This is the third in a short series of posts on the arguments commonly used by classical Apologists to prove the existence of a deity. The first post addressed the Cosmological Argument, while the second post focused on the Teleological Argument. This post is about the Ontological Argument, which argues for God’s existence based on the assertion that God is the Greatest Conceivable Being.
The 12th-century philosopher and theologian Anselm originally formulated the Ontological Argument. Anselm’s logic is a bit complicated, although a good explanation of each step in his progression can be found here. Although the ontological argument can be a bit confusing, the basic idea is that God is the Greatest Conceivable Being. That is, whatever being is the greatest one we can possibly think of is the being that we call God. Anselm then argues that to exist is greater than not to exist. Therefore, the Greatest Conceivable Being must possess the quality of existence.
According to this reasoning, if the Greatest Conceivable Being does not exist, then that being is really not the greatest at all. This is because we would be able to conceive of a being that does exist, and thus is greater than our Greatest Conceivable Being wannabe.
Because the Greatest Conceivable Being must exist in order to be the greatest, therefore–to avoid logical contradictions and general absurdity–this Greatest Conceivable Being must, and does, exist. In conclusion, this Greatest Conceivable Being is the being we call God, and thus God’s existence has been demonstrated.
Next post we will look at the fourth and final argument: the Moral Argument.