IB Philosophy 10.3.4 Proofs for the Existence of God Notes

The Strategic Role of God in the Meditations

1. Having established the cogito (10.3.2) and the clarity and distinctness criterion (10.3.3), Descartes faces a critical problem. The Cartesian Circle (discussed in 10.3.3) threatens to undermine his epistemological project unless he can independently prove that a non-deceiving God exists.
2. Descartes needs God for a specific philosophical purpose: to guarantee that what he perceives clearly and distinctly is objectively true, not merely psychologically compelling. Without this divine guarantee, the method of doubt cannot be definitively overcome.
3. God's existence also provides the bridge from the solitary certainty of the cogito to knowledge of the external world. If God exists and is not a deceiver, then the strong inclination to believe in an external world of material objects must be generally reliable (to be developed in 10.3.6).
4. Descartes offers two distinct types of argument for God's existence in the Meditations: the causal arguments of Meditation III and the ontological argument of Meditation V. Each takes a different approach but arrives at the same conclusion.
5. The philosophical context is important: Descartes writes during the Counter-Reformation, and proving God's existence through reason alone serves both philosophical and theological purposes. His arguments aim to demonstrate that faith and reason are compatible, not opposed.
6. Understanding these proofs is essential for the philosophy of religion (Unit 8) and connects to broader questions about whether the existence of God can be established through purely rational argument or requires faith, revelation, or empirical evidence.
7. Unlike the Confucian tradition (10.2), which shows little interest in proving the existence of a supreme being, and unlike Ayer's logical positivism (10.1), which dismisses theological claims as meaningless, Descartes places rational theology at the very centre of his philosophical system.
8. The proofs also raise fundamental questions about the relationship between epistemology (the study of knowledge and what justifies belief) and metaphysics (the study of what exists and what the fundamental structure of reality is). Can we know anything about the world without first establishing metaphysical truths about God?
   1. Descartes' answer is that metaphysics grounds epistemology, a controversial claim that his critics vigorously contested.

The Causal Argument: The Trademark Argument

1. The first proof appears in Meditation III and is known as the trademark argument or causal argument. Descartes begins by examining the idea of God that he finds within his own mind: the idea of a being that is infinite, eternal, immutable, independent, supremely intelligent, and supremely powerful.
2. Descartes applies a causal principle (the rule that a cause must always contain at least as much reality as its effect): the idea of an infinitely perfect being can only come from a cause that itself is infinitely perfect. A finite, limited mind is simply not a big enough source to generate an idea of something infinite and unlimited.
   1. A finite mind cannot be the adequate cause of an infinite idea.
3. Since Descartes himself is a finite, imperfect being, he cannot be the source of the idea of infinite perfection. Nor can the idea come from nothing, since causes must be adequate to their effects.
   1. Therefore, the idea must have been placed in him by a being that actually possesses all the perfections the idea represents.
4. A second version of the causal argument asks who or what sustains Descartes in existence from moment to moment. Since he cannot sustain himself (if he could, he would have given himself all perfections), there must be an external cause of his continued existence.
   1. Tracing this chain of causes leads ultimately to God, the only being capable of sustaining infinite existence.