17th century French Christian philosopher and theologian. Agrees roughly with Anselm of Canterbury, says existence is a Predicate of the Perfect Being.
Descartes’ argument for the existence of God
He formulated his own ontological argument for the existence of God based on perfection as a necessary attribute of God:
- God possesses all perfections
- Existence is a perfection
- Therefore God exists If God is the most perfect being then he must exist.
The Geometric Analogy
The Analogy of a Triangle
- A triangle has predicates (necessary characteristics); for example, all of its internal angles must add up to 180 degrees. If these predicates are removed the triangle is no longer a triangle.
- Anselm of Canterbury said, in the same way, existence is a predicate of God i.e. It is impossible to think about God without existence, just like you couldn’t imagine a triangle with four sides.
René Descartes reformulated the ontological proof, in terms of the concept of necessary existence. It appealed to him as a rationalist philosopher to seek to prove the existence of God by reason alone, rejecting as untrustworthy information that comes from the senses alone.
Like Anselm of Canterbury, Descartes wanted believers to realise that when we use the word ‘God’ we mean a supremely perfect being superior to all. He maintained that the use of reason enabled the terms to be clarified in a distinct and intelligible way.
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I exist.
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In my mind, I have the concept of a perfect being.
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As an imperfect being, I could not have conjured up the concept of a perfect being.
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The concept of a perfect being must therefore have originated from the perfect being itself.
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A perfect being must exist in order to be perfect.
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Therefore, a perfect being exists.
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The idea of God is the idea of a supremely perfect being
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A supremely perfect being has all perfections
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Existence is a perfection
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A supremely perfect being has the perfection of existence
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It is impossible to think of God as not existing
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Therefore, God exists
Descartes maintained existence belonged analytically to God in the same way that three angles are analytically predicated of a triangle.
He suggested that the notion of a perfect being is in some way innate, but this seems to be something of a simplification. He also claimed that an imperfect being cannot think up the concept of a perfect being.