Unit 1: History of Modern Western Philosophy (Descartes)
Table of Contents
Introduction to Modern Western Philosophy
The modern era of Western philosophy is traditionally marked by a shift from the dogmatic authority of the Church and Scholasticism toward reason and scientific inquiry. Rene Descartes (1596–1650) is widely regarded as the "Father of Modern Philosophy" because he sought to establish a firm, indubitable foundation for all human knowledge.
Descartes: Method
Methodological Doubt (Cartesian Doubt)
Descartes did not use doubt for the sake of being a skeptic. Instead, he used it as a tool to find something that could not possibly be doubted. This is known as Universal or Radical Doubt.
- Step 1: Doubting the Senses: Since our senses sometimes deceive us (e.g., optical illusions), they cannot be a foundation for absolute certainty.
- Step 2: The Dream Argument: Descartes argues that we cannot be certain we are not dreaming, as the sensations in dreams are often as vivid as reality.
- Step 3: The Evil Demon (Genius) Hypothesis: He imagines a powerful, deceitful being that tricks his mind even about mathematical truths (like 2+2=4).
"Cogito, Ergo Sum" – I think, therefore I am.
Even if a demon is deceiving him, he must exist to be deceived. The act of doubting is an act of thinking, and thinking requires a thinker. This is the first indubitable truth of his philosophy.
Descartes: Ideas
Having established his own existence, Descartes examines the contents of his mind, which he calls Ideas. He classifies ideas based on their origin:
| Type of Idea | Source | Example |
|---|---|---|
| Innate Ideas | Born with the mind; placed by God. | God, Perfection, Infinity, Identity. |
| Adventitious Ideas | From external sensory experience. | Heat of the sun, sound of music. |
| Factitious Ideas | Invented by the imagination. | Chimeras, Sirens, Unicorns. |
The Proof of God from Ideas
Descartes argues that his idea of a Perfect Being (God) could not be factitious (he is imperfect) or adventitious (God isn't sensed). Therefore, it must be innate. Since the cause must have at least as much reality as the effect, only a perfect God could have placed the idea of perfection in a human mind.
Descartes: Substance
Descartes defines substance as "a thing which exists in such a way as to depend on no other thing for its existence." Strictly speaking, only God fits this definition. However, in a relative sense, he identifies two created substances.
Mind-Body Dualism (Cartesian Dualism)
Descartes proposes that reality consists of two distinct, independent substances:
- Res Cogitans (Thinking Substance/Mind): Its essential attribute is Thought. It is non-extended, indivisible, and free.
- Res Extensa (Extended Substance/Body): Its essential attribute is Extension (taking up space). It is unconscious, divisible, and governed by mechanical laws.
Exam-Oriented Enhancements
Frequently Asked Questions
Q: Why is Descartes called a Rationalist?
A: Because he believes the foundation of knowledge is reason (the Cogito and Innate Ideas) rather than sensory experience.
Q: What is the "Cartesian Circle"?
A: Critics argue Descartes uses God to prove the reliability of clear/distinct ideas, but uses clear/distinct ideas to prove God exists—this is circular reasoning.
Mnemonics for Ideas
To remember the three types of ideas, use "I.A.F.":
- Innate (Inside us from birth)
- Adventitious (Arrival from outside)
- Factitious (Fiction of the mind)