Before I attempt to prove God through logic, I want to make it clear that God is self-evident. Psalm 19:1 states, “The universe declares the glory of God; the skies proclaim the work of His hands.” It doesn’t take complicated mathematics or intellectual superiority to understand who God is. Why? Finding God is more of a heart issue than a mental issue. That being said, let’s talk about how modal logic can help us understand the truth about God’s existence.
Modal Argument for the Existence of God.
1. It is possible that God exists. 2. If it is possible that God exists, then God exists in some possible worlds. 3. If God exists in some possible worlds, then God exists in all possible worlds. 4. If God exists in all possible worlds, then God exists in the actual world. 5. If God exists in the actual world then God necessarily exists.
First, what does it mean when a philosopher says “possible world?” It means a hypothetical situation and is generally a way to test an idea to see if it’s logical by asking, could it exist in a possible world like our own? However, the one thing that Atheists don’t often understand is how God is defined. Some will say that we are just imagining God into existence, like for instance, a “unicorn.”
One might ridicule the ontological argument by saying: So let’s imagine this mystical being that has one horn and exists. By the above definition, such a being must exist. Therefore, the unicorn exists. Here’s the problem. You are falling into the error of how God is defined. So then, how is God defined differently than a unicorn?
First, there are 3 ways entities are defined: An entity can be impossible, where it exists in no possible worlds. For example, a square circle. This is logically incoherent. Second, an entity can be contingent. That means this entity can exist in some possible world, like a unicorn or Cyclops. The third entity is defined as Necessary, meaning it has to exist in all possible worlds.
Now, what do I mean when I say something necessarily exists in all possible worlds. Examples might include numbers, absolute truths, and shape definitions. There can not exist a square with 3 sides in any possible world because that would be logically incoherent. So, a square must only exist with 4 sides in all possible worlds. Therefore, a necessary entity is something that cannot be false or fail to exist in any possible world.
If God exists, he would have to be a necessary entity because He must exist in all possible worlds. Why? God is defined as a maximally great being, which possesses all qualities that are better to have, such as necessity, in all possible worlds. These properties that exist in the metaphysical realm are properties like love, justice, and goodness. Since we know these entities exist in the actual world, these entities must derive from a necessary being, who we would call God. God is the source for where all these maximally great properties derive from.
Now let’s think back about the way three entities are defined in analytical logic. If God was contingent, like the unicorn (only existing in some dream state), then God would not be a maximally great being since he does not exist in all possible worlds. Therefore, the unicorn example fails premise 3, 4, and 5 because it does not exist in the actual world. It is a contingent entity. However, since God is defined as a maximally great being, then he must exist in all possible worlds to be the greatest conceivable being.
By definition, inserting God into the equation commits no fallacy. What must be done next is for you to debunk premise 1. Premise 1 states that it is possible that God exists. Premise 2-5 is modal logic, which is logically coherent. If premise 1 is true, then premises 2-5 are logically coherent. In order for you to demonstrate that premise 1 is logically incoherent, you must give evidence that it is impossible for a maximally great being to exist.
The most common way this is tried is with the omnipotence paradox. I am sure you have heard of it. It goes like this: “Can God create a stone so heavy that even He can’t move?” If God can not create the stone, then he is not all-powerful, but if God can not move the stone then he is not all-powerful either. Therefore, the idea of God is impossible. However, this is a logical absurdity. Asking, “Can God create a stone so heavy that even He can’t move?” implies that all-powerful is defined as able to do the logically impossible, but this is not consistent with the definition of a being that is omnipotent. It means almighty in power; it doesn’t mean the ability to do everything. God can’t do the logically impossible. He can’t create a square with 3 sides or tell you the shape of purple. All these questions are logically incoherent and can’t exist in any possible world. Since this fails entity 1, the logically impossible, it’s not evidence to demonstrate that premise 1 is logically incoherent.
Other arguments that philosophers have attempted beside this paradox is the problem of evil or the reverse of the ontological argument. Until, and unless Atheists can show the proof for this argument as invalid, it still remains that God is more rational than non-existence.
Conform to Jesus 
As premise 1 is false, your argument is flawed. It is only true if god exists, otherwise god is impossible, by your own argument. So, in the end, you only have shown that god exists if it exists, otherwise it doesn’t. Wow.
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You will have to demonstrate that premise 1 is false, as I mentioned towards the end of my article. Premises 2-5 follow modally and are therefore logically coherent. It is a disjunctive syllogism. Either P or Q. Not P.Therefore, Q. The 4 most common ways that Atheists refute premise 1 are: 1. Omnipotence Paradox 2. Logical Problem of Evil. 3. Problem of Imperfection. 4. Reverse Ontological Argument.
You may need to be more specific in why you are arguing premise 1 is false. I think you are using argument #4 by reversing the ontological argument to say instead that “it is possible that God does NOT exist, then God does NOT exist in any possible world. Therefore, God does NOT exist. Is that what you are trying to say? By the way, “wow” is an ad hominen attack and won’t help strengthen your rebuttal.
If I am assuming correctly, let’s talk about the logical problem of the reverse ontological argument. The reverse ontological argument concludes that it is impossible that a maximally great being is impossible by simply reversing the process from It is possible that God exists to It is possible that God does NOT exist.
The problem, however, is premise 2. If you say, “it is possible that God, who is a maximally great being, doesn’t exist, then God doesn’t exist in some possible worlds.” That is incoherent since a maximally great being is an entity that can exist in some possible worlds. You would have to prove that it is logically absurd for a maximally great being to exist in some possible world before you use the reverse ontological argument.
More importantly, however, is that when you conclude that maximal greatness is impossible through the reverse ontological argument, this even goes against the modal perfection argument by Robert Madle. He established that maximal greatness is a possible property. Here is how it is explained.
1. If a property is a great making property, its negation is a lesser making property. 2. Great making properties do not entail lesser making properties. 3. Maximal greatness is the greatest great making property, therefore maximal greatness cannot entail its negation of non-maximal greatness.
In modal logic, it is perfectly reasonable for a property that is impossible to entail its opposite. Take for example, square circularity. Since square circularity is an impossibility, then all things must negate square circularity, meaning everything entails non-square circularity. But if everything entails non-square circularity, then we must include all impossible properties as well. This means that square circularity entails non-square circularity.
Therefore, if we conclude that maximal greatness is impossible, then all things must negate maximal greatness. If all things negate maximal greatness, then all things must entail non-maximal greatness, including impossible properties, such as maximal greatness. If this is the case, then maximal greatness entails non-maximal greatness. But looking back, through the modal perfection argument, we can determine that maximal greatness cannot entail its negation of non-maximal greatness because great making properties can’t entail lesser making properties. It would be logically absurd.
If maximal greatness is a possible property, then therefore it is possible that maximal greatness exits. If maximal greatness exists, it can be defined by the greatest conceivable being. Therefore, the modal ontological argument still stands with premise 1. It is possible that God exists. If it is possible that God exists, then God exists in some possible worlds. If God exists in some possible worlds, God, a maximally great being, must exist in all possible worlds. Therefore, God exists.
I know this is a lot of information. Please let me know your thoughts. Thanks again for the great conversation!
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Do you believe in Platonic entities? They are abstractions, like numbers, constants of the universe, emotions, etc. Basically, Plato had this idea that there is an entity called “happiness”, and we only experience happiness because of this abstract being. When added to the God discussion, it is rather fascinating to consider how these things might or might not be involved. They would be “necessary beings”, and yet, by definition, there can only be one necessary being if God exists.
Side-note: If you haven’t ever come across it, take a look at reasonablefaith.com
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Thanks for the reply Justin. You are exactly right. Plus, it makes more sense that entities that are great making properties like “happiness” “love” and “justice”, which exist metaphysically, are not founded in some abstract platonic form. If they were, then these great making properties can’t be judged properly, for numbers don’t have “moral obligation”. They cant judge between “great making properties” and “lesser making properties.”
Therefore, its more logical to assume that these great making properties are found in an intelligent mind who determines with moral intent why these properties are necessary entities, and why love and happiness are good and why corruption and hatred are bad. This takes a rational mind that morally obligates these necessary entities to be actualized into the real world.
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