The Ontological Argument is a deductive argument in that it attempts to show that its premises lead to a logical conclusion which can’t be doubted. In this case, philosophers have attempted to show that the phrase ‘God Exists’ is an analytic statement in that it is logically impossible for it not to be the case, just as it is impossible for a bachelor to not be an unmarried man. This type of argument is known as ‘a priori’ because it is based on logical reasoning.
Descartes form of the Ontological Argument in Meditation3 and 5, followed a similar pattern to that of Anselm who formulated the argument originally. For both Anslem and Descartes the definition of God is crucial to the argument. Anselm had stated that ‘God is that than which nothing greater can be conceived’. By this, he meant that it was not possible to think of anything greater than God and logically, it must be better for this God to exist in reality and not just in the mind. Therefore, if we accept this definition, and Anselm felt that even Atheists would, we must logically conclude that the greatest possible being must exist in reality, otherwise there would be the possibility of something greater existing. Therefore, logically, God exists! Anselm’s second form of the argument focused on God’s ‘necessary existence’, again overlapping with themes later proposed by Descartes.
Descartes’ background in Mathematics was undoubtedly influential in his argument with his use of logical reasoning to formulate an argument evident from the outset. It should also be noted that Descartes believed that each of us had an innate knowledge of God within us, often compared to a company stamp placed within each of its products before leaving the factory. This is important because the idea that everyone has an innate idea of God would lead to the assumption that we would all therefore have a definition of God.
For Descartes, the definition of God which he felt would be acceptable to everyone was a ‘Supremely Perfect Being’. Using the same principles as Anselm, he argued that once this definition is accepted, then the existence of God cannot be doubted. His reasoning was that a predicate of perfection should include existence. A predicate is a necessary quality which something must possess so if we accept that God is perfect, then according to Descartes, logically we must accept that He exists.
Continuing to focus on the word ‘perfection’, Descartes believed that the definition of the word perfection is that it cannot lack anything. Therefore, it is illogical for God, an omnipotent being, to lack existence. Similarly to Anselm, Descartes concluded that God must exist ‘necessarily’. His reasoning came from his belief in an immutable and transcendent God, who was not subject to the contingent universe. If God wasn’t necessary he would lack but a Supremely Perfect Being cannot lack anything.Therefore, existence is one of God’s necessary qualities. He is the sum of all parts, as he is that of which nothing greater can be concieved, so he cannot cease to exist, as it would be a logical impossible.
Descartes used the example of a triangle to emphasise that A Supremely perfect Being and existence were inseparable. When we think of a triangle, even if we have never seen one, we know that it must possess three sides and three angles which total 180 degrees. If either of these properties is removed, then it is no longer a triangle. if we accept that God is a Supremely Perfect Being, then we cannot deny that he possesses existence as a necessary quality/part of His essence. Existence is as fundamental to the nature of what God is as 3 sides are fundamental to the nature of what a triangle is.
Descartes then goes on to use a futher example of a mountain, which cannot exist without a valley; likewise it is not possible for God to exist without perfection because God is perfect and part of perfection is existence.Therefore, it is within God's nature to exist as if he didnt, this would be changing the word 'God'.
To conclude, Descartes did not intend on formulating an argument, but a demonstration of the existence of God.He uses an example of a triangle and mountain to illustrate, that if we examine the word God, a predicate of God is perfection.To argue differently is contradictory and therefore it can logically be stated that ‘God exists’ is an analytic statement.