a demonstration about why that type of argument to prove God’s existence won’t work. And, this is particularly illuminating because he himself was raised in a Lutheran tradition and seems to be someone who takes seriously the possibility that God does exist. That is, as far as Kant is concerned, God can exist even if it’s impossible to prove that God exists, and, perhaps it isn’t surprising, given what God might be understood to be, that God’s existence cannot be proven.

The three categories of argument that he considers are Ontological, Cosmological, and Teleological. What follows is a brief assessment of his thoughts about why, for each such category, no argument for God’s existence, from within the context of that category, can succeed.

Ontological Argument. According to Kant, existence is not a quality or property that makes something greater or more perfect; it’s just a condition for being real. Therefore, you cannot define God into existence simply by saying that the concept of God includes existence. That is, Anselm’s argument, and any similar Ontological Argument, is going to fail because existence isn’t a property that things have.

Cosmological Argument. The Cosmological Arguments focus on experience or empirical information about the world. Aquinas and Aristotle both argued that there must be an unmoved mover, because this followed from their observations about the motions of objects in their experience. Kant identified a few flaws. One of those is that these arguments all require experiences to gather evidence, but no one directly experiences God, so the conclusion is a jump that’s not warranted. Another concern he had was a sort of failure of our imagination. We might believe that there are necessary beings, but our believing this doesn’t make it true. If we’re going to use evidence and observations to prove something, we have to limit our scope to what is empirically accessible.

Teleological Argument. Even if the things we observe do exhibit design, it doesn’t follow that there’s one designer, it certainly doesn’t follow that the designer is omniscient or good, and, for all we know, there might be many different designers. Not only that, but it wouldn’t follow from the fact that individual things within the universe are or exhibit design that the universe itself was designed. That’s an analogy that’s unwarranted.

Conclusion

The contributions of philosophy to the problems of identifying and understanding God’s attributes or existence are many and varied. Some of the arguments are excellent as demonstrations of how arguments work (how conclusions do or should follow from premises) and many of them provide compelling additional considerations about the universe, morality, intelligence and free will. Arguments about God and God’s existence are connected to deep problems and profound spiritual matters, like why people suffer, and why, sometimes, it seems like people suffer needlessly or meaninglessly. This section serves as a very brief introduction to some of the most famous ideas in this vast realm.

Comprehension Questions

1. We
2. The
3. At the end of the chapter,

Reading Suggestions

Primary Sources

Anselm, Proslogion (chapters 2-4)

Aquinas, Thomas, Summa Theologica, (First Part, Question 2, Article 3)

Augustine, Confessions (Book VII, chapters 10-11)

Descartes, Rene, Meditations on First Philosophy (Meditation III and V)

Hume, David, Dialogues Concerning Natural Religion (Parts II, V, and IX)

Secondary Sources

Mackie, J.L., The Miracle of Theism

Plantinga, Alvin, God and Other Minds

Swinburne, Richard, The Existence of God

Great Works of Fiction

Dostoevsky, Fyodor, The Brothers Karamazov

Lewis, C. S., The Screwtape Letters

Miller, Walter M. Jr., A Canticle for Leibowitz

Russell, Mary Doria, The Sparrow