The 'Causal Adequacy Principle' is definately a dubious point, especially due to Descartes' lack of commitment to actually proving it. He simply states that it is 'manifest by the natural light' and self evident. I do not think that you can be spontaneously aware of this principle in the same way as you can with the cogito, which is what Descartes is implying here. The ambiguity here, coupled with counterexamples, affect Descartes' position.
A fine example is used by Cottingham when he says that a cake may have the property of sponginess which is not at all present in its ingredients of eggs, flour and butter. Now obviously the ingredients change chemically during the cooking process and so you could perhaps argue that sponginess is potentially in them, but Descartes could not use this line of defence for this would invalidate his whole argument. If the cause of my idea of God only had the potential to be perfect then this cause would be less than perfect itself and so a perfect God would not exist until this potential was realised, if indeed it ever was. This is clearly contradictory to Descartes idea of a God that is perfect in every way (he says existence is a perfection) which means the proof yields a false conclusion in this case.
We also need to look at the initial premiss of the idea of a perfect God, for without it agument is obviously not going to function. When I think of God do I have to think of a being perfect in every possible aspect? Descartes says that even if I do not strictly think of God in this way, the mere fact that I understand what is meant by infintely perfect, infinitely powerful and so on is enough of an idea to base his theory on. I may not be able to grasp what God really is like, but I acknowledge the existence of infinity and so can logically move through the argument, even if I am an atheist.
This can be countered by proposing an alternative source of infinity- I am finite and so is everything I encounter in the material world, and the opposite of this is the idea that I have of infinity. I have no experience of infinity and find it hard to get to grips with if analysed, but as a 'thinking thing' I can surely make the step from a finite substance to its negation on my own, rather than having to rely it having been planted in me by a God. In fact, my lack of true understanding of the idea of infinity supports this- if God had indeed given me this idea then surely he would have made it clearer in my mind, given that he is perfectly good and powerful and so on. However, when I personally think more deeply about infinity I feel it is something which I have a very loose grasp of, and when trying to visualise it more clearly I often think of it as the opposite of finite. The best way I can get infinity without refering to the finite is by taking an example such as a queue of people waiting for the bus and imagining it to be longer and longer and realising it could go on forever. This, however, is open to doubt as it is based upon experiences from the senses along with other visualisations to do with counting, and so if I seek to learn more about infinity by merely thinking I must first use my idea of the finite.
The second argument is an a priori proof, as opposed to the above approach which is causal. It is very concise, but still open to criticism. Descartes again takes that idea of God as an all perfect being, but this time he justifies it by claiming existence does not have to be addressed before we can talk about something. He says that when we imagine a triangle, we think of a list of properties and can use them, regardless of whether triangles really exist in the material world.
It is then stated that if God is supremely perfect, then existence must be one of the properties held, for existing is more perfect than not existing. Hence God must exist. This last part can be attacked by saying another conclusion could be that if there was a supreme being then he would have to exist, but there is no reason to suppose that anything qualifies as such a being. Descartes is trying to show a real existence of God, but this criticism isolates his argument so that it cannot move on from ideas in the mind- just because we associate existence with perfection in our minds does not mean that God actually exists. It can also be argued that there is no reason that existing should be more perfect than not existing- it may seem an obvious truth but it cannot be taken for granted in my opinion. Some might disagree with me by saying this
There is also the 'overload' objection, which refers to the direct consequence of this method- that other things besides God can pass the test for existence. An example used by Cottingham the idea of a Pegasus- he says that we can take this concept and add the property of actually existing. This means the Pegasus necessarily exists. I do not agree with this, because Descartes requires that God be all perfect in order to exist, whereas the Pegasus does not share these perfections and so cannot be said to exist by the same reasoning.
In conclusion I believe that both arguments have good and bad points, and certainly neither can be taken as a cast iron proof. As with other parts of Descartes' writings many points are dependent on the personal views of the reader, such as whether or not existing is more perfect than existing. Some might find it a self evident truth, much like 'I am thinking, therefore I exist', but I personally do not share this belief.
