Descartes’ Philosophy: A Deep Dive into Rationalism
Descartes: A Pioneer of Modern Philosophy
Context
Subjectivist philosophy takes a significant turn with René Descartes. He posited that the world is not directly known; humans only know what exists within their consciousness, namely, ideas.
Descartes was born in La Haye in 1596. He participated in the Thirty Years’ War, then resided in Holland, and finally moved to Stockholm, where he tutored the Queen of Sweden. He died there in 1650. As a physicist, he laid the groundwork for kinematics. As a mathematician, he developed analytic geometry. As a philosopher, he is credited with founding modern rationalism and philosophy.
Some of his notable works include Meditations on First Philosophy, The Passions of the Soul, and Principles of Philosophy.
Key Characteristics of Rationalism
The primary proponents of rationalism during this period were Descartes, Leibniz, Spinoza, and Malebranche. They asserted that:
- Humans only know what is in their minds: their ideas.
- Reason is the sole source of knowledge.
- Reality is perceived as a substance.
- Knowledge is perceived as certainty and, therefore, cannot be doubted. Descartes believed that certainty is characterized by clarity and distinction.
- Ideas are explained using the deductive method, whereby a few simple elements, obtained through intuition, lead to more complex ones.
- Mathematics is considered a form of knowledge, as it always operates with certainty.
The Cartesian Method
Descartes aimed to achieve certain knowledge, free from any reasonable doubt.
Cartesian philosophy is methodical. Since all humans possess reason, errors are not due to a lack of intellectual capacity but rather to the absence of a proper method. The Cartesian method comprises rules designed to identify certain knowledge. It consists of four steps:
- Rule of Evidence: Only accept as true that which presents itself with absolute evidence. The criteria are clarity and distinction.
- Rule of Analysis: Reduce the problem to its constituent elements.
- Rule of Synthesis: Once the problem has been broken down and its elements identified, reconstruct it through synthesis.
- Rule of Enumeration: Review the entire process.
Methodical Doubt
The human mind must discover within itself the fundamental truths from which all knowledge can be derived. It should seek a primary truth capable of serving as a starting point. This pursuit of truth necessitates questioning all previously held knowledge that lacks absolute certainty. Methodical doubt has two key features:
- It is methodical, serving as a means to reach truth.
- It is hyperbolic. Descartes exaggerates doubt, believing that the more rigorous the doubt, the clearer the truth that overcomes it will be.
Theory of Knowledge: Ideas
Firstly, all ideas are equal because they are all events occurring in our minds. Secondly, there are three types of ideas:
- Factitious: Ideas constructed by the mind from other ideas (e.g., a centaur, formed from the ideas of a man and a horse).
- Innate: Ideas inherent to reason itself (e.g., infinity or thought).
- Adventitious: Ideas related to natural things that we believe originate from outside ourselves (e.g., feeling fire or seeing the sun).
The Metaphysical Notion of Substance
Descartes defines substance as something that exists and needs nothing else to exist. He also suggests that substance can refer to things that only require God to exist. God, body, and soul are the three types of substances that constitute reality. Each substance is further distinguished by certain attributes.
Physics
Descartes viewed the universe as a vast machine governed by the following laws:
- Law of Inertia: Every body remains in the same state of motion or rest unless an external force acts upon it.
- Law of Motion in a Straight Line: A body moves in a straight line unless an external force intervenes.
- Law of Conservation of Motion.
Descartes believed that a vacuum does not exist. For instance, if a bottle contains no liquid, it is not empty because it is full of air.