Philosophy of Religion (booklet)

The Ontological Argument

“But clearly that than which a greater cannot be thought cannot exist in the understanding alone. For if it is actually in the understanding alone, it can be thought of as existing also in reality, and this is greater... Without doubt, therefore, there exists, both in the understanding and in reality, something than which a greater cannot be thought.” [St Anselm, Proslogion, Chapter 2]

The ontological argument attempts to prove God’s existence through abstract reasoning alone. The argument is entirely a priori, i.e. it involves no empirical evidence at all. Rather, the argument begins with an explication of the concept of God, and seeks to demonstrate that God exists on the basis of that concept alone. The argument is ingenious. It has the appearance of a linguistic trick, but it is a difficult task to say precisely what, if anything, is wrong with it. All forms of the argument make some association between three concepts: the concepts of God, of perfection, and of existence. Very roughly, they state that perfection is a part of the concept of God, and that perfection entails existence, and so that the concept of God entails God’s existence.

The ontological argument was first formulated in the eleventh century by St. Anselm in his Proslogion, Chapter 2. Anselm was a Benedictine monk, Archbishop of Canterbury, and one of the great medieval philosopher-theologians. Anselm’s ontological argument rests on the identification of God as “that than which no greater can be conceived”. Once it is understood that God is that than which no greater can be conceived, Anselm suggests, it becomes evident that God must exist.

A form of the ontological argument also constitutes the crux of Rene Descartes’ Meditations. Having presented the argument from dreaming - the sceptical argument that we are not justified in believing that there exists an external world on the basis of sense-perception because one might have the same sense-perceptions in a dream - Descartes rescues himself from scepticism on the basis of his belief in God. God is no deceiver, Descartes argues, and so our clear and distinct perceptions of the external world can be trusted. Descartes arrives at the belief that there exists a trustworthy God via a form of ontological argument.

The most prominent modern advocate of the ontological argument is Alvin Plantinga. Plantinga is best-known for his defence of the view that religious belief is foundational, i.e. that religious belief does not stand in need of external justification, but is also known for his work on modal logic, i.e. on the logic of possibility and necessity. Plantinga applies his approach to modal logic to the ontological argument, presenting it in a revised form.

The critics of the ontological argument are no less distinguished than are its advocates. Among them is St. Thomas Aquinas, the thirteenth century Dominican and the greatest philosopher of religion of all. Aquinas was canonised in the fourteenth century, when he was said by the Pope to have met the criterion for canonisation of having performed three miracles in virtue of the answers that he had given to perplexing philosophical questions about God. Aquinas rejected the ontological argument in his Summa Theologica, First Part, Question Two.

The earliest critic of the ontological argument, though, was a contemporary of Anselm, the monk Gaunilo of Marmoutier. Gaunilo objected to the ontological argument on the ground that it seemed possible to use its logic to prove the existence of any perfect thing at all. Gaunilo sought to demonstrate this by constructing an ontological argument for the existence of the perfect island. This argument, he suggested, is clearly fallacious, and so the ontological argument for the existence of God, which relies on precisely the same logic, must be fallacious too.

The most vaunted criticisms of the ontological argument, however, are those of Immanuel Kant. Kant argued against the ontological argument on the grounds that existence is not a property of particulars but a property of concepts, and that whatever ideas may participate in a given concept it is a further question whether that concept is instantiated. Whether his criticisms are sufficient to undermine all forms of the ontological argument remains a matter of much dispute.

h of these things.

There are also other, more cynical ways in which we can exercise control over our beliefs. Using the techniques of hypnosis it is possible to induce beliefs in a subject without any regard for evidence at all. If one were thoroughly convinced of Pascal’s Wager, therefore, then one might choose to exercise control over one’s beliefs by hiring a hypnotist.

There are, then, some things that we can do to influence our beliefs even if doxastic voluntarism is false. Even if we cannot induce in ourselves a belief in God simply by an act of will, we can exercise control over our beliefs in other ways. If Pascal’s Wager is to be resisted, therefore, then this must be done on some other ground than that we cannot choose our beliefs.

Anselm’s Ontological Argument

St Anselm’s version of the ontological argument appears in his Proslogion, Chapter 2. His is the definitive statement of the argument. It has the form of a reductio ad absurdum, which means that it takes a hypothesis, shows that it has absurd or otherwise unacceptable implications, and so concludes that the hypothesis is false. In the case of Anselm’s ontological argument, the hypothesis treated in this way is the hypothesis that God does not exist.

Anselm’s argument rests upon the conception of God as “that than which no greater can be conceived”. It is this conception of God with which the hypothesis that God does not exist is supposed to conflict. If God does not exist, Anselm argues, then something can be imagined that is greater than God, namely a God that does exist. If, though, God is that than which no greater can be conceived, then nothing can be imagined that is greater than God. The hypothesis that God does not exist thus seems to give rise to a logical absurdity: that there both is and is not something that can be imagined that is greater than God. A hypothesis that gives rise to a logical absurdity, though, must be false. God, therefore, exists.

A formal statement of this argument might be constructed as follows:

(1) God is that than which no greater can be conceived.

(2) If God is that than which no greater can be conceived then there is nothing greater than God that can be imagined.

Therefore:

(3) There is nothing greater than God that can be imagined.

(4) If God does not exist then there is something greater than God that can be imagined.

Therefore:

(5) God exists.

The first premise of this argument, (1), is Anselm’s conception of God. (2) is a simple logical truth; if God is the greatest conceivable being then there is no greater conceivable being. (3) follows simply from (1) and (2).

Anselm argues in support of (4) by comparing a non-existent God with an existent God. An existent God, says Anselm, is greater than a non-existent God. If God were non-existent, therefore, then we could imagine a God greater than he, namely an existent God. (5) follows simply from (3) and (4).

Anselm - Proslogion

This central argument of this chapter is described in Anselm’s ontological argument. The Proslogion itself goes as follows:

Chapter 2: God Truly Is

And so, O Lord, since thou givest understanding to faith, give me to understand - as far as thou knowest it to be good for me - that thou dost exist, as we believe, and that thou art what we believe thee to be. Now we believe that thou art a being than which none greater can be thought. Or can it be that there is no such being, since “The fool hath said in his heart, ‘There is no God’”? But when this same fool hears what I am saying - “A being than which none greater can be thought” - he understands what he hears, and what he understands is in his understanding, even if he does not understand that it exists. For it is one thing for an object to be in the understanding, and another thing to understand that it exists. When a painter considers beforehand what he is going to paint, he has it in his understanding, but he does not suppose that what he has not yet painted already exists. But when he has painted it, he both has it in his understanding and understands that what he has now produced exists. Even the fool, then, must be convinced that a being than which none greater can be though exists at least in his understanding, since when he hears this he understands it, and whatever is understood is in the understanding. But clearly that than which a greater cannot be thought cannot exist in the understanding alone. For if it is actually in the understanding alone, it can be thought of as existing also in reality, and this is greater. Therefore, 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.

Gaunilo’s Perfect Island

The ontological argument is the argument that it follows from the concept of God that God actually exists. God is, as Anselm put it, that than which no greater can be conceived. A God that does not exist, though, cannot be that than which no greater can be conceived, for he could be conceived to exist which would be greater. God, therefore, cannot be non-existent; he must exist.

One problem with this argument is that it invites parody. Parallel arguments purporting to prove the existence of any perfect thing at all can be constructed. This objection was first raised by one of Anselm’s contemporaries, the monk Gaunilo of Marmoutier, who constructed an ontological argument for the existence of the perfect island.

The perfect island, this argument goes, is the island than which no greater can be conceived. Any island that does not exist, though, cannot be the island than which no greater can be conceived, for it could be conceived to exist which would be greater. The perfect island, therefore, cannot be non-existent; it must exist.

Similar arguments for the existence of the perfect baseball pitcher, or the perfect husband - for the existence of any perfect thing at all - can be constructed.

If any of these arguments is sound, it seems, then they must all be sound. Clearly, though, they are not all sound; the perfect baseball pitcher does not exist, and neither does the perfect husband. All of these ontological arguments, then, must be unsound, including the ontological argument for the existence of God.