René Descartes

Western Philosophy 17th-century philosophy
René Descartes. Portrait by Frans Hals, 1648.
Name	René Descartes
Birth	31 March 1596 La Haye en Touraine, Indre-et-Loire, France
Death	11 February 1650 (aged 53) Stockholm, Sweden
School/tradition	Cartesianism, Rationalism, Foundationalism
Main interests	Metaphysics, Epistemology, Science, Mathematics
Notable ideas	Cogito ergo sum, Methodic Doubt, Cartesian coordinate system, Cartesian dualism, ontological argument for existence of God; regarded as a founder of Modern philosophy
Influences	Plato, Aristotle, Ibn al-Haytham, Averroes, Avicenna, al-Ghazali, Anselm of Canterbury, St. Augustine, Thomas Aquinas, William of Ockham, Francisco Suárez, Marin Mersenne, Sextus Empiricus, Michel de Montaigne, Duns Scotus
Influenced	Baruch Spinoza, Thomas Hobbes, Antoine Arnauld, Nicolas Malebranche, Pascal

René Descartes (March 31, 1596 – February 11, 1650) was a famous French philosopher and physicist. He wrote two books that are very important in the fields of physics and philosophy.

Descartes and physics (the study of the world)

In his Discourse on Method (1637) Descartes wrote about the scientific method, that he had invented. He also wrote about shapes (Geometry), light (Dioptrics), and the weather (Meteorology). He then came up with a way of describing shapes by using coordinates, and also a theory of what a rainbow is. Descartes' physics was important for a later thinker, Sir Isaac Newton who said about him and James Hook: "If I have seen further it is because I was standing on the shoulders of giants!"

Descartes and philosophy (the study of abstract ideas)

In his Meditations on First Philosophy (1641) Descartes used his scientific method to look at philosophical questions. He argued against skepticism (the view that the world was not real, and did not exist).

He found that he himself must be real (exist) because he felt that he was thinking and if he was thinking then he must be real. This is because if he was not real then how would he have this feeling that he was thinking. This view was shortened by him into the Latin saying Cogito ergo sum meaning 'I think therefore I am'.

He also thought he could show that God exists, in the same way that he felt that he was thinking. Descartes said that God was the same as infinity and that he could clearly see infinity because he could think of every larger object but no largest object. Descartes said that if God exists then the world must exist as well, as God was good and would not let us think the world is real (exists) if it didn't.

Finally, Descartes thought that because he knew he was thinking, but could only know anything else about himself (for example that he had two arms and two legs) because he knew that God exists, then he must in fact be made up of two things: the mind that thinks, and the body that does not. This is called "Cartesian Dualism".

Descartes used a lot of ideas related to Plato, while most people at that time used ideas related to Aristotle. He is often called a rationalist, because he looked inside his mind for answers to his questions. Although Descartes wanted to fight skepticism, his description of it in the meditations has become very famous and is often called Cartesian Skepticism after him.

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