Thus Anselm felt that he had demonstrated not only the existence of God, but also that his existence was necessary.
Descartes developed Anselm’s argument. His definition: that God is a ‘supremely perfect being’, is the basis for his argument. From this, Descartes believes we can conclude that God exists, because existence is a predicate of a perfect being; therefore God must exist to avoid being self-contradictory. Descartes says that trying to imagine God without the predicate of existence is illogical, like imagining a triangle without three sides.
From our examination of God as a perfect being, or that being than which no greater can be conceived, we can see that one of the elements of his perfection, one of the ingredients of the very definition of God, must be his existence. Hence, unlike any other concept, whose definition does not entail that it must exist, or does not include existence as one of its properties, the concept of God includes in its very nature that God is an existent being. Thus, merely from the idea of God, we can tell that He necessarily exists, in the same way that from a definition of a triangle, we can tell that the sum of its interior angles equals 180o.
Before considering some of the many criticisms that have been levelled against the ontological argument for the existence of God, it should be pointed out that some philosophers who employed the argument did not set out to prove that there is a God, but rather to explain the nature of a divine being. Descartes, for instance, did not offer the argument as a means to nullify atheism, but introduced it only after he believed he had established the existence of God by other means. Then, if one already accepted the fact that God existed, the value of the ontological argument was that it made clear what sort of a being God is, as distinguished from all others. God, alone, of all the objects we know of, is such that the concept of Him includes the idea of necessary existence, whereas no other thing that we can conceive of includes this within itself, or within the definition of it, its necessary existence. This showed for people like Descartes, that God alone is the cause of himself, and so is a self-existent being.
Ever since the original presentation of the ontological argument by St Anselm in the Middle Ages, philosophers have attempted to show that there was something particularly wrong with this form of reasoning. The earliest critique was sent to Anselm by a contemporary of his, Gaunilon, a monk of Marmoutier, who wrote in defence of the ‘fool’ who Anselm claimed could say, but could not believe, that God did not exist, since as soon as he understood what the concept of God was, he could see that it followed from his definition that He existed. In order to demonstrate what was wrong with the ontological argument, Gaunilon pointed out that if this sort of reasoning were legitimate, one could also show that al kinds of unreal or imaginary objects must also exist. For example, if one could imagine that there is a perfect island beyond the point that any explorer could possibly go, it follows that if this island is perfect or is that island than which no greater can be conceived, then according to Anselm’s argument, the island must exist. If it did not, then it would not be perfect, r be the island than which none greater could be conceived. But since by definition it is perfect, and no greater island can be imagined, then from that concept alone, we can be sure that it must actually exist. By indicating that one could develop all sorts of ontological arguments about all sorts of ideas, Gaunilon sought to show that the argument contained elements that are absurd and contradictory.
Anselm, in his own defence, claimed that the ontological argument applied only to God, since no other concept could be that of a perfect object – you could always add one more palm tree to the island to make it more perfect.
Immanuel Kant undertook the task of demonstrating why existence is not the kind of property that can be part of the definition of any concept. The idea or conception we have of anything involves a series of properties or predicates (e.g., that’s it is square, green, heavy). But can existence be such a predicate? If we conceive of something, and then conceive of it as existing, is our idea of the thing any different? In one illustration, Kant pointed out that the idea of £100 and of a real £100 contains the same monetary elements. Its economic value is the same, whether I am merely thinking of it, or whether I have the money in my pocket. One does not change the concept involved whether one merely thinks of it, or thinks of it as existing. As applied to the argument for the existence of God, the force of the concept or idea of God or a perfect being is not increased by thinking of it as existing, or merely thinking about it. Hence no bridge can be built from the idea of a perfect being to the actual existence of such a being. We can either prove something trivial or nothing at all using the argument. Either it is shown that we can define the term ‘God’ in such a way, that the proposition ‘God necessarily exits’ can be derived from the definition, or nothing is shown, since the idea that of a being than which no greater can be conceived is the same whether we are thinking of this object as something in our minds, or whether we are thinking of it as a real independent object.
Gattlob Frege distinguishes between first and second order predicates. First order predicates tell us something about the nature of the object we are describing, for example ‘the horses are brown’. Second order predicates tell us about concepts, for example, the horses are ‘numerous’. Frege says that Anselm and Descartes both treat existence as a first order predicate when it is in fact a second order predicate – thus offering no further addition to the ‘nature’ of God, merely describing the concept of him.
Bertrand Russell, however, claims that existence cannot be treated as a predicate. If it were, we could construct the following argument using the same deductive reasoning: ‘Man exists. Santa Claus is a man. Therefore, Santa Claus must exist.’ This is a syllogism - A form of deductive reasoning consisting of a major premise, a minor premise, and a conclusion.
Russell is saying that existence is not a property of things, but of the ideas of those things. Therefore to say that ‘dragons do not exist’ is to say that, of all the things that do exist, none of them are referred to by the word ‘dragons’.
Russell states that to label and define something is to provide an intention concerning the object under discussion. Therefore if w were to say that a cow is a quadruped with udders etc. my intention would be to describe a cow. The fact that the cow exists provides an extension to my intention. Therefore existence is an extension of an intention.
He concludes that ‘that than which no greater can be conceived’ is simply the totality of everything that can be conceived by the human mind. This is the intention of the phrase, and its extension can be proved because is any idea can be said to exist, then ‘that than which no greater can be conceived’ must exist, as it’s the totality of all ideas. It does not have to have any physical existence, or even be conceived, as long as it’s conceivable. Therefore Russell would support Anselm’s claim that God is the greatest thing we can think of, but not the belief that this proves he exists in reality.
Although many thinkers believe that the existence of God can be established by means of rational or natural evidence, other philosophers maintain that no satisfactory rational evidence can be adduced to prove God’s existence. Others have concluded that the difficulties involved in all the proofs are due to the nature of the subject, which is, perhaps, beyond our rational capacities. These thinkers have claimed that the problems involved in finding rational or natural evidence establishing the existence of God may indicate that one must seek another type of evidence entirely, and abandon the quest by means of reason.
