The arguments Descartes uses to demonstrate the existence of God

University Degree Historical and Philosophical studies

Critically examine Descartes arguments for the existence of God

In this essay I will look at the two arguments Descartes uses to bring about proof of the existence of God. Looking firstly at the cosmological argument, I will then examine the ontological before bringing both to a conclusion to see if Descartes is successful in convincing us of the existence of God.

After the Cogito meditation, Descartes claims that whatever is clear and distinct as an idea is certain. Our idea of a God, or perfect being, is one such thought. I can be just as convinced that God exists as I can that I myself exist. After the Cogito, Descartes needs something from the contents of his own consciousness to prove the existence of the world around him, and the idea of God leads him outside his consciousness. The idea of God is unique amongst our ideas because purely by being there it shows that God must exist. According to Descartes we could not have a sense of the idea of God without this meaning that God existed – if one has an idea of God, it must follow that he exists.

Descartes uses two arguments to prove this existence: the cosmological, and the ontological argument. The first states that an idea can only be explained in effect of its cause, or ‘whence can the effect draw its reality if not from its cause?’ Here, Descartes must show how he has the ‘idea’ of God in virtue of it being the effect of some cause. The reality of the idea of God must have a cause with ‘as much reality as its effect’. Relying on the necessary principle that the lesser cannot give rise or creation to the greater, Descartes hopes to prove that to conceive of something far greater than himself, that idea must have been placed there by that greater thing. The idea cannot exist ‘unless [it] had been put into me by some substance which was truly infinite’ (p.124).

Descartes conceived of having many ‘ideas’ of things, including ‘men, or animals, or angels’ (p.121), which could have come from himself. However, he saw that the problem here would be that such ideas could go on forever, and that there must have been one first, ultimate idea. Without this ultimate ‘one idea may give birth to another’, and since ‘there cannot be infinite regression…one must eventually reach a first idea’ (p.120). Descartes then asked what the cause of this idea could be, concluding that it must lay beyond the world of his own ideas, to have pre-existed in his mind. The only thing powerful enough to exist beyond this realm, and be a cause unto itself, must be this ‘first idea’ and what it represents. This, according to Descartes, is ‘the notion of God’.

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Because we have God within us, it follows that the only thing that could have put the idea of this infinite being into us, finite beings, is God, for ‘Where can the effect get its reality from, if not from its cause?’ (p.119). Descartes is questioning how a thing can exist without there being some ultimate cause. To answer this he considers three possibilities: our parents, ourselves (or something less than God), and finally God. The notion of existing because we ourselves are the cause has two problems. Firstly, it would mean that we would have had to exist before we existed, which is absurd. Secondly, if we were to exist because we ourselves brought this about, surely we would have given ourselves the properties of which we can conceive God to posses, such as omnipotence and omniscience. It follows from this that if our parents were the cause of our existence they also would have given us these properties, and bestowed them on themselves too. This means that the only answer can be God, He alone can bestow body and soul in a substance.

I am in doubt about some things.
I lack at least one perfection.
I am not altogether perfect.
I know I am not altogether perfect.
I know what ‘not altogether perfect’ means.
I know what ‘altogether perfect’ means.
I have an idea of absolute perfection, that is, of God.

‘Despite its plausibility’, Kenny states, ‘the argument is unsatisfactory as can be seen from the following parallel:

I am not triangular.
I lack at least one shape.
I am not omniform (i.e., I do not have every shape).
I know I am not omniform.
I know what ‘not omniform’ means.
I know what ‘omniform’ means.
I have an idea of an omniform shape (i.e., a being with every possible shape).’

The problem that exists here is the confusion over what Descartes means by ‘idea’ and ‘perfection’. Having every perfection may be as ridiculous as possessing every shape. Perfection is meant to be a feature of a thing, but here it is other features that contribute to a thing being ‘perfect’ of its kind. The cosmological argument points to a feature of the world we know to exist and make the claim that this feature requires causal explanation, which can only be provided by God. Using the principal ex nihilo nihil fit Descartes shows that a thing can only come from something as or more perfect than itself.

The ontological argument takes place mainly in the fifth meditation. It makes the same assumption as the causal argument in that because we have an idea of God, He must exist. Descartes claims this is just as obvious that knowing a triangle exists is to know it has three angles which add up to two right angles. Having an idea of God is to have the idea of something ‘whose existence belongs of necessity’ (p.147), or which would not conceivably not exist, or ‘to whose essence alone existence belongs’ (p.145). It therefore follows that God exists. If we imagine God not existing, then we are not imagining God at all but something inferior to him. If we imagine an immortal, omniscient and perfect being, we must also imagine them to exist. Kenny lays out the argument thus:

God’s existence is possible.
God is by definition all-powerful and independent.
God can exist by His own power.
What can exist by its own power, does exist.
God exists.

Premise (1) is said to be true because we have the idea of God in our minds, and it follows from this idea of perfection that (2) is also true. Premise (3) is explained by Kenny that ‘If you can do something by your own power and you do not do it, then it can only be because you do not want to do it’, whilst (4) follows that ‘everything wants to exist’. All of these add up to (5) that God exists. Historically, these premises are important because they make the distinction that there exist two worlds – the world around me, given by God on whom we rely, and also the world of me, existing as I observe the world. Descartes, in another section of the meditations distinguishes between the two worlds of ‘body’ and ‘mind’ in his famous Cartesian Dualism.

There are two major problems with the ontological argument. The first is that we cannot prove a things existence on the strength of our own ideas. This is not to say, however, that contemplation of our ides can tell us nothing of reality. As Jonathan Ree shows: if a person ‘traces back his ancestry through the past, then, as long as neither he nor any of his ancestors has parents who are blood relations, each time he goes one generation back, he will find that the number of his ancestors doubles. Thus it seems to be possible after all to acquire knowledge by reflection on ‘mere ideas’.’ Also, Descartes wasn’t trying to say that he could prove a things existence or learn about reality by reflection of our own ideas, only that God could be (he was the exception). Another problem is that if it is acceptable to define something as existing because one has the idea of it, and it necessarily follows that it must exist, we do not have to restrict this to God. If we can conceive of a perfect human, existence would presumably have to number amongst their traits, but this doesn’t mean that this person is actually walking around the planet.

An important question to now look at, is what is meant by ‘the idea of God’? God is defined as being ‘the meaningfulness of our ideas’, but a complication exists in the ‘idea’ of God. If we identify God with being the effect of ‘the idea of God’, and if a thing exists only because we have an idea of it, it exists only as that idea, and the idea of that idea, ad infinitum.

Descartes responded to this, however, by saying that God is ‘an archetype…in ideas’. God must exist if ideas are ever capable of representing anything, otherwise they are just meaningless symbols with no end.

So, having established God’s existence, Descartes goes on to construct and account for the existence of the world around him. He claims that ‘I know that God exists and…that He created me…It therefore follows that He is concerned with my intellectual and moral welfare. So, if I think out carefully all my ideas, God, in his benevolence, will make them so. However much I suspend the doubts of my existence, I am strongly disposed to believe that the material world exists. Because I have this belief, and have carefully analysed my beliefs to be sure that they are not founded on error, God at the end will make sure that I have not been systematically and fundamentally wrong.’ This is Descartes way of refuting the scientific or philosophical sceptic. To deny the existence of God after being confronted by these two arguments would be as bad as to deny that two times two equal four. If a person is in good faith and thinks hard enough about these arguments, they will come to see the world, unable to deny its existence.

The problem with Descartes arguments to prove the existence of God are that surely by proving God’s existence and the fact that he made the world, Descartes is showing that God must have created us as well, which is a proof of our existence. Doesn’t this make the second meditation (the cogito) redundant? There, Descartes showed how we exist because we are thinking beings, but that has proved to be only a stepping stone to the more important conclusion, that God exists and that he created us in his own image. Also, as Kenny states, ‘what right has Descartes to assume the substance, of which his thought is an attribute, exists?’ He goes on: ‘If I can be sure that a triangle has its three angles equal to two right angles without being sure that any triangle exists, why can’t I be sure that ego cogito without being ego existo?’ Kenny is saying that if we exist because we think we do, why does the triangle not also exist when we think of it? By resting his two arguments for the existence of God on the principles that both he and God exist, Descartes has shown that both cannot be true together. If God exists he does not have properties, and this means that we do not exist because we are thinking things, since thinking is a property. Adversely, if a thing does not exist and does have properties, he can show that he exists (he exists because he thinks), but not that God exists on the basis that we have an idea of Him (God is non-existent but has properties).