Can we prove God exists?

The sense of wonder many of us feel when looking at the world around us is not only a fundamental driving force in the quest for scientific knowledge, but it also points us beyond the scientific realm to the reality of God. If you had asked St Paul whether we can prove God exists, he would have answered with a resounding “yes!” In his letter to the Romans, he writes: “Ever since the creation of the world, [God’s] invisible nature, namely, His eternal power and deity, has been clearly perceived in the things that have been made.” 

In the 13th century, St Thomas Aquinas famously proposed five ways to prove God’s existence, and much has been written about them since. St Thomas’s fifth way bears some similarity to an argument that has become increasingly popular in recent years. This is the fine-tuning argument, and it goes as follows: when we look at the constants that govern the laws of physics, we see that they need to be remarkably well-tuned if the universe is to be capable of sustaining life. For instance, if the so-called strong force that governs the behaviour of protons and neutrons had been much stronger, then all hydrogen would have been burnt up in the early universe, but if the strong force had been much weaker, very few elements beyond hydrogen would have been formed. So in either case, the conditions for life would be almost impossible. The argument thus concludes that there must therefore be some supernatural agency to fine-tune the constants of physics to make them just right for a universe capable of sustaining life.

Not everyone is convinced. One common objection to the fine-tuning argument is the multiverse hypothesis, that there is an unfathomable number of universes each with their own physical constants, and we just happen to live in a universe where these physical constants allow for the possibility of life. But even if this rather implausible explanation could account for the possibility of life in our universe, it wouldn’t undermine some other proofs for God’s existence. 

Take St Thomas’s second way. He argues that nothing in the physical world is the efficient cause of itself. Nothing that potentially exists can bring about its own actual existence, so there must be something pre-existing that causes it to exist. Therefore, in order to avoid an infinite regress, there must be an ultimate first efficient cause on which the existence of everything else depends, and this we call God.

But again, not everyone is convinced. In his book The Grand Design, Stephen Hawking writes: “Because there is a law like gravity, the universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist. It is not necessary to invoke God to light the blue touch paper and set the universe going.”

However, the problem with Hawking’s explanation is that in claiming there is a law like gravity, he is presupposing there is already something existing which this law describes. Thus, Hawking is speaking of something that is actual and that is full of potential. And it is this distinction between potentiality and actuality that St Thomas appeals to in his second way. It is because of this distinction that a just judge will only punish actual criminals rather than potential criminals. Likewise, we tend only to reward and congratulate people for their actual achievements rather than their potential achievements. Some people may try to deny this distinction, but nobody actually lives this way. On the other hand, when we accept this fundamental distinction between potentiality and actuality, the fact of our actual existence and the existence of everything around us should fill us with a sense of wonder because potentially everything might not have existed.

So when children see a magician pulling a rabbit out of a hat, they naturally want to know how the magician did it – they don’t suppose they have just witnessed something coming into existence without any cause. Anyone who does suppose this is no friend of science because they are closing their minds to that wonder which is such an important driving force in humanity’s quest for scientific knowledge. So when we hear scientists tell us that things can come into existence without any cause, or that the universe can and will create itself from nothing, they are not speaking in their capacity as good scientists but only as bad philosophers.

Fr Robert Verrill OP is based at the Dominican Priory in Cambridge

This article first appeared in the January 2022 issue of the Catholic Herald. Subscribe today.