Over the centuries a large number of philosophers and theologians have tried to argue that God's existence is somehow necessary. Descartes argued that the mere fact that we can talk about a supremely perfect being implies that that being exists, because perfection and existence somehow go together. Others such as Kant reject this kind of 'ontological' argument on the grounds that 'existence' is not a propoerty of something in the way that, say, redness is. Yet the ontological argument is still explored – partly, some say, more as a meditation than a purely philosophical exercise.

There is only one major argument for God's existence that is a priori, deductive, and that was called the Ontological Argument by Immanuel Kant, though several versions of it predated Kant by centuries.

St Anselm – anybody who doubts God's real existence is a fool

The origins of the Ontological Argument are usually seen in the writings of St Anselm of Canterbury. Anselm's "argument" in Proslogion 2 was a reflection or prayer rather than a formal piece of philosophy. He tightened up his thoughts in two developed arguments found in the Monologion (written before the Proslogion, though it did not appear until later) and Proslogion 3. In Proslogion 2, Anselm began with a quotation from Psalm 14:1 and then reflected on its truthfulness. Anselm defined God "aliquid quo nihil maius cogitari possit", or that than which no greater can be conceived. This a priori being accepted, he observes that anybody who doubts God's real existence is a fool ... It is always greater to exist in reality (in re) than just in the mind (in intellectu) [this claim is often discussed in terms of the relationship between formal and intentional existence]. The doubter must have a concept of God in the mind to doubt or reject. If the concept of God is that of the greatest conceivable being it must be of a formally, really existing being ... The doubter is essentially saying "God, who exists, does not exist" – they are asserting a straight contradiction. As Anselm wrote???

The word ontological was first used to describe deductive, analytic arguments for the existence of God by Kant in the Critique of pure reason. The word "ontological" is derived from ontos, the present participle of the Greek verb einai to be; it literally means "being", so the argument is that God's existence
follows from the nature of being, existence, itself. There are many ontological arguments, some more sophisticated than others, but they share the characteristics of being deductive, analytic, and a priori or propter quid arguments. They attempt to demonstrate that existence is part of God's nature or being and do not depend on observations.

Gaunilo's riposte 'on behalf of the fool'

The simple argument in Proslogion 2 was reduced to absurdity by Anselm's fellow Benedictine, Gaunilo, in a witty reposte entitled Liber pro Insipiente or "On behalf of the fool". Gaunilo ignored the fact that Anselm had already published a tighter version of the argument in Proslogion 3 and focused on the claim that God's nature as the greatest conceivable being must include existence. He used the example of a perfect island, observing that if a man should try to prove to me by such reasoning that this perfect island truly exists, "either I should believe that he was jesting, or I know not which I ought to regard as the greater fool: myself, supposing that I should allow this proof; or him, if he should suppose that he had established with any certainty the existence of this island."

Gaunilo suggested that the ontological argument, if it is to work in proving God's existence, should also prove the existence of all other perfect things - islands, women, unicorns – which we all know don't exist in the real world. To put it simply, no amount of believing or arguing is going to change the fact that when you get to your paradise island there will be cockroaches in the bathroom and nothing you can say about the love of your life will stop her from aging, having PMT and occasionally nagging about leaving the loo seat up!

Anselm's next move – the necessary existence of God

Anselm wasted no time in refuting Gaunilo's criticism. He developed the existing argument in Proslogion 3 into a more substantial piece of philosophy in the Responsio. Anselm stuck with his definition of God as the greatest conceivable being and still observed that it was greater to exist in re than just in intellectu but he went on to ask whether it is greater for a being to have contingent existence (i.e. existence which can be conceived not to exist) or to have necessary existence (i.e. existence which cannot be conceived not to exist). Naturally, necessary existence is greater and thus must be a necessary property of the greatest conceivable being, of God. "For it is possible to conceive of a being which cannot be conceived not to exist; and this is greater than one which can be conceived not to exist. Hence if that than which nothing greater can be conceived can be conceived not to exist, it is not that..."

The property of necessary existence is only a property of the greatest conceivable being - only God must exist, necessary existence is his nature - existence is only part of the natures of other things. Thus the argument cannot be applied to other things even if they seem to share in the perfection which is God's nature as well. In other words, God's greatness is not like the greatness of other things - they can be more or less great but God is greatness itself - they can contingently exist but only God necessarily exists.

De re necessity and de dicto necessity

In order to understand the ontological argument it is necessary to understand the term "necessary". In the cosmological argument God's "necessary" existence entails his self-sufficiency as the prime mover, uncaused causer and sustaining non-contingent entity which gives rise to our reality. As such God is de re necessary - he depends on nothing, is outside time and space, having no potential, wholly simple, perfect etc. In the ontological argument God's existence, admittedly entailing some or all of the characteristics of the de re necessary god of the cosmological argument, is demonstrated to be de dicto necessary - true from the word, or definition of God. When Anselm and later other advocates of ontological proofs, speak of God's existence being "necessary" they mean that existence is an inescapable part of the concept of God.

St Thomas Aquinas argued that God's de re necessity could be demonstrated through inductive natural theology but that God's de dicto necessity could never be known in this life. He observed that all ontological arguments depend on an a priori definition of God which he felt to be impossible. For Aquinas all claims about God are analogical - they share some meaning with similar claims made about created things but should not be understood to be univocal. We can move from experience to the conclusion that God exists and from that conclusion to making claims about the nature of his existence as a necessary being - but the sense of our understanding of God's nature is too limited to allow for a definition to be analysed for a de dicto proof of His existence. Aquinas denied the univocal use of language which Anselm's proof assumed - and thus undermined the ontological approach to proving God's existence. As he wrote "Because we do not know the essence of God, the proposition ‘God exists' is not self-evident to us." Aquinas objected to the whole idea of a deductive ontological argument for God because this type of argument starts with a definition which can then be analysed - something which is not possible in the case of God.

John Duns Scotus' definition of God

John Duns Scotus agreed with Aquinas that we can only prove the existence of God by an argument quia (from effect to cause) and not by an argument propter quid (from essence to characteristic) and further that we cannot know the full nature of God in this life. Scotus was more positive about the possibility of defining God univocally though and does not subscribe to Aquinas' doctrine of analogy. As for Aquinas, ??? for Scotus our concept of God is framed in language based on temporal experience. But as this experience derives from God, and we must thus be able to talk about him as a result of experience, our language must be applicable to God. Scotus works from a distinctive definition of God as an infinite being. He argued that this is a much better way of understanding God's nature than the Thomist definition of God as wholly simple. Aquinas' definition is negative - God is not bounded by the limited contingencies of time and space. Scotus' definition is positive - God possesses all pure perfections, all those qualities which are better to have than not, in infinite degree, as an infinite being.

Descartes' calculation

Rene Descartes (1596-1650) proposed several versions of the ontological argument, the clearest of which is contained in his fifth Meditation and develops Anselm's argument in Proslogion 3.

1. I have an idea of a supremely perfect being
2. Necessary existence is a perfection
3. Therefore a supremely perfect being exists

For Descartes the concept of God entails existence in the way that the concept of a triangle entails three sides, three angles and 180 degrees, in the way that the concept of a hill entails valleys. God de dicto exists. Essentially Descartes argument tries to demonstrate equivalence between the words "‘God", "perfection" and "existence". In the same way that the number 4 can be written alternatively as 1+1+1+1, 2+2 or 2x2, for Descartes the ontological argument just shows that the three terms necessarily relate. Note that Descartes starts from the confident assertion that one can know the essential nature of God.

On some occasions Descartes claims that his "argument" is simply a self-evident axiom, grasped intuitively by a mind free from philosophical prejudice. Certainly, the idea of God, or a supremely perfect being, is one that I find within me just as surely as the idea of any shape or number. And my understanding that it belongs to his nature that he always exists is no less clear and distinct than is the case when I prove of any shape or number that some property belongs to its nature.' One interesting question is to consider what Descartes really means by existence. As a rationalist philosopher, he sees truth being reached through the operations of the mind and dismisses sense data as potentially flawed and limited. God exists for Descartes in the way that a number exists - I can't photograph the number 2 in the wild but I can see how it applies to other things and I can reasonably say that the number is real or exists. God, the principle of supreme perfection, is as undeniable as any mathematical truth - but I can't see or touch (or photograph) it in itself. For Descartes that idea of God is a necessary feature of our understanding which makes other judgments possible.

Descartes, like Anselm, concludes that denying God's existence is denying an essential predicate of his nature. The atheist is a fool because he/she asserts "God, who exists, does not exist" - as nonsensical as talking of two-sided triangles or flat hills. This claim, that existence can be seen as an essential predicate of anything, is the focus of the criticisms of the classical argument levelled by Kant and later Russell.

Leibniz's principle of non-contradiction

In the early eighteenth century, Gottfried Leibniz (1646-1716) attempted to fill what he took to be a shortcoming in Descartes' view. Descartes' argument focused on a psychological question, whether the idea of God entailed his existence, whether a clear and distinct understanding of God would make accepting His existence inescapable. Leibniz' argument focused instead on the logical possibility of God's necessary existence. According to Leibniz, Descartes' arguments fail unless one first shows that the idea of a supremely perfect being is coherent, or that it is logically possible for there to be a supremely perfect being.

Leibniz set himself the task of proving that there is no contradiction within the concept of a supremely perfect being. Leibniz developed "the principle of non-contradiction", that is that a concept is valid, possible, true and real if it does not contain contradictions. For example the concept of a married bachelor is nonsensical, or a square circle. Square circles are impossible and not real. He made a distinction between what he took to be flawed concepts, such as the highest number and the greatest speed, and those concepts of perfection which he maintained to be possible. He argued that all possible perfections are simple, unanalyzable, and thus ultimately compatible. They can all be drawn together within a single possible concept of supreme perfection.

Leibniz argued that existence is a perfection and that supreme perfection would entail infinite existence. Leibniz, like Descartes, was a rationalist. He believed that ultimate reality is metaphysical. His argument sought to demonstrate that God's necessary existence, as a concept, contained no contradictions and thus is logically possible. If the idea is possible and the idea relates God's nature with formal existence, then God must formally exist.

Kant: God surpassing definition

The epistemology of Immanuel Kant (1724-1804) prevented him from deriving a proof of God's existence from an a priori definition of his nature. For Kant, knowledge is based on experience and what can be induced or deduced from it. Knowledge of God and of "necessary existence" is beyond our experience and thus it would be impossible to develop a definition strong enough to be the subject of analysis. This criticism is similar to that put forward by Aquinas. Kant allows for the objection to this criticism, voiced earlier by Scotus (above), by arguing that certainly experience indicates regularity, order, laws but that we cannot prove the existence of the God, the supreme good, which most probably explains them - we can only postulate the existence of such a being. Language is based on experience and can be used to explore it and indeed to arrive at evidence to support the postulate of God - but it cannot be used to provide proof in itself.

Kant first distinguished between synthetic and analytic statements - the first referring to existence and the second making a claim about the relationship between concepts.
1. Synthetic: this ball is red
2. Analytic: unmarried men are bachelors

Kant observed that Descartes moved from the analytic claims "perfection entails existence" and "supreme perfection entails necessary existence" to synthetic claims, "perfect things exist" and "the supremely perfect being exists". Though Kant accepts that these analytic statements are not self-contradictory and thus possibly real by Leibniz's definition of reality, he does not accept Leibniz's definition of reality.

For Kant reality is not just about logical plausibility, it is what we experience. He notes that making a synthetic claim is a different matter from making an analytic one. There are no instances of perfect things or supremely perfect beings to refer to so we cannot conclude that they exist. Kant criticised the argument's concept of "necessary existence". He noted that to argue that there is a necessary being is the same as to say that to deny its existence is self-contradictory, remember, saying "God, who must exist, does not exist" makes you a fool according to Anselm. If this was the case then it would mean that at least one analytic statement must be synthetically true - God exists. But Kant argues that it is logically impossible for any synthetic, existential proposition to be logically, analytically necessary. For Kant, every synthetic, existential proposition must contain the possibility of it being otherwise - this ball may or may not be red, may or may not exist. The concept of necessary existence is thus a contradiction, a "miserable tautology".

Russell's criticism

Bertrand Russell (1872-1970) made a similar criticism of the ontological argument in his article On denoting (1905). He distinguished between two types of propositions - predicative (those which add to the concept) and existential (those which claim a reference between a concept and a state of affairs) Russell argued that everyday use of language makes it possible to talk about non-existent things with apparent meaning. Although we should say "are there things which match the description of cows?" before talking about cows, in fact we just start talking about cows. He used the example of "the present King of France" - as soon as I start talking about this meaningless entity, even if to state that it does not exist, I imply that the concept is a valid one. For Russell, statements can only be true or false if they refer to a meaningful concept. There is no way that I can affirm the existence of any instance of "necessary existence" before embarking on an ontological argument which seeks to conclude the God's necessary existence is necessary - therefore the whole enterprise is meaningless.

Existence as perfection

Kant also criticised the assumption, made by Descartes, Leibniz and Anselm for that matter, that existence is a perfection – i.e. they had all claimed that it is better to exist than not to exist and thus that the most perfect being would have to exist. Kant rejected this because he argued that existence is a necessary ground for any other perfection to be meaningful rather than just another in a list of perfections. Imagine a job interview. The panel look through the CVs of two well qualified candidates - it turns out that candidate A exists and candidate B is made up. There is no real contest between the two. Candidate B never really had any of the qualities the CV claimed and was nonsense all along. Candidate A's existence is not just another qualification which tips the balance in her favour! Kant makes the point that a statement about existence is not the same as a statement about other perfections of an object thus it is inappropriate to argue that "existence is a perfection, therefore the supremely perfect being must exist." Note that Kant's concept of existence is rooted in experience - it appeals to common sense but does not engage with the rationalist argument on equal terms.

Kant criticised Descartes and Leibniz for seeing existence as a predicate of God. Descartes and Leibniz defined God's perfection in terms of a list of attributes - just as a perfect flower would be colourful, scented, have petals and leaves etc, the supremely perfect being would be all-powerful, all-knowing, have necessary existence. He added existence as another attribute of the object but Kant argued that this is flawed. Existence adds nothing to the concept of the flower; it merely refers to whether there are instances of the concept. Existence is not a predicate; to use it as one is simply bad grammar.

Predicate and subject

Kant made a specific criticism of Leibniz, saying, "If I reject the predicate while retaining the subject, contradiction results; and I therefore say that the former belongs necessarily to the latter. But if we reject subject and predicate alike, there is no contradiction; for nothing is then left that can be contradicted ... the same holds true of the concept of an absolutely necessary being. If its existence is rejected, we reject the thing itself with all its predicates; and no question of contradiction can then arise." He did not accept Leibniz's principle of non-contradiction; although influenced by Leibniz's work as a young man, Kant later came to refer to Leibniz as "dogmatic" and claimed that reading Hume "awoke me from my dogmatic slumbers". For Kant, ultimate reality was not accessed by pure reason and truth was not demonstrated by the coherence of its conceptual parts. God's existence could not be proven by showing that the concept of God as a supremely perfect, necessarily-existing being is non-contradictory.

Real and imaginary

What is the difference between a real hundred pounds and an imaginary hundred pounds? Kant observed that the concept in question is identical whether the notes are in my pocket or not. There is a difference between claiming something about a concept and claiming that a concept exists. He concluded that... "The attempt to establish the existence of a supreme being by the famous ontological argument of Descartes is therefore merely so much labour and effort lost; we can no more extend our stock of [theoretical] insight by mere ideas than a merchant can better his position by adding a few noughts to his cash account."

Essentially then, for Kant:
– Whatever adds nothing to the concept of an essence is not part of that essence,
– Existence adds nothing to the concept of an essence
– Existence is not part of the essence of a thing, it is not a perfection.

Experience and semantics

Whereas Descartes argued that the conceptual relationship between perfection and existence within the idea of God rendered his necessary existence de dicto necessary, Kant observed that such analytic truths are simply semantic. Certainly the relationship between "unmarried man" and "bachelor" is undeniable but the sort of undeniable truth that it is extends only to how language should be used. For Kant, synthetic claims, claims about existence such as "this ball is red", must refer to a state of affairs which can be experienced if they are to be meaningful. It is the experience of seeing the ball that carries the meaning, not the words we use to describe that experience. If I look at the ball and say "that ball is red" and Francois, having the same experience says "ceci, c'est rouge!" we know we mean the same thing because we are experiencing the same thing. Analysing statements about things we cannot experience does not really get us anywhere. For Kant all synthetic propositions can either be true or false in relation to an actual state of affairs, a state of affairs within our experience. There can be no analytic demonstrations concerning the existence of anything.

Findlay's paradox

John Niemeyer Findlay's 1948 article "Can God's existence be disproved?" tightened the criticisms levelled by Kant and Russell and attempted to provide an ontological proof of God's impossibility. Findlay began by agreeing with Anselm's point in Proslogion 3, that only a necessary being would really be the greatest conceivable, really be God and thus really worthy of worship. He then claimed "it was indeed an ill day for Anselm when he hit upon his famous proof. For on that day he not only laid bare something that is of the essence of an adequate religious object, but also something that entails its necessary non-existence."

Simply, building on Kant's dismissal of "necessary existence" as a contradictory proposition, he developed what Hartshorne later called "Findlay's Paradox"

1. a contingent being would not deserve worship
2. a necessary being is a logical absurdity

This could be seen as an ontological proof of God's non-existence! However, Charles Hartshorne criticised Findlay on two counts: 1. If it makes sense to talk about God's necessary nonexistence then it makes just as much sense to talk about his necessary existence (Russell's argument in "On denoting" which ??? would see both discussions as equally meaningless!) and 2. Findlay, like Kant and before him, Hume, assumes that all existential propositions are contingent. Hartshorne points out that this is not a universally accepted assumption.

Malcolm and 'language games'

Norman Malcolm agreed with Hartshorne on his second point. A pupil of Wittgenstein, he saw that meaningful propositions are not restricted to the analytic or synthetic, but that meaning is derived from the usage of language. Rather, he accepted Wittgenstein's "language games" theory - and once again shifted the truth/reality framework in which the argument is played out. Malcolm asserts that within a religious form of life the concept of necessary existence has real meaning, its effect can be seen in the lives of believers. Therefore Findlay's neat extension of Kant's critique should not be accepted lightly. "In those complex systems of thought, those ‘language games', God has the status of a necessary being. Who can doubt that?... I believe we may rightly take the existence of those religious systems of thought in which God features as a necessary being as disproof of the dogma, affirmed by Hume and others, that no existential proposition may be necessary."

Malcolm then returned to Anselm's argument from Proslogion 3 and developed it:

1. God, as the greatest conceivable being, cannot be a limited being.
2. Therefore, if God does not exist he cannot come into existence.
3. Similarly, if God does exist he cannot cease to exist.
4. If 2, then if God does not exist his existence is impossible, and if 3, then if God does exist his existence is necessary.
5. Either God does exist or he does not exist.
6. Therefore God's existence is either impossible or necessary.
7. God's existence is not impossible [see Leibniz - there is no contradiction within the concept of necessary existence - Kant did not contest this; he just asserted that the coherent concept could be altogether rejected.]
8. Therefore God necessarily exists.

Hick's critique of Malcolm

John Hick (b 1922) claimed that Malcolm confused two different concepts of necessary being - factually necessary being and logically necessary being. Factually necessary being equates to de re necessity, to aseity, to Anselm's notion of a being "which cannot be conceived not to exist" - logically necessary being equates to de dicto necessity, to analytic truth. Hick claims that Malcolm, like Anselm, Descartes and other proponents of the ontological argument, has fallen into the trap of moving from logical necessity to factual necessity. He noted that proposition 6, "God's existence is either impossible or necessary", is where Malcolm shifts from talking about God's de re, factual necessity, to talking about his logical, de dicto necessity. Like Kant, he observes that there is no contradiction in rejecting the whole concept of God as a factually, de re necessary being and argues that proposition 6 should read ‘God's existence is either impossible or eternal' - hence there is no need to accept necessity for fear of accepting a contradiction.

Hick, like Malcolm, is not trying to use the ontological argument in the same way that Anselm, Descartes and Leibniz were. Many twentieth-century writers have focused on the argument as a logical/meditative exercise rather than as a proof. Broadly speaking, Hick is broadly a reformed epistemologist - he is not interested in proving God's existence through argument - or in disproving it. He sees that his job as a philosopher of religion is to pre-empt criticisms which could be used as "defeaters" to undermine belief and show either that religious people don't accept the flawed arguments or that there are ways around them. However unsatisfactory the amended arguments may be as a basis for faith - at least they stand up as logical defences of faith that exists independently of them.

Alvin Plantinga: God's 'maximal greatness'

Alvin Plantinga is another reformed epistemologist whose more complex ontological argument is designed to evade the classic criticisms and show that belief can be defended through the argument - if not based on it: "what I claim for this argument therefore, is that it establishes not the truth of theism, but its rational acceptability." Plantinga dismissed Malcolm's version of the argument, noting that Malcolm has shown that it is possible that a logically necessary
being exists but not that it is necessary that God is a logically necessary being. He suggested a more complex argument instead:

1. The property "has maximal greatness" entails the property "has maximal excellence in every possible world"
2. Maximal excellence entails omnipotence, omniscience and omnibenevolence.
3. Maximal greatness is possible as there is nothing contradictory in this claim, hence we can claim that there is a possible world in which it exists
4. There is a world W and an essence E
5. For any object X, if X has exemplified E then X exemplifies the property "has maximal excellence in every possible world"
6. E entails the property "has maximal excellence in every possible world"
7. If world W had been actual, it would be impossible that E fail to be exemplified
8. There exists a being that has maximal excellence in every possible world
9. So this being must exist in this world...

Plantinga, for all his complex logic, goes back to Leibniz and makes the old assumption that whatever is non-contradictory must be possible and that whatever is logically necessary must then be factually necessary; though you might be forgiven for missing the assumptions through being blinded with jargon!

Godel

Kurt Godel (1906-78), who has been called the most important logician of our times, put forward a version of the Ontological Argument in his private papers, which was formalised and published after his death. Like Plantinga's argument, Godel's relies on modal logic and is almost incomprehensible to the layman. The argument is very impressive; it apparently convinced Godel, who was no fool. Yet it may still be criticised for supposing that what is logically necessary is also factually necessary and exist, though of course it depends on the definition of existence that he was working with.

Karl Barth

In Faith seeking understanding Karl Barth (1886-1968), like Malcolm, Hick and Plantinga, focused on the ontological argument's importance for the person with pre-existing faith. For Barth, Anselm's arguments should not be seen as such - they begin and end with a prayer, an address to a God who is already accepted to exist. Barth sees Anselm's negative definition of God as that than which nothing greater can be conceived is actually a revealed "name" of God, which Anselm sees as a norm of theological thinking, one which reinforces the limits of human understanding rather than assuming that humans can fully understand God. Barth sees the assertion of God's necessary existence in Proslogion 3 as an admission of the total dependency of contingent beings, such as ourselves, on the creator, rather than as a clever "sleight of hand trick" (Schopenhauer). He concluded: "The reason why there is such a thing as existence is that god exists. With his existence stands or falls the existence of all beings which are distinct from him. Thus with the prohibition against conceiving anything greater than him and with this prohibition ruling out the thought of His non-existence - thus alone does God confront man. Thus he and he alone is objective reality."

This observation of Barth's is strangely reminiscent of a little-known but distinctive ontological argument put forward by Immanuel Kant in his pre-critical work "The only possible argument in support of a demonstration of the existence of God" (1763). He dismissed the possibility of a classical argument working from a definition of God's nature, using an early statement of his later criticism "existence is not a predicate" based on his reading of Hume. Yet he supported the idea of a proof for God from general ontology to a certain extent. In the Critique of pure reason (1781) he waters this down somewhat to fit in with his general epistemology and to ‘leave room for faith', he leaves the impression that it may provide grounds for belief beyond the postulation based on "the moral argument". This little-considered version of the ontological argument works not from a definition of God but rather from a definition of reality, of being itself. If reality is to be possible (i.e. not contain a contradiction) it must contain an explanation of itself and yet if our understanding of reality is limited to our contingent experience then this is not forthcoming. There must be that which explains contingent experience, which makes reality possible. "Accordingly, there must be something whose nonexistence would cancel all internal possibility whatsoever. This is a necessary thing." Kant here sees that God could be the material ground of possibility. This argument shares a lot with Aquinas' Third Way, though it is recast as a deductive proof rather than an inductive argument. Kant firmly dismissed the inductive version along with other cosmological arguments in the Critique of pure reason, but is more intrigued by the "only possible argument".

Iris Murdoch: God as goodness

Iris Murdoch (1919-99) is best remembered as a novelist and through the story of her struggle with Alzheimer's, which was told in the film Iris with Kate Winslet and Judi Dench. She was, however, also a respected philosopher and literary critic, holding the unusual position of being a modern Platonist. She maintained that ideals such as goodness, beauty, truth have a real existence - though she stopped short of ascribing them to any definite ‘world of the forms' outside the mind. Although no obvious theist, she was fascinated by the ontological argument as she saw in it a way of reaffirming the connection between well-known concepts of power, knowledge, love etc. and the concept of god as supreme perfection. As she saw, it the ontological argument is primarily a faith-exercise which helps the individual to accept the reality and coherence of goodness, of God, within their own lives. In The metaphysics of morals Murdoch recounted a story of believers praying to a relic that was, in fact, a dog's tooth. Through the veneration it is given by the sincere villagers, the tooth begins to glow, it becomes the miraculous relic they think it is. "Here we may make sense of the idea of loving good. At its highest point, love is a determination to create the being which it has taken for its object." Here indeed we come back to the Ontological Proof in its simpler version, a proof by perfection, by a certainty derived from love. The good artist, the true lover, the dedicated thinker, the unselfish moral agent solving his problem: they can create the object of love. The dog's tooth, when sincerely venerated, glows with light."

Murdoch takes the same theme in her novel The Sea. The worshipper endows the worshipped object with power, real power not imaginary power, that is the sense of the ontological proof, one of the most ambiguous ideas clever men ever thought of. God is all-powerful and all-knowing in that he defines every aspect of our understanding and by applying our understanding we affirm his existence in every thought. "There is no plausible 'proof' of the existence of God except some form of the ontological proof, a 'proof' incidentally which must now take on an increased importance in theology as a result of the recent 'de-mythologising'."

If considered carefully, however, the ontological proof is seen to be not exactly a proof but rather a clear assertion of faith (it is often admitted to be appropriate only for those already convinced), which could only be confidently be made on a certain amount of experience. This assertion could be put in various ways. The desire for God is certain to receive a response. My conception of God contains the certainty of its own reality. God is an object of love which uniquely excludes doubt and relativism. Such obscure statements would of course receive little sympathy from analytical philosophers, who would divide their content between psychological fact and metaphysical nonsense ...

A question of existence

The central question which the ontological argument raises is, appropriately enough, that of existence. What does it mean to exist? For Anselm, Descartes and Leibniz existence is metaphysical while for Hume and Kant it is primarily physical. For Malcolm, Plantinga, Hick and Murdoch to exist is to make a difference in the life of an individual or community. Clearly, an argument which seeks to demonstrate that God exists is affected by the definition of existence just as much as by the definition of God. The classical ontological argument makes a series of assumptions, each of which can be challenged:
1. We can define God
2. It is better to exist formally (in "reality") than to exist intentionally (just in the mind),
3. Existence is a perfection
4. Existence is a predicate
5. Necessary existence is possible
6. Whatever is possible possibly exist,
7. Logical necessity can entail factual necessity

Although Arthur Schopenhauer referred to the ontological argument as a "sleight of hand trick", as a "charming joke" and although, more recently, Graham Oppy concluded that ontological arguments for God's existence are "completely worthless", it retains value. As a logical exercise the argument demonstrates a great deal about language, and as a meditative exercise the argument has the power to affirm personal faith. Perhaps, as GE Moore once remarked, "The lot of critics is to be remembered by what they failed to understand."