Fortunately for the world, Rene Descartes lived. Descartes received a Jesuit education at Jesuit College of La Fleche. At age seventeen Descartes went to the University of Poitiers. Descartes received degrees in civil and canon law. In 1618, Descartes became healthy enough to enlist in the army of Prince Maurice of Nassau.
During a campaign on November 10, 1619 Descartes escaped the cold weather by shutting himself in a heated room. In this heated room Descartes had visions. Descartes described flashes of light and thunder, leading to the formation of analytical geometry and the method of applying mathematical modeling to philosophy.
The Stanford Encyclopedia of Philosophy includes an entry by Gary Hartfield titled Rene Descartes. Hartfield writes the following concerning Descartes, “During the course of his (Descartes) life, he was a mathematician first, a natural scientist or ‘natural philosopher’ second, and a metaphysician third.” However, it was plain to see that Descartes played a bit in an exhaustive list of studies including mathematics, physics, astronomy, anatomy, physiology, psychology, metaphysics, epistemology, ethics, and theology. In the pursuit of knowledge, Descartes thought he should start with a clean slate. Descartes stated, “The chief cause of our errors is to be found in the prejudice of our childhood.” To avoid this, Descartes started out by doubting everything. Robert C. Solomon, author of Introducing Philosophy, states that Descartes “would accept as true only those things that were demonstrably true to him.”
Descartes needed to find one proposition that was beyond doubt. Descartes could not doubt his own existence, so he exclaimed one of the most famous thoughts in philosophy, “Je pense, donc je suis.” (I think, therefore I am.) He reasoned that doubt was a thought, and thought could not take place without someone to think it. This led to a century long Great Debate in Western Europe between faith and reason.
Descartes published many important works on geometry, philosophy, metaphysics, and more. These works include:
• the Discourse on the Method (in French, 1637)
• with its essays, the Dioptrics, Meteorology, and Geometry
• the Meditations on First Philosophy (i.e., on metaphysics)
• with its Objections and Replies (in Latin, 1641)
• the Principles of Philosophy, metaphysics and philosophy (in Latin, 1644
• Passions of the Soul, on the emotions (in French, 1649)
• Letters (in Latin and French, 1657–67)
• World, or Treatise on Light, containing the core of his natural philosophy (in French, 1664);
• Treatise on Man (in French, 1664 physiology and mechanistic psychology
• the Rules for the Direction of the Mind (in Latin, 1704