A decent short video which may help to understand the ontological argument
I attempted this question in 25 minutes. It is not one that has come up in any recent exam, but students are required to have knowledge of Gaunilo’s challenges. So it would be useful to look it over.
Gaunilo of Marmoutier disagreed with Anselm that the existence of God could be logically proved based on an understanding of his essence or his definition. Anselm’s claim that only a fool says ‘there is no God’ (because this is like saying ‘the thing that has to exist doesn’t exist’) is disputed by Gaunilo because he doesn’t believe it is possible to have an understanding of who God is in himself anyway.
This kind of belief that it is impossible to know the nature of God is often labelled a kind of agnosticism. This is not the usual use of the term for people who are undecided about God’s existence, but instead it means a more general lack of knowledge about who God is in himself. For instance Aquinas is also convinced that it is impossible to know the nature of God, because as creatures, our knowledge, or rationality is only capable of knowing things concretely. God, being an incorporeal being, and one who surpasses all created things in perfection, thus goes beyond the limits of what we can know with our reason.
Gaunilo claims that Anselm’s dependence in his argument on a definition of God as ‘that than which nothing greater can be conceived’ is flawed, as we simply cannot hold such a definition. Furthermore, to have this notion of God’s nature in one’s mind, as Anselm claims, would also be impossible for our reason.
Gaunilo’s second and more famous challenge to Anselm is that we cannot go from the definition of something to it’s existence. He uses a reductio ad absurdum argument, which aims to show the absurdity of holding the viewpoint of Anselm, by using the example of an island. He says: We can conceive of a perfect island. A perfect island must be more perfect in reality than in the mind. Therefore a perfect island exists. The perfect island stands for Anselm’s perfect being. Gaunilo aims to show with this example that Anselm’s argument is fallacious, as you can use his argument to prove the existence of things such as perfect islands.
Clearly, it is hard to see how a perfect island would have to exist just because of this argument, and Gaunilo believed he had proved that Anselm’s similar argument was flawed. However, in Reply to Gaunilo, Anselm refers him to the Proslogion 3, in which Anselm had pre-empted such a challenge with a second version of the ontological argument.
Start with: Descartes’ method of doubt by which he tries to establish foundations beyond doubt upon which to build knowledge.
In his book Meditations, arrives at one certainty – that he is a thinking being (as he could be deceived about what he is thinking, but not about that he is thinking). Asks if there is anything else he can be certain of.
Decides that he can form clear and distinct impressions of mathematical objects and numbers, but these things exist in some sense independently of his mind. He can “draw the idea of something from my thought”.
Explain the method he uses to do this, which is to meditate upon the essence of something, ie. what makes it what it is. With a triangle this is that its internal angles add up to 180 degrees.
This truth about triangles exists in his mind clearly and distinctly, and he argues that he can be certain of it.
How does he do this? From the preceding thought experiment he found out that the one thing he could be certain of was that he was a thinking thing, but that he might be deceived about having a body etc.
Therefore, he argues, things of the mind are more certain than physical things.
They are much more clearly and distinctly known than that of the body.
One such idea is the idea of God that Descartes finds in his mind. He says:
1. I have an idea of God, a perfect being.
2. There must be as much reality or perfection in the cause of any thing as in the effect.
a. This applies not only to the existence of ideas, but also to the reality of what they represent. Not only must the existence of the idea be explained, but also what it represents.
3. The idea of God represents something so perfect that I could not have been the cause of this idea.
Therefore, God must exist as the only possible cause of the perfection found in my idea of Him.
So far, this is all background to get you as far as Descartes’ idea of God in the mind. If you understand how he arrives at that, then you will be better equipped to answer a part b question.
Descartes then uses his version of the ontological argument – the idea of God can be said to exist in reality, because existence is a perfection God cannot lack.
Use the example of rivers not being able to exist without banks – they logically have to go together. Triangles have to have three internal angles. God necessarily exists because he has all perfections (that’s what we mean by God) therefore God must have existence, as that is a perfection.
To explain this further talk about God’s essence including existence. Descartes tries to show that it is impossible for God not to exist.
“Philosophy is merely thought that has been thought out. It is often a great bore. But man has no alternative, except between being influenced by thought that has been thought out and being influenced by thought that has not been thought out. The latter is what we commonly call culture and enlightenment today. But man is always influenced by thought of some kind, his own or somebody else’s; that of somebody he trusts or that of somebody he never heard of, thought at first, second or third hand; thought from exploded legends or unverified rumours; but always something with the shadow of a system of values and a reason for preference. A man does test everything by something. The question here is whether he has ever tested the test.”
From The Common Man by G. K. Chesterton
We are all philosophers. Some people are just regurgitators of other people’s beliefs, whilst some have thought them through (or out, as Chesterton puts it) a bit more. But none of us can inhabit some kind of neutral space, devoid of values and beliefs. All we can do is be more of less aware of the world view we do hold.