Descartes’ Quest for Certainty: Method and the Cogito
Descartes’ Method for Attaining Certainty
Descartes aimed to develop a system of truth by accepting nothing as assumed. For that, he established a method consisting of four rules to arrive at certain knowledge:
Rule 1: Evidence and Methodical Doubt
Evidence: Do not accept anything as true unless it is known evidently to be so. A truth is evident when it presents itself to the mind with clarity and distinction. An idea is clear when we know all the elements that comprise it. An idea is distinct when it cannot be confused with another.
Questioning the Senses
Descartes implements this rule by questioning the reliability of the senses. The senses lead us to error. Therefore, they are not a criterion for certainty.
The Dream Argument
The impossibility of distinguishing waking from sleep presents a second, even more radical doubt. We perceive the world as real, but we also perceive things as real in dreams.
Mathematical Truths
However, there is a kind of truth, mathematical truths, which seem to resist this stage of methodical doubt. Whether awake or asleep, the sum of the angles of a triangle is always 180º. Therefore, mathematical truth, for now, resists methodical doubt.
Evil Genius Hypothesis
Perhaps there is some evil spirit of extreme power and intelligence who strives to mislead us. This is an unlikely scenario, but I cannot prove it false.
Cogito Ergo Sum: The First Certainty
Descartes finds a truth we can state with confidence: our own existence. This leads to Descartes’ famous statement: “I think, therefore I am” (Cogito ergo sum).
We can doubt the existence of God, the objects around us, and even our own body, but we cannot doubt that we, who think all these things, exist. We cannot be nothing while we are thinking. Cogito ergo sum is the first certainty—clear, distinct, and indubitable—which underpins all knowledge and certainty.
Rule 2: Analysis
Analysis: This involves dividing complex difficulties and problems into their simplest components. Sense experience often presents us with compound things; we arrive at the simple elements through the use of reason via analysis.
Rule 3: Synthesis
Synthesis: This involves conducting thoughts in an orderly manner, starting with the simplest and easiest objects to understand, and ascending slowly and gradually to the knowledge of the most complex.
Rule 4: Enumeration
Enumeration: Make complete enumerations and general reviews of the process to ensure nothing is omitted. This last rule can be considered a form of verification.
From Solipsism to God: Types of Ideas
Having established the first truth (Cogito ergo sum), Descartes finds himself potentially locked in solipsism (the view that only one’s own mind is sure to exist). Descartes examines the types of ideas he possesses and identifies three kinds:
- Adventitious ideas: Those that seem to come from outside us (e.g., sensory experiences).
- Factitious (or Fictitious) ideas: Those produced by our imagination (e.g., a unicorn), often combining elements of adventitious ideas.
- Innate ideas: Those that do not come from outside nor are constructed by the subject, but are found within the mind itself, often characterized by clarity and distinction. For example, the idea of God.
Proof of God’s Existence and External Reality
Descartes needed to prove the existence of God to escape solipsism. He uses three arguments; we will look only at the one stating that knowing is a greater perfection than doubting. I find within myself the idea of perfection. This idea cannot be adventitious (from outside) nor factitious (created by me, as I am imperfect). Therefore, it must be innate. If it is innate, it must have been placed in me by something truly perfect, a being possessing all perfections, since the cause must be adequate to the effect. Therefore, God exists. Descartes believes that once the existence of a non-deceiving God is established, this guarantees the existence of an extramental reality corresponding to our clear and distinct ideas.