Descartes' Method of Doubt: Foundations of Rational Philosophy

Descartes' Method of Doubt

The methods described in Discourse on Method. Descartes proposes an alternative method for discovering what is true and what is false, and for finding a certainty and conviction that lead to security. Matmata, Kier, and others have sought an alternative method of philosophy that leads to the same security. Through the alternative methods of mathematics, deduction, and reasoning from the first truth, some truths follow. In this way, a philosophical building could be built on a solid foundation.

The Purpose of Doubt

Doubt: Descartes' first step in his method is to doubt, in order to achieve his goal of distinguishing what is true from what is false. He thinks that doubting at the beginning removes apparent knowledge. This doubt has three special characteristics:

• Universal: One must doubt everything, and must even doubt all beliefs and all the philosophical principles that supported them.
• Methodical: This is not skeptical doubt. Doubt is an instrument for achieving truth; it does not end in itself but serves as a means of building philosophy.
• Theoretical: It does not target the standards of ordinary beliefs but the plane of philosophical reflection.

Why Doubt?

"What concrete doubt?" Descartes gives three reasons for doubt:

• The senses deceive us, and we are led into error; therefore we should not fully trust them.
• Doubt about the external world: we may be dreaming, and what we perceive as something real may be like the dreams of the external world.
• Doubt about our own reasoning: our understanding can err when it reasons, so we must doubt even ourselves.

The Rules of the Method

The rules of the method are described as: "To the rules that are certain and easy to understand, and that take away the possibility of taking false as true [...]" Descartes does not stay in this destructive phase, since he pretends to reconstruct reality.

He explains all the second phase of this process, which seeks the first truth and certainty, while avoiding long chains of reasoning. This is the basis of reasoning from concrete, intuitive ideas, because they are the only ones that admit no possible error.

Intuition and Deduction

Descartes distinguishes two sources of rational knowledge: intuition, which is the natural light of reason that allows us to capture simple ideas immediately, without any chance of error, and deduction, through which reason allows us to discover the necessary connections among simple ideas.

The Cartesian rules are three:

• Evidence: We must never accept anything as true unless we recognize it clearly and distinctly as such, in our precise understanding (criterion of certainty).
• Analysis: Reduce difficult problems into simple parts.
• Synthesis: Once we have identified the simple elements, we must reassemble them in order, from the simplest to the most complex.

Descartes also insists on enumeration: a complete review, so that nothing is omitted. Through evidence we arrive at the first truth, from which the others are deduced in a clear and distinct way.

The Result of Doubt: The Cogito

Descartes sweeps away all opinions and suspends judgment on all beliefs, sciences, and morals, "in order to keep living." There is one first certainty that resists all the attacks of doubt: even if a malignant spirit deceives him, that spirit cannot prevent him from existing while he thinks. Since my thinking is there, I exist.

This doubt ends with the indubitable truth: cogito ergo sum ("I think, therefore I am"). The thought of the effect and the being of the cause coincide absolutely in my own consciousness, and I am certain, with absolute evidence, that I exist while I doubt.

In the cogito ergo sum, Descartes finds the principle he was searching for: clear, distinct, and firm. It is the foundation on which he builds the whole edifice of philosophy, allowing him to deduce all other truths. It is not a syllogism; it is a first intuition, clear and distinct, an immutable truth. Its limitation is that only the existence of the thinking self is known with certainty.

Analysis and Classification of Ideas

The first truth Descartes seeks must be clear and distinct, beyond all question. Descartes classifies ideas into three groups according to their origin:

• Adventitious ideas: These seem to come from outside us, from our external experience, such as trees and things. We cannot know for certain that the external world exists.
• Factitious ideas: These come from our imagination and will, such as a centaur or a winged horse. They do not have real existence.
• Innate ideas: These are born with the understanding and are part of our nature.

This is the controversial, fundamental affirmation of rationalism: the innate principles of the understanding, the first clear and distinct ideas, such as the principles of identity and non-contradiction, and some metaphysical principles (Meditations, Third Meditation).