Anselm's Ontological Argument for the Existence of God

By: Gregory S. Neal

Anselm, probably the greatest theologian to become Archbishop of Canterbury, was the first to develop a comprehensive ontological argument for the existence of God. His is a two stage thesis which begins with a primary formula, or name, for God: the "that" beyond which nothing of any greater quality (power, intelligence, love, truth) can be conceived. Anselm then goes on to use this formula as a basis for the two basic forms of his argument: 1) the intrinsic quality of God's existence in relation to the divine nature and, 2) the absolute necessity of God's existence in relation to this very same nature. His is, ostensibly, an argument based on reason. It is also, as will become clear, a tautological argument which is difficult to support without reference to a pre-existent faith.

Anselm begins, as has already been stated, by rooting his Christian understanding of God within the following formula: "a being than which nothing greater can be thought." (p. 73) This is a greatness, not in size or space, but in perfection -- perfection of intelligence, power, truth, love, all that makes perfection is found within this being. It should also be noted that this most perfect conceivable being is not, contrary to some thought, the most perfect being in existence. By simple definition, a most perfect being does exist; this being, however, may not be what Anselm posits as God. Therefore, rather than establishing that God is the most perfect being in existence, Anselm argues that God is so perfect that no more perfect being can even be conceived. This issue, while it sounds like the splitting of hairs, will become important when the objection of Gaunilo is addressed.

The two basic stages of Anslem's argument follow upon this description of God's nature; while separate, both clearly support and rely upon each other for their common argument. In the first stage of his argument, Anselm addresses the difference between the two forms of existence: mind and reality. If the most perfect conceivable being existed only in the mind, a clear contradiction would be established since it is obviously possible to conceive of a still more perfect being--essentially, this would be the same being which was originally understood as existing only in the mind, but now it is understood as also existing in reality. This argument is found in chapter two of Anselm's Proslogion:

....if that than which a greater cannot be thought is in the understanding alone, this same thing than which a greater cannot be thought is that than which a greater can be thought. But obviously this is impossible. Without doubt, therefore, there exists, both in the understanding and in reality, something than which a greater cannot be thought (SM-Anselm: p. 74).

This "something than which" is a being which exists both in mind and in reality. The differentiation is between actual and theorized existence: those things which have only imaginary existence are considered to be of lesser perfection than those which exist.

In the third chapter, Anslem states his argument again; however, here he is not interested in merely the existence of God, but in the sheer necessity of God's existence. This necessity is rooted in the self-existence of God, which leads Anselm to the notion that a lack of existence is impossible for God. Since God is a being of such perfection that none more perfect can be conceived, God can never be understood as having come into existence, nor can God be thought of as ceasing to exist. To entertain such thoughts would make God contingent upon something beyond the divinity, and this is ruled out by God's nature as a being of self-existence--or, more literally, as a being dependent on none other than itself for existence. It, therefore, follows that:

.....something can be thought of as existing, which cannot be thought of as not existing, and this is greater than that which can be thought of as not existing. Thus, if that than which a greater cannot be thought can be thought of as not existing, this very thing which a greater cannot be thought is not that than which a greater cannot be thought. But this is contradictory. So, then, there is truly a being than which a greater cannot be thought--so truly that it cannot even be thought of as not existing (SM-Anselm: p. 74).

Put much more succinctly: the very nature of the divine as being the ultimate perfection beyond which nothing greater can be posited assumes the necessity of its existence. This is the reverse of the first form of the argument for, instead of first positing the divine existence in mind, then in reality, the argument is one of existence as a necessary component of God's perfect, self-sufficient nature. For God, existence is a necessity -- not a luxury.

In introducing the ontological argument, Anselm refers to the psalmist's "fool" who says at heart, "There is no God." (Psalms 14:1 and 53:1) Even such a person, he says, possess the idea of God as the greatest conceivable being, the implications of which lead to the inescapable conclusion that this being must have actual, as well as imaginary, existence. Gaunilo, a monk at Marmoutiers in France and a contemporary of Anselm, in his work In Behalf of the Fool, claimed that Anselm's reasoning must necessarily lead to outrageous conclusions if carried to their fullest extent. Gaunilo establishes an apparently parallel ontological argument in which the question is not the existence of God, but rather the existence of a most perfect island.

When someone tells me that there is such an island, I easily understand what is being said, for there is nothing difficult here. Suppose, however, as a consequence of this, he then goes on to say: you cannot doubt that this island..... actually exists somewhere in reality, because it undoubtedly stands in relation to your understanding. Since it is more excellent, not simply to stand in relation to the understanding, but to be in reality as well, therefore this island must necessarily be in reality. (Hick, John, ed., Classical and Contemporary Readings in the Philosophy of Religion (Englewood Cliffs: Prentice-Hall, Inc., 1970), p. 33.)

What can be identified as Gaunilo's basic error in his counter-argument is that he spoke of the most perfect island instead of the most perfect island conceivable. In Anselm's formulation, it is this very nature which separates the Divine from the mortal. The second stage in his ontological argument provides Anslem with his response to Gaunilo, and it extends from just this point: the idea which is lacking in the concept of a perfect island is its necessary existence. Any material object, including an island, is part of the contingent world. Even a most perfect island -- so long as it was a real island, being part of the physical world -- is, by definition, a dependent reality which can, without contradiction, be thought not to exist.

....if anyone discovers something for me, other than that "than which a greater cannot be thought," existing either in reality or in thought alone, to which the logic of my argument can be applied, I shall find his lost island and give it to him, never to be lost again.(SM-Anselm: p. 94)

Therefore, Anselm's principle does not apply to the island parallel, or to any object other than the divine; the principle only applies to the most perfect conceivable being, which is defined as having eternal and independent, or necessary, existence.

The question of the existence of God was solved, for Anselm, through a rational approach. His conclusions, however, do not provide a proof for the existence of God. The reason for this rests, primarily, in the fundamental premise of his argument. It is, first and foremost, an argument from a position of faith. True, Anselm's address of the subject has many characteristics of a syllogism, with a logical progression of thought, clearly and precisely laid out as the argument moves from point one to point two. However, Anselm's reasoning is tautological -- that is, it argues in circles. He begins with a fundamental premise, assumed to be fact: God is "a being than which nothing greater can be thought" (SM--Anselm: p. 73.). He "proves" it only through an appeal to divine revelation, and as such it is a faith-based premise. As was clearly recognized by John Duns Scotus, Anselm's arguments are a priori in nature because they derive from divine revelation, and not from "actual and distinct knowledge of God" (SM--John Duns Scotus: p. 435). Anselm's entire argument is then built from this definition of the divine. Both stages require this starting point, and if they are followed through to their conclusions they eventually end up where they begin--ie., affirming that God is "a being than which nothing greater can be thought" (SM--Anselm: p. 73). In this way, Anselm's ontological argument may serve a believer well in providing a better understanding of God, and the divine relationship to reality, but it cannot prove, apart from faith, that God does actually exist.

This conclusion can be demonstrated, not with Gaunilo's island argument, but through a basic question: what if Anselm's fundamental premise -- the definition of God as the that beyond which nothing greater can be conceived -- is false? This question is not asking if the definition of God is inaccurate, which leaves the way clear for Anselm's response to Gaunilo. Instead, the question is keyed to the possibility that God may, indeed, not exist. While the author of this paper denies the question as ultimately untrue (i.e., God does exist), it is a valid one to ask in just this type of a discussion. Anselm's argument requires an initial assumption of God as existing in some state -- at least in the mind. The idea that the thought of God's existence makes it requisite that God does, indeed, exist, is just another appeal to the initial faith premise.

Matthew of Aquasparta provides us with a fairly good view of the way in which Anslem might be understood. He addresses the question of faith as opposed to knowledge, and establishes two important distinctions. Firstly, he posits that in the face of "full, clear, and immediate evidence there cannot be faith. On the contrary, this altogether eliminates faith" (SM--Matthew of Aquasparta: p. 418). Secondly, when confronted with "partial and mediate knowledge there can be faith, and it does not destroy faith' (ibid). This second type of understanding requires the mediation of reason in order to make sense of those things believed through faith, and it is this second form of knowing that Anselm apparently uses. Whether or not Anselm understands himself as doing so is not the question; indeed, we are simply searching for another way to come to grips with the question of the use of reason in the contemplation of faith assumptions.

Anselm's ontological argument is a syllogistic tautology which attempts to prove that God exists, but does so a priori and not from a premise which can be demonstrated apaprt from faith. His fundamental premise is that God's nature is such that nothing greater that God can even be conceived. The proof extends from this assumption, stating that God exists not only in the mind, but also in reality, due to the very nature of "Godness." Also, God cannot be understood as not existing, since the existence of God is necessary. That this is not a proof of God's existence does not invalidate Anselm for a faith approach to an understanding of God, but it does leave the field open for further attempts to prove the existence of the Divine through rational means.

Selected Bibliography

Fairweather, Eugene R. ed., A Scholastic Miscellany: Anselm to Ockham. Philadelphia: The Westminster Press, 1966.

Hick, John, ed., Classical and Contemporary Readings in the Philosophy of Religion. Englewood Cliffs: Prentice-Hall, Inc., 1970.

Hick, John, ed., The Existence of God: A Reader. London: Collier-Macmillian Limited. 1964.

Hick, John, Philosophy of Religion. Englewood Cliffs: Prentice-Hall, Inc., 1985.

© 1990 Gregory S. Neal*
All Rights Reserved

*This paper was written in 1990 for a Course in Historical Theology, which Rev. Neal took while in the Masters Degree program at Duke University.

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The Reverend Dr. Gregory S. Neal is the Senior Pastor of the First United Methodist Church in Commerce, Texas, and an ordained Elder in the North Texas Conference of The United Methodist Church. A graduate of Southern Methodist University, Duke University, and Trinity College, Dr. Neal is a scholar of Systematic Theology, New Testament origins, and Biblical Languages. His areas of specialization include the Theology of the Sacraments, in which he did his doctoral dissertation, and the formation and early transmission of the New Testament. Trained as a Christian educator, he has taught classes in these and related fields while also serving for more than 25 years as the pastor of United Methodist churches in North Texas.

As a popular teacher, preacher, and retreat leader, Dr. Neal is known for his ability to translate complex theological concepts into common, everyday terms. HIs preaching and teaching ministry is in demand around the world, and much of his work can be found on this website. He is the author of several books, including
Grace Upon Grace: Sacramental Theology and the Christian Life, which is in its second edition, and Seeking the Shepherd's Arms: Reflections from the Pastoral Side of Life, a work of devotional literature. Both of these books are currently available from