This week a man asked me, “Does the big bang make God unnecessary?” One could give a simplistic answer: “Of course not! Where do you think the big bang came from?” But there is a better answer, one more complex and more true. At root, this man’s question reveals a profound misunderstanding of the Catholic doctrine of God. It is a misunderstanding shared by many atheists. Let me explain why.
Catholics holds that the existence of God can be known by the light of human reason. The most famous arguments for God’s existence are summarized in St. Thomas Aquinas’s Five Ways. (Summa Theologica 1.2.3.) These arguments proceed by considering what is evident to our senses and then they reason backwards to its source and origin in God.
Many people assume that St. Thomas reasons backwards in time, as if he were trying to account for the beginning of the universe in time. This is what my interogator thought. If he could account for this beginning on other terms (a highly questionable thesis), then why invoke God? The problem is that this is not how St. Thomas argues for God’s existence. As a Catholic, Thomas believed that the world had a beginning. He just didn’t think you needed to prove this in order to show that God exists. Accounting for the beginning of the world just doesn’t enter into his argument. Even an eternal world, for St. Thomas, would still stand in need of explanation. Invoking the big bang, even an infinite series of “bangs” and “busts,” would not change this.
St. Thomas does reason backwards, from effect to cause, but not backwards in time. A true cause (what he calls a per se cause) exists at the same time as its effect. As I write with a pen, for example, my hand is the cause of the pen’s motion, but it is a cause that exists at the same time as the pen’s motion. For St. Thomas, any kind of change, any kind of motion, has to be explained by causes of this sort, operating here and now, and not just in some distant past.
To illustrate, we can explain the pen’s motion by pointing to the hand, but then we have to explain the hand’s motion as well. We do so by identifying a host of hierarchically ordered causes all operating here and now, each one addressing deeper and more fundamental layers of reality: the muscles and nerves of the hands, the firing of the motor neurons, the chemical changes of the brain, the motion of subatomic particles, etc. At each step we can ask, “Is this mover moved by something else?” Eventually, at the deepest level, we must posit a mover that is not moved itself, “The Unmoved Mover.”
Why can’t we proceed to infinity in movers of this sort? Why, at the deepest level, must we arrive at an unmoved mover? The reason is simple. The pen has no “intrinsic motion” – no actual motion – unless unless it is moved by something else. In fact, we can divide all of reality like this, into that which is actualand that which is merely potential. Now imagine an infinite series of real, per se causes that possess their causal power only potentially, and none of them actually or intrinsically. The thing is absurd! It is like positing an infinite number of train cars but no engine. Such a series (if it could exists) would have no instrinsic causal power. Therefore, we must arrive at a cause that causes not just potentially, but actually. In fact, we arrive at that which is pure actuality.
What is true of motion is also true of existence itself. For every being in the universe other than God, the act of existence is not something instrinsic to its nature. It is possible for it “not to be.” Unless actualized by another, its essence or nature has being “only potentially.” Thus,we explain its existence with reference to a series of ordered causes. Eventually, we arrive at that which contains within itself the reason for its existence. One whose very nature is to be. In fact, Catholic philosophers define God as “the very act of ‘to be’ itself,” ipsum esse subsistens.
The God of Catholic faith is not just a powerful artist or craftsman who builds a world and then sets it moving, like a watchmaker. Such a god would be simply one being (albeit a very powerful being) among many, his being essentially disconnected from the being of his creatures. But Catholics believe in a God who is actively causing the being of the universe here and now, not simply at some point in the finite past. This is why the question (Does the big bang make God unnecessary?) profoundly mistates the Catholic understanding of God. If it could be shown that the universe came into being at the big bang, this would do absolutely nothing to destroy the case for God. (It might strengthen it, since “coming-into-being” is precisely what something does when it derives its being from another.)
When atheists say they don’t believe in God, many times they have in mind the kind of watchmaker God that Catholics also reject. (This fellow who asked about the big bang obviously did.) They think that if they can explain motion or change within the ordered system of nature, that they have no need for God. As if God were simply a hypothesis to account for gaps in our understanding. The God of the Gaps! But this just isn’t what Catholics mean by God. He is not simply the explanation for this or that discrete event, but rather the ground of every explanation, the actuality behind every potential, the very act of “To Be” itself. As St. Paul says, “In Him we live, and move, and have our being.” (Acts 17:28)