Rationalism and the Method of Doubt: Descartes’ Philosophy
Rationalism and the Search for Certainty
The rationalist’s primary goal is to establish a reliable method for thinking, acting, and reconstructing human knowledge based on mathematical principles. This method adheres to specific rules:
Rules of the Method
- Evidence: Accept only clear and distinct ideas as true, rejecting those that are doubtful or confused.
- Analysis: Reduce complex concepts into simpler, undeniable truths (intuitions).
- Synthesis: Build complex arguments and deductions from these simple elements.
- Enumeration: Verify all steps in the process.
- Conclusion: True knowledge is achieved through the intuitive evidence of clear and distinct ideas.
All factual reality and truth must be founded on clear, simple, distinct, and true intuitions. Absolute certainty should be sought in all matters.
Methodical Doubt and the Existence of the Self
Following the method’s rules, it’s necessary to doubt all knowledge not based on indubitable evidence. Descartes aims to examine the possibility that all our truths might be mistaken. He proposes several reasons for this hypothesis:
Reasons for Doubt
- Permanent Deception of the Senses: Our senses can mislead us; it’s possible they deceive us constantly. We cannot reliably distinguish between wakefulness and sleep, as both involve perceptions, albeit different ones.
- Deceiver God Hypothesis: An omnipotent God could deceive us, even in mathematical knowledge. This contradicts the idea of a benevolent God who wouldn’t deceive us.
- Evil Genius Hypothesis: An evil genius might be manipulating our perceptions, causing a continuous state of deception.
Despite these doubts, one thing remains evident: the existence of the self that thinks and doubts. Descartes’ famous statement, “I think, therefore I am” (Cogito Ergo Sum), encapsulates this realization. The very act of doubting proves the existence of a thinking subject.
Substance and the ‘I Think’
The “I think” expresses a substantial and permanent self. This thinking substance is the first substance Descartes discovers. The ‘Cogitans’ (thinking thing) is a real entity that thinks. Descartes views God as ‘res infinita’ (infinite substance) and the world as ‘res extensa’ (extended substance). He attributes characteristics of substance to each. Rationalism, therefore, is realistic; everything that exists has its own substantial entity.
Of the three substances, only the “I think” is immediately evident. From this, Descartes derives arguments to affirm the existence of the other two.
Ideas and the External World
The existence of the “I” as a thinking entity is evident in its ideas, which represent reality. Descartes categorizes ideas into three types:
- Adventitious: Derived from external experience, although we cannot be certain of their accuracy due to our uncertainty about external reality.
- Factitious: Created by the mind from other ideas, products of imagination.
- Innate: Present in the mind from birth, not derived from experience. These ideas possess perfect evidence as they pertain to the essence of the thinking self.
God and the World
From innate ideas, Descartes deduces the existence of God and the world. He identifies the idea of infinity, which cannot originate from a finite source. Therefore, there must be an infinite being, God (res infinita). This argument is based on causality and the ontological argument, which states that the idea of a perfect being (God) necessitates its existence, as existence is a perfection.
Descartes argues that God, being truthful, wouldn’t allow our ideas about the external world to be false. These ideas align with the concept of extension, suggesting that the world must be extended. The third substance, then, is the extension of things: the continuity of matter. God is the first cause of the universe’s constant movement, replacing final causes with efficient causes, leading to a mechanistic view of the universe, including biological mechanisms in animals and humans.
Mind-Body Dualism and the Passions
The division of thinking substance and extended substance results in a substantial distinction between the soul and the body. Humans are composed of these two distinct substances. There is an interaction between them, evident in the analysis of feelings, which are mediated through the pineal gland.
Descartes identifies six primary passions: admiration (an intellectual passion), love, hatred, desire, joy, and sadness. These passions originate in the soul but can affect it. The soul must control them according to reason, which provides judgments about good and evil. Reason is the foundation of freedom, and its proper use leads to human perfection and happiness. For Descartes, freedom lies in choosing according to the will, guided by the understanding, which comprehends the order of reality.