Descartes' Arguments for God

3rd Meditation

We deduce existence from infinity of idea of God
     He put the idea in my mind

I have the idea of God
I could not have invented that idea by myself.
So God must exist
     That the only way to explain the presence of this idea in my mind.

5th Meditation

God's existence part of his essence

     Perhaps Descartes is playing with variations of same ideas.
But the argument itself decisively different

God, by definition, has all perfections.
Existence is a perfection.
Hence God exists

This is such a strange argument. Let's analyze it

Suppose God has properties. power, goodness, foreknowledge, and so on.

It seems odd to add existence.

Existence is not a property.

It is odd to describe something and add a property existence, as if that another fact about its physical qualities

If there is a mountain, there can be a valley
     One inseparable from the other

But this doesn't show that there are any valleys.
     Only that if there are mountains, there are valleys.

Is the proof of God's existence any better?

For Descartes, the idea of God is innate.

Whenever I think of God I think He exists