René Descartes

René Descartes was a French philosopher, mathematician, and scientist who is regarded as the founder of modern philosophy. His work on method, on knowledge, and on the mind-body relation shaped the development of philosophy and of the sciences.

Early Life and Education

Descartes was born in 1596 in La Haye, in Touraine, and was educated at the Jesuit college of La Flèche. He studied law at Poitiers.

He served in the army of Maurice of Nassau and travelled in Europe. He spent most of his adult life in the Netherlands, where he wrote his major works.

He was a Catholic in a Protestant country and sought to avoid controversy. He later moved to Sweden at the invitation of Queen Christina.

The Discourse on Method

The Discourse on Method, published in 1637, sets out his approach to the pursuit of truth. He resolved to doubt everything that could be doubted and to accept only what was clearly and distinctly known.

The method of doubt led him to the famous conclusion that he could not doubt that he was thinking, and hence that he existed. Cogito ergo sum, I think therefore I am, is the foundation of his system.

He set out four rules of method, requiring the division of problems into parts, the ordering of thoughts from simple to complex, and the review of the whole. The work was written in French rather than in Latin.

The Meditations

The Meditations on First Philosophy, published in 1641, is his most influential work. It develops the method of doubt and the argument for the existence of God.

He argued that the idea of a perfect being could not have been produced by an imperfect mind and must therefore have been placed in him by that being. The argument is a version of the ontological argument.

He distinguished the mind from the body and argued that they are two distinct substances. The mind is thinking and unextended, and the body is extended and not thinking.

The Mind-Body Problem

The dualism of Descartes raised the problem of how the mind and the body interact. He suggested that they interact through the pineal gland.

The problem has occupied philosophers ever since and has generated a range of positions, including occasionalism, parallelism, and materialism. The interaction problem is one of the most discussed issues in the philosophy of mind.

His account of the passions and of the emotions was written for Princess Elisabeth of Bohemia, who corresponded with him about the problem.

Mathematics and Science

Descartes invented analytic geometry, which connects algebra with geometry. The Cartesian coordinate system, named after him, is a fundamental tool of mathematics.

His physics was based on the vortex theory of matter and was superseded by the work of Newton. He made contributions to optics and to the theory of the rainbow.

He died in Stockholm in 1650. His remains were later moved to Paris and interred in the church of Saint-Germain-des-Prés.

Legacy

Descartes is regarded as the father of modern philosophy. His insistence on method and on clear and distinct ideas set the agenda for the rationalist tradition.

His dualism and his theory of knowledge continue to be debated. His mathematical work is of lasting importance.

He is remembered for the cogito and for the method of doubt. His name is associated with the search for certainty and with the beginning of modern thought.

The Rules and the Method

Descartes' early work Rules for the Direction of the Mind set out the rules of method. The project was concerned with the direction of the mind towards the discovery of truth.

He distinguished simple natures, which are known intuitively, from compound natures, which are deduced. The method was to reduce complex problems to their simple components.

The work was unfinished and was published after his death. The method of analysis and synthesis became a model for later mathematical and philosophical inquiry.

Geometrical and Physical Work

Descartes developed analytic geometry and showed how algebraic equations could be represented by curves. The method made possible the solution of problems that had resisted the classical geometers.

He formulated the law of refraction of light and explained the rainbow. He also made contributions to the theory of lenses.

His physics was based on a plenum of vortices and on the law of inertia. The theory was superseded by Newton, but it shaped the science of the seventeenth century.

The Passions of the Soul

The Passions of the Soul was Descartes' last work, published in 1649. It analysed the emotions and the relation between the body and the mind.

He identified six primitive passions: wonder, love, hatred, desire, joy, and sadness. The other passions are composed of these.

He argued that the passions are caused by the animal spirits and that they can be controlled by reason and by the cultivation of virtue. The work influenced the study of the emotions.

Correspondence

Descartes was a prolific correspondent, and his letters are an important source for his thought. He corresponded with Marin Mersenne, with Pierre Gassendi, and with Princess Elisabeth of Bohemia.

The correspondence with Elisabeth concerned the mind-body relation and the passions. It led to the writing of the Passions of the Soul.

The letters also reveal his views on theology, on medicine, and on the natural sciences. They show a thinker engaged with the intellectual community of his time.

See also

• Cartesian dualism
• Rationalism