Can God be proven? Is it possible to prove the existence of God a-priori, by use of reason and logical deduction? St. Thomas Aquinas would say, “Yes. Most definitely.”
By Deacon Frederick Bartels
2 September 2019
Sometimes the question of God’s existence seems more an accusation against Christianity than a question, yet it’s a fair question, and there are many who sincerely ask it. Most of us have heard, “You can’t prove God exists, and I can’t prove he doesn’t, so let’s just leave it at that.” Such a statement, though, is false. God can be proven to exist—not with the natural sciences but with human reason. Given that fact, every Catholic should be ready to answer objections in terms of God’s existence and offer proof in support of God.
Philosophers have long noted that it is not possible to prove the non-existence of God. In other words, it’s impossible to prove that God does not or cannot exist. Why? Because in order to prove that, one has to show that God’s existence is logically contradictory in some way. For instance, if it could be logically proven that a non-contingent, uncreated being is an impossibility, then that would be a logical proof against God’s existence. As another example, if it could be shown that a spiritual, non-physical being is a logical contradiction, that, too, would show that God does not exist. If God were defined as a square circle, that would prove he cannot exist since a square circle is a logical contradiction. The problem, however, for people who desire to prove that God cannot exist, is that there are no logical contradictions against his existence.
Can The Physical Sciences Prove God Exists?
Although the physical sciences can and do offer lots of evidence pointing to the existence of God, they cannot prove whether God exists or not. The subject of God is outside of the scope of inquiry of the physical sciences, which means he is beyond their field of study. As is so often said, “You can’t put God under a microscope.” God transcends the physical world. Consequently, he cannot be directly observed, tested, or verified by the sciences. While they indirectly indicate that God exists, the physical sciences cannot prove it in the way you might prove that the sun is largely composed of hydrogen and helium.
Is The Bible Useful?
Can God be proven to exist using the Bible? First, for those who do not believe in God, the Bible is of no use in proving anything. For these folks, it’s just a book—perhaps interesting, perhaps disturbing, perhaps scandalous—that talks about God but doesn’t prove anything about him. In fact, today’s new atheists often use the Bible as a weapon against God by pointing out so-called inconsistencies or passages that seem, at first glance, to portray God as vengeful and unjust. Working from Scripture requires that one first believe God exists, then believe that Scripture is the Inspired Word of God. In the case of the latter, faith is required, which is a theological virtue infused into the soul via repentance and Christian baptism. Without faith, a person will not have the necessary component required to believe that the Bible is the inspired Word of God. The Bible is best suited to be used in a later stage, to help people who believe God exists to come to a full knowledge of his plan in Christ and the Church. It’s not normally useful for those folks who doubt or reject God’s existence.
Catholics understand that God can be proven to exist by reason alone. By the power of man’s intellect, he can come to know with certainty that God exists—albeit in a confused way lacking full knowledge of divine revelation, as St. Thomas Aquinas noted. Pius XII echos in Humani Generis that same fact: man faces a number of obstacles in coming to know the truth about God:
Though human reason is, strictly speaking, truly capable by its own natural power and light of attaining to a true and certain knowledge of the one personal God, who watches over and controls the world by his providence, and of the natural law written in our hearts by the Creator; yet there are many obstacles which prevent reason from the effective and fruitful use of this inborn faculty. For the truths that concern the relations between God and man wholly transcend the visible order of things, and, if they are translated into human action and influence it, they call for self-surrender and abnegation. The human mind, in its turn, is hampered in the attaining of such truths, not only by the impact of the senses and the imagination, but also by disordered appetites which are the consequences of original sin. So it happens that men in such matters easily persuade themselves that what they would not like to be true is false or at least doubtful.Pius XII, Humani generis, 561:DS 3875
Nevertheless, God can be known to exist by use of reason and logical deduction. Catholicism embraces reason, rationality, and philosophy. Therefore Catholics are in a special position to help others who mistakenly think there’s no proof for God and who, consequently, reject his existence.
However, dialogue is by nature reciprocal. You can lead a horse to water, but you can’t make it drink …. More than a few atheists have no intention of believing in God; they will not entertain any proof of God; they fear the idea that God may be real; they reject the notion of obedience and submission to God; and some display a real hate for God. When confronted with these types of folks, there is little we can say. Perhaps we can offer to explain things to them if they are ever willing to listen with an unprejudiced mind. Certainly, we can pray for them—and should. It’s often best to simply say something like, “God has completely changed my life.” Then, wait and see if they approach the subject another day.
Can God be Proven? For Those Who Are Willing To Listen, What Can We Tell Them?
St. Thomas Aquinas offered five proofs of God which soundly prove, through reason alone, that God indeed exists. They do so mainly by showing in some way that God is a necessary being, whether for the existence of the physical universe as its First Cause or the motion within it or something else.
For instance, since the existence of the physical universe is contingent on something outside of itself (a physical thing cannot bring itself into existence; it cannot be its own cause), it must have as its cause a non-physical, non-contingent, uncaused Creator who transcends the physical universe, and who possesses the unrestricted power necessary to bring the physical universe into being from nothing. Said another way, since the universe cannot explain itself, a non-physical Creator-Agent is necessary to explain its existence. We call this non-physical, uncaused, non-contingent creator: God.
The proof described above is a simplified logical proof from contingency. It’s based on the fact that things in the universe are contingent beings (a being can be anything from a rock to a tree to a person to a star—all depend on things outside of themselves for their existence). Contingent beings cannot explain themselves in themselves; they cannot cause their own existence; nor are they self-sustaining in their ability to go on existing (their lack of self-subsistence is a subject for another post).
The First Cause Argument
St. Thomas presented a similar argument known as the First Cause argument. It’s based on cause and effect, and the fact that every effect is preceded by a cause. When the chain of causes and effects is followed to its point of origin, an uncaused Creator is required, which might be called the First Cause of all things. This First Cause is God. It’s really a quite simple, straight-forward argument that anyone can quickly grasp. Here’s my version of it:
All material reality in the universe is a result of a series of causes and effects. For each effect, such as wind, there must be a cause: in this case it is the sun; i.e., the sun causes the earth’s weather patterns due to uneven heating of the earth’s surface. The terrestrial planet we call Earth is the effect of a gathering of material together in orbit around the sun. And the sun is the effect of a compaction of hydrogen and helium under gravitational pressure that ignited into a very, very, very hot ball.
As another example, we exist due to our parents’ joining in sexual union. Looking back in time, our grandparents caused our parents to exist. If we follow this chain of cause and effect back far enough we arrive at the first link in the chain: the first human parents. Biblically speaking, we call them Adam and Eve. Regardless of the argument one might make about how God brought these first humans into being, what does not work is to say that they brought themselves into being. That’s not possible. Therefore a Creator (an uncaused, non-contingent being) is necessary as the First Cause (or first-order cause) of Adam and Eve.
One could argue that life developed (evolved) over billions of years in order to produce the first humans. That’s fine, with a few careful and necessary qualifications. However, it will never work to say that life brought itself into being from nothing. Physical life is not its own cause. It can’t be because that’s a logical contradiction; i.e., what is caused is not uncaused.
A thing cannot bring itself into being from nothing. Why? Because nothing can’t do anything. To say that nothing can become something in and of itself is a logical contradiction.
Similarly, regardless of what cosmologists may conclude about the development of the physical universe through cause and effect over time, what is certain is that there must be a First Cause (first-order or primary cause that transcends the universe) that brought the universe into being from nothing, thus setting into motion its further development. In order for the universe to come into being, a non-physical, non-contingent, uncreated Creator is required, who transcends the physical universe and who possesses the unrestricted power necessary to bring it into being from nothing and order it accordingly in a way that makes it intelligible and capable of sustaining life. That does not mean the physical universe appeared suddenly in its completed form (which is still incomplete in that it is developing!). It simply means that an uncaused, transcendent, all-powerful Creator is necessary to explain how the universe came to exist, as well as the intricate and beautiful order it displays.
In simple terms, the physical universe requires a cause, and that cause is God.
Steven Hawking once proposed that the cause of the universe is gravity. It’s like saying there’s a gravity-god, that gravity is responsible for the creation of things. But that can’t work. It’s simply a step backward from the Big Bang. One still has to explain why gravity exists and from where it came. It doesn’t explain itself, in other words. Gravity is responsible for a lot of development in the universe. In fact, if the force of gravity was altered even minutely, the universe as we know it could not exist. There might be nothing but one big black hole or one giant mass of floating hydrogen gas, but not a universe anything like the present. The intricate fine-tuning we observe in the universe—gravity being an example—is one way that the physical sciences point to God’s existence. Is random chance an adequate explanation for the intricate design and order we observe in the cosmos? Nope. Not even close.
Some posit that the physical universe has existed eternally. That is, it never had a beginning. This is sometimes referred to as the “perpetual universe theory.” Although the Big Bang theory is extremely well corroborated and accepted by the majority of cosmologists and astronomers as scientifically proven, some say the material universe regresses infinitely in time, with no point of beginning. There are a number of variations on this theory, including bubble universes that pop out from an original parent universe that can be traced infinitely back in time. At first glance, infinite regression seems to negate the requirement for a Creator. However, it doesn’t.
Although physicists have recently shown that infinite regression of the physical universe is not possible given its present characteristics (see the Borde-Vilenkin-Guth theorem), should it be possible, an explanation for its existence is nevertheless still required. In other words, infinite regression doesn’t explain why there is something rather than nothing.
Imagine a chain of infinite length. Although it’s not possible for such a chain to really exist, let’s suppose it does theoretically. Should it exist, it would still require a manufacturer. In other words, it cannot create itself. It can’t forge its own links. It does not explain its own existence. A similar argument is often made using an imaginary book with infinite pages. If that book did exist, its existence would still require an author.
Infinite regression is not a logically valid work-around that negates the necessity of the Creator.
What Caused God?
One mistake people make is in thinking that absolutely everything must have a cause. In understanding that material things in time each have a cause, which is correct, it is reasoned incorrectly that it’s not possible to have a thing that is uncaused. However, God is the exception. God has no cause. God is a non-physical, non-contingent, uncaused Being who transcends the physical universe and who subsists in himself. He is being and life itself. God is self-sufficient being. According to Thomas Aquinas: ipsum suum esse subsisten (God subsists in himself).
Since God subsists in himself, there’s no logical contradiction in saying that God is uncaused and uncreated.
It’s just as illogical to say that the universe brought itself into being as it is to say that you exist but have no father and mother, or that a tree suddenly sprung from a jar of nothingness. The point is, the physical universe and all beings (other than God) require an explanation for how they came to be. They do not and cannot fully explain their own existence.
That doesn’t mean there’s no explanation for how God exists. It simply means that he’s unlike any other being. He is singularly unique—a divine singularity in that there is only one God. His existence is explained in himself. In other words, he did not come to be, but rather he is, dwelling eternally, outside of time and changeless yet present to all creation. God is the transcendent, non-contingent, first-order Creator of all things visible and invisible. God is life itself from Whom all life finds its origin and sustaining force.
And, God is a plurality of Divine Persons: Father, Son, and Holy Spirit. But that’s a topic for another day.
Deacon Frederick Bartels is a member of the Catholic clergy who serves the Church in the diocese of Pueblo. He holds an MA in Theology and Educational Ministry and is a Catholic educator, public speaker, and evangelist who strives to infuse culture with the saving principles of the gospel.