Descartes' Three Proofs for the Existence of God
Descartes' Proofs for God's Existence
For Descartes, the thinking self is not perfect but possesses the idea of perfection, infinite substance (*res infinita*), which is an innate idea of God. God is the uncreated substance, the cause of all created beings.
God is defined as a substance that is:
- Infinite
- Eternal
- Immutable
- Independent
- Omniscient
- Omnipotent
- The guarantee of veracity
Descartes provides three proofs for the existence of this divine substance:
1. The Idea of Perfection and Infinity
The human subject, despite being neither perfect nor infinite, possesses the idea of perfection and infinity. The finitude of the subject stands in opposition to the infinity found in God. Descartes argues that God is the cause of the idea of infinity present in man.
Starting from the idea of infinity in humans, Descartes asserts that this idea is the effect of an infinite cause, which is God. God imprints the idea of infinity upon the human mind. This argument relies on the metaphysical principle of causality: every effect must have a cause.
2. The Contingency of the Self
Descartes identifies a paradox in man: being a limited being (evidenced by our frequent doubts) while simultaneously possessing the idea of infinity in the mind. If man were his own author, he (being a contingent being—one who might not have existed) would have made himself perfect.
The true author of man must be the infinite being (God), who creates the finite being (the doubting self) and implants the idea of infinity (God) in the mind as an innate idea.
Descartes begins by verifying this psychological human paradox (the effect) and then traces it back to the real cause of man (the infinite being, God). This proof also utilizes the metaphysical principle of causality, moving from the human paradox (effect) back to the Creator (cause).
3. The Ontological Argument
This argument is inspired by the ontological argument developed by St. Anselm of Canterbury (11th–12th centuries).
When we conceive of an idea, that object possesses certain qualities with clarity and evidence. This quality belongs to that object necessarily.
Consider these examples:
- A triangle necessarily possesses the quality that the sum of its angles equals two straight angles.
Similarly, God, defined as infinite, possesses all perfections, including existence. This quality belongs to God necessarily. God's existence, according to the ontological argument, is the result of a deduction, which, for Descartes, is a series of intellectual intuitions.
God as the Guarantee of Veracity and Knowledge
God serves as the guarantee for discarding the most important reasons for doubt. Because God is good and powerful, he prevents the thinking self from being deceived.
Thus, Descartes overcomes Solipsism (the state of being locked within oneself) and can move from the assertion of one's own consciousness to the existence of the external world.
In Descartes' philosophy, God is the resource that guarantees the application of the criterion of certainty, allowing the self to know the world. God cannot permit what the self conceives clearly and distinctly, with evidence, to be false. Therefore, God guarantees our knowledge of reality.