How does Descartes prove the existence of things other than himself and God? Discuss.

The Cogito and Initial Certainty

Descartes begins his philosophical journey by systematically doubting all his beliefs. He questions the reliability of sensory experience, arguing that our senses can deceive us. He even entertains the possibility that he is being deceived by an evil demon, a powerful being dedicated to misleading him about reality. However, he realizes that even if he is being deceived, the very act of being deceived requires a ‘deceiver’ and a ‘deceived’ – meaning that *someone* must be thinking. This leads to the famous ‘cogito ergo sum’ – “I think, therefore I am.” This is the first indubitable truth, the foundation upon which Descartes attempts to rebuild knowledge.

Proving the Existence of God

Having established his own existence, Descartes turns to proving the existence of God. He presents several arguments, most notably the ontological argument and the causal argument. The ontological argument, based on the concept of a perfect being, argues that existence is a perfection, and therefore a perfect being must necessarily exist. However, this argument is often criticized. Descartes relies more heavily on the causal argument.

The causal argument states that the idea of a perfect being could not have originated from an imperfect source (i.e., himself). The cause of an idea must have at least as much formal reality (perfection) as the idea itself. Since Descartes, as a finite and imperfect being, lacks the perfection inherent in the idea of God, the idea must have been placed in his mind by a perfect being – God. This argument establishes God as the ultimate cause of his existence and the source of all truth.

Establishing the Reality of the External World

Once God’s existence is established, Descartes argues that God, being perfect and benevolent, would not allow him to be systematically deceived about the nature of reality. God guarantees the reliability of our clear and distinct perceptions.

Clear and Distinct Perceptions: Descartes defines clear perceptions as those that are present and apparent to an attentive mind, and distinct perceptions as those that are so clear and complete that they cannot be doubted. He argues that anything perceived clearly and distinctly is true. Since God is not a deceiver, our clear and distinct perceptions of the external world – things like shapes, sizes, and motions – must correspond to reality. This allows Descartes to conclude that objects exist independently of his mind.

However, this doesn’t mean all our perceptions are accurate. Errors arise from our judgments, not from God’s deception. We make mistakes when we rush to judgment or extend our perceptions beyond what is clearly and distinctly presented to us.

Addressing Potential Objections

Descartes acknowledges that the argument relies on the assumption of a benevolent God. Critics argue that even a powerful God might allow deception. Descartes counters by asserting that systematic deception would be a form of imperfection, incompatible with God’s nature. He also addresses the problem of dreams, arguing that dreams lack the coherence and logical structure of waking experience, and therefore cannot be mistaken for reality.