Descartes’ Support for the Ontological Argument

Rene Descartes (1596-1650) is generally regarded the founder of modern western philosophy. Descartes was instrumental in bringing about the Age of the Enlightenment in Western Europe. His writings challenged conventional beliefs which were still based upon Church teachings.

Descartes imagines the entire universe to be the work of a malevolent demon who creates the illusion that things exist. This is known as Cartesian Doubt. Descartes asked the question, ‘How can I be sure that what I am experiencing through my senses is true?’ After speculating that he is being deceived by a demon he concludes that the only thing he can be sure of is the fact that he is thinking. This gives rise to probably the most famous quote in western philosophy, “I think, therefore I am.” >p> Having established that at least he exists, Descartes begins to look at things in the universe which can be established independently of empirical investigation i.e. a priori things e.g. mathematics. Anselm’s deductive ontological argument became a powerful tool in Descartes hands.

Like Anselm, Descartes thought of God in terms of a perfect being. Following Anselm’s first argument, Descartes was in agreement that existence was more perfect than non-existence. For Descartes, God’s existence was part of His essence. For Descartes, there are some qualities that an object necessarily has or else it would not be that object. To illustrate this Descartes argued that the essence of a triangle is a ‘three sided plane figure’. To say that God does not exist is rather like saying ‘a triangle does not have three sides’ or that the internal angels don’t add up to 180o. In the same way, existence cannot be separated from the concept of God.

Descartes took on board Gaulino’s criticism of Anselm’s first argument. Like Anselm before him, Descartes points to the distinction between a necessary being and a contingent being. The argument applies only to an absolutely perfect and necessary being. The argument cannot be applied to islands, dragons, unicorns or even pizzas! For Descartes, God alone is the being whose essence entails His existence. There cannot be more than one such being.

God then becomes the guarantor of the certainty that the external world exists. There is no longer the fear that there might be a malevolent demon out to deceive you. God is both omnipotent and omnibenevolent, He would not permit such a thing. God becomes the basis of Descartes’ epistemology.

Criticism of Descartes’ Ontological Argument

A priest called Caterus responded to Descartes’ argument. Caterus argued that the statement ‘If God exists then he is highest being’ was a tautology (the truth of the statement is self evident). But Caterus emphasised the word ‘if’. It was not illogical to say, ‘God does not exist therefore there is no highest being’. To use Descartes’ analogy of a triangle it is possible to say, ‘If a triangle exists it has three sides’. However, all this really tells us is something about triangles. It is equally coherent to say, ‘triangles do not exist therefore three sided things do not exist.’ Likewise, we might say, ‘unicorns have one horn’ but this does not prove there are any unicorns.