René Descartes

René Descartes ( or ; ; Latinized: Renatus Cartesius; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science.

Mathematics was paramount to his method of inquiry, and he connected the previously separate fields of geometry and algebra into analytic geometry.

Descartes spent much of his working life in the Dutch Republic, initially serving the Dutch States Army, later becoming a central intellectual of the Dutch Golden Age.

Although he served a Protestant state and was later counted as a deist by critics, Descartes was Roman Catholic.

René Descartes was born in La Haye en Touraine, Province of Touraine (now Descartes, Indre-et-Loire), France, on 31 March 1596.

In May 1597, his mother Jeanne Brochard, died a few days after giving birth to a still-born child.

Descartes' father, Joachim, was a member of the Parlement of Rennes at Rennes.

René lived with his grandmother and with his great-uncle.

Although the Descartes family was Roman Catholic, the Poitou region was controlled by the Protestant Huguenots.

In 1607, late because of his fragile health, he entered the Jesuit Collège Royal Henry-Le-Grand at La Flèche, where he was introduced to mathematics and physics, including Galileo's work.

While there, Descartes first encountered hermetic mysticism.

After graduation in 1614, he studied for two years (1615–16) at the University of Poitiers, earning a Baccalauréat and Licence in canon and civil law in 1616, in accordance with his father's wishes that he should become a lawyer.

From there, he moved to Paris.

In Discourse on the Method, Descartes recalls:

"I entirely abandoned the study of letters. Resolving to seek no knowledge other than that of which could be found in myself or else in the great book of the world, I spent the rest of my youth traveling, visiting courts and armies, mixing with people of diverse temperaments and ranks, gathering various experiences, testing myself in the situations which fortune offered me, and at all times reflecting upon whatever came my way to derive some profit from it."

In accordance with his ambition to become a professional military officer in 1618, Descartes joined, as a mercenary, the Protestant Dutch States Army in Breda under the command of Maurice of Nassau, and undertook a formal study of military engineering, as established by Simon Stevin.

Descartes, therefore, received much encouragement in Breda to advance his knowledge of mathematics.

In this way, he became acquainted with Isaac Beeckman, the principal of a Dordrecht school, for whom he wrote the Compendium of Music (written 1618, published 1650).

While in the service of the Catholic Duke Maximilian of Bavaria from 1619, Descartes was present at the Battle of the White Mountain near Prague, in November 1620.

According to Adrien Baillet, on the night of 10–11 November 1619 (St. Martin's Day), while stationed in Neuburg an der Donau, Descartes shut himself in a room with an "oven" (probably a cocklestove) to escape the cold.

While within, he had three dreams, and believed that a divine spirit revealed to him a new philosophy.

However, it is speculated that what Descartes considered to be his second dream was actually an episode of exploding head syndrome.

Upon exiting, he had formulated analytic geometry and the idea of applying the mathematical method to philosophy.

His best known philosophical statement is "cogito, ergo sum" ("I think, therefore I am"; Je pense, donc je suis), found in Discourse on the Method (1637, in French and Latin, 1644) and Principles of Philosophy (1644, in Latin, 1647 in French).

The statement has either been interpreted as a logical syllogism or as an intuitive thought.

Descartes' Meditations on First Philosophy (1641) continues to be a standard text at most university philosophy departments.

Descartes' influence in mathematics is equally apparent; the Cartesian coordinate system was named after him.

He is credited as the father of analytic geometry—used in the discovery of infinitesimal calculus and analysis.

Descartes was also one of the key figures in the Scientific Revolution.

Many elements of Descartes' philosophy have precedents in late Aristotelianism, the revived Stoicism of the 16th century, or in earlier philosophers like Augustine.

In his natural philosophy, he differed from the schools on two major points.

First, he rejected the splitting of corporeal substance into matter and form; second, he rejected any appeal to final ends, divine or natural, in explaining natural phenomena.

In his theology, he insists on the absolute freedom of God's act of creation.

Refusing to accept the authority of previous philosophers, Descartes frequently set his views apart from the philosophers who preceded him.

In the opening section of the Passions of the Soul, an early modern treatise on emotions, Descartes goes so far as to assert that he will write on this topic "as if no one had written on these matters before."

Descartes has often been called the father of modern philosophy, and is largely seen as responsible for the increased attention given to epistemology in the 17th century.

He laid the foundation for 17th-century continental rationalism, later advocated by Spinoza and Leibniz, and was later opposed by the empiricist school of thought consisting of Hobbes, Locke, Berkeley, and Hume.

The rise of early modern rationalism—as a systematic school of philosophy in its own right for the first time in history—exerted an influence on modern Western thought in general, with the birth of two rationalistic philosophical systems of Descartes (Cartesianism) and Spinoza (Spinozism).

It was the 17th-century arch-rationalists like Descartes, Spinoza, and Leibniz who have given the "Age of Reason" its name and place in history.

Leibniz, Spinoza, and Descartes were all well-versed in mathematics as well as philosophy, and Descartes and Leibniz contributed to science as well.