Descartes’ Cogito and the Criterion of Truth
The Cogito and the Criterion of Truth
Second Level of Certainty: “I Am”
Descartes argues for a certainty surpassing even mathematical truths, a certainty immune to deception by any malicious spirit. This is the undeniable certainty of one’s own existence. Even in doubting, I affirm my existence as the doubter. Whether mistaken, dreaming, or deceived, I must exist to think, to doubt, to be. Thus, I exist as a “thinking thing.”
Avoiding Misunderstandings
Descartes’ famous dictum, “I think, therefore I am” (Cogito ergo sum), should be interpreted carefully:
- “I” refers broadly to any mental activity, including doubting, dreaming, and being deluded.
- “Therefore I am” is not a logical conclusion but an intuitive grasp of self-evident truth. Certainty is revealed within the very act of doubting.
The Precedent of St. Augustine
St. Augustine, in his arguments against Academic Skepticism, arrived at a similar understanding of the undeniable certainty of the thinking self. While Descartes was aware of this precedent, it doesn’t hold the same central importance in his philosophy.
Critique of Kant
Kant viewed Descartes’ “I” as a mere formal consciousness accompanying our representations, a logical subject of thought. This formal condition of knowledge, Kant argued, lacks the concrete content to establish the continued existence of a personal self.
Problems
Despite its certainty, the Cogito presents challenges for Descartes’ philosophy. The self-evident existence of the thinking self proves to be a dead end, unable to support further conclusions. The subject is trapped in a solitary circle of certainty, unable to affirm anything beyond its own existence. The hypothetical evil genius, while unable to deceive us about our existence, can still deceive us about everything else, including:
- The existence of the body
- The existence of other minds
- The existence of the world
- The validity of mathematical truths
The Criterion of Truth
Descartes’ criterion of truth is the clarity and distinctness of ideas: “All that I perceive clearly and distinctly is true.” This principle stems from the Cogito: if the self-evident truth of the Cogito is clear and distinct, then clarity and distinctness must be the mark of truth. This criterion aims to guarantee that subjective evidence corresponds to objective truth, ensuring the adequacy of thought to reality. However, the reliability of this criterion is not absolute. The evil genius hypothesis raises the possibility that even clear and distinct ideas could be objectively false. The problem of mathematical truths is a specific instance of this broader problem.
Goodness and Truth of God
To address these problems, Descartes argues for the existence of God: “God is good and therefore truthful. Therefore, God cannot deceive us by allowing us to believe in the world, other minds, our bodies, and mathematical truths if these things are not real.” This argument aims to eliminate the possibility of a deceiving evil genius.
The Existence of God: Third Level of Certainty
By proving God’s existence, Descartes establishes a third level of certainty, a guarantee of the reliability of the criterion of truth. This level of certainty is necessary because the Cogito only guarantees its own truth. According to Descartes, the atheist, lacking this guarantee, cannot know anything for certain.
The Cartesian Circle
Critics have pointed out a circular relationship between Descartes’ criterion of truth and his proof of God’s existence. He relies on the criterion of truth to prove God’s existence, and then relies on God’s existence to validate the criterion of truth. However, this is not a vicious circle, as the criterion of truth is initially subjective, while God’s existence is objective.