Descartes: Rationalism and the Method in 17th-Century Philosophy
René Descartes: A Philosophical Revolution
Life and Context
Born in the 16th century in La Haye, Touraine, René Descartes studied at La Flèche before enlisting as a volunteer at the beginning of the Thirty Years’ War. A series of three dreams led him to conceive the foundations for his groundbreaking invention: analytic geometry and the method. He was born in a time of great intellectual upheaval, where the authority of the Church and Aristotelian scholasticism were being questioned.
Major Works
- 1637: Discourse on the Method, followed by essays on optics, meteors, and analytic geometry.
- 1641: Meditations on First Philosophy, his most systematic work, which sparked controversy and debate.
- Later works: Principles of Philosophy, Passions of the Soul, and Rules for the Direction of the Mind.
Philosophical Current: Rationalism
Descartes is a central figure in rationalism, a philosophical current that includes Spinoza, Leibniz, and Malebranche. Rationalism stands in opposition to empiricism. It posits that true and valid knowledge about reality stems from reason and understanding. Rationalism aligns with the ideals of modern science: our understanding of reality can be deductively constructed from certain self-evident ideas and principles. These foundational principles and ideas are innate to the understanding.
The Necessity of Method
Descartes believed that while wisdom is universally possessed, it is not always effectively applied. He argued that a suitable method is crucial for developing talents and discovering new aspects of knowledge. The educational environment of Descartes’ time, based on repetition and tradition, hindered innovation. The modern age sought a new criterion of truth to replace the authority of the Church and Aristotelian scholasticism, moving away from the syllogism, a deductive reasoning form dependent on a major premise. Descartes, along with Francis Bacon, criticized the syllogism, deeming it useless for scientific invention and the pursuit of truth. They believed it only served to expound upon what was already known.
The Mathematical Method
Descartes was deeply impressed by mathematics, particularly its emphasis on simplicity and clarity. He believed that only what is clear, distinct, and simple can provide certainty (his criterion of truth). Clarity is the absence of obscurity, revealing something as it truly is. A sound logical deduction establishes an identity with itself, distinctly separable from all else. Clarity is invariably accompanied by distinction, eliminating confusion and establishing an order from simple to complex, influenced by geometry.
Intuition and Deduction
Given the vast diversity of philosophical thought, Descartes sought a universal knowledge applicable to all branches of knowledge, both technical and practical. He attributed the previous lack of such knowledge to the absence of a valid method. Descartes proposed the mathematical method, characterized by intuition and deduction. Intuition grasps undoubtable truths, while deduction derives conclusions from things known with certainty. These necessary conclusions allow for the rigorous proof of other truths. The mathematician proceeds step by step, relying on clear links of intuition.
Finite Substances: Bodies and Souls
Descartes proposed that finite substances, bodies and souls, require God to exist.
- The Soul: Thought is its sole attribute, making it res cogitans (thinking substance). This is supported by a mental fiction: one can imagine not having a body but cannot imagine not thinking.
- The Body: Extension is its sole attribute, with shape and movement as its “modes.” The reasoning is: “I think, therefore my body and others exist, as ‘God cannot deceive,’ which ensures the existence of the physical world.”
This demonstrates Cartesian dualism: Res cogitans (Soul) versus res extensa (Body), substances that do not require each other to exist.