PROVING THE EXISTENCE OF GOD

Augustine had demonstrated from the ascending order of excellence in the universe that there must be a God. That was an exercise with a character and purpose closely in tune with that of Anselm in the Monologion, which he called a ‘meditation on the Divine Being’ (essentia). It may be, he begins, that there is someone who does not know of the one Nature (natura), the Highest of all things which have being (summa omnium quae sunt), alone sufficient to itself in its eternal beatitude (beatitudo), giving and causing, through its own omnipotent goodness. Anselm hazards the possibility that there is not only someone who does not know but even someone who does not believe that this is so. He promises that even the unbeliever can be won round by reasoning. But the tone of the promise is that of a master among friends and pupils, a monastic superior among his monks, engaged in a philosophical meditation together in a context of faith and prayer.  The purpose is to heighten faith, and ground it in intellectual apprehension, not to win to faith recalcitrant or slow minds. It is of the first importance here that Anselm’s Highest is described in one breath as not only existing but omnipotent, good, sufficient to itself and the source of the being of all creatures. There is, as it were, a package, Neoplatonically made up, in which the existence of God comes with certain inseparable attributes. It is important in reading Anselm’s ontological argument to recognise that the same is true of the Proslogion proof. In the Preface to the Proslogion, Anselm explains that he had become dissatisfied with the arguments of the Monologion, not because he now thought them unsound, but because they were inelegantly strung together as if in a chain. He had since been looking for a single argument which would prove not only that God truly exists (quia uia Deus vere est), but also all the other concomitant truths in the ‘package’, that he is the Highest Good, needs no other, and is the source of the being and well-being of all creatures, and whatever else we believe about the divine Being (substantia). The vere is perhaps important. It implies, as had the hypothetical character of the person in the Monologion requiring a rational demonstration, that we are dealing here with the meditations of the faithful rather than with the convincing of unbelievers. Everything about the Proslogion’s construction suggests as much, its opening chapter of prayer and the interludes throughout in which, like Augustine in the Confessions, Anselm addresses God directly in gratitude or supplication. It is for this reason that we must say that, in a sense, Anselm only ‘appears’ to be seeking to prove the existence of God. We have not yet arrived at a situation comparable with that which confronted eighteenth-century apologists, for whom the individual who denies that there is a God is not a literary fiction, the ‘Fool’ of the Psalms, but a person who really needs to be convinced. Anselm’s originality lies in the structure of the Proslogion argument itself. In the Monologion he had proceeded in roughly Augustine’s way, to lead the reader from his own direct knowledge of good things in the world to infer the existence of a common and higher Good from which they all derived, and from which they draw that which is good in themselves.  The hierarchy of excellence and the notion that some one thing must stand at the top of it are indispensable to this argument. It enables Anselm to show that the supreme Nature exists through itself and has no prior cause (Monologion, 1–6). He is able to go on from there and demonstrate both the basic Christian principles of creation: that God made all things from nothing, although he had had the ideas which give them their form in his mind from all eternity; and that he sustains his creation in being.. He is also able to show that God is supreme Justice, without beginning and end, immutable, omnipresent and yet in no place or time . In the Proslogion he makes an entirely fresh use of the hierarchy of excellence. God may be described as ‘that than which nothing greater can be thought’. We begin at the top of the ladder of understanding up which Anselm invited us to climb in the Monologion. He forces us to confront the question whether what we think of as God must, because it thus lies at the ultimate limit of an understanding which is itself attainable only when thought aspires to the highest, be more than a thought. It is self-evidently true that if ‘that than which nothing greater can be thought’ exists in reality as well as in the mind, it is in fact greater than a ‘that than which nothing greater can be thought’ which is only in the mind. If there is not only a possibility we can think of, but also a self-evident truth about that possibility, Anselm would argue that to say that God exists only in thought must involve a contradiction.  ‘That than which a greater cannot be thought’ would not be ‘that than which a greater cannot be thought’, for we have thought of a greater. Since that is manifestly impossible, Anselm says that there can be no doubt that ‘that than which a greater cannot be thought’ exists both in the understanding and in reality (et in intellectu et in re) (Proslogion, 2). He develops the principle in his next chapter. If it were possible to think that this ‘that than which a greater cannot be thought’ did not exist, then it would manifestly not be ‘that than which a greater cannot be thought’, for it would not be being thought at all. There remains the Fool, who appears to be doing the impossible, when he says in his heart that there is no God (Psalms 13.1, 52.1). We must distinguish, says Anselm, between thinking mere words and thinking the thing which the words signify.  The Fool might think the words, but he could not think the thing. Anselm can now apply his reasoning to all the other things we believe about God, as he promised (Proemium). God is whatever it is than not to be, just, truthful, happy, and so on, as can be proved in the same way as his very existence. It is important that God’s existence is never fully separated in Anselm’s mind, or in Anselm’s system, from the complement of ultimately Platonic assumptions about the divine nature with which it is accompanied in Augustine and in Anselm’s own earlier Monologion. We are dealing with a Being which has of its substance a number of attributes. It was Gaunilo, monk of Marmoutiers, who insisted that the nub of the matter was the argument for God’s actual existence.

He wrote a reply to Anselm in the person of the Fool, contending that he for one could think that which Anselm said it was impossible to think. He suggested that if Anselm’s argument were sound, it would also be true that the most beautiful island one could think of would necessarily exist in reality as well as in imagination, and so on for the best of everything. Anselm was pleased with this subtle response, and thought the point worth answering. He instructed that Gaunilo’s reply and his own rejoinder to it should be inserted at the end of the copies of the Proslogion thereafter. His answer was that God must be unique in being of such a kind that his existence can be proved by Anselm’s argument. Gilbert Crispin, one of Anselm’s monks at Bec and later abbot of Westminster, made some use of Anselm’s formula, but with the difference that he preferred to describe God as ‘that than which a better cannot be thought’. But we have to wait for Aquinas to take up Anselm’s argument again and criticise it fully. He saw that the Proslogion argument falls into a class by itself. He considers it apart from other arguments, under the question whether the existence of God is self-evident (ST I.q.2.a.1). In Objection 1 he summarises Anselm’s argument of the Proslogion and replies to it by saying that Anselm makes an unjustified leap from thought to reality. It must also be conceded, Aquinas argues, that those who deny that God exists demonstrate by their position that the existence of God is not self evident. Whether or not Aquinas put his finger on a real weakness, it is certainly the case that Anselm did not succeed in settling the matter of God’s existence once and for all. But on the other hand, his argument has never been decisively refuted, because it has proved impossible to determine on exactly what it turns. It is of some importance here that it hangs upon precisely the question of that intersection between thought and reality which was central to mediaeval work on epistemology and language. William of Conches made an early attempt at a type of proof of the existence of God which Aquinas was to exploit more fully in the Summa Theologiae, and which has respectable philosophical ancestry. William argues that to move at all, bodies must be animated by spirits. Spirit would not join itself to body unless some powerful agent caused it to do so, and held it in its relationship to body. No creature could have the necessary wisdom to do that. So we must postulate the existence of a Creator. Aquinas constructs five proofs which depend in various ways upon reasoning back from an observable effect in the created world to a Creator. Some things are visibly in motion. Whatever is moved must be moved by a mover. But there cannot be an infinite regression of movers, for then there would be no movement at all, because no initial impetus. Therefore there must be a First Mover, and that is God. In a similar way, Aquinas argues from effects to causes, to a chain of causes, and thence to the necessity for a First Cause. Thirdly, he suggests, we may take the fact that in the created world, where there is generation and corruption, it is always possible for things not to be. If there were nothing whose being was necessary, a situation might arise when all possible existences at once were not, and so there would be nothing in existence at all. If that happened it would not have been possible for anything to come into existence, because nothing could have brought anything into existence. He completes the third proof by explaining that if we postulate not only one but a chain of such necessary existences, one dependent upon the next, we must, as in the case of the Prime Mover and the First Cause, come ultimately to a Necessary Being which has its being of no other, and which is God. The fourth proof is of the ‘hierarchy of excellence’ kind. Aquinas argues that to say that something is more or less good, true, and so on is to say that it resembles to a particular degree something which is the best and greatest.

He cites (as Augustine and Anselm were not in a position to do in their versions of this argument) Aristotle’s Metaphysics (II.i, 993b30): what is greatest in truth is also greatest in being. In any class of things there must be something, he says, which is the cause of everything in that class. Aristotle says a little earlier in the Metaphysics, for example, that fire, which is the maximum of all heat, is the cause of all hot things (II.i, 993b25). Aquinas reasons that there must be something which is the cause of being, goodness and every other perfection in all things, and this is God. A fifth proof can be drawn from the governance of all things. Natural bodies act as if for a purpose, and yet where there is no sentience, there can be no self-determination. There is clearly an intelligence in charge, an archer directing the arrow, and this is God (ST I.q.2.a.3). The mediaeval essays in proving the existence of God need to be set in the context of a question which was of much more frequent interest to the classical philosophers: what is to be said of his ‘being’.



By Gillian Rosemary Evans in the book 'Philosophy and Theology in the Middle Ages', Routledge, London & New York, 1993, p. 51-55. Edited and adapted to be posted by Leopoldo Costa.