The ontological argument is associated with the medieval philosopher Anselm, known to Catholics as Saint Anselm, who lived from 1033 to 1109. Although born in northern Italy, he eventually became Archbishop of Canterbury in England. In that position he was often in conflict with the reigning English king and was twice exiled, the second time because he refused to consecrate prelates (bishops) appointed by the king. He felt they were unworthy.

As stated by Anselm, the ontological argument is simple, yet subtle. He said that God is the greatest Being we can imagine. If He did not exist, we could imagine a greater being—namely, a divine being who exists. But since there is none greater than God, it follows that He exists.

In all candor, Anselm's argument is not convincing, as we will see. Yet it has had great heuristic value in stimulating fruitful discussions about the nature of God and the credibility of theistic argumentation. Even in the last century, Anselm's argument has attracted partisans. Whole books have been written in its defense, but the verdict of most modern theologians is that it is little more than word play.

Anselm defines God as the Being who is so great that none greater can be imagined. He then treats existence as enhancing greatness. His starting definition is therefore equivalent to saying that God is the Being who exists. In other words, He exists by definition. We conclude that Anselm's argument, assuming the very fact that it is seeking to prove, cannot settle whether God exists in reality. It is circular reasoning.

The Argument Reformulated

We need not abandon Anselm's argument, however. Indeed, by pointing us to the supreme greatness of God, Anselm has done us a great service. He has given us a head start on a theistic argument that is both substantive and profound. This may also be called the ontological argument. Unlike Anselm's version, which fails because it tries to establish its conclusion by deductive logic, the new version proceeds inductively through a series of general observations and questions.

Every good we can see in our world is imperfect. There is beauty, but it is imperfect. There is love, but it is imperfect. There is moral righteousness, but it is imperfect. There are pleasure and happiness, but they are imperfect.
Despite this imperfection wherever we look, each of us is able to imagine that beauty, love, righteousness, pleasure, and happiness exist somewhere in perfection.
Where does the idea of perfection come from if it does not correspond to anything in the physical world? How could such an idea evolve by chance in a world strictly physical in nature? The only satisfying explanation is that this idea has a counterpart in reality. There is a real perfection.
Yet though perfection exists, how could it enter into our knowledge, since we have no direct experience of it? The answer must be that perfection is an attribute of the Creator, who has implanted in our minds a predilection to conceive of perfection so that we might better understand His own nature.

The highest magnitude we can reach on any scale of measurement is finite. We can count only so far. We can look only so far into the distance and remember only so far into the past and scan only so far into the future. However large our view, we see nothing that is actually infinite, and however small our view, we see nothing that is actually infinitesimal.
Although our experience is limited to finite magnitudes, we can grasp the idea of infinity. When a little child learns his numbers, you can teach him that there is no end to counting—that it goes on endlessly to infinity—and he readily comprehends what you mean. The first to point out how remarkable it is that we understand the meaning of infinity was Pascal.
Where does the idea of infinity come from if there is nothing of infinite (or infinitesimal) magnitude either in dimension or quantity among the things that actually exist? Again, the most satisfying explanation is that the idea of infinity must have a counterpart in reality beyond the physical world.
How has the concept of infinity dawned upon our minds if not through experience? Again, the most satisfying explanation is that an infinite Creator made us capable of understanding something about infinity so that we might know Him better.

1. No man has ever seen God, at least not in His transcendent state.

2. Yet every man has a concept of God.

John 1:9

Romans 1:28

3. What exactly is our concept of God? If we search out its depths, we find that we cannot divorce it from three absolutes. The God we perceive in our souls has the properties of perfection and infinity, the two absolutes we have already discussed, as well as the property of absolute existence (noncontingent being). In other words, God is the absolutely existing One who is both perfect and infinite. By "absolutely existing" we mean that He is not dependent on anything else for His existence.

Our concept of God is so firmly joined to the concept of His existence that we can avoid the conviction that He exists only by a strong effort of will. This, I believe, is the essence of Anselm's argument. He is saying that no man can deny the existence of God without contradicting what he himself believes.

4. Where does our firmly rooted idea of God come from? Is it the product of genetic mutation and natural selection? Hardly. This idea must also have a counterpart in reality. There must in fact be a God such as we imagine.

5. This God is within our thoughts because He is the One who created us, and He created us with a capacity to know Him. He desires our fellowship. Indeed, for this purpose alone were we created.

The Scriptural Basis

The Bible teaches that God has implanted "the world" in man's heart.

He hath made every thing beautiful in his time: also he hath set the world in their heart, so that no man can find out the work that God maketh from the beginning to the end.

Ecclesiastes 3:11

The word "world" here is olam, which frequently in the Old Testament follows "for" and is translated "ever." In many instances it unmistakably means "eternity," as in Psalm 90:2, and usually it is so translated in this passage. "He has set eternity in their hearts."

The verse goes on to explain why God has done this. So that man, in his investigation of the world about him, will realize that what he knows falls far short of everything to be known, that his own experience has not comprehended any absolute, whether eternity, infinity, or perfection. Why is it important for man to perceive his own limitations? We will venture the following answer. In consequence of seeing himself as a finite being, man cannot regard the eternity in his heart as a manifestation of his own nature. Sensing that his heart is a window to something real, he may decide that the window looks upon the realm of a Being greater than himself, of a Being who is limitless though man is limited. A view of God gives man an understanding that everything from beginning to end in the vastness of eternity is God's work.