René Descartes

Key ideas

In the Meditations Descartes sets out to rebuild knowledge on certain foundations. He applies the method of doubt: the senses sometimes deceive, he might be dreaming, and an all-powerful Descartes' evil demon might be deceiving him about everything. Yet even a deceiver cannot deceive him about the fact that he is thinking. Hence the cogito: I think, therefore I am.

From there he argued for God's existence and, through God's goodness, for the general reliability of clear and distinct ideas, a route critics found circular (the Cartesian circle). He also argued that mind and body are two different kinds of substance, one thinking and unextended, the other extended and unthinking. This substance dualism defines the mind-body problem problem as we still discuss it, especially the question of how the two could interact.

He was equally important as a mathematician and scientist. He invented the coordinate geometry that bears his name and held a mechanical view of nature, including animal bodies, which he regarded as machines.

“I think, therefore I am.”

René Descartes, Discourse on the Method, Part IV, trans. Haldane and Ross (1911)

Life, briefly

Descartes was educated by the Jesuits at La Flèche, studied law, and served briefly as a gentleman soldier. In 1619, in Germany, he had a series of dreams that he took as a calling to found a new science. He spent most of his working life in the Netherlands, moving house often.

In 1649 he accepted an invitation from Queen Christina of Sweden to teach her philosophy at five in the morning in the Stockholm winter. He died of pneumonia within months.

Major works

• Discourse on the Method (1637)
• Meditations on First Philosophy (1641)
• Principles of Philosophy (1644)
• The Passions of the Soul (1649)

Schools of thought

Skepticism · Rationalism

Further reading

• EncyclopediaStanford Encyclopedia of Philosophy: René Descartes
• WikipediaRené Descartes