Descartes' Cosmological Argument in Meditation III

Introduction

In our last lesson, we journeyed with Descartes through the first two Meditations. We followed his method of radical doubt, which swept away all his former beliefs—from the testimony of his senses to the truths of mathematics—culminating in the hypothesis of an all-powerful "evil demon." From this abyss of skepticism, he salvaged a single, unshakable certainty: Cogito, ergo sum ("I think, therefore I am"). He established that he exists, at a minimum, as a res cogitans, a thinking thing.

However, this victory leaves him in a state of solipsism—isolated in his own consciousness, with no proof that anything else exists. To escape this "veil of ideas" and rebuild knowledge of an external world, Descartes must first prove that he is not alone in the universe. His strategy is to demonstrate the existence of a perfect, non-deceiving God, which would in turn vanquish the evil demon and guarantee the truth of his clear and distinct perceptions.

Today's lesson focuses on this crucial step. Your learning outcome is to analyze Descartes' cosmological argument for God's existence in Meditation III. This argument is called "cosmological" because it reasons from an existing thing in the cosmos—in this case, an idea in Descartes' mind—to the existence of its ultimate cause, God. Be prepared; this is one of the most intricate and demanding arguments in the Meditations.

1. Descartes' Metaphysical Toolkit

Before we can tackle the proof itself, we must understand the specific—and perhaps unusual—set of concepts Descartes uses to build it. He inherits some of this terminology from medieval scholastic philosophy but adapts it for his own purposes. The argument is impossible to grasp without a firm handle on these distinctions.

The following video provides an exceptionally clear explanation of these foundational concepts. It is essential to master them before moving on.

To see how Descartes introduces these ideas himself, let's turn to the primary text. You will notice his language is dense, which is why the video guide is so helpful.

2. The Cosmological Argument from the Idea of God

With the conceptual machinery in place, we can now reconstruct the argument. Descartes' strategy is to find an idea in his mind whose objective reality is so great that he, a mere finite substance, could not possibly have been its cause. The only plausible cause, he will argue, is a being with at least as much formal reality as the idea has objective reality.

The video you watched earlier continues with a brilliant, step-by-step reconstruction of the proof.

This argument is often called a "trademark" argument. The idea of God, an infinite substance, is like a craftsman's mark left on their creation. Because Descartes finds this "mark" (the idea of God) in his mind, and he could not have created it himself, he can infer the existence of the craftsman (God).

Now, let's examine the core of this argument in Descartes' own text and with another commentator's analysis.

The argument essentially unfolds as follows:

1. I have an idea of God (an infinite, perfect substance).
2. This idea has an infinite degree of objective reality.
3. The Causal Adequacy Principle: The cause of an idea must have at least as much formal reality as the idea has objective reality.
4. Therefore, the cause of my idea of God must have infinite formal reality.
5. I am a finite substance. I only have a finite degree of formal reality.
6. Therefore, I cannot be the cause of my idea of God.
7. Thus, a being with infinite formal reality—God—must exist and be the cause of my idea.

3. Conclusion: The Mark of the Workman

Having established, to his satisfaction, that God exists, Descartes concludes the meditation by reflecting on how he acquired this idea. He rules out its coming from the senses or being an invention of his own mind. He concludes it must be an innate idea.

This innate idea of God is Descartes' bridge out of solipsism. He has now proven that something other than himself exists. Furthermore, this being is perfect, and as he will argue later, a perfect being would not be a deceiver. The evil demon's power is about to be broken.

Conclusion

In this lesson, you have analyzed Descartes' first and most complex argument for the existence of God. It is a dense and challenging piece of philosophy that required you to master a new conceptual vocabulary.

Key Takeaways:

• Degrees of Reality: Descartes' metaphysics is hierarchical, distinguishing between infinite substance (God), finite substances (minds, bodies), and modes (properties).
• Formal vs. Objective Reality: Formal reality is the actual reality a thing possesses. Objective reality is the representational reality of an idea, determined by the formal reality of its object.
• The Causal Adequacy Principle: The central engine of the argument is the principle that there must be at least as much formal reality in a cause as there is objective reality in its effect.
• The Argument's Structure: Descartes argues that since he has an idea with infinite objective reality (the idea of God), its cause must have infinite formal reality. Since he himself is finite, he cannot be the cause. Therefore, an infinite being, God, must exist.
• The Innate Idea of God: Descartes concludes that the idea of God is not derived from experience or imagination but is innate, like a "mark of the workman" imprinted on his mind by his creator.

With this proof, Descartes believes he has secured his escape from the prison of his own mind. He has established an external anchor of certainty.

Preview of the Next Lesson: While the argument in Meditation III is a cosmological one, Descartes has another, very different proof for God's existence up his sleeve. In our next lesson, we will jump to Meditation V to analyze his famous ontological argument, which attempts to prove God's existence from the very definition, or essence, of God.