9. Rene Descartes (1596AD - 1650AD)

1. In science, Descartes discarded tradition and supported rationalization and logic rather than ideas based upon experiences. Mathematics was his greatest interest; building upon the work of others, he originated the Cartesian coordinates and Cartesian curves; he is often said to be the founder of analytical geometry. He contended that emotion was finally physiological at base and argued that the control of the physical expression of emotion would control the emotions themselves.
2. Descartes’ main method of acquisition of knowledge was to doubt everything. This meant that to him the existence of everything was doubtful and anything that he is feeling or he is seeing may be an illusion. By logically, following his skepticism and his doubt Descartes had come to the conclusion that he could doubt everything. For example, when a person sits on a chair, according to Descartes, the chair may not actually exist and it might just be a deception of his or her senses. If a person is eating something, the food might not be there and it might just be his or her senses which are making him believe that he is eating. Following his skepticism and his theory of doubting everything, Descartes reached the conclusion that he could doubt everything in this world except for one; that was the fact that he is doubting. In other words doubting according to Descartes was beyond doubt. This conclusion further led him to conclude that a person can doubt everything in this world except for his thinking. Based on these conclusions, Rene Descartes went on to say that because he thinks therefore he exists. This conclusion was beyond doubts, a correct conclusion. Descartes gave his conclusion as a French term: “Cogito ergo sum.” It means that “I think therefore I am.” In other words, once again thinking signifies the existence of a person.
3. Descartes went on to divide the human being into two parts based on his conclusions of superiority of thoughts. The two parts of the human beings are:
   • The part that thinks - The thinking part was obviously the mind or the soul. It thinks, contemplates, and makes decisions for the body. Then these decisions are conveyed to the part that has to act, which obeys the orders of the thinking part or the mind.
   • The part that acts - The part that acts is the body of the human being. This meant, based on the conclusion that thinking was above anything else, that the mind or the soul was superior to the body.
4. Another great contribution of Rene Descartes was, that based on his conclusion about mind and the body, he proclaimed that the body is like a machine that obeys the orders of the mind. We can discover the operative laws of the body as we can discover the operations of a machine. This meant that Descartes supported the separation of body from the soul. The ancient Greek philosopher Aristotle had put forward the view of the unity of the soul and the body, but Descartes refuted his claim. This separation of body from the soul is called “Dualism” in psychology.
5. Further, Descartes was of the opinion that the soul is metaphysical while the body is physical. The soul of the person and his mind interact and influence each other. This is also proven by the fact that the soul thinks and orders the body which obeys, while on the other hand the body feels and receives stimuli for the soul. In his view, the soul affects the body by a gland that he called “Pineal Gland,” which he thought was the seat of the mind.
6. Descartes also distinguished between two types of thoughts:
• Innate thoughts - Innate thoughts are thoughts that we are born with. In other words these thoughts are inherited.
• Acquired thoughts - On the other hand some thoughts are acquired thoughts that a person acquires through the course of his or her life, based on the experiences that he encounters.