The Ontological Arguments

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by R. Gil Student

In the past, we have discussed a number of proofs, or more accurately arguments, for God’s existence. The Ontological Argument is the most unintuitive of the arguments, but perhaps the one most potentially viable as a proof. To most people, this will sound like word games. However, the challenge lies in determining precisely why or if the argument does not work. This has proven surprisingly difficult, with some philosophers still claiming today that they can prove God’s existence with variations of this proof.

I. God Must Exist

In truth, there are two main Ontological Arguments as advanced by Anselm of Canterbury (d. 1109), at least as commonly understood. We will discuss the first, which goes something like this:
* The greatest conceivable being must exist because existence is greater than non-existence. That being is what we call God.

Formulation of the argument is key and my formulation above lacks precision, due to my own limitations, the type of conversation we are having, and the many versions of this argument. In fact, people have been reformulating it over the last century to try to overcome criticisms. But the above suffices for our purposes.

II. Three Objections

Even in Anselm’s day, one of his contemporaries, Gaunilo, raised objections to the argument. First, you can’t just define God into existence. Just because I can conceive of God doesn’t mean that He exists. We can respond that we are not creating God but discovering Him. We can do that through thinking about the world and existence. In a similar fashion, we discover what kinds of numbers exist via math theorems. That is the nature of thinking deeply and critically about things, the essence of philosophy.

Second, we cannot conceive of God because we do not understand Him. Our minds cannot contain the concept of God. Therefore, the Ontological Argument fails because it describes man conceiving God, which is impossible. We can respond that we can think about God in general, even if we cannot fully comprehend Him. The argument does not require full comprehension of God.

Finally, Guanilo responds that using this logic, we can argue that anything exists if we make it the greatest conceivable of its kind. For example, the greatest conceivable unicorn must exist because existence is greater than non-existence. However, there is an inherent difference between the greatest conceivable being and the greatest conceivable unicorn. For the greatest conceivable being, all of its properties are greatest — it is omnipotent, omniscient, etc. A unicorn has limitations as an animal, with many properties that are not greatest. The largest unicorn is not necessarily the greatest, because it would be monstrous. The best color might be pure whites or might be the perfect shade of gray. The horn could not be too long because that would be comically out of proportion. In other words, the term “greatest conceivable unicorn” is nonsensical because a unicorn’s properties do not allow for one being the greatest. Only something that is greatest in all aspects can be the greatest conceivable, and that is the greatest conceivable being. [1]On the three criticisms and responses, I draw heavily from Stephen T. Davis, God, Reason & Theistic Proofs (Grand Rapids, MI, 1997), pp. 26-31 but the formulations are my own.

III. Perfection

I think that the response to the third criticism is easier to see with Descartes’ formulation of the Ontological Argument. Without getting into his details, which is unnecessary for our purposes, we can say that Descartes focused on the the Supremely Perfect Being and considered existence to be a perfection. Something that is perfect in every way must exist, because existence is also a perfection. A unicorn cannot have every perfection because everything in nature has flaws. Therefore, the Ontological Argument can only apply to God and not to any other object.

What Descartes highlights, Kant attacks. Descartes said that existence is a perfection. Kant argued to the contrary, that existence is not a predicate, i.e. an attribute. There is no difference between one hundred imaginary dollars and one hundred actual dollars except that one exists and the other doesn’t. Conceptually they are the same, just the actual money is an instantiation of the conceptual money. Therefore, Kant argues, the greatest conceivable being need not exist because existence is not an attribute. Kant’s claim that existence is not a predicate cannot be proven. It has been debated ever since he stated it, and the debate continues. If existence is a perfection, as Descartes claims, then perhaps the Ontological Argument works as a proof for God’s existence. If existence is not an attribute, as Kant claims, then the argument fails.

IV. Begging the Question

I think William Rowe expressed my thoughts on this argument, although of course my thoughts were fleeting while he developed and attempted to prove them. Rowe argues that the concept of the greatest conceivable being presupposes that God exists. [2]Described in Davis, pp. 35-42. He says that hidden within this argument is the premise that “no non-existing thing is God.” Since God is the greatest conceivable being, and the greatest conceivable being must exist, we are presupposing at the beginning that God must not not-exist. In other words, the premise assumes the conclusion, which is called question begging. Stephen Davis (God, Reason & Theistic Proofs, p. 39) responds: “But this is just not true… The definition ‘greatest conceivable being’ by itself, that is, apart from the other premises of the Ontological Argument, entails nothing about the existence or non-existence of anything. And if it did, the Ontological Argument would be informally invalid and not particularly interesting.”

The debate over the Ontological Argument continues. [3]See the entry in Stanford Encyclopedia of Philosophy for “Ontological Arguments”, section 10: “Ontological Arguments in the 21st Century”. What does it mean for religious Jews? The Ontological Argument did not originate in the Jewish tradition and has largely remained outside it, probably for historical reasons. Maimonides presumably had no access to this argument and his discussions set the stage for the Jewish philosophical conversations throughout the subsequent generations. However, we can find within this argument a description of our beliefs. God exists, is perfect, and sustains the universe’s existence. While we cannot define God or understand Him, we know that our existence is only possible and understandable within the context of His existence. Regardless of whether this proves God’s existence, it retains meaning to those who believe in Him.


1On the three criticisms and responses, I draw heavily from Stephen T. Davis, God, Reason & Theistic Proofs (Grand Rapids, MI, 1997), pp. 26-31 but the formulations are my own.
2Described in Davis, pp. 35-42.
3See the entry in Stanford Encyclopedia of Philosophy for “Ontological Arguments”, section 10: “Ontological Arguments in the 21st Century”.

About Gil Student

Rabbi Gil Student is the Editor of, a leading website on Orthodox Jewish scholarly subjects, and the Book Editor of the Orthodox Union’s Jewish Action magazine. He writes a popular column on issues of Jewish law and thought featured in newspapers and magazines, including The Jewish Link, The Jewish Echo and The Vues. In the past, he has served as the President of the small Jewish publisher Yashar Books and as the Managing Editor of OU Press. Rabbi Student currently is serving his third term on the Executive Committee of the Rabbinical Council of America and also serves as the Director of the Halacha Commission of the Rabbinical Alliance of America. He serves on the Editorial Board of Jewish Action magazineand the Board of OU Press. He has published four English books, the most recent titled Search Engine volume 2: Finding Meaning in Jewish Texts -- Jewish Leadership, and served as the American editor for Morasha Kehillat Yaakov: Essays in Honour of Chief Rabbi Lord Jonathan Sacks.

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