Descartes (René Descartes), the philosopher of “I think therefore I am” (“Cogito ergo sum”) was born on March 31, 1596 in La Haye, in Touraine.
In 1604 he entered the Jesuit college of La Flèche and remained here until 1612. Later, in the Discourse on the method, Descartes himself conducted a close criticism of the methods and contents of the education received in the Jesuit college, considering them unsuitable for promoting the critical spirit of the students.
Between 1619 and 1630 Descartes composed Rules for directing the genius. In this period Descartes is in the militia and participates in the Thirty Years’ War, but the military custom of the time leaves the nobles ample freedom and the philosopher can therefore travel at will throughout Europe, devoting himself to the studies of mathematics and physics. , and continuing to elaborate its own doctrine of the method.
In 1628 he settled in Holland, both to enjoy the philosophical and religious freedom that is characteristic of the country and to be able to work at ease, without being distracted by those obligations of society that in Paris and in the provinces would steal a lot of time.
In the meantime he began to compose a treatise on metaphysics and resumed the study of physics: he plans to write a treatise on the world and call it Treatise on light. But the condemnation of Galilei (22 June 1633) leads him to abandon the idea of publishing the work, in which he supports the Copernican doctrine.
Later he chooses to divulge at least some of the results achieved, articulating them in the three essays on Diopter, Meteors, and Geometry; to these three works he prefaces a preface entitled Discourse on method, published in Leiden in 1637.
He then resumes, and concludes, the drafting of the metaphysical treatise published in 1641 with the title Meditations on philosophy before.
Later Descartes reworked the treatise on the world giving it the form of a summary intended for schools: the Principles of Philosophy (1644).
The correspondence with Princess Elizabeth of the Palatinate then suggests the idea of the psychological monograph The passions of the soul, published in 1649. In this same year, the philosopher yields to the repeated invitations of Queen Christina of Sweden and goes to settle in her court. In October he arrived in Stockholm, but in the harsh Nordic winter he fell ill with pneumonia and died on 11 February 1650.
Descartes in his writings speaks in the first person: he does not want to teach, but to describe himself.
His discomfort stems from the sense of disorientation felt at the end of the school of La Flèche, where he had successfully assimilated the knowledge of his time without acquiring, however, any criteria to distinguish the true from the false. In fact, Descartes states that philosophy must not be purely speculative, but also practical, for which man can become the master and possessor of nature.
Consequently, the method must be a single and simple guideline, which helps man in both the theoretical and practical fields and which has as its ultimate goal the advantage of man in the world.
This is what he writes in the Rules for directing ingenuity together with the awareness that human wisdom is one, what are the objects to which it applies, because one is man in his various activities.
Since mathematics already possesses the method, it will be enough to understand it, abstract it, justify it and bring it back to man.
The following are the rules of the Cartesian method:
- evidence: to accept as true only what is evident, that is clear and distinct, excluding any element on which some form of doubt is possible;
- analysis: break down each complex problem into its simplest elements;
- synthesis: going back from the simple to the complex;
- enumeration and review: enumerate all the elements identified through the analysis and review all the steps of the summary.
The method, however, does not have its own justification in itself, but needs to be philosophically legitimized. It therefore goes back to man as subjectivity, or as reason.
Descartes believes it is necessary to make a radical critique of all the knowledge already given and, therefore, to doubt everything and consider at least temporarily as false everything about which doubt is possible. If a principle is found that resists doubt, it will be so firm that it can be taken as the foundation of all other knowledge. Hence the name of the methodical doubt, which initially concerns sensitive knowledge, but which with the hypothesis of the evil genius – an evil power, which could have created humanity (not being man aware of his origin), making us what is false and absurd appear clear and evident – it also extends to mathematical knowledge and becomes hyperbolic or universal doubt.
The only truth that escapes doubt (as doubt itself confirms it) is the following: cogito ergo sum¹ (I think therefore I am). A revolutionary declaration with respect to the then dominant philosophical-theological creed, which placed at the center not the relativity and responsibility of the subject, but the authority of God and of religious law.
¹Cogito ergo sum “I think therefore I am”; the famous maxim is part of a broader sentence by the French philosopher Descartes which reads dubito ergo sum, vel quod item est, cogito ergo sum, “I doubt therefore I am, or what is the same, I think therefore I am”.
The expression means that I can doubt everything, but not the fact that I am doubting, that is, that I am thinking; but if I think (cogito) I exist (I am) (sum), then the ability to doubt is the basis of the certainty of existing.