Descartes and the nature of the body and mind

The nature of the body

According to Descartes, the body is formed of physical matter and, therefore, has properties common to any material, such as size, weight and motor skills. Thus, the laws that govern physics, also govern the human body.

By this line of reasoning, Descartes noted that some bots at the time created to entertain people, had their movements performed via pipes wherever she went, pressure water causing moving parts of robots (legs, arms and head) win that imitated the movements of the human being.

However, he realized that, even though a human movement, robots just moved because of the water that flowed in their tubes, not being a result of the voluntary action of the machine. Thus, the human being is something far more complex than movements, and can perform actions independent of his will.

This issue caused Descartes prepare the idea of the undulatio reflex, modernly known as reflex Act theory, according to which an external stimulus can generate a body movement that does not depend on the will of the subject, such as the leg moves when a doctor hit in the knee with a small hammer (patellar reflex). By this theory, the reflection behavior does not involve thinking.

The work of Descartes served as subsidy for the scientific hypothesis of prediction of human behavior. This hypothesis says that human behavior could be predicted, since they know the stimuli applied to the subject. Thus, a kebab on the arm, should necessarily generate a withdrawal reaction of the local arm of the stimulus and this reaction is common in all subjects.

This would have created the distinction between humans and animals, the latter being considered as soulless and therefore without feelings or desire, acting only for acts, reflexes similar to robots.

The nature of the mind

According to the theory of Descartes, the mind is immaterial in nature, i.e. has no shape, weight or measure, however, is provided with ability of thoughts and other cognitive processes (cognition = ability to acquire a knowledge), providing the human being information about the outside world.

This ability to separate your mind thinking of the entire physical world. Therefore, to study it is necessary to know how to separate the physical emotional reactions. How the mind has the capacity of thought, perception and desire, she influences the body and is influenced by him. For example, when we perform some action, this decision influences the muscles to perform the desired action. Likewise, when the body receives some stimulus such as light, for example, the mind captures this stimulus, the plays and determines the appropriate response.

For Descartes the single act really real and that is produced by the mind's thought, being all the rest, including the material world to doubt, i.e. everything we see, feel, touch, can be the fruit of our imagination, not really. Just the thought has strength and proof of truth.

Thus, through the mere act of thinking, Descartes proved the existence of thought, without which no one could doubt it. Imagine anything and you'll see that she can be questioned, but the thought not, because the Act of thinking in itself proves the existence of thought. Hence the famous phrase of Descartes "I think, therefore, I exist". Following this reasoning, the thought is the only truth that can't be disputed.

Mind-Body Interaction

The theory of mind-body interaction of Descartes needed through research on the exact point in which occurs this interaction, before it was completed. For him, the mind was a unit and, therefore, should interact with the body in a single point. His research led him to believe that that point was the brain, because he realized that the sensations were traveling to him, where appeared the movements.

It was clear to him that the brain was the centerpiece of the functions of the mind and the only unitary brain structure would be the pineal body (gland located behind the third brain cavity) or conarium. Descartes considered this point as the center of mind-body interaction.

He used the concepts of the mechanism to describe the mind-body interaction. Proposed that the movement of the animal spirit (as it was named the essence of life, the soul) in the tubes causes a nervous impression on the conarium and hence mind produces the sensation. In other words, the amount of physical movements, produces a mental amount or sensations. The reverse also occurs: the mind creates an impression in the conarium and that impression causes the flow of animal spirit until the muscles, resulting in body movement.

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