Descartes' Metaphysics: Proving God's Existence

Descartes' Proof of God's Existence

Once certain of one's existence as a thinking being, Descartes proceeds to the second major step of his metaphysics: the proof of the existence of God. It is crucial to understand that merely possessing the idea of an infinite substance does not automatically mean God exists; it only signifies our comprehension of the idea of absolute perfection.

Human reason, by its very nature, is not perfect, as evidenced by doubt and hesitation. A defect is not characteristic of a perfect entity. If we are imperfect creatures, how then could we possess a perfect idea, such as the idea of God?

Levels of Existence in Descartes' Philosophy

Before delving into the proof of God's existence, it is important to note that Descartes distinguishes different levels of existence:

• Objective Existence: The existence of an idea in our mind, as an object of thought.
• Formal or Actual Existence: The existence of the object outside our mind.

Regarding these concepts, Descartes states that the objective reality of every idea must be received from a cause that has at least as much formal reality as objective reality. This is because the cause must possess as much reality as, or more reality than, its effect, never less.

Descartes' Arguments for God's Existence

Descartes seeks to answer whether this innate idea of God is merely objective. For this, he develops the following arguments:

1. The Principle of Causality and Ideas

There must be as much reality in the cause as in the effect. As applied to ideas, this leads us to affirm that the formal existence of the cause of an idea must have as much or more reality than the objective existence of the idea itself.

2. The Argument from Self-Existence

This is a variant of the first argument, stating: "I, a being who thinks and has the idea of God, to whom do I owe my existence?"

We have three options: myself, my parents, or a being more perfect than my parents and me, but less perfect than God.

• I cannot be the cause of my own existence, because in that case, I would possess all the perfections of the idea of God, which I obviously do not.
• Nor are my parents, because although they have given me bodily existence, they have not made me a thinking substance.
• And it cannot come from a being less perfect than God, because that being would need to have the idea of God to place it in me. In that case, the cause of the idea of God would be God Himself, or I would have received it from another superior being, who, ultimately, would also have to be God.

3. Saint Anselm's Ontological Argument

This is the most important argument and perhaps most consistent with Cartesian principles. It is Saint Anselm's ontological argument, first articulated in the eleventh century:

"The idea of God, a perfect being, necessarily includes His existence, because a perfect God who did not exist would contradict His own definition."