Descartes' Rationalism and Method

Descartes' Knowledge

Rationalism is the philosophy initiated by Descartes. Reason is the only power that can lead to knowledge of the truth. Descartes, aided by reason and motivated by the disappointment generated by most of the knowledge he acquired, proposes the development of a scientific method that would unite all the sciences. He chooses to formulate the mathematical method, aiming for universally accepted solutions.

The Cartesian Method

His new method is based on the pillars of intuition and deduction, with conclusions being apparent through reason. Thus, he tries to build a method which brings us to absolute truth.

Intuition, being one of the pillars of the new method, is revealed as the search for the first indubitable truth on which to pursue the deductive process. Finding that first precept is certainly a question of universal certainty.

The Method of Doubt

Therefore, Descartes doubts the senses because doubt leads to mistakes. He doubts the external world because it does not establish a boundary between the conscious and dream world. He doubts the arguments of reason because they may contain errors. And he doubts himself because he believes that there is an evil genius that leads him to mistakes.

Rules of the Method

Furthermore, the aim is to achieve accurate truth. Thus, we avoid error. The application of the method is restricted by its normal rules, which are:

• Evidence
• Analysis
• Synthesis
• Enumeration

Ultimately, the entire method reduces to the evidence that must be achieved for the first truth, from which one can figure out the rest of the truths.

The First Truth: Cogito Ergo Sum

As we have seen, the method sweeps away everything at a stroke, but there is certainly an intuitive, concrete reality: that human beings can think. And this leads Descartes to the conclusion: "I think, therefore I am," or Cogito ergo sum. He has found a clear idea, like a syllogism, an immutable truth.

Classification of Ideas

From this truth arises the classification of ideas:

• Adventitious ideas (from external experience)
• Fictitious ideas (from imagination)
• Innate ideas (are natural to man)

These latter are the result of the inability of the other ideas [to provide certainty]. Innate ideas are clear and distinct, and contribute to the affirmation of rationalism.