Descartes: Rationalism and the Method of Doubt
Descartes: Rationalism and the Pursuit of Certainty
Descartes, a proponent of rational authority, believed that truth resides in reason. His grand project was to achieve the certainty of universal knowledge. In epistemology, Descartes argued that we must doubt all knowledge to arrive at the truth. He posited that knowledge is acquired through reason, and the objects of knowledge are ideas, which are immediately comprehended.
For Descartes, certainty is found in mathematical knowledge, as these are evident truths that cannot deceive us. He employed the deductive method (going from the universal to the particular) to develop solid, universal knowledge based on fundamental principles, articulated through the mathematical method. Descartes defined the method as a series of easy and certain rules such that anyone who observes them will never mistake something false for true and will reach a true understanding of all things within their capacity.
Descartes distinguished two ways of knowing through reason:
- Intuition: The basic element of knowledge, an idea immediately understood. A clear idea, according to Descartes, is one that expresses no doubt.
- Deduction: An operation by which we understand all things that are necessary consequences of things understood with absolute certainty. It’s a series of intuitions brought together by reason.
Descartes defined four rules of the method to use reason properly:
- Rule of Evidence: Do not accept anything as true unless it is clear and distinct (we need direct acquaintance with the concept).
- Rule of Analysis: Divide difficulties to understand them better.
- Rule of Synthesis: Proceed from simpler objects of knowledge to more complex ones.
- Rule of Enumeration/Review: Make complete lists and reviews to ensure nothing is omitted.
The first two rules constitute the method of analysis; the latter two, the method of synthesis. The method is universal, applicable to everyone, sequential, simple, and mathematical.
Descartes’ Methodical Doubt
Descartes’ methodical doubt defines the research method aiming at certainty, the truth of our knowledge. It should be applied by all human beings and is valid for all types of knowledge. It is theoretical and applies to theoretical knowledge, excluding politics and morality. Descartes distinguished these stages in the process of doubt:
- Doubt about information grasped by the senses (sensory perceptions), as the senses can deceive us. Descartes gives the example of a stick appearing broken in water.
- Doubt about reason: He questioned the distinction between sleep and wakefulness, as we seem to think in dreams as if we were awake.
- Doubt about our cognitive apparatus: He considered that God might have created us in such a way that what we believe is true is actually false. He dismissed the idea of an evil being deceiving people, as God cannot be evil.
For Descartes, the question of consciousness is preserved. “I think, therefore I am” (“Cogito, ergo sum”) is the first Cartesian certainty and the first intuition. I can doubt everything except that I am the one who is doubting.