The Ontological Argument

The ontological argument is an example of an a priori argument. That is, one which doesn’t rely on the evidence of the senses, or the world around us, for either its premises or its conclusion. The argument is structured in such a way as to make the conclusion it reaches the only possible one that could be deduced from its premises.
The argument attempts to prove God’s existence from the meaning of the word God.
Anselm was a major contributor to the argument. He defined God as “that than which nothing greater can be conceived.” His argument was based on the premise that God does exist- he set out to show that not believing in God was an absurd position to hold. This was a reductio ad absurdem argument- it tried to show that the existence of God could not be denied because to do so would involve adopting a nonsensical argument. His case was that God cannot not exist.
Anselm based the argument on the word “God” and what is meant when the word is used. He made an assumption which is crucial for the argument to work, and that is that “God” is effectively shorthand for “that than which nothing greater can be conceived” or “the being that which nothing greater can be thought.”
His argument is that when believers (and non believers, for that matter) speak of God, they intuitively understand what is meant by the concept of God- that he is “greater” than all other beings, not spatially but in the sense that he is supremely perfect.
“That” than which nothing greater can be conceived” must possess all perfections in order to be so described and when we speak of God we speak of such a being.
Futhermore, Anselm argued that if such a being does possess all perfections, than it must exist. This is based on the principle that existence is a perfection. God’s necessary existence is de dictio necessary, that is necessary by definition. To deny his existence would be absurd.
Anselm is aware that the existence of God is denied by the atheist. In response to this, he cites psalm 53: “the fool has said in his heart that there is no God.” He says that the denial is because the atheist has failed to understand the full implications of God, since for him to deny God, the atheist at least has a concept of God in his understanding.
René Descartes reformulated the argument, which he set out in Meditations.
He began by doubting that he knew anything, and then concluded that the only thing he could know was that he was thinking: “Cogito ergo sum”- I think therefore I am.
Descartes defined God as a supremely perfect being. From this definition, Descartes tried to prove God’s existence.
He argued that because God is a supremely perfect being, He possesses all perfections. This perfect state includes existence, which is a perfection in itself. Existence is a predicate of a perfect being. Therefore God exists.
There are some things that an object has to have in order for it to be an object. For example, two wheels are essential to a bicycle and a bachelor has to be unmarried. Descartes argued that God must exist in the same way that a triangle must have three sides and three angles that add up to 180°: “it appears that the existence of God must be no more separated from the essence of God...than the equality of its three angles to its right angles, from the essence of a (rectingular) triangle.”
This argument cannot apply to objects affected by space and time. It can only apply to something that is perfect. Only God can have absolute perfection- there cannot be two absolutes.
Norman Malcolm considers Anselm’s arguments, and concludes that the second section (Proslogion 3) is more accurate than the first (Proslogion 2). This is because he believed that, Proslogion 2 is subject to criticism whilst Proslogion 3 isn’t.
He developed Proslogion 3 by saying: “ God’s existence is either impossible or necessary. It can be the former only if the concept of such a being is self- contradictory or in some way logically absurd. Assuming that this is not so, it follows that He necessarily exists.”
Alvin Plantinga developed the philosophical notion of “possible worlds.” For example, in our world John F. Kennedy was the President of the United States. However, he could have made a different career choice and become an estate agent. This is an example of a possible world.
Plantinga offers the description of another possible world: there is a possible world W, in which there exists a being with “maximal greatness.” A being has maximal greatness only if it exists in every world. His argument states that to be maximally great, a being has to exist in every possible world. Plantinga introduced the concept of “maximal excellence”. He states that maximal greatness entails maximal excellence and maximal excellence entails omnipotence, omniscience and moral perfection.
Therefore, there is a possible world in which there is a being, which is maximally great. It has maximal excellence (entailed within maximal greatness). If omnipotent, omniscient and morally perfect, and maximally great, it is existent in our word. Therefore, there is a God.