Thomas Aquinas (c. 1225 – 1274 CE), was a famous Catholic theologian, philosopher and prolific writer. Above all else he is remembered for his “quinquae viae”, or five proofs for the existence of God, expressed in his Summa Theologica. Ideological battles over the existence or non-existence of God have probably been waged since the dawn of human cognition, and continue into the present day. Yet the word “proof” implies irrefutable evidence, which raises the question of how these arguments can even continue. In fact, as I shall attempt to demonstrate in this essay, Aquinas’ proofs do not prove anything, or at best “prove nothing” – a statement I will qualify later. If I am to have any hope of refuting the five proofs, I must first demonstrate a full understanding of the arguments behind them. So first I will provide an analysis of the five proofs, citing the text of Summa Theologica, and then explain the critical fallacy of each one.
The first proof is an argument first presented by the Greek philosopher Aristotle (384 – 322 CE), that of the “Prime Mover”. The basic idea here is that all things that are in motion were put into motion by something else, which can be called a mover. Since there cannot be infinite movers, there had to be – at the start of this chain of motion – a mover who started it all. According to Aquinas’ extrapolation of the concept:
“Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects [...] It is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e. that it should move itself. Therefore, whatever is in motion must be put in motion by another [...] But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover [...] Therefore it is necessary to arrive at a first mover, put in motion by no other.” (Summa Theologica, 1:2:3)
The problem with this “proof”, and one we shall find common to all five, is that it is built upon a number of presuppositions. First and foremost is the assumption that at any time in the universe there was no motion at all. A “first mover”, by definition, would have had to perpetrate a “first motion”, meaning that prior to that event there was an absence of motion. On what infallible pretext are we to base this notion? What evidence is there that the universe was ever anything other than “in motion”, in some respect? There is no such evidence.
As we understand the universe today – and Aquinas can be forgiven his lack of foresight into the discoveries of science five hundred years after his death – all energy and matter are conserved. That is to say they cannot be “destroyed”, or made to not exist. If all energy is conserved, then that means that all energy in the universe today has always existed. Existence then, in these terms, has no necessary prerequisites. Furthermore, motion requires energy; in fact, energy alone is often the “mover” for a thing. If energy has always existed, then its action upon any given thing to make it move was always a possibility. Energy itself is always in motion, being transferred from one thing to the next, through one medium or another. Even when talking about the “potential energy” of a non-moving object, that energy exists in the form of interplay between the constituent parts of that object, going as far “down” or perhaps even deeper than the atom.
Not only is there no evidence for the idea that there was ever no motion, but literally everything in the universe that we can conceive of suggests the opposite to be true – that motion itself is a fundamental property of the universe. Should anyone suggest that this “pre-motion” state of the universe lies outside the realm of human cognition, they should also acknowledge that there really is no point in a human trying to logically “prove” anything that operates outside of that realm. That would altogether negate Aquinas’ first proof. That spurious reasoning aside, the only way that the first mover argument holds is if we assume that all energy and matter at one time did not exist, and was introduced into an empty universe. If “God” was the agent that brought matter and energy into this void, this nothingness, then God itself would also have to be nothing. This is what I was referring to when I suggested that Aquinas’ arguments were proof for nothing. At least it can be said at this point that he has not successfully proven anything.
The second proof for the existence of God has to do with causality. For every event there was an earlier event that caused it, and since there cannot be an infinite series of causes, there had to have been a “first cause”. As Aquinas put it himself:
“There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible. Now in efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of the intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several, or only one. Now to take away the cause is to take away the effect. Therefore, if there be no first cause among efficient causes, there will be no ultimate, nor any intermediate cause.” (ibid)
Since the second proof is more or less a rephrasing of the first, the arguments used above could be reapplied. However, there is an important point to be made about causality that provides a further argument against the second proof. Hardly any event is “caused”, in the pure sense of “A” acting to produce “B”. Most, if not all, events in the universe are the result of numerous contributing factors, some having greater effect than others. The chain of “causality” is actually a web of correlation. The innumerable phenomena of our universe, from the quantum to the celestial, all play off of one another as energy flows throughout the system.
Even where a given “effect” can be traced to a specific “cause”, it is impossible for any one thing to operate on any other single thing without also influencing the things around it. Conversely, no one thing can affect another without contributions from those things around it. If we simplify this argument, and concede that there are discrete “effects”, but that indeed that must have had multiple causes, we would have a causal branching that would spread out to infinity. This would mean that there were an infinite number of first causes, not just one. If the “first cause” or “God is an infinity, then it must include all of us, making us all constituents of God, and therefore meaning that the first effects were of God causing itself. Yet according to Aquinas:
“There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible.” (ibid)
I am not suggesting this to be the case, but merely offering this point to counter the idea that there need even be any identifiable chain of causality, such as to require a “first cause”.
There is another assumption central to both the first and second proofs just begging to be mentioned, but it must wait. To give the reader a hint, I will say that it has to do with a certain quintessentially “western” way of perceiving the world. Moving on to the third proof, we find the same argument again, only presented in slightly different terms. Aquinas states:
“We find in nature things that are possible to be and not to be [...] But it is impossible for these always to exist, for that which is possible not to be at some time is not. Therefore, if everything is possible not to be, then at one time there could have been nothing in existence [...] If at one time nothing was in existence, it would have been impossible for anything to have begun to exist; and thus even now nothing would be in existence–which is absurd. Therefore, not all beings are merely possible, but there must exist something the existence of which is necessary.” (ibid)
From here Aquinas goes on to restate the second proof, and how this “necessary existence” – which he considers to be God – brought everything else out of non-existence. It goes without saying by now that the same arguments against first mover and first cause could be applied here. The additional fallacy in the third proof is that nowhere in the universe do we witness existence emerging from non -existence or nothingness. Such would defy the law of conservation. What we do see in nature is that the “creation” of any new thing results technically from the “destruction” of other things. Everything is composed of energy and/or matter, both of which by the law of conservation must have always existed. Therefore, all “creation” and “destruction” can only be manifestations of change, and do not merely exist or fail to exist. Furthermore, if God, as that necessary existence, has always existed, it is reasonable to assume that other things could have always existed as well – indeed as all energy and matter must have. The argument of “first existence” thus becomes unnecessary.
The fourth proof discusses the properties of things and the degrees to which they exhibit those properties. Aquinas says that the way we measure any property of a thing is by determining how close it comes to that which exhibits that property to the highest degree:
“Among beings there are some more and some less good, true, noble and the like. But ‘more’ and ‘less’ are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; so that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being…” (ibid)
The fundamental flaw in Aquinas’ reasoning is that he speaks of absolutes, as if for all properties there must be a maximum. Worse, he assumes that for every property there is something which exhibits it to that maximum, and by that something we judge all others. Using Aquinas’ own example, we can show how this is simply not true. Heat is a form of energy, and so for something to be the “hottest”, it would have to contain all energy in the universe. This is because if any other energy existed outside of this hottest thing, then adding that energy to it would make it hotter still, meaning that it was not the hottest possible. If any one thing contained all the energy in the universe, then nothing else would exist, and there could be no quantitative comparison for the property of “hotness”.
When we move to properties such as “goodness” or “truth”, those which simply cannot be quantified, how can we even attempt to measure them? And if we cannot measure them, how can we determine what is “more good” or “more noble”? The answer is that we cannot. As I mentioned earlier, the problem here is speaking of things in absolute terms. Qualities such as goodness are relative – infinitely so – as those values change with respect to a thing’s surroundings. When Aquinas says “goodness”, one can only assume he means in the ethical sense, as in not doing harm to others directly or indirectly – by proxy or by inaction in the face of harmful acts being performed. As any Christian (like Aquinas) would be forced to admit (or be accused of hypocrisy), doing harm to another can be justified. For the party being harmed, such actions are “evil” or at least not good, while for the harming party, or a third party for which it acts as agent, its actions may be good. This relativism of good and evil further shows that there is no universal way of measuring goodness. If there is no way of measuring it, then there can be no identifying a “greatest” good, either. Thus does the fourth proof fall apart at the seams.
The fifth proof advocates intelligent design. According to Aquinas, things that lack intelligence are incapable of acting towards any specific goal. Therefore, where their actions are towards a certain end, it must be that they are being driven by an intelligent being. Using the same logic as proofs one, two, and three, the suggestion here is that at the beginning of all things set into action towards any given end, there must have been an intelligent designer. In Aquinas’ own words:
“Whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.”
The first problem with this argument, again, lies with an incorrect assumption. There are many things in the universe which act towards an end that neither have intelligence nor are compelled to act by any outside intelligence. It is generally agreed that most animals are not “intelligent” – at least not as we apply the term to humans, or as we could only presume to apply to God. Yet they most certainly act towards certain ends – the most prevalent of which are procreation and survival. Unless we assume that God is acting upon every animal directly, their actions do not presume nor require any intelligence whatsoever. The inevitable counter-argument must be that God would not have to act upon the animals directly if he intelligently designed them to perform all of the actions they do. The problem with that explanation is that it again implies a certain chain of causality – the same one central to the first three proofs.
Here, finally, I will present another criticism of that idea. It is a truly western assumption that all things in time and space operate only in a linear fashion. All things always must either come “before” or “after”, maintaining discrete positions in time or the “chain” of causality. As I insinuated through the more accurate term “web of correlation”, the interplay of phenomena throughout the universe is anything but linear. We see cyclical action and reaction in everything from the microcosmic to the macrocosmic, and so it does not even take a “leap of faith” to assume that causality operates in the same way.
There is yet another problem with the fifth proof, one that is in fact contained within all of the proofs. At the end of each, Aquinas makes a statement which assumes that everyone believes in or acknowledges the existence of God.
“…and this everyone understands to be God.”
If everyone understood it, if everyone believed or acknowledged it, then the labor of “proving” the existence of god would be entirely pointless. Clearly, by sheer fact, and in that Aquinas felt the need to offer his proofs, not everyone understands or believes. Even if we were to ignore all of the other glaring flaws in Aquinas’ proofs, and accept their most basic claims, there are many possible conclusions that could’ve been drawn. If there was a “first mover”, why must we assume that it was something as great and intelligent as a god, as opposed to some random instigator? If there was a “first cause”, are we to assume that that first action, and the immeasurably complicated network of effects stemming from it, was all part of some brilliant plan?
This certainly calls into question the concept of free will, which most god-fearing people must believe in if they are to reconcile the existence of a benevolent god with humanity’s rejection of tyranny. And while I feel no need to argue against the possible role of an intelligent designer in our universe, there is huge leap between the suggestion that unintelligent things do not act towards an end, and the necessity that their actions are driven by an outside intelligence. The other, perhaps more likely possibility, is that some things simply do not act towards an end, or with a purpose, at all.
In conclusion, I must reiterate what I said at the beginning of this essay. If Aquinas’ quinquae viae were indeed “proofs” for the existence of God, then I would not be able to argue against them at all. If even one point that I have made against them has even an iota of validity, then that alone automatically disqualifies them as proofs. Aquinas’ attempts were noble (how noble? It is impossible to know!), but in the end, his arguments do not hold. Indeed, the five proofs are exceeded in their greatness as a philosophical examination of reality only by their monumental failure in what they purport to accomplish.