Ontology is the philosophical study of being or existence. It explores questions about the nature of reality, what it means to exist, and the different categories of existence. Thus, the “Ontological Argument” for God is a philosophical argument that tries to prove the existence of God solely based on the concept of God itself. This is an “a priori” argument, meaning it relies on reason and logic alone, not on experience or observation of the world. It does not seem to be a strong argument, but it is very famous. Therefore, I have included this argument in this chapter. It is traditionally attributed to Saint Anselm of Canterbury, who lived from 1033 to 1109 AD. He presented the argument in his book titled “Proslogion”. Although Anselm is credited with its most well-known version, there have been other philosophers who formulated similar arguments throughout history. Nevertheless, Anselm's version of the argument is the one most often discussed and debated. Following is the gist of the argument:

Definition: We can define God as the greatest being imaginable. A being above which no greater can be conceived.

Greater with Existence: If something exists only in our minds (like any fictional character), it is less great than something that exists both in our minds and in reality. In this way, real money in my hand is greater than the money in my mind only.

Contradiction: If the greatest being imaginable (God) only exists in our minds, then we could imagine something greater – a being with all the greatness of God, plus the additional property of existing in reality.

No Contradiction Allowed: This contradicts our initial definition of God as the greatest conceivable being.

Conclusion: Therefore, God must exist in reality, not just in our minds.

The ontological argument remains a debated topic in the philosophy of religion. While some find it persuasive, others believe it has fundamental flaws.  Some critics of the argument say that existence is not a property like greatness or perfection. Just because we can conceive something does not mean it exists in reality. Others give a “Greater Island Analogy” that imagining the greatest island with the most beautiful beaches does not mean that that island exists.

To refute the Ontological Argument, someone might argue for the existence of the greatest possible pizza using similar logic used in the Greater Island Analogy. Well, actually, you cannot give this example because the definition of pizza implies limitations like a limited size and being able to be broken. But for the sake of argument suppose if you consider a pizza that was indestructible, eternal, all-powerful, and infinitely large, it would not be a pizza anymore. Such an imaginary pizza would have these attributes that are common to God, and this is not possible. Such a pizza nobody says exists. So, the Ontological Argument cannot be used on such things as this pizza. No one says such a pizza exists; however, there is a concept of God throughout the history of mankind.