فصل 8

chapter 8

The Perfect Island

Anselm and Aquinas

We all have an idea of God. We understand what ‘God’ means, whether or not we believe that God actually exists. No doubt you are thinking about your idea of God now. That seems very different from saying that God actually exists. Anselm (c.1033–1109), an Italian priest who later became Archbishop of Canterbury, was unusual in that with his Ontological Argument he claimed to show that, as a matter of logic, the fact that we have an idea of God proves that God actually exists.

Anselm’s argument, which he included in his book Proslogion, starts from the uncontroversial claim that God is that being ‘than which nothing greater can be conceived’. This is just another way of saying God is the greatest being imaginable: greatest in power, in goodness and in knowledge. Nothing greater can be imagined – or that thing would be God. God is the supreme being. This definition of God doesn’t seem controversial: Boethius (see Chapter 7) defined God in a similar way, for example. In our minds, we can clearly have an idea of God. That too is uncontroversial. But then Anselm points out that a God that only existed in our minds but not in reality wouldn’t be the greatest being conceivable. One that actually existed would certainly be greater. This God could conceivably exist – even atheists usually accept that. But an imagined God cannot be greater than an existing one. So, Anselm concluded, God must exist. It follows logically from the definition of God. If Anselm is right, we can be certain that God exists simply from the fact that we have an idea of God. This is an a priori argument, one that doesn’t rely on any observation about the world to reach its conclusions. It is a logical argument that, from an uncontroversial starting point, seems to prove that God exists.

Anselm used the example of a painter. The painter imagines a scene before painting it. At some stage the painter paints what he imagines. Then the painting exists both in the imagination and in reality. God is different from this sort of case. Anselm believed that it was logically impossible to have an idea of God without God actually existing, whereas we can quite easily imagine the painter who never actually painted the picture he had imagined, so that the painting only existed in his mind, but not in the world. God is the only being like this: we can imagine anything else not existing without contradicting ourselves. If we truly understand what God is we will recognize that it would be impossible for God not to exist.

Most people who have grasped Anselm’s ‘proof’ of God’s existence suspect there is something fishy about how he arrives at the conclusion. It just doesn’t feel right. Not many people have come to believe in God purely on the basis of it. Anselm, in contrast, quoted from the Psalms that only a fool would deny God’s existence. In his own lifetime another monk, Gaunilo of Marmoutiers, however, criticized Anselm’s reasoning. He came up with a thought experiment that supported the fool’s position.

Imagine that somewhere in the ocean there is an island which no one can reach. This island has incredible wealth, and is filled with all the fruit, exotic trees and plants and animals that are imaginable. It isn’t inhabited either, which makes it an even more perfect place. In fact it is the most perfect island anyone can think of. If someone says that this island doesn’t exist, there’s no difficulty understanding what they mean by this. That makes sense. But suppose they then went on to tell you that this island must really exist because it is more perfect than any other island. You have an idea of the island. But it wouldn’t be the most perfect island if it only existed in your mind. So it must exist in reality.

Gaunilo pointed out that if anybody used this argument to try and persuade you that this most perfect island actually existed, you’d probably think it was some kind of joke. You can’t conjure a perfect island into real existence in the world just by imagining what it would be like. That would be absurd. Gaunilo’s point is that Anselm’s argument for the existence of God has the same form as the argument for the existence of the most perfect island. If you don’t believe that the most perfect island imaginable must exist, why believe that about the most perfect being imaginable? The same type of argument could be used to imagine all kinds of things into existence: not just the most perfect island, but the most perfect mountain, the most perfect building, the most perfect forest. Gaunilo believed in God, but he thought that Anselm’s reasoning about God in this case was weak. Anselm replied, making the point that his argument only worked in the case of God and not with islands, since other things are only the most perfect of their kind, whereas God is the most perfect of everything. That’s why God is the only being that necessarily exists: the only one that couldn’t not exist.

Two hundred years later in a short section in a very long book called Summa Theologica, another Italian saint, Thomas Aquinas (1225–74), outlined five arguments, the Five Ways that were meant to demonstrate that God exists. These Five Ways are now much better known than any other part of the book. The second of these was the First Cause Argument, an argument which, like much of Aquinas’ philosophy, was based on one that Aristotle had used much earlier. Like Anselm, Aquinas wanted to use reason to provide proof for God’s existence. The First Cause Argument takes as its starting point the existence of the cosmos – everything that there is. Look around you. Where did everything come from? The simple answer is that each thing that exists has a cause of some kind that brought it into being and made it as it is. Take a football. That is the product of many causes – of people designing and making it, of the causes that produced the raw materials, and so on. But what caused the raw materials to exist? And what caused those causes? You can go back and trace that. And back and back. But does that chain of causes and effects go on back for ever?

Aquinas was convinced that there couldn’t be a never-ending series of effects and their earlier causes going back endlessly in time – an infinite regress. If there had been an infinite regress that would have meant that there would never have been a first cause: something would have caused whatever you think was the first cause of everything, and something must have caused that too, and so on to infinity. But Aquinas thinks that logically there must at some point have been something that set everything going in this chain of causes and effects. If he’s right about that, there must have been something that wasn’t itself caused that began the series of cause and effect which has brought us to where we are now: an uncaused cause. This first cause, he declared, must have been God. God is the uncaused cause of everything that is.

Later philosophers had plenty of responses to this argument. Some pointed out that even if you agree with Aquinas that there must have been some uncaused cause that began everything, there is no particular reason to believe that that uncaused cause was God. An uncaused first cause would have to be extremely powerful, but there is nothing in this argument to suggest that it need have any of the properties religions usually assume God has. For instance, such an uncaused cause wouldn’t need to be supremely good; nor would it have to be all-knowing. It could have been some kind of surge of energy rather than a personal God.

Another possible objection to Aquinas’ reasoning is that we don’t have to accept his assumption that there couldn’t be an infinite regress of effects and their causes. How do we know? For every suggested first cause of the cosmos we can always ask ‘And what caused that?’ Aquinas simply assumed that if we kept asking that question we would come to a point where the answer would be ‘Nothing. This is an uncaused cause.’ But it is not obvious that this is a better answer than that there is an infinite regress of effects and causes.

The saints Anselm and Aquinas, with their focus on belief in God and their commitment to a religious way of life, provide a stark contrast to Niccolò Machiavelli, a worldly thinker whom some have compared with the devil.