Biography of René Descartes | Mathematician and philosopher.
(La Haye, France, 1596 - Stockholm, Sweden, 1650) French mathematician and philosopher. After  the splendour of ancient Greek philosophy and the apogee and crisis of  Scholasticism in medieval Europe, the new airs of the Renaissance and  the scientific revolution that accompanied it would result, in the 17TH  century, the birth of modern philosophy. 
René Descartes
Supposed portrait of Descartes
René Descartes
Descartes with the Queen Cristina of Sweden
René Descartes
René Descartes
The first of the philosophical ISMS of modernity was rationalism; Descartes,  its initiator, proposed to make tabula rasa of the tradition and  construct a new building on the basis of reason and the effective  methodology of mathematics. Their «methodic doubt» not questioned God but quite the opposite; However, like Galileo, he had to suffer persecution because of their ideas. 
Biography
René  Descartes educated are in the Jesuit College of La Flèche (1604-1612),  then one of the most prestigious in Europe, where it enjoyed a certain  treatment of favour in view of his delicate health. Studies carried out in this Centre had a decisive importance in his intellectual formation; known turbulent youth of Descartes, no doubt in La Flèche base of their culture was based. Traces of such education manifested objective and sharply in all the philosophical ideology of the Sage. 
René Descartes
Program  of studies of that school (according to various testimonies, among  which figure the same Descartes) was varied: revolved essentially around  the traditional teaching of the Liberal Arts, which added notions of  Theology and practical exercises useful for the life of the future  gentlemen. Even if the program itself should be  rather light and oriented in essentially practical sense (not intended  form wise, but men prepared for high political missions to rank allowed  them to suck), more active or curious students could complete them on  their own through personal readings. 
Years later, Descartes would bitterly criticize received education. It  is perfectly possible, however, that their discontent in this regard  not so much philosophical considerations about the natural reaction of a  teenager who for so many years was subjected to a discipline, and the  feeling of uselessness of everything I learned in relation to their  possible future occupations (militia or bureaucracy). After  his time at La Flèche, Descartes was awarded the title of Bachelor  degree in law from the Faculty of Poitiers (1616), and at the age of  twenty-two left for the Netherlands, where he served as a soldier in the  army of Maurício de Nassau. In 1619 he enlisted in the ranks of the Duke of Bavaria. 
As it reported the own discards in the Discourse of the method, during the harsh winter of that year found himself locked in a town in the upper Danube, possibly near Ulm; There remained locked up next to a stove and away from any social relationship, without more company than of his thoughts. In  such a place, and after a strong crisis of skepticism, revealed it the  foundations on which to build his philosophical system: the mathematical  method and the principle of the cogito, ergo sum. Victim  of a feverish excitement, during the night of November 10, 1619 had  three dreams, during which sensed his method and knew its profound  vocation to devote his life to science. 
Supposed portrait of Descartes
After  relinquishing the military life, Descartes traveled through Germany and  the Netherlands and returned to France in 1622, to sell their  possessions and thus ensure an independent life; He spent a season in Italy (1623-1625), and settled in Paris, where related to the majority of scientists of the time. 
In  1628, he decided to settle in Holland, a country in which scientific  research enjoyed great consideration and, in addition, were favored by a  relative freedom of thought. Descartes  considered the most favorable place to meet philosophical and scientific  objectives that had been set, and resided there until 1649. 
The five first years mainly dedicated to develop its own system in the world and its conception of man and of the human body. In 1633 should already have very advanced a broad text of metaphysics and physics entitled treatise on light; However, the news of the condemnation of Galileo frightened him, since Descartes also argued in that work the movement  of the Earth, opinion that believed not objectionable from the  theological point of view. As I was afraid that  such text could contain reprehensible theories, he renounced his  publication, which would take place posthumously. 
René Descartes
His famous discourse on the method, presented as a prologue to three scientific essays appeared in 1637. By  audacity and newness of concepts, the genius of the discoveries and the  momentum of ideas, the book was enough to give the author an immediate  and deserved reputation, but also therefore caused a flood of  controversies, which henceforth would be tiring and dangerous life.
Descartes proposed in the Speech a  methodical doubt, that to refer to trial all the knowledge of the time,  although, unlike the skeptics, his was a doubt Search recent principles  on which solidly build knowledge-oriented. This  principle found him in the existence of one's consciousness that doubt,  in his famous formulation 'I think, therefore I exist'. On  the basis of this first evidence could partly retrace the path of their  skepticism, finding the = s ultimate guarantor of the truth of the  evidence of reason, which manifest themselves as "clear and distinct"  ideas in God. 
The  Cartesian method, Descartes proposed for all sciences and disciplines,  is to break down complex problems into parts progressively easier to  find its basic elements, simple ideas, presented to reason in a clear  way, and proceed from them, by synthesis, to rebuild the entire complex,  requiring every new relationship established between simple ideas the  same evidence of these. Scientific trials that followed the speech offered a compendium of his physical theories, notably his formulation  of the law of inertia and a specification of their method for  mathematics. 
The  foundations of his mechanistic physics, making the extension the main  property of the material bodies, were exposed by Descartes in metaphysical meditations (1641), where he developed his demonstration of the existence and the  perfection of God and the immortality of the soul, already pointed in  the fourth part of the discourse on the method. The radical mechanism of physical theories of Descartes, however, determined that they were later overcome. 
As  grew his fame and the dissemination of their philosophy, they  arreciaron the criticisms and threats of religious persecution by some  academic and ecclesiastical, authorities in the Netherlands and France. Born in the middle of discussions, metaphysical meditations were earning him several allegations promoted by the theologians; something like that happened during the drafting and publishing other works their own, such as the principles of philosophy (1644), and the passions of the soul (1649). 
Descartes with the Queen Cristina of Sweden
Tired  of these struggles in 1649 Descartes accepted an invitation from the  Queen Cristina of Sweden, who urged him to move to Stockholm as his  tutor of philosophy. They had previously  maintained an intense correspondence, and, despite the intellectual  satisfaction that he provided Cristina, Descartes was not happy in "the  country bears, where the thoughts of men appear, like water,  metamorphose in ice". He was accustomed to the  comforts and was not easy to get up every day at four in the morning, in  the dark and cold winter gnawing you the bones, to indoctrinate a Queen  who did not have more free time because of their obligations. The  madrugones Spartans and cold could more than the philosopher, who died  of pneumonia in early 1650, five months after their arrival. 
The philosophy of Descartes
Descartes  is considered the initiator of the modern rationalist philosophy by its  approach and resolution of the problem of finding a foundation of  knowledge that ensures its certainty, and as the philosopher who is the  final breaking point with the scholastic. In the discourse on the method (1637), Descartes said that its project to develop a doctrine based on  completely new principles came from disenchantment to philosophical  teachings he had received. 
Convinced  that the entire reality responded to a rational order, its purpose was  to create a method that made possible to achieve in the whole area of  knowledge the same certainty that provide its arithmetic and geometry. His method, exposed in the speech, is composed of four precepts or procedures: not accept as true anything which does not have absolute certainty that is it; break down each problem in its minimal parts; go more understandable to the most complex; and, finally, completely review the process to ensure that there is no omission.
René Descartes
The system used by Descartes to meet the first precept and achieve certainty is «methodical doubt». According  to this system, Descartes puts into question all their knowledge  acquired or inherited, the testimony of the senses and even his own  existence and that of the world. Now, in doubt there is something of what we can't doubt: the same doubt. Put another way, we can't doubt of that we're doubting. Thus we arrive at a first obvious and absolute certainty that we can accept as true: doubt.
I think, then I exist
The doubt, then reason Descartes, is thinking: doubt is thinking. Now, you cannot think there is. The  suspension of any really concrete, the same doubt, is an act of thought  which immediately implies the existence of thinking "I". Hence his famous formulation: I think, therefore I am (cogito, ergo sum). We can therefore be firmly confident of our thinking and our existence. We exist and we are a thinking, spiritual substance.
From this made Descartes all his philosophy. Since  you can not rely on things whose existence has not been demonstrated,  Descartes tries to splitting of thought, whose existence has already  been demonstrated. Although it can refer to the outside, thought does not consist of things, but of ideas about things. The  question that arises is if there are in our thought any idea or  representation that we can perceive with the same «clarity» and  «distinction» (the two Cartesian criteria of certainty) that we perceive  as thinking subjects.
Kinds of ideas
Descartes then goes to revise all the knowledge that had previously ruled out at the start of their search. And  to reconsider them observed that representations of our thinking are of  three kinds: ideas "innate", like beauty or justice; "adventitious" ideas that come from outside, such as the star or horse things; (e) 'fictitious' ideas, which are mere creations of our fantasy, as for example the monsters from mythology.
«Fictional» ideas, mere sum or combination of other ideas, not obviously serve as handle. And  with regard to 'adventitious' ideas, originated by our experience of  foreign things, act with caution, since we are not sure there are  external things. It might, says Descartes,  "adventitious" knowledge, that we consider relevant to impressions of  things that actually exist outside of us, had been caused by a  "malignant genius" who wanted to fool us. Or what we think the reality is not more than an illusion, a dream of which we have not awakened.
Of the self to God 
But  considering "innate" ideas, without sensitive outer correlative, find  in us a very unique idea, because it is fully away of what we are: the  idea of God, a supreme being infinite, eternal, unchanging, perfect. Humans, finite and imperfect, can form ideas like "triangle" or "justice". But  the idea of an infinite and perfect God can not be born of an  individual finite and imperfect: has necessarily been placed in the  minds of men by the same Providence. Therefore, God exists; and  being as it is a perfect being, cannot deceive or delude ourselves, or  allow the existence of a "malignant genius» who fooled us, making us  believe that it is real to a world that does not exist. The world, therefore, also exists. The existence of God thus ensures the possibility of a true knowledge.
This  demonstration of God's existence is a variant of the ontological  argument, already employed in the 12th century by Saint Anselmo de  Canterbury, and she was harshly attacked by the adversaries of  Descartes, who accused him of falling into a vicious circle: the  criteria of clarity and distinction are used to prove the existence of  God and thus to ensure knowledge of the outside world , but the reliability of such criteria is justified also by the existence of God. Such  a criticism aims not only to the validity or invalidity of the  argument, but also to the fact that Descartes does not seem to apply at  this point its own methodology.
RES cogitans and res extensive
Admitted the existence of the external world, Descartes goes to examine what is the essence of beings. Please  enter here your concept of substance, which is defined as what «exists  in such a way that you only need himself to exist». Substances manifested through their modes and attributes. They attributes are properties, or essential qualities that reveal the identification  of the substance, i.e., are those properties without which a substance  would be such substance. Modes, on the other hand, are not properties or qualities essential, but merely accidental.
René Descartes
The  attribute of the bodies is the extension (a body can not lack of  extension, if you lack of it it is not a body), and all other  determinations (color, shape, position, movement) are only modes. And the attribute of the spirit is the thought, because the spirit 'always thinks'. There is, therefore, a thinking substance (res cogitans), devoid of extension and whose attribute is thinking, and a substance that makes up the physical bodies (wide res),  whose attribute is the extension, or, if you prefer, the  three-dimensionality, quantitatively measurable in a space of three  dimensions. Both are completely separate and mutually irreducible. It is what is called the Cartesian "dualism".
To  the extent that the substance of the matter and bodies is the  extension, and that this is observable and measurable, it must be  possible to explain their moves and changes by mathematical laws. This  leads to the mechanistic view of nature: the universe is like a huge  machine whose performance we can get to know through the study and  discovery of the mathematical laws governing it.
The communication of substances
The radical separation between matter and spirit is applied rigorously, in principle, to all beings. Thus, animals are more than complex machines. However, Descartes makes an exception when it comes to the man. Since it is composed of body and soul, and as body material and extensive (wide res), and the thinking and spiritual soul (res cogitans), should be among them an absolute isolation. 
However,  in the Cartesian system does not, but that the soul and body  communicate among themselves, not to the classic mode, but in a unique  way. The soul is seated in the pineal  gland, located in the brain, and from there ruled the body as «the nauta  governs the ship» by animal spirits, intermediates between spirit and  body by way of fine particles of blood, transmitting orders of the soul  to the body. Solution of Descartes was not satisfactory, and the so-called problem of communication of substances would be long discussed by later philosophers.
Its influence
So  by not having successfully defined the notion of substance as by franco  dualism established between two substances, Descartes raised the  fundamental problems of 17TH-century European speculative philosophy. Understood  as strict and closed system, Cartesian philosophy was not excessive  followers and lost its validity in a few decades. However,  Cartesian philosophy became point of reference for many thinkers, a few  times to try to resolve the contradictions that locked up, as did the  Rationalist thinkers, and others to rebut it frontally, as the  empiricists. 
Thus,  the German philosopher Gottfried Wilhelm Leibniz and Baruch Spinoza  Dutch established forms of psycho-physical parallelism to explain the  communication between body and soul. Spinoza,  in fact, went further, and said that there was a single substance,  which included in itself the order of things and ideas, and that the res cogitans and res wide were not but attributes, which came to Pantheism.
From  a completely opposite point of view, the British empiricists John Locke  and Thomas Hobbes denied that the idea of a spiritual substance would  be provable; They stated that there is no innate ideas, and that philosophy should be reduced to the field of what is known by experience. The  Cartesian conception of a mechanistic universe, finally, decisively  influenced the genesis of classical physics, founded by Newton. 
It  is not too much say, in sum, that although Descartes did not resolve  many of the problems raised, such problems became central issues of  Western philosophy. In this sense,  modern philosophy (rationalism, empiricism, idealism, materialism,  phenomenology) can be considered a development or a reaction to the  Cartesian philosophy.
Extracted from the website: Biografías y Vidas
