The valuable contributions of René Descartes to psychology.

Review of History of Psychology: Descartes' contributions to the study of the mind.

René Descartes was a typical example of a Renaissance intellectual: soldier, scientist, philosopher, and speculative psychologist..

He studied with the Jesuits, and his training was both metaphysical and humanistic. His influence has been decisive for his reformulation of rationalismand its inclusion in a mechanistic system.

Descartes (1596-1650) and Rationalism

Just as the skepticism of the sophists was answered with Plato's rationalism, Descartes' rationalism was a response to the humanistic skepticism of the previous period which, having placed man at the center of the world, did not trust in his own powers to sustain him.

Descartes did not accept the skeptics' belief in the skeptics' belief in the impossibility of knowledgenor in the weakness of reason. He decided to systematically doubt everything until he found something that was so blatantly true that it could not be doubted.. Descartes discovered that he could doubt the existence of God, the validity of sensations (empiricist axiom), and even the existence of his body.

Cogito ergo sum: the first and indubitable truth.

He continued along this path, until he discovered that he could not doubt one thing: his own existence as a self-conscious and thinking being. One cannot doubt that one doubts, because, in doing so, one performs the very action that one denies. Descartes expressed his first indubitable truth with the famous: Cogito ergo sum. I think, therefore I am.

From his own existence, Descartes justified the existence of God by means of arguments that were already questioned at that time. He also established the existence of the world and of his own body, and the general accuracy of perception.

Descartes believed that a correct method of reasoning can discover and prove what is true. He advocates, as a good rationalist, the deductive method: to discover by reason the obvious truths and to deduce from them the rest.. This method is opposed to the inductive method proposed by Francis Bacon and adopted by the empiricists.

Descartes, however, did not discard the usefulness of the senses, although he thought that facts have little value until they are ordered by reason.

From Philosophy to Psychology and Knowledge about Cognition

Descartes was not the first to justify one's existence in mental activity. Already the first rationalist, Parmenideshad already asserted "For it is the same thing to think and to be(for Descartes, on the other hand, who doubts any transcendent Truth, the question would have been "if I deceive myself, I do not exist"), and only a century earlier, according to Gomez Pereira: "I know something, and whoever knows exists exists" (for Descartes, on the other hand, who doubts any transcendent Truth, the question would have been "if I deceive myself, I do not exist").I know that I know something, and he who knows exists. Therefore I exist."The Cartesian novelty lies in sustaining all meaning on doubt, and founding the only certainty in logical truth.

From Descartes onwards, philosophy will become more and more psychological.The first generation of psychologists, however, was the first generation of psychologists, and Descartes affirmed the existence of the mind through introspection, until the appearance of psychology as an independent scientific discipline in the 19th century, based on the study of the consciousness through the introspective method (although only for the first generation of psychologists).

Descartes affirms the existence of two types of innate ideasOn the one hand, the main ideas, those that cannot be doubted, although they are potential ideas that require experience to be actualized. But he also speaks of innate ideas with respect to certain ways of thinking (what we would now call processes, without specific contents, only ways of operating: for example, transitivity). This second kind of innatism will be developed in the eighteenth century by Kantwith his synthetic a priori judgments.

Universal Mechanicism

Descartes enriches the theory of Galileo with principles and notions of mechanics, a science that had achieved spectacular successes (clocks, mechanical toys, fountains). But Descartes was also the first to consider mechanistic principles as universal, applicable to inert matter as well as to living matter, to microscopic particles as well as to celestial bodies.

The mechanistic conception of the body in Descartes is as follows: the characteristic of the body is that of being res extensa, material substance, as opposed to res cogitans or thinking substance.

These different substances interact through the pineal gland pineal gland (the only part of the brain that does not repeat itself hemispherically), affecting each other mechanically.

The body has receptor organs and nerves or hollow tubes that communicate internally some parts with others. These tubes are traversed by a kind of filaments which at one end are united with the receptors, and at the other with some pores (like lids) of the ventricles of the brain which, when they open, allow the "animal spirits" to flow through the nerves, which influence the muscles causing movement. He did not, therefore, distinguish sensory and motor nerves, but he had a rudimentary idea of the electrical phenomena underlying nervous activity.

The legacy of René Descartes on other thinkers

It will be Galvaniin 1790, who, based on the proof that the contact of two different metals produces contractions in the Muscle of a frog, demonstrated that electricity is capable of provoking in the human body an effect similar to that of the mysterious "animal spirits", from which it could easily be deduced that the nervous impulse was of a bioelectrical nature. Volta attributed this effect to electricity, and Galvani understood that it was generated by the contact of two metals; from the discussion between the two arose, in 1800, the discovery of the battery, which initiated the science of electric current.

HelmholtzIn 1850, thanks to the invention of the myograph, he measured the reaction delay of the muscle when stimulated from different lengths (26 meters per second). The mechanism of the sodium pump was not discovered until 1940.

The importance of the pineal gland

Descartes locates in the pineal gland the point of contact between the spirit (res cogitans( res cogitans, thinking substance) and the bodyThe pineal gland has a double function: control over excessive movements (passions) and, above all, consciousness. Since Descartes does not distinguish between consciousness and conscience, he deduced that animals, which did not possess a soul, were like perfect machines without psychological dimension, i.e. without feelings or conscience. Already Gómez Pereira had already denied the psychological quality of sensation in animals, leaving their movements reduced to complicated mechanical responses of nerves actuated by the brain.

The result was that a part of the soul, traditionally associated with movement, became an intelligible part of nature and, therefore, of science. Psychological behaviorism, which defines psychological behavior as movement, is indebted to Descartes' mechanicism. The psychism was configured, on the other hand, only as thought, a position that would reappear later on.This position would reappear later with cognitive psychology, if the latter is defined as the science of thought. For Descartes, however, thought was inseparable from consciousness.

One feature, however, common to these approaches, as is broadly the case in the rest of the modern sciences, is the radical separation between the knowing subject and the object of knowledge. Both movement and thought will become automatic, proceeding according to causal chains predetermined in time.