Yes, my 3-legged cat can prove the existence of God.
Even if we assume, for the sake of argument that the universe has no beginning in time…
Through Aquinas 3rd way from this famous Summa Theologiae but let’s
Cosmological arguments begin with evidence from the world around us and rationally examines this evidence to discover what best or most fully accounts for what we observe.
One of the most popular cosmological arguments for the existence of God is the Kalam Cosmological Argument (KCA) which often goes something like this:
Premise One: Everything which begins to exist has a cause for its Existence
Premise Two: The Universe began to exist
Conclusion: The Universe has a cause for its existence
From the conclusion, proponents of the KCA go on to elaborate on the nature of this cause and conclude that this cause is something very much like God. The most famous defender of the KCA is the laudable philosopher, William Lane Craig. If you want to know more about the KCA, I can’t think of a better place to start than him. (1)
For various reasons, which I may come to in later posts, I’m not as taken with the KCA as many other philosophers of religion seem to be. This isn’t to say that I don’t think that the argument has merit, because it certainly does, but I just don’t think it has quite the range of explanation or strength of other Cosmological arguments.
Which brings me back to Aquinas’ Third Way. What’s interesting is that Aquinas famously argued that it is impossible for reason to know whether or not the universe had a beginning in the past. Nevertheless, he still maintained that we can know with reasonable certainty that God exists– which, runs contrary to how most people think about Cosmological arguments.
Despite the various attempts at interpreting Aquinas’ 3rd way as arguing for a temporal beginning by professional philosophers and amateurs alike, Aquinas begins by granting the possibility that the physical world has been chugging along indefinitely. (2)
Whether or not it is the case that the universe has a beginning is for a different discussion but for now I think we can appreciate the approach Aquinas takes here. Just think about it, as Stephen Hawking wrote in his recent work, Brief Answers to Big Questions:
“But of course the critical question is raised again: did God create theStephen Hawking, Brief answers to the Big Questions, 26 PDF version.
quantum laws that allowed the Big Bang to occur? In a nutshell, do we need a God to set it up so that the Big Bang could bang? I have no desire to offend anyone of faith, but I think science has a more compelling
explanation than a divine creator.”
By granting this possibility, Aquinas puts his ideological opponent in a more advantageous position and yet sets out to demonstrate that God exists in spite of it.
If Aquinas is successful, and I think that he is, then it just goes to show just the power of his third way and other arguments. If you’re in a boxing match and allow your opponent to throw kicks as well, but you still win, then you simply demonstrate how much more effective of a fighter you are compared to your opponent.
Perhaps the best way to go about this is to read St. Thomas’ argument and take it step by step:
The third way is taken from possibility and necessity, and runs thus. We find in nature things that are possible to be and not to be, since they are found to be generated, and to corrupt, and consequently, they 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.
Now if this were true, even now there would be nothing in existence, because that which does not exist only begins to exist by something already existing.
Therefore, 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.
But every necessary thing either has its necessity caused by another, or not. Now it is impossible to go on to infinity in necessary things which have their necessity caused by another, as has been already proved in regard to efficient causes.
Therefore we cannot but postulate the existence of some being having of itself its own necessity, and not receiving it from another, but rather causing in others their necessity. This all men speak of as God.Thomas Aquinas, Summa Theologiae I Q. 2 A. 3 co.
The Tertia Via has four basic components:
- It’s starting point: Things generate and corrupt, which is to say they come into and go out of existence. These things are what Aquinas calls possible beings.
- Not everything can be a possible being.
- There must, therefore, be at least one necessary being which is to say something that does not come into or go out of existence. A necessary being can be necessary either through itself (per se) or through another (per aliud).
- Necessary being cannot simply be per aliud but there must be at some point something that is necessary through itself (per se).
- This is what we call God, therefore God exists.
While this is not exactly a formal rendering of the argument, I think that addressing will help make this argument easier to understand.
As I’ve already mentioned, Aquinas offers a similar argument in the Summa Contra Gentiles 1.15 (SCG) and his use of terms in this argument will help us understand what’s going on here in the Third Way of the Summa Theologiae. In the SCG, when Aquinas highlights that we find things that generate and corrupt he clarifies his meaning by saying,
“We find in the world, furthermore, certain beings, those namely that are subject to generation and corruption, which can be and not be [possibilia esse et non esse].”SCG 1.15.5
Alright, fair enough. We see this all the time. At one point the three-legged cat I owned in high school, Elmo, did not exist and he later ceased to exist. Elmo is a perfect example of what it means to be a possible being and anything else that we encounter like Elmo, that is, things that come into existence or go out of existence, are also possible beings.
Continuing his analysis of possible beings, Aquinas remarks that:
“But what can be has a cause because, since it is equally related to two contraries, namely being and non being [esse et non esse], it must owe to some being the existence which accrues to it.”SCG 1.15.5
In the context of generation and corruption, we have an important principle at work: anything which comes into existence does so because of something which already exists. Elmo, for instance, only came into existence because of the actions of his parents and looking at just this stage of the argument we can say that Elmo’s existence was caused by his parents reproducing. (4)
But we shouldn’t get too hung up on his parents here because the fact that Elmo came into existence tells us something about his metaphysical structure which should give us pause.
Aquinas would say that Elmo is equally related to two contraries: being and non being. What does he mean by this?
Just to keep things simple: When I talk about “Elmo”, I know exactly who I’m talking about. At some point after Elmo came into existence, he had existence. Now that he’s dead, he no longer has existence. Hence Elmo, considered precisely in himself, does not include “actually existing” as a part of what it means to be him. For anything that is neutral to two contraries, there must be a cause to explain why we have one state of affairs over another, i.e., why my coffee is cold instead of hot.
Therefore, since Elmo could either exist or not exist, then for any moment that Elmo exists there must be some cause to explain why he exists rather than not exist. (See note 4 for a more in-depth look at how we know this to be the case and why Elmo can’t be the explanation for his own existence, I also include a brief biography of Elmo. Note 4 is almost as long as the post, so be ready :-))
Those familiar with Aristotle will recognize that the phrase “to be and not to be” has an Aristotelian lineage. However, I do not think that it is accurate to say that Aquinas is making an Aristotelian argument. In Aristotle, for things to generate and corrupt does nothing more than to denote the relationship between matter and form.
For a substance to exist is simply to have the form inhering in the matter and without form, the thing doesn’t exist at all. Although Aquinas does not contradict Aristotle on this point, he broadens the purview of generation and corruption beyond anything conceived by Aristotle.
For Aquinas, as will be shown shortly, the term “possible being” also extends to the universe as a whole or even to immaterial substances– should such things exist. To be sure, Aquinas does not neglect principles of being such as matter and form. In fact he calls form the principle of being [principium essendi] in various places throughout his works.
What makes Aquinas’ approach to generation and corruption distinct from Aristotle is that whereas Aristotle attends only to how form actualizes matter, Aquinas turns his sights on what he sees as an actuality prior to form: esse or the act of existing.
This shouldn’t be too difficult to see, actually, nothing could be real if it did not have existence and therefore every other principle presupposes existence in order to operate at all. A thing can’t do anything at all if it doesn’t first exist. Therefore when Aquinas turns his attention to why things come into existence or go out of existence, his concern is with the most intensive property that extends to all things have in common: existence.
From something as simple as a cat, Aquinas seeks to determine the question “why do we find things existing at all?” And with special pertinence to the third way, he asks “Could everything that exists be a possible being?”
Which moves us on to stage two.
Stage Two: Is everything merely possible?
The second stage determines that the sum total of reality cannot merely be made up of possible beings. It’s at this stage that many, if not most, interpreters get stuck and I hope to clear up any confusions. But before we get there, I think that in this stage Aquinas offers yet another consession to his opponent by considering the possibility of an infinite duration of time to wait for something to be generated. Remember that a possible being is one whose existence is caused or conditioned by something already existing, which would be a necessary being.
Aquinas argues that if everything were a possible being then at some time there would be nothing in reality. Since things can only come into existence from something that already exists then it would follow that nothing exists now, since nothing would have existed before now to generate new things. However this is absurd because at the very least, I know that I exist.
There have been quite a number of attempts at solving this riddle.
Some question the idea that whatever can cease to exist must cease to exist.
Others accuse the third way of committing a composition fallacy or a quantifier shift fallacy because he seems to be saying “since every individual possible thing ceases to exist at some time then the sum total of possible things will cease to exist at the same time.”
Here’s how that works:
Since possible beings, like Elmo, depend on something besides themselves for their existence then without whatever a possible being depends upon, the possible being would cease to exist entirely or never exist at all. The phrase “at some time is not” need not be taken temporally but rather in reference to what would be the case if the cause of the possible thing were absent.
In Latin, the phrase “at some point” is quandoque but the use of quando can also be used to specify certain conditions or requirements for a certain state of affairs. One example of this would be in his Summa Theologiae q. 33, a. 6, ad 3 where Aquinas points out the conditions when (quando) fraternal corrections are not a good thing.
When we understand Aquinas’ phrase to mean “If it were the case that nothing were causing the existence of possible beings then all things would not exist.” So the “time” at which possible things don’t exist is when they do not have a concurrent, external cause for their existence. Not only does this completely avoid the aforementioned fallacies, it should be something that is straight-forwardly obvious.
If a thing does not have existence then it clearly does not exist. But if that were the case then nothing would exist now since everything that comes into being can only come from something that already exists. Even if given infinite time, nothing would arise from nothing because there would never have been anything In the first place.
Hence it is impossible that all things should be possible beings but there must be at least one thing that exists necessarily which causes or conditions the existence of possible things at any given moment.
Aquinas’ argument has less to do with looking at an accidentally ordered series, that is one in which the cause precedes the effect in time, but a causal series ordered per se which considers the conditions necessary for anything to exist in the present moment.
Hence, if all possible things were without the necessary conditions or causes for their existence to obtain then, if course, they would never exist and nothing would exist now. But, again, things exist now which means that there must be at least one necessary being to condition or cause the existence of possible things.
And now, on to stage three. (I admire your stamina!)
Stage Three: Necessary Being(s?)
Once we’ve reached this stage, I think it would actually be possible to get to God rather quickly. However, Aquinas doesn’t take this route and instead elects to place another roadblock in his argument so as to further prove the strength of his conclusion.
A philosopher whose convictions differ from those of Aquinas may argue that as the act of a possible being, the esse is in some way dependent on the possible thing.
This approach opens up the discussion to reflections from the philosophy of nature which in some ways concludes with things that do not generate or corrupt. In the ancient context, entities such as angels or the celestial spheres (planets and the sun) would qualify as necessary beings.
In our own day, the universe itself may be understood as a necessary being. The universe has been chugging away without beginning and without end, so perhaps the universe is the one necessary being required for things to exist at all.
A mighty beast indeed…
Stage Four: Necessary How?
The fourth stage of the Third Way sets out to demonstrate why it is entirely unfeasible to hypothesize that the only things that exist are possible beings and necessary beings per aliud. What we find at this stage is a reference to the second way, which argues from efficient causality, and eliminates the possibility of an infinite series of necessary efficient causes.
A necessary cause of existence either has necessary existence through itself (per se) or through the action of another (per aliud). For reasons I’ll discuss shortly, if we arrive at a cause of existence that has necessary existence through itself then we’ve simply arrived at God Himself. At this point, the argument would successfully conclude.
Well, what about necessary causes which necessarily exist through another? Could these explain existence?
No. And here’s why.
Suppose you have A, a possible being whose existence is caused by B, a being that is necessary through yet another necessary being, C.
If B’s existence is caused in it by C then the essence of B is existence-neutral in the same way that the essence of A is existence-neutral (see note 4).
The difference, of course, is that if B exists then it exists without generating or corrupting but still depends on C for its own existence.
Just by way of thought experiment to give you an approximation of what this means, imagine a ball sitting on a pillow. The pillow, considered in itself, does not have a convex indentation on it but relies on the roundness of the ball to make this impression.
Now, just imagine that the ball was never placed on the pillow but had always been there and always will be. In such a case the ball still causes the convex indentation on the the pillow, even if there were to be no initial point at which the ball began to rest on the pillow.
Similarly, a necessary being could still be caused, albeit in a non-temporal manner.
Now we’re actually right back to where we were in stage three because it is not feasible for a possible being to derive its existence from any number of things necessary through another. Why?
No matter how many things we pile up that are existence-neutral, their collective action could not cause rise to the existence of even the most humble fundamental particle.
It’s like a simple math equation.
Adding 0 to 0 will always equal zero.
Adding a thousand 0’s to 0 will always equal 0.
Even if we resort to adding infinite 0’s to 0, we will still only get 0 as our sum.
In order to get a positive number, there must be an addend which is a number greater than 0, like 1 or 2.
Similarly, no matter how many existence-neutral necessary beings one adds together they will never be able to cause the feeblest of existence-positive possible beings.
At some point on the “causal side of the equation”, you will need some necessary being which exists in virtue of itself, in whom existence and essence coincide.
Furthermore, in principle, we can know that there can only be one such being. In order to have more than one thing in which essence is identical to its essence, there would have to be a real principle of differentiation to make one really distinct from another.
However, there is no principle outside of esse that one could add to esse. Rather, any difference between the two would involve some reduction of esse by an essence. But this would just introduce yet another thing which has an existence-neutral essence and would therefore require a cause in which essence and existence coincide (Hereafter Ipsum Esse Subsistens).
Of course, for those who have been paying attention, there can be only one thing which is Ipsum Esse Subsistens whereas existence and essence are really distinct in everything else.
What have we come to?
I’d like to keep this next part relatively brief and take it up more in the next post. But just to round out the discussion, what is it that we can know about the nature of the First Necessary Being.
The universe itself cannot be the First Necessary Being for a few reasons.
First, it’s not entirely clear that the universe is actually some individual thing rather than a just a collection of things. So, in that sense if the sum total of every individual thing in the universe is possible then all of them taken together could not be a necessary being.
You might as well try to build a house with liquid water.
Second, even if we do grant the universe some “thing-hood” then it still cannot be the First Necessary Being. The universe is made of matter and matter is made out of parts. But parts could be united or not united and therefore any whole made of parts requires a cause to determine the parts as constituting an actual unity or disunity. Since the universe is presumably a whole made out of parts then the universe likewise needs a cause.
So, the universe cannot be the First Necessary Being.
But what justifies my contention that we can call this thing God?
When Aquinas looks at the meaning of esse and the role it plays in reality he recognizes it as that:
“All the perfections of all things pertain to the perfection of being [de perfectio essendi]; for things are perfect precisely so far as they have being [esse] after some fashion.”Summa Theologiae I q. 4 a. 2, co.
Aquinas rightly concludes that as Ipsum Esse Subsistens God’s essence contains all the perfections of existence. This would mean that whatever perfection such as being, goodness, intelligence, personhood, love, or wisdom must be found in God– although it is found in Him in a way qualitatively different than what we find in His creatures.
Whereas creatures have these perfections in some limited manner, God possesses them in an infinite and essential manner.
Aquinas states this beautifully in De Ente et Essentia:
“[God] has all the perfections which are in every genus. This is why he is called simply perfect, as the Philosopher and the Commentator say in book five of the Metaphysics. But he has these perfections in a more excellent way than all things because in him they are one, whereas in other things they have diversity. And this is so because all these perfections belong to him according to his simple existence. If some one could perform the operations of all the qualities through some one quality, he would have every quality in that one quality; so too God has all these perfections in his existence itself. “Aquinas, De Ente et Essentia, 91
Insights stemming from something as simple as my 3-legged cat demonstrate the most profound reality: that all things find their origin in God who is Subsisting Existence Himself.
There you have it.
In later posts I’ll use much of what has been discussed here to address many other issues such as:
- A deeper engagement with what is entailed by the First Necessary Being
- Why the universe e cannot be the the First Necessary Being.
- The legitimacy of using existence as a first-order predicate.
- How Aquinas’ understanding of negative existential predication is justified.
- The doctrine of existential inertia and why nothing could exist if God was not causing it to be at every moment.
- Questions from readers :-).
Alright, I have a lot of other projects at hand but I look forward to your input.
Jonathan L. Stute, M.A, MaPhil
Professor of Philosophy at Holy Apostles College and Seminary
P.S. Okay, I know that this post was pretty heavy on the philosophy. But if you made it this far: you’ve got some serious intellectual fortitude!
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(1) Google “William Lane Craig” and “Kalam” and you will end up with an endless supply of resources from which to choose.
(2) Stephen Hawking, Brief answers to the Big Questions, 26. (PDF version)
(4) In middle school, a friend of my sister had a cat who gave birth to a litter of kittens. Of course my sister brought one of the kittens home, we named him Elmo. He was pretty good at being a cat. Even after losing a hind-leg in an accident when he was about a year old, he still managed to somehow catch birds. Brilliant.
Unfortunately, his missing leg caused a number of problems. His leg remaining leg began to develop arthritis, he was diagnosed with diabetes, and eventually died at a fairly young age.
This sad, sad story illustrates something that we see every single day to some extent. Just as Elmo came into existence as the result of reproduction and went out of existence when his body ceased to function, various objects come into existence when the conditions are right and go out of existence when those conditions fail to obtain for one reason or another.
What’s more is that we recognize that anything that comes into existence comes from something that already has existence. The thing, no matter what it is, cannot give rise to itself– that’s simply impossible. Why? Because in order to do anything at all, including causing itself to exist, a thing would have to exist. But that would mean that it would have to exist while simultaneously not existing before it could cause itself to exist. That’s just absurd– nothing causes itself.
You can kind of think of it like this: On more than one occasion, I’ve locked my keys in my house (thanks ADHD). I could get my house keys, of course, but I would first have to get into my house to get my keys but to get in my house I need my keys….
Of course there are different ways for me to get into my house. I could break a window and climb in, I could call my wife or a friend., or I could kick the door down (I did this once).
However, there are no other options when it comes to existence. A thing must exist prior to anything else it does in realty.
On the other end of Elmo’s life, at some point he ceased to exist entirely. Exactly when he ceased to exist isn’t all that important because at some point whether it be when his metabolic functioning ceased or when he was turned to ash in the crematory– it’s clear that the “to be” of a cat-corpse or ash is qualitatively different than a living cat, namely, my cat Elmo.
It’s not my idea of Elmo that ceased to exist, I still know the exact cat that I’m talking about. No. When I say “Elmo ceased to exist” I mean precisely that. The same thing, Elmo, that once had existence no longer exists.
First, this every-day experience indicates to us that a thing that comes into existence relies on certain conditions to come into existence, which always stems from something else that already has existence.
Second, that whatever comes into existence is not the source of of its own existence.
Third, that this existing thing depends on some concurrent sufficient conditions for its existence which we can know because a thing can and at some point cease to exist. If it were the cause for its own existence then it could not fail to exist.
Fourth, that a thing which ceases to exist does so once the sufficient conditions for its existence fail to obtain.
Why should this give us pause?
Because if a thing came into existence, is not the source of its own existence, and can lose its existence while remaining identical with itself…
Then this thing, whatever it is, is distinct from its own existence.
In another way this should be fairly straight forward since we can understand what a thing without knowing whether such a thing exists in reality.
Of course, no thing could be or do anything at all if it did not first exist in some way. As it turns out, there is no Meinongian slum where things hang out before they are somehow instantiated in reality.
How are things instantiated in reality? In one of three ways: Either as a concrete individual instance, or as existing in the intellect, or both.
Elmo, again, at one point existed as a thing in the real world even before he was known by anyone. At some point, however, I knew Elmo himself. A little while later, he ceased to exist as a concrete extra-mental reality and only continued to exist as something known.
Now if what it means to be “Elmo”, or his essence, necessarily includes existing in reality then he couldn’t exist as a thing known as such. Sort of like how part of Elmo’s essence as being a cat precludes him from being a dog or a bird. Those just are ways of existing incompatible with what it means to be “Elmo, the cat”. Why? Well, to explain that I want to offer a brief clarification about what I mean by “essence”.
An essence is not some metaphysical goo that exists out in the ether or some strange ectoplasm that covers a thing. No. An essence is simply what a thing is in its totality, including form and matter. So, on that, let’s have a brief word about form and matter.
Without getting too bogged down in details…
Form is an internal principle of organizational unity in a thing which makes all of its other parts work together whereas matter is that out of which a thing is made. While form and matter in one thing are not distinct substances, they are distinct causal realities in a thing, so form is real but you’ll never see it with your eyes in the same way you see matter. You can perceive form as a real feature of the world by the way that the same “hunk” of matter can take take on different ways of existing. The same atoms that make up a mouse can be reorganized to make up a snake. Hence something other than matter is at work in this relationship, which we call form.
The relationship between form and matter in material things is one of co-dependence but this co-dependence is not equal. Form gives matter its manner of existing and matter is open to receive a variety of ways to exist. Hence form actualizes matter, that is it makes it real, whereas matter is the subject of actualization, meaning matter is what receives a particular way to exist. Form also gives us the intelligible content of what a thing is but in a way that is not particularized, i.e., we can know “cat” rather than “this cat, Elmo”.
The essence of an individual thing is their form and matter considered together. So to think of Elmo’s essence would be (“cat” + the matter of this cat, considered generally). Form and matter, then, are the two most basic constituent parts of an essence. Because Elmo’s essence is “this cat” then he could never be instantiated in dog matter or with bird form simply because those are contraries to the principles of his essence.
Similarly, if Elmo’s essence were limited only to existing as known then he couldn’t exist in concrete realty.
Thus, when considered precisely in himself, Elmo’s essence is existence-neutral even though in order to actually found in the real order he must be existence-positive as a real being or in the mind as a being of reason.
We’ve already determined that for Elmo to come into existence at all that he must be caused to exist at some point. But could Elmo continue to exist after his parents die? Yes. In fact, he did!
So, how did Elmo exist during his lifetime? Does he explain himself?
Well, it would seem not. And here’s why:
Whatever a thing does, it does in virtue of what it is. Vaguely, a cat does cat things, a dog does dog things, and a human does human things.
From what we’ve already discussed, we can know that what it means to be Elmo does not entail that Elmo exists in virtue of himself.
- He must be caused to exist
- He can cease to exist
- He is neutral to existence but…
- He must exist either mentally, in the concrete world, or both in order to do anything proper to what it means to be Elmo
Hence, whatever it means to be “Elmo” presupposes that he exists and that he does not exist essentially.
At any moment during Elmo’s existence, he relied upon a host of other conditions or causes to keep him in existence. We can know this because if it were not the case that he relied on certain conditions or causes then he would be the condition for his own existence in which case he would never cease to be. What sort of causality are we looking at here?
We could look to the parts of Elmo’s essence: form and matter.
Matter doesn’t actualize anything. In fact, it restricts form to a particular instance of that form. What’s more is that some flaw or insufficiency in matter can actually inhibit the “full-power” of the form. If you get hit in the head too many times, you won’t think too good anymore. So matter, in a way, doesn’t cause the existence of anything in a positive way but restricts or limits it to one instance of a particular kind. What’s worse is that, considered without form altogether, matter cannot exist at all in any way. So if a material thing loses its form then it will cease to exist instantaneously.
What about form? Well form does act on its matter so that the matter exists as a particular kind of thing. However, the form of something like a cat cannot exist as a cat unless it exists in matter somehow. So, form depends on matter to exist as a concrete thing in reality. Additionally, if the form did not exist in someway prior to the matter then it could not ever act in such a way so as to organize the matter into a particular instantiation of that form. Sort of like how if the form of a house never existed in the mind of the builder then the heap of building materials would remain just that.
For a material thing to exist, then, it depends on something more than just form and matter: it depends on some efficient cause. Obviously for something like a cat, it has an initial cause, its parents, but his continued existence would still require some explanation. Since his existence cannot be accounted by the principles of his essence, his continued existence relies on some efficient cause outside of himself in order to exist at all.
As we’ve already discussed, a thing must exist before it can do anything whatsoever. Hence whatever causes any currently existing thing to exist must also exist.