Descartes on the Necessity of God’s Existence
The Need for Justifying God’s Existence
This formulation poses the philosophical question of the necessity of the existence of God, according to which Descartes holds that there must be a God. Descartes developed his philosophy in a period in which those who denied the existence of God were persecuted. He based his system on assertions about the existence of God, so this issue is a very important part of Descartes’s philosophy. Therefore we ask: Why is it necessary that God exists? What constitutes this need? What justifies Descartes? How does Descartes demonstrate the existence of God? Throughout this essay I will attempt to answer these questions and address other problems that arise from Descartes’s thought and his stance on this issue.
Descartes was one of the most important philosophers in history and his philosophy influenced many later thinkers. His position on this issue helped him avoid clashes with the Church and thus enabled him to develop his philosophy. Descartes claims that God is necessary because the criterion of truth is guaranteed by God.
Descartes’s Three Arguments for God’s Existence
Descartes gives three arguments to explain the existence of God and, at the same time, the necessity of this existence.
Argument from the Theory of Ideas and the Infinite Idea
First, he explains the existence of God through the infinite idea in his theory of ideas. According to Descartes, ideas are alike in being ideas but differ in content; therefore he distinguishes three types of ideas according to content:
- Adventitious ideas, which are those ideas that come from outside the mind, from the perception of the senses.
- Factitious ideas, which are ideas the mind constructs from others, namely those created by the imagination.
- Innate ideas, which are those ideas that thought itself possesses.
According to Descartes, these innate ideas are not born with us in the sense of being physically present at birth, but they are natural to thought, i.e., ideas that are naturally formed by the mind. From the establishment of innate ideas, Descartes discovered the idea of Infinity, rejecting the possibility that it is merely adventitious or factitious. While it had been felt that the idea of infinity is built from the idea of the finite, Descartes argues instead that the idea of the finite derives from the idea of the infinite. Descartes identifies the idea of the infinite with the idea of God’s infinitude, so the idea of God is an innate idea since it is an idea we have in ourselves, not derived from any sensory experience.
The establishment of the idea of God is a turning point in Descartes’s philosophy, for from here he builds the rest of his system. Initially, Descartes held that the idea’s existence explains its objective reality, namely that the existence of God is explained by the idea of God. Therefore the existence of God is necessary because it is the first idea he would use to explain the world; if God did not exist, then many of his conclusions would be formed from an incorrect premise.
Argument from Objective Reality and the Idea of Perfection
Secondly, God explains the existence of our ideas in order to explain his own existence. That is, according to Descartes, we all have an idea of a perfect being, yet we do not consider ourselves perfect; so if there were no perfect being, how could we say that we lack something if we had no example of perfection? Descartes explains that the objective reality of our ideas is proportional to the reality of their causes; the idea of God, as an idea of perfection, implies an actual perfect being. We try to approximate that perfection, which we obviously do not possess, because we have the concept of perfection itself.
Thus, if God did not exist, there would be no exemplar of perfection by which to measure and compare our own imperfections.
Ontological Argument
Third and last is an ontological argument, as formulated by St. Anselm and taken up by later thinkers. In this argument Descartes attempts to explain the existence of God from the very idea of God. According to him, if one discards the existence of a perfect being, that being would be more perfect if it existed in reality and not only in thought; therefore the idea of a perfect being implies that such a being must exist not only in thought but also in reality. To illustrate, Descartes uses the example of a triangle and a circle: we know that a triangle has three sides and that in a circle all points are equidistant from the center. In the same way, we know that God exists because the very idea of God includes perfection.
Summary of the Three Arguments
- Innate idea of the infinite: the idea of God as infinite is native to thought and cannot be derived from finite ideas.
- Objective reality and perfection: the idea of a perfect being requires a real cause that possesses at least as much reality as the idea itself.
- Ontological argument: the concept of a supremely perfect being entails existence, just as geometrical concepts entail necessary properties.
Conclusion
In conclusion, Descartes argues for the existence of God through three arguments: God is an innate idea, God must exist as the cause and measure for the existence and knowledge of human beings, and God exists because the idea of God entails existence. Thus, once God is demonstrated, Descartes can reject the hypothesis of the evil genius: the intention to deceive cannot be attributed to God.