In book five of the Meditations, Descartes puts forward a further proof of Gods existence (in addition to the trademark argument in book three). This argument draws together some of his previous thoughts and extends his arguments.

So what does Descartes mean by clear and distinct ideas? Earlier in the Meditations he discussed types of thought, including judgements (statements about the external world) and ideas (images in the mind). He argued that an idea that exists in the mind and has no relationship to the external world could not be doubted. An example is Descartes visualising a triangle in his mind; he cannot doubt that he is visualising a triangle in his mind. However if he were to state that he could see a triangular object, this could be doubted, as he could be deceived by his senses. Thus, he argues he can be in error with his judgement, but not ideas.

This, however, does not complete Descartes purpose. He wishes to prove the existence of the external world in order to achieve his aim of a new system of knowledge built on solid foundations. Thus, he examines the relationship between the external world and his mind. To illustrate this he recalls an experience with a piece of wax. He describes in detail the sense impressions of the wax. He then places it near his fire and after it has melted notes that all of the sense impressions are different. However, he still knows that the melted wax is the same wax as the original solid piece of wax. How is this so? Whilst it may seem obvious that the existence of the wax remains constant throughout this process this is not borne out by his sense impressions. Thus, Descartes concludes, his mind has imposed its understanding. In other words, Descartes' mind has allowed him to know that the wax is the same throughout the process, despite the conflicting sense data.

This, Descartes states, is the mind's understand of the extension of an object in time and space and provides a useful link between our perception of the outside world and the mind. Descartes then goes further and states that as we can understand the essence (primary qualities - e.g. mathematical, measurable properties) of something in our minds, the essence of the material things is provided by the mind. Thus, if this knowledge is contained in the mind, and not provided by the sense organs Descartes can know it as well as an idea wholly formed in his mind. He terms this understanding of the essence of an object having a 'clear and distinct' idea of it. He declares that knowing something clearly and distinctly thus means it cannot be doubted.

Now that Descartes' terms of reference are clear we may examine Descartes proof of God in the fifth meditation. His argument is thus:

1. Necessarily, God is perfect (true by virtue of meaning)
2. If God didn't exist he would be less than perfect
3. Therefore God exists

This involves Descartes' clear and distinct ideas because he argues that he can no more consider a triangle without three sides than an imperfect God. Just as the concept of a triangle (the clear and distinct idea) goes with three sides necessarily, so then, Descartes argues does the concept of God and his existence. The fact that he can clearly and distinctly conceive of Gods perfection necessarily shows that God exists.

However, this argument runs into some problems. The clear and distinct ideas of which Descartes talks are true by virtue of the fact that they are judgements internal to his mind. They only concern the outside world in that they may aid his interpretation of the outside world. For example, when Descartes talks of a triangle necessarily having three sides as a clear and distinct idea, he is not referring to an instance of a triangle that exists, he is referring to the concept of a triangle. The concept of a triangle is of a three-sided shape, so the statement is necessarily true.

However, when a similar argument is applied to God, the implication of that argument is that existence is a necessary property of the concept of God. If existence is not a property (i.e. part of the essence or primary qualities) of a thing then the argument falls apart. This is how some philosophers have attacked Descartes' proof of God.

Moreover, by applying a clear and distinct idea to prove the existence of something in the external world, Descartes appears to break his own rule of clear and distinct ideas. The argument can only prove that the concept of God exists in Descartes mind.

By taking Descartes' argument to a logical absurdity, it is possible to see how it appears to allow him to will anything he could conceive of into existence. If he can have a clear and distinct idea of a time machine existing it does not necessarily follow that it exists.

However, others have responded to this criticism of Descartes' proof, arguing that existence can be a property. An example is contrasting the concepts of 100 real coins with 100 imaginary coins. The concept of 100 real coins includes the purchasing potential of that money (necessarily dependent on their existence), whereas the concept of the imaginary coins does not. However this argument can be countered by arguing that the concept of real coins includes the concept of existence and thus pre-judges the conclusion. It has also been argued that it is not possible to compare something that exists with something that does not, as the non-existing thing is simply not there to be compared with anything.

Lastly, there is an element of circularity to Descartes' argument as he has discarded the argument from deception put forward in book one as God is all good, and would not deceive him or allow him to exist purely to be deceived. Thus, if God is required to allow him to have clear and distinct ideas, which then prove God's existence the argument is circular.

Thus, in conclusion, we can state that the Cartesian notion of clear and distinct ideas is not a sufficient proof for God's existence. This is because not only is the logic of the proof under question (is existence a property?), but that the Cartesian concept of clear and distinct ideas requires God's existence in order to be true (and thus a test of existence in this case), rendering the argument circular.

Tutor: Oliver McAdoo MA

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