Descartes’ Philosophy: Method, Doubt, and Existence of God
Descartes’ Philosophical Method
Descartes starts by critically discarding traditional teachings, asserting that mathematics is the only science with clear reasoning. He bases his method on mathematical principles.
Descartes’ Method of Reasoning
Descartes posits that reason has two ways of knowing: inductively (ideas from one’s own reasoning) and deductively (combining simple ideas into complex ones). His method is a set of clear and easy ideas, based on mathematical operations, with four key tenets:
- Criterion of Truth: An idea is true if it is clear and distinct. Clarity is the perception of an idea in our minds, and distinction is the separation of that idea from others.
- Analysis: Breaking down complex ideas into simpler components.
- Synthesis: Progressing from simpler to more complex ideas gradually.
- Verification: Reviewing the analysis through memory and the synthesis through a final check.
The Methodical Doubt
Descartes applies his method to philosophy, starting with the Cartesian doubt that nothing is real until it is clear and distinct. He initially considers nothing to be true, until it is clearly and distinctly perceived by the mind. He bases this doubt on:
- The senses are not completely reliable and can deceive us.
- There is no clear distinction between dream and reality, as dreams can seem real.
- Even mathematics, which seems certain, could be manipulated by an evil genius.
Criteria for Accuracy
Descartes argues that we are always thinking, and even an evil genius cannot control this. When he doubts everything, he concludes that the act of thinking is real: “I think, therefore I am.” For Descartes, thought includes denying, affirming, imagining, and feeling. He bases his philosophy on this, as thinking is clear and distinct.
Descartes argues that our thinking is not about things themselves, but about our ideas of them. These ideas are classified as:
- Adventitious Ideas: Ideas that come from external sources (e.g., horse, land, water).
- Fictitious Ideas: Ideas created by our minds (e.g., a table with wings).
- Innate Ideas: Ideas that are not derived from experience, but are always present (e.g., the idea of infinity).
Existence of God
Descartes claims that the idea of infinity is innate, not created by us. The finite comes from the infinite, and the idea of infinity must have been placed in us by someone. He asserts the existence of God through three arguments:
- Epistemological Argument: The idea of perfection exists, but it does not come from us, so it must have been placed there by a perfect being.
- Causal Argument: We are imperfect, and if we had created the idea of perfection, we would be perfect. Therefore, a more perfect being must exist.
- Ontological Argument: The idea of a perfect being implies the existence of that perfect being, which is God.
Existence of the World
Since God’s existence is demonstrated, Descartes concludes that God is perfect, good, and all-powerful. God guarantees that what we perceive is real. Everything exists because of God, but does not persist through Him. Substance is what exists thanks to God. There are two types of substance: thinking substance and extended substance, both existing independently of each other.
Man
Descartes states that man is composed of thinking substance (soul) and extended substance (body). When we die, the extended substance disappears, but the thinking substance is immortal.