Descartes' Methodical Doubt and the Cogito Axiom

Discourse on Method, Part IV: Commentary

Author: René Descartes

Historical Context and Setting

Descartes was in France, often associated with the Jesuits, during a period of significant transition. National monarchies and empires were rising, and a new economic form, capitalism (later criticized by Marxism), was emerging. Two key intellectual events influenced this work: anthropocentrism (Descartes writing in the first person) and the Scientific Revolution.

Central Theme and Philosophical Problem

The central problem is the search for a first, undeniable truth (axiom) that can serve as a starting point for a secure and universal philosophy. This search establishes existence by finding the subject as a thinking substance, or res cogitans.

Key Philosophical Concepts

Descartes employs methodical doubt to achieve certainty:

• Since men are prone to error in reasoning, the starting point for philosophy cannot be based on flawed or doubtful premises.
• The perfections previously accepted in the mind were no more true than the illusions experienced in dreams.
• The foundational point of Cartesian philosophy is the axiom: Cogito ergo sum (I think, therefore I am).

The Cartesian Method and Types of Ideas

All subsequent ideas are connected through Descartes' systematic method. The method uses the premise "I think" to reach the undeniable conclusion "therefore I am."

Descartes' Three Types of Ideas

• Innate: Ideas we possess at birth.
• Factitious: Ideas derived or constructed from other existing ideas.
• Adventitious: Ideas derived from external experience.

The Four Rules of the Method

The method is governed by four essential rules:

1. Evidence: Do not accept as true anything that can be put in doubt.
2. Analysis: Divide each difficulty into as many parts as possible.
3. Synthesis: Lead thoughts starting with the simplest objects to the most complex.
4. Checking: Be sure not to omit anything in the review process.

The Proof of the Existence of God

After reviewing the ideas present in the mind, Descartes argues:

Ideas of limited objects (such as other people or physical objects) can be produced by the self (the *Ego*), as the self is also limited. However, the idea of God is defined as perfect and represents an infinite substance. A limited substance (the self) cannot be the source of the idea of an infinite perfection. Therefore, the presence of the idea of God in the mind proves that God, the infinite substance, exists and must have placed that idea there.