The Existence of God - Trent Horn

Trent Horn - 9 Questions

In a debate hosted by Pints with Aquinas, Trent Horn debated Alex O’Conner on the existence of God. He presented 9 questions whose answers lead to God. 

This article is a near direct transcription of the debate. However, I have added additional sources to accompany his arguments. All credit goes to Trent Horn.

A link to the debate can be found here: https://www.youtube.com/watch?v=5PF1JgXOKDQ


(“the cause of the universe” = “the first cause”)

1. Does the universe have an explanation for its existence?
2. Does the universe explain it’s own existence?
3. Is the cause of the universe changeable?
4. Is the cause of the universe temporal?
5. Is the cause of the universe material?
6. Is the cause of the universe limited?
7. Is the cause of the universe necessary?
8. Is the cause of the universe personal?
9. Is the cause of the universe good?


IF the answers to these questions are answered, then we have proved that the cause of the universe is an immutable, eternal, immaterial, unlimited, necessary, and good personal being. This description could only be described as God.

1. Does the universe have an explanation for its existence?


We know some objects in the universe are contingent (their existence must be explained by something else). For example devices such as phones and laptops are contingent on factories, power sources, and the workers who make them. No phone or laptop simply exists outside of a creator. All of these things are contingent, they don’t explain their own existence and must be explained by something else. So how do we explain them?



a. Infinite Chain

One way would be to posit an infinite chain of contingent things explaining each other. But that doesn’t explain why the whole series of things exists any more than an infinitely long chain explains why a chandelier is hanging over my head.

b. No Explanation

You could also say that an object’s existence doesn’t need to be explained. But this violates the principle of sufficient reason (PSR). As the Stanford Encyclopedia of Philosophy defines,


“The Principle of Sufficient Reason is a powerful and controversial philosophical principle stipulating that everything must have a reason, cause, or ground.”

We should assume this to be true because if it wasn’t, we would expect to see many other things pop into existence uncaused. Science relies on PSR being true because otherwise we could never rule out the conclusion that things we observe simply have no reason why they exist. Finally without PSR we couldn’t explain negative states of affairs. For example, it doesn’t make sense to ask at this moment, “Why isn’t my hair on fire?” But it would make sense to ask that if there was a blowtorch directly hitting my scalp and my hair remained unburned.

Both cases presuppose that things which exist must have reasons for why they exist and they don’t exist for no reason at all. But the explanation for the contingent things we observe cannot be another contingent thing, so it must be something beyond the universe or the collection of all contingent things that explains why everything exists. 


As Aquinas notes in the Summa Theologica [I, Q. 86, Art. 3],

“Contingent things can be considered in two ways; either as contingent, or as containing some element of necessity, since every contingent thing has in it something necessary: for example, that Socrates runs, is in itself contingent; but the relation of running to motion is necessary, for it is necessary that Socrates move if he runs. Now contingency arises from matter, for contingency is a potentiality to be or not to be, and potentiality belongs to matter; whereas necessity results from form, because whatever is consequent on form is of necessity in the subject. But matter is the individualizing principle: whereas the universal comes from the abstraction of the form from the particular matter.”

2. Does the universe explain its own existence?

No, because that would make the universe a necessary thing or something that has to exist by its very nature. There are no reasons to believe that the universe is necessary and many reasons to believe it is not necessary. For example the question, “Why is that triangle black?” prompts an intelligible answer whereas the question, “Why does that triangle have three sides?” Merely deserves the retort, “Because it’s a triangle.”

But the question, “Why does the universe exist?” Doesn’t prompt the retort, “Because it’s a universe.” Since existence is not a necessary property of universes. It’s more like the question of why the triangle is black, it warrants an explanation beyond the thing that needs to be explained. There are two other factors that count against the universe of being its own existence:



a. Its property of change

Change occurs when a potential x becomes an actual y. This can involve intrinsic change like growth or extrinsic change like motion. But not potential x can become an actual y on its own anymore than water can freeze itself or a train car could propel itself. Instead, something like a freezer or locomotive must actualize the potential for change in these objects. But of course, those actualizers only change because something else actualized their potential for change.

Could an infinite series explain this kind of change? No, just like an infinitely long chain of boxcars would sit motionless without a locomotive, an infinite number of things that must be actualized by something else would be changeless unless there was a cause of the series that was just pure actuality and had no potential. Just as a locomotive pulls without being pulled, This instance of pure actuality would actualize without being actualized by anything else.

Since the universe contains a mixture of potential and actual, it is not the purely actual cause we are looking for.


b. Its finite past

What about the universe’s finite past? Something is necessary only if it is impossible for it to not exist. But if the universe came into existence, then it can’t be necessary. It would instead stand in need for an explanation for why it exists. One reason to believe why the universe has not always existed is because the past contains causal chains that explain objects and events in the present. However, no past causal series that terminates in the present can be infinitely long because that would lead to a contradiction.  

Consider Robert Koon’s Paper Passer thought experiment. Imagine beings called “paper passers” who exist at every January 1st in the past. Their job is to receive a piece of paper from the passer who held it during the year before them and to see if it is blank. If the paper is blank then they write a unique number assigned to them on it. If the paper they receive already has a number on it, then they just pass it along to the next paper passer. Now here is the question, “What number is written on the paper given to the paper passer on January 1st 2023?” There has to be some number written on it because if it were blank then the 2022 paper passer would have written his number on it, but it can’t be blank because if it were the 2021 paper passer would have written his number on it. If there are an infinite number of paper passers we have a paradox: There is a piece of paper that arrives in the present that isn’t devoid of numbers, but also can’t have any particular number written on it.

This isn’t unique to this scenario. Other thought experiments like Thomson’s Lamp or the Grim Reaper paradox show that objects can not have infinite causal histories. This means causal series must be finite in nature and the first member of the series would have to be uncaused and since causal chains must be finite, this means the number of events before today must be finite and so time is finite. If the past is finite then our universe began to exist and would require an uncaused cause for its existence.

Notice that we are at an important juncture. We’ve seen the universe has an explanation for its existence and that explanation is not the universe itself. Instead this explanation is necessary or it explains its own existence, it is uncaused because it is the source of all causes, and it is pure actuality because it is the source of all change in motion in the universe.

3. Is the cause of the universe changeable?

No, for two reasons. First, change only happens when potential is reduced to actual. But this cause is pure actuality so it can’t change. Second, since causal chains can’t be infinite this means there can’t be an infinite series of events. Because change is an event this means the first cause can not be subject to such an event or it must be changeless.

4. Is the cause of the universe temporal?

No, because time is how we measure change and because the cause of the universe is changeless, it follows that it must be timeless as well.

5. Is the cause of the universe material?

No, for two reasons. First we know the cause is changeless and matter is always changing (at least on the atomic and subatomic levels). Second, if the cause is timeless then it must also be spaceless or immaterial because to be in space is to be in time. Even if the cause were a simple thing with no proper parts it would still change in relation to other things or points in space. So it can’t be confined to space just as it can’t be confined to time.

6. Is the cause of the universe limited?

No, because that would contradict the cause being pure actuality. To impose a limit on something would be the same as saying there is a potential for that thing, which the thing in question can never actualize. That means the cause’s causal power could not be limited, which is another way of saying the cause is all powerful or there is nothing it can’t do.

7. Is the cause of the universe necessary?



Yes, because if it were contingent then this cause would need an explanation for why it existed. Our argument would then start all over again. Also because this cause is changeless it can’t go out of existence because going from being existent to non-existent is a temporal and mutable process, but we know the cause of the universe is timeless and changeless. Moreover, being pure actuality this cause would have no potential for non-existence and could not fail to exist.

8. Is the cause of the universe personal? 


Yes, and here are 5 reasons to think so:



1. There are only two kinds of entities that exist: concrete ones (like two toy blocks) and abstract ones like the number 2 or shape of a cube. But unlike concrete objects abstract objects like numbers and shapes have no causal power. Therefore the cause of the universe can not be an abstract object like a number, but must be some kind of concrete object. But we also know this cause must be an immaterial concrete object and the only immaterial causal reality we know of is some kind of mind. The cause must be personal in nature.

2. There are only two kinds of explanations for physical phenomena: Scientific ones and personal ones. Scientific explanations consist of physical laws that describe matter/energy interactions. For example the scientific answer to the question, “Why is that pot boiling?” Is that heat is agitating the water molecules and causing evaporation. The personal explanation would involve an intention of an agent like, “The pot is boiling because I wanted tea.” A universe beginning from nothing can not have a scientific explanation because a state of nothingness lacks the matter, energy, and descriptive laws that make up those explanations. Therefore only a personal explanation of the universe remains.

3. This cause of the universe explains not just the cause of material objects, but abstract objects like numbers, mathematical truths, and propositions. But these entities only exist in the mind and so if these objects have necessary existence then they must reside in a necessary existing mind that is explanatorily prior to them. Moreover if this mind has no potentiality then its knowledge of these truths could not be limited so it must be all knowing.

4. Many atheists say they’d believe in God if they saw something like an amputated limb healed through prayer. But this means they’d pick a divine explanation for an event over simply saying the event has no cause whatsoever. But if our universe came into being just as an amputated limb did, then atheists should be consistent and conclude that the universe has a divine cause.

5. Our universe contains moral properties that only make sense if they have a transcendent moral source. Now morality only applies to persons, so if the cause of the universe is the source of these moral properties then it must be a supremely good person and not an immoral, impersonal, source.

9. Is the cause of the universe good?

By good we mean in both the moral and nonmoral sense of that word. A car has a bad timing belt not because the belt is disobedient, but because it can’t fulfill its purpose of synchronizing an engine’s valves. It’s bad because it lacks something it needs in order to act in accord with its nature. And this is true not just for artificial objects, but also for natural ones like trees and animals. Now if the cause of the universe has no potential and is pure actuality, then it must be good by definition. That’s because it wouldn’t lack anything and so it could not be bad in the non-moral sense of that word. But the cause is also morally good because it is the source of objective morality or what Trent Horn calls “moral facts.” Alex said in his debate with frank Turek that if objective morality or moral facts existed, then this would be a compelling argument for God. So we can make an argument like this:



P1. If moral realism is true, then God exists.
P2. Moral realism is true.

C1. Therefore, God exists.

Moral realism is the view that human beings discover moral truths and don’t create them. Truths like, “rape is always wrong” or “all human beings have equal worth” do not depend on human beings for their existence. Alex seems to agree with premise one and other famous atheists also agree. But why should we agree these moral facts exist? Well we are confident the external world is real and other minds exist simply because those things seem to be real. If moral truths like, “rape is always wrong” seem just as real then the burden of proof is on the moral skeptic to show us why we should think otherwise.

Conclusion

As shown above, the universe has an explanation for why it exists, does not explain its own existence, and this explanation must be immutable, eternal, immaterial, unlimited, necessary, personal, and good. So when all these points are considered, they make a strong case for the existence of God.