1. The Ontological Argument
Rene descartes

2. Descartes wanted to prove what we can be certain of in the universe.
He concluded his own existence by his ability to think :“Cogito ergo sum.”
What else can I prove exists?
A priori things e.g. Maths...aware of properties of a
Even if a triangle had never existed, they would still have distinct characteristics...3 sides, 3 angles.
His senses would not derive those properties as clearly & distinctly as his mind.
Descartes wanted to prove what we can be certain of in the universe.

3. First part God exists as idea in mind.
Certainly, the idea of God, or a supremely perfect being, is one that I find within me...
God exists as idea in mind.
God = ‘supremely perfect being.’
Relying on innate idea of God people
possess.
God’s necessarily exists because that is where our idea of God came from...as imperfect beings we can’t develop that idea.
Existence is one of God’s many perfections.
...the less do they[God’s characteristics]appear capable of proceeding from me alone...we must conclude that God necessarily exists.

4. Second part Existence is a predicate of God.
As ‘supremely perfect being’ God must possess existence otherwise that being is not perfect.
Concludes, God must exist as existence is predicate of ‘supremely perfect being.’
God must exist in reality...absurd to think otherwise...goes against definition.
God without existence same as mountains without valleys, triangles without three sides.
Reductio ad absurdum
...the mind cannot conceive of perfection without also conceiving of existence...

5. Descartes responses to possible objections
Same is not true when referring to God...concept of God means God exists
Just because we have concept doesn’t mean they exist
Argument only applies to God because God is the only supremely perfect being from whom we are to infer existence.
I cannot conceive God unless as existing...existence inseparable from him...necessity of the existence of God