Descartes’ Method: Seeking Certainty Through Doubt

This fragment belongs to the “Discourse on the Method” of Descartes and addresses the question of knowledge. This philosopher seeks a new philosophical method to attain real knowledge of things. His approach is influenced by Galileo’s mathematical model. The proposed method has distinct rules to achieve knowledge:

1. Evidence

Something must be clear and distinct to be considered true.

2. Analysis

Divide each difficulty into as many parts as possible, moving from the simple to the complex to ensure certainty and avoid falsehoods.

3. Synthesis

Conduct thoughts in an orderly manner, starting with the simplest and progressing to the most complex. This process is done through deduction, moving from the universal to the particular through successive intuitions.

4. Review

Check and revise all obtained truths to ensure accuracy and eliminate errors.

Descartes employs a method of voluntary doubt to analyze all previous knowledge and determine what is truly certain. He doubts knowledge from the senses, the distinction between dreams and reality (“thoughts we have when awake can also come to us when asleep”), and even considers the hypothesis of an evil genius deceiving us. However, Descartes eventually rejects the possibility of an evil genius.

Descartes’ Methodical Doubt

• Methodical: Its purpose is to achieve certainty.
• Universal: It questions all kinds of knowledge.
• Theoretical: It challenges existing knowledge to find firm foundations, not to be applied directly to practical life.
• Radical: It challenges the senses and common sense.

It follows the first rule of the method, accepting as true only what is presented with absolute clarity and distinction, i.e., with evidence. This is a core tenet of rationalism: we can only accept beliefs reviewed by reason. This doubt is temporary and abandoned when an obvious proposition is found.

In his process of doubting everything, Descartes finds one undeniable truth: “I think, therefore I am.” This conclusion is the first principle of his philosophy, based on the mathematical method. This proposition is true because we cannot doubt our own thinking. We can pretend our body is an illusion, but not that we are not thinking. This demonstrates our existence as thinking beings, or thinking substance.

For Descartes, substance is that which needs nothing else to exist and is the basis of attributes and modes. He identifies three substances: thinking substance, extended substance (body), and infinite substance (God). The existence of thinking and extended substances leads to Descartes’ anthropological dualism: the immaterial soul and the material body. It is easier to know the soul than the body. Other philosophers propose different types of substances.

The conclusion that we are thinking beings comes through intuition, the immediate perception of an obvious idea or truth. Deduction is then used to proceed from the universal to the particular, deriving further truths. This approach is central to Descartes’ mathematical method.

The existence of the first principle leads to Descartes’ criterion of truth: something is absolutely true if it is presented clearly and distinctly, with evidence. If we doubt, we are not perfect, as knowledge is more perfect than doubt. If we are not perfect, we must have an idea of perfection in our minds, which must come from a more perfect being: God. Therefore, God exists.

Descartes presents God as the infinite substance, the guarantor of our knowledge, countering the idea of an evil genius. Descartes is an epistemological optimist, seeking absolute truth and knowledge. He abandons solipsism, the view that only one’s own existence can be guaranteed.