Descartes' Method for Reaching Universal Truth

The Foundation of Universal Reason

Descartes believes that there is a reason common to all men that, if used properly, can achieve a single truth. Therefore, a method is needed to help us use reason correctly. Furthermore, this method will serve all sciences, since they are all part of a single reality.

Defining the Cartesian Procedure

Descartes defines the procedure as a set of rules "certain and easy, such that those who observe them will never take something false as true and will come to the understanding of all things that do not exceed their capacity."

The Two Powers of Reason

Reason is exercised through two primary powers: intuition and deduction.

Intuition: Clarity and Distinction

The first is the ability to perceive something with no chance of it being false. It is exercised when we are convinced that something is true because it seems clear and distinct. Therefore, intuition is based on clarity and distinction. We understand clarity as the way of presenting something as true, and distinction as the property of those realities which are separate from everything else and become simple realities.

Deduction: Inferring Certainty

Deduction is the ability to infer other facts known with certainty; that is, shifting from other true facts to those that will necessarily also be true.

The Four Rules of the Method

If the powers of the mind are intuition and deduction, the method is based on rules to use reason properly. Descartes believes that a few rules followed rigorously are better than a large number that are not met. The four precepts are:

1. Methodical Doubt: This is the refusal to admit anything as true unless it is absolutely clear, with no room for the slightest doubt. We only accept the obvious, understanding evidence as the mental state that occurs when something is presented clearly and distinctly to the mind.
2. Rule of Analysis: Inspired by mathematics, this involves dividing complex problems into the simplest parts possible. Once presented clearly and distinctly to the spirit, they become evident and exceed doubt.
3. Rule of Synthesis: Also inspired by mathematics, this consists of moving from the simple to the complex in an orderly fashion, constructing complex knowledge from simple and obvious data.
4. Rule of Enumeration: This involves reviewing the previous steps to check for mistakes. Since the system is foundational, everything relies on the accuracy of the previous steps.