Who was Descartes?

Descartes was a french Philosopher, and writer of the famous text 'Meditations'. Meditations is a great book to start with as an original philosophical text, as it is understandable and digestible. It is a great one to criticize and use in philosophy essays if you study at college or university.  Descartes most famous phrase is 'I think, therefore, I am.'

Meditation 3

In meditation 3, Descartes begins to argue for the existence of God. He sees God to be perfect. Not only perfect, but infinite. This brings descartes to infinite regression - another cause should always be found. Descartes presumes here that God exists as a first cause. He argues that since, as a human being, he is a 'thinking' thing, the idea of God itself must have a cause, or must have come from somewhere. He presents the idea that the concept of God is innate, because God stamps his mark on every human being. This is often referred to as the 'Trademark Argument'.

Meditation 5

It is clear that descartes in not happy with the way in which he dealt with God in Meditation 3, because he deals with it again in Meditation 5. 

Meditation 5 demonstrates the main part of Descartes Ontological Argument - the idea of God as a supremely perfect being. He has both essence, and existence, and possesses all perfection.

Descartes sees existence as a predicate - that something is said to have or lack - just like any other predicate or property. He claims that existence must be included amongst the defining predicates of God. Just as having three sides and internal angles totally 90 degrees are predicates to the existence of a triangle, existence is a predicate of God. Existence is as necessary to God as a mountain to it's valley.

We could not infer not infer that triangles exist, because existence is not the essence of triangularity. But we most certainly can infer that God exists because existence is an essential attribute of an unlimitedly perfect being.


Kant is probably the most famous critic of this argument. Kant denied that existence could be a predicate of something. It does not add anything to the description of a thing. For example, I wouldn't offer you a chocolate bar, and then say - and it exists! Of course it exists, but adding existence does not add any properties to the description of the chocolate bar itself!

What do you think? Do you agree with Descartes argument? Or Kant's criticism? Do feel free to leave your comments below.

Introducing Descartes 3ed
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I have found this to be the best book on Descartes. The cartoon style illustrations and examples make the content extremely easy to understand.