Cartesian thought

Descartes is considered the father of modern philosophy, and one of the most important rationalist philosophers in history. He accomplished a true philosophical revolution. But what constitutes Cartesian thought?

Descartes’ Historical Context

René Descartes was a great modern philosopher and mathematician. He was born in France in the year 1596 and died in the year 1650. He lived during the period of great cultural and philosophical renaissance that occurred in Europe during the 14th-16th century, and this was fundamental for the formation of Cartesian thought.

Descartes was influenced by the growing scientific advances that were occurring at that time in Europe, and as many traditional scientific theories were being overthrown, a very skeptical environment was created in the intellectual circles of his time, so much so that one of the principles of the Cartesian method would be doubt.

For him, if man wishes to reach the truth, then he must investigate his own knowledge, and to do this, it is necessary to put the “truth” in question.

The Cartesian thought

Discourse on Method

In his work, called Discourse on Method, Descartes exposes the methods necessary to achieve complete and rational knowledge. His philosophical-mathematical method is based on a rational chain of ideas. The four main rules that must be followed in order to reach true knowledge are:

  • Rule of evidence: We should not admit things as true, there should always be the possibility to doubt. One should accept only that which is “evident,” without a shadow of doubt.
  • Rule of analysis: each question must be broken down, so that we can resolve all the difficulties.
  • Rule of synthesis: start our thinking from the simplest and most easily understood things, and then, understand more complex and difficult things.
  • Dismemberment rule: You must analyze things well and list them so that nothing is forgotten.

What is the importance of doubt for Cartesian thought?

The importance of doubt to Cartesian thought is because “doubt” is present in all 4 of Descartes’ rules of method, the first being:

  1. doubt of the known object;
  2. the second, the “doubt of the doubt”;
  3. the third, doubt of what we do not know well;
  4. and the fourth, the doubt of the first three rules;

René Descartes’ highly rational and somewhat skeptical method made doubt the central theme of his thinking, and this led him to a conclusion about his existence: “I think, therefore I am.

Descartes cast doubt on everything that did not seem evident to him. His goal was to achieve an indubitable truth, for what he had learned since childhood were truths handed down by tradition and forced upon him by religious or social authority.

He doubted even the existence of his body and the material world. Then, after much doubting, he came to the conclusion that he could doubt only one thing: the certainty that he thinks, that he is a thinking substance, res cogitans

For him this is the self-evident truth that cannot be doubted, because to doubt whether we really think, we must think, exist.

The divine substance res infinita

The certainty of material reality

After recognizing the thinking substance, Descartes recognizes the divine substance res infinita, this is because, previously he had thought about the idea of “perfect” and came to the conclusion that he was “imperfect” and that, therefore, only a perfect being (God) could have put the idea of perfection in him.

God’s perfection concerns his non-deceptive and truthful nature.

After admitting the idea of God, Descartes admits the existence of material reality, res extensa. God guarantees the true knowledge of things, consciousness guarantees the knowledge of the reality that I am in. In other words, the material world, even if it is not evident, is assured by the existence of God. The world is not an illusion, because God would never deceive us.

If there is God, there is a link between cognitive knowledge and reality.

Cite This Work

Vieira, S. (2021, July 08). Cartesian thought. Filosofia do Início. Retrieved from

Vieira, Sadoque. “Cartesian thought.” Filosofia do Início, July 8, 2021.

Vieira, Sadoque. “Cartesian thought.” Filosofia do Início, 8 Jul. 2021,


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