Ontological Argument Made Simple


Ontological Argument Made Simple


In his 1078 work Proslogion, Anselm of Canterbury came with the idea which is known as ‘the ontological argument’. In this argument God’s existence is not just possible or probable or very likely, but is logically ensured. Anselm defined God as “that than which nothing greater can be thought”. Anselm said that this being must exist in the mind, even in the mind of the person who denies the existence of God, aka an atheist. He proposed that, if the greatest possible being exists in the mind, it must also exist in reality. Why? Because if it only exists in the mind, then an even greater being must be possible—one which exists both in the mind and in reality. Therefore, this greatest possible being must exist in reality.


‘Ontological’ comes from ‘ontology.’ I know, ‘ontology’ sounds very smart, but its meaning is actually pretty simple: Ontology is the study of the nature of being or existing. So the Ontological Argument simply means a logical argument that, if true, argues in favour of the existence of God. It relies on nothing else than good old logic to show that, if the premises are true, God must exist.

Actually, Anselm formulated two versions of the ontological arguments. This was only just discovered in the 1960s by Malcolm and Hartshornei. Groothuis says that Anselm was puzzled over the unbelief of ‘the fool’ and labours to construct an argument to defeat this fool and, thereby, atheism.ii His first argument goes as follows:

  1. God is understood or defined as a being “than which nothing greater can be conceived.” Even the fool possesses this concept of God.
  2. A thing exists either in (a) the understanding only (such as the idea of a painting before it is painted) or (b) in both the understanding and reality, such as existing in the mind of the painter and then existing on the canvas.
  3. It is “greater” to exist in reality than to exist merely in the understanding.
  4. If God exists merely in the understanding (existing only in the mind of the fool), then God is not the greatest possible being, since a being that existed in reality would be greater than a being that existed only in the understanding.
  5. But God is by definition the greatest possible being (from 1).
  6. Therefore, God exists not merely in the understanding (as the fool claims) but in reality as well. By reductio ad absurdum (which means that this conclusion is the only right one because all other conclusion are reduced to absurdity, other conclusion contradict the first premise).


One of the arguments given by critics comes from Kant. Kant basically said that this argument leans on the term ‘existence’. He said that Anselm made ‘existence’ into an attribute or quality of God. Just like we say that God is love. Love is the attribute. But ‘existence’, so the critics say, cannot be an attribute. However, imagine reading a fairytale to a child. The child might ask whether the animals in the story exist or not. You would say that horses exist in reality, but the flying elephant doesn’t. In this case the child asked a legitimate question right? The child makes ‘existence’ into an attribute of the animals.

Others would say that an imaginary God would do just fine. But, when they say this, they totally missed the point of that what is great. Ones my wife and I had four children. We really wanted a fifth one. What a great thought! We had to wait five years before God gave us our fifth child. Having the boy in reality is even greater than just in my understanding or in my thoughts. A god that only exists in people’s mind isn’t the greatest thing that one can imagine. The greatest possible God we can think of has to exist. If He only exists in our minds, a simple tool like a hammer is greater because it actually exists in reality. This is what we call reductio ad absurdum, reduction of absurdity.

Modal Ontological Argument

As I said, the original argument is a bit daunting. At least it is for me and many philosophers who are way better trained in this field than I am. I think that Alvin Plantinga’s variant on the argument is a bit easier to understand. His argument is what we call the ‘Modal Ontological Argument’.

Plantinga uses modal logic, which is a method of forming arguments based on three types of objects.

  1. Impossible Objects: Impossible objects are objects that cannot exist rationally, like a square circle or a married bachelor.
  2. Contingent Objects: Contingent objects are objects that depend on something else for their existence, like apples depend on apple trees or eggs depend on chickens. In reality all space-time objects are contingent, they depend on physics to exist if nothing else.
  3. Necessary Objects: Necessary objects are objects that depend on nothing for their existence. The number 3 might be a necessary object, for example.

In addition to these three types of objects we also need to add another modal logic concept to our repertoire, the idea of possible worlds. A possible world is not another planet or a parallel dimension. In logical arguments, possible worlds are simply descriptions of the way reality could be. You could imagine for example, a world in which the great war was lost by the allies and the Nazis would rule the world. Or imagine a world in which no poverty existed. These are possible worlds. But! A possible world cannot be an impossible world. There cannot be a universe in which there are 4 sided triangles. These things are logically absurd and cannot exist in any possible world.

Are you still with we me? Else try to read it again on my website. I’ll put a link to this transcript in the description of the video below.

Definition of God

And finally, before we look at Plantinga’s argument we also need to define what we mean by ‘God’. Anselm saw God as, what he called a Maximally Great Being. He said that God would always be the greatest being that anyone could imagine. In other words, if someone could imagine a greater being, then that being would be God. Anselm also said that God would have only properties that would make Him great. There are no properties in Him that make Him less. Let me give you a few examples:

Maximally Great

Less great


Limited by time


Limited by space


Limited by matter

All powerful

Lacking some power

All knowing

Not knowing some things

Eternally living


All good

Sometimes good

Planinga’s Modal Ontological Argument

  1. It is possible that a maximally great being exists.
  2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.
  3. If a maximally great being exists in some possible world, then a maximally great being exists in every possible world.
  4. If a maximally great being exists in every possible world, then a maximally great being exists in the actual world.
  5. If a maximally great being exists in the actual world, then a maximally great being exists.
  6. Therefore, a maximally great being exists.

The fun thing about this argument is the fact that, among most philosophers, premises 2, 3, 4 and 5 are impossible to deny or disprove; they recognise that they just simply follow from premise 1. In fact, most professional philosophers only debate the first premise.

So How Does This Work?

For many the conclusion might be a bit abrupt. When I heard this argument the first time, I right away started to look for the catch. It can’t be right! So, how exactly does this work?

The first premise:
The first premise makes a truth statement. This statement can be accepted or rejected. It says that it is possible that a maximally great being exists. Most atheists readily accept that it is possible that God exists. The thing is that they just don’t believe that God does exist.

Premise 2 just repeats the first premise by using ‘possible worlds’ which is an easier way of looking at the argument because anything that is possible is possible in some possible world by definition.

Premise 3 puts forward that if a maximally great being exists in some possible world, he exists in every possible world. Why? Because he is maximally great. And if he only exists in one possible world, he is just a little great. But when he exists in two possible worlds he is better than the one in only one possible world. But now we are talking about a maximally great being and as such he must exist in ALL possible worlds.

Premise 4 begins to wrap thing up. Because if a maximally great being exists in all possible worlds, then a maximally great being exists in the actual world we live in. Our world is not only a possible world, but it is the actual world.

Premise 5 simply follows the logic that if a maximally great being exists in the actual world, then a maximally great being exists.

Return to the first premise: It is not just possible that God exists, but it is logically necessary. And so we can say that God exists!

How About That?

Now think of the possibilities! When someone accepts that it is possible that God exists, he or she just entered an inescapable deductive reasoning, a foolproof logical case that inevitably leads to the fact that God does exist.

Because of the Ontological Argument, atheistic and other unbelieving philosophers find themselves in a pickle. If they want to hold on to their world-view, they have to insist that it is impossible that God exists. But be that as it may, if they want to keep there position and being intellectual honest at the same time, they must demonstrate in what way the very concept of God is illogical or in other words, how can God be impossible. So, the atheist must debate, in modal logical terms, that God is not only not necessary but is also an impossible object. The fun thing is, that when they cannot prove that God is impossible, we can pick were we have left and show through the Ontological Argument that failing to prove God as impossible is the same as logical evidence that God exists.


Okay, throughout the almost 1000 years many attempts have been made to debunk the Ontological Argument. Many atheists on the internet try it as well, and some believe they actually did. You see, that’s because many of them are way smarter than all the philosophers combined throughout the ages.

Anyway, there are some sophisticated rebuttals out there, but I am not going to tackle them. Except one! The one with the unicorn. But because I am not so fond of them I use a dragon instead.iii

  1. It is possible that a maximally great dragon exists.
  2. If it is possible that a maximally great dragon exists, then a maximally great dragon exists in some possible world.
  3. If a maximally great dragon exists in some possible world, then a maximally great dragon exists in every possible world.
  4. If a maximally great dragon exists in every possible world, then a maximally great dragon exists in the actual world.
  5. If a maximally great dragon exists in the actual world, then a maximally great dragon exists.
  6. Therefore, a maximally great dragon exists.

And there you go!! Debunked… Or not?

Nope can’t do. Why not you ask? Well the dragon is a physical object and as such a contingent and not necessary object. This is a problem because there might be a possible world in which space and time never started to exist or quickly collapsed into a singularity. A dragon, because it is physical, simply cannot live or exist in such a possible world.

Also, being a maximally great physical being, the dragon, is not logical because to be maximally great means that it should be able to live without the limitation of physical existence.

Now the critic starts to get a bit cynical and says “that these objections might be valid for dogs and cats, but their dragon is mythical, just like God. They claim to have a maximally great mythical being.”

However, the mythology of a dragon says that it is a huge physical fire breathing lizard with wings. When the critic says that he believes this mythology to be true would be the same as confirming that these dragons really exist. Enormous fire breathing, flying dragons are physical objects that exist in time and space. Therefore, a dragon can never be seen as a necessary object.

But the critic, who, by now starts to look like a dragon himself, says “This is a very special dragon, my dragon is timeless, space-less, immaterial, etc.”

Too bad! Now the critic has just cut his own fingers. By stripping the dragon from his own unique properties, and then giving it the properties of God, shows that the critic just admitted that God exists. The biggest difference now is that you call God your Father in heaven, and the critic has given Him the name ‘dragon’.


There is much more to say about this argument and all the objections. But this will have to do for now. I hope I’ve made this argument a little more clear. Agreed, it is not the first argument I would use when I encounter an unbeliever at my mother’s tea party—especially because the depth of the ontological argument may make it hard to access for many—but still, it is a nice arrow to have in your apologetic quiver. Of course, there are those who may think that they can ridicule this argument but by doing so they only demonstrate a poor philosophical inside. Which is actually pity full because mostly these people think very highly of themselves. You know, the sort of thinking like everybody in the whole world is wrong accept he or she.

Another thing about this argument is the fact that is a so-called ‘a priori argument’, which means that it isn’t depending on any other experiments or arguments, and as such it does not directly clarify how this maximally great being revealed himself in history.

But, if God is perfect, then we know for sure that He cares about His creation, and will reach out to his creation in one way or another. Also, the idea of the Trinity is supported by the ontological argument, because a perfect and all-loving being needs to have something to love outside His creation. And the Trinity is also guaranteed to us in the Bible. So, we have a very strong rational indication to believe the stories in the Bible about God who came to live among us in the person of Jesus Christ because He wanted to save us.

And so the circle is complete! You start with a daunting philosophical argument, and you end up with a bullet-proof rational reasoning that the Bible actually tells you the truth. Don’t you just love it!

Also take a look in the description of this video! You’ll find a lot of information there. Whenever I find or use some interesting things, I’ll link it there. But you can also find ways to support me. Some of you already did and some are doing it regularly! Thank you very much for that. I would also like to invite you to my Odysee channel. Odysee is a platform which based on a new protocol called LBRY. It is censorship free, unlike YouTube or others. It would be great if you start following me there. I am mostly active on that channel. You may comment on my videos on BitChute or YouTube, but you most likely won’t receive a reply. You can also start your own channel on Odysee. If you use my invitation in the description we will both receive some free LBC!

As always, thank you for watching, God bless you and we see each other in the next video!

i Norman Malcolm, Knowledge and Certainty: Essays and Lectures, (Englewood Cliffs, N.J.: Prentice-Hall, 1963), pp. 149-50; and Charles Hartshorne, Anselm’s Discovery: A Re-examination ofthe OntologicalArgument for God’s Existence, (Chicago: Open Court, 1965).

ii Groothuis, D., Christian Apologetics: A Comprehensive Case for Biblical Faith, Intervarsity Press, Downers Grove Illinois, 2011, pp. 184-185.

iii Waner, C., (06-06-2019) The Ontological Argument, [Internet] Theology Think Tank <https://theologythinktank.com/the-ontological-argument/> [accesed 11-10-2021].

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