René Descartes he 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 was decisive for his reformulation of the rationalism, And its inclusion in a mechanistic system.
Descartes (1596-1650) and rationalism
As the skepticism of the Sophists was answered by the rationalism of Plato, Descartes’ rationalism was a response to the humanistic skepticism of the earlier period who, having placed man at the center of the world, did not trust his own strength to support him.
Descartes did not accept the belief of skeptical about the impossibility of knowing, Nor in the weakness of reason. He decided to systematically doubt everything until he found something that was so blatantly true that he couldn’t doubt it.. 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 incontestable truth
He continued on this path, until he discovered that he could not doubt one thing: his own existence as a conscious and thinking being. There is no doubt that it is in doubt, for in doing so, the very action that is denied is performed. Descartes expressed his first indisputable truth with the famous: I think so I am. I think, therefore I exist.
From his own existence, Descartes justified the existence of God by means of arguments already in doubt. He also established the existence of the world and the body itself, as well as the general correctness of perception.
Descartes believed that a correct method of reasoning can discover and prove what is true. Advocates, as a good rationalist, by the deductive method: to discover by reason the obvious truths and to deduce the rest from them. This method is opposed to the inductive method proposed by Francis Bacon and adopted by the empiricists.
Descartes, however, did not rule out the usefulness of the senses, although he believed that facts are of little value until they are ordered by reason.
From philosophy to psychology and knowledge of cognition
Descartes was not the first to justify his own existence in mental activity. Already the first rationalist, Parmenides, He had declared “Because it is the same thing to think and to be”, and Saint Augustine had written “if I am wrong, I exist”, I do not exist “), and only a century before , according to Gomez Pereira: “I know that I know a little, and who knows that there is. So I exist. ” The Cartesian novelty consists in supporting all the sense on the doubt, and to cement “the only certainty in the logical truth”.
From Descartes philosophy will become more and more psychological, Seeking to know the mind through introspection, until the emergence of psychology as an independent scientific discipline in the nineteenth century, based on the study of consciousness by the introspective method (but only for the first generation of psychologists ).
Descartes claims the existence of two types of innate ideas: On the one hand the main ideas, the ones that there is no doubt about, although they are potential ideas that require experience to update. But he also speaks of innate ideas about certain modes of thought (what we would now call processes, without specific content, just modes of operation: now transitivity). This second class of innatism will develop in the 18th century by Side, With its synthetic judgments a priori.
Descartes enriches the theory of Galileo with principles and notions of mechanics, a science which has had spectacular success (clocks, mechanical toys, fountains). But in addition, Descartes is the first to consider the mechanistic and universal principles, applicable to both inert matter and living matter, to microscopic particles and to celestial bodies.
The mechanistic conception of the body in Descartes is as follows: the characteristic of the body is to be nothing of extended, material substance, as opposed to nothing of cogitan or thinking substance.
These different substances interact through the pineal gland (The only part of the brain that doesn’t repeat hemispherically), affecting each other mechanically.
The body has receptor organs and nerves or hollow tubes that communicate internally with certain parts. These tubes are crossed by a kind of filament which, at one end, joins the receptors, and at the other of the pores (like lids) of the ventricles of the brain which, once opened, allow it to pass through the nerves of the brain. , “which influence the muscles causing movement. He therefore did not distinguish between sensory and motor nerves, but he had a rudimentary idea of the electrical phenomenon underlying nerve activity.
René Descartes’ legacy among other thinkers
Will be Galvani, In 1790, who, from the verification that the contact of two different metals produces contractions in the muscle of a frog, demonstrates that electricity is capable of causing in the human body an effect similar to that of the mysterious animals “spirits” “, from which one could easily deduce that the nerve impulse was bioelectric in 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 was born, 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 time of the muscle to be stimulated at different lengths (26 meters per second). The mechanism of the sodium pump was not discovered until 1940.
The importance of the pineal gland
In the pineal gland, Descartes places the point of contact between the mind (nothing cogitan, thinking substance) and the body., Perform a dual function: the control of excessive movements (passions) and, above all, of consciousness. As Descartes did not distinguish between consciousness and consciousness, he deduced that the animals, which did not possess a soul, were like perfect machines without a psychological dimension, that is to say without feelings or consciousness. now Gómez Pereira he had denied the psychological quality of sensation in animals, leaving their movements reduced to complicated mechanical responses of nerves acting from 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’ mechanism. The psyche has been configured, on the other hand, only as a thought, A position that would reappear later with cognitive psychology, if it is defined as the science of thought. For Descartes, however, thought was inseparable from consciousness.
However, a feature common to these approaches, as is largely the case in the rest of modern science, is the radical separation between the subject who knows and the object of knowledge. Movement and thought will become automatic, proceeding through causal chains predetermined in time.