René Descartes

Cogito, ergo sum

The one thing that survives all doubt: that I, the doubter, think and therefore am.

💡 Did you know? „I think, therefore I am“: even one who doubts everything cannot doubt that he is doubting, and so thinking.

methodical doubt

The senses can deceive, life could be a dream, an evil demon could be conjuring it all.

💡 Did you know? Descartes provisionally doubted everything (even the existence of the outer world) to find an unshakeable starting point.

dualism

Thinking substance (res cogitans) and extended substance (res extensa): the mind-body problem occupies philosophy to this day.

💡 Did you know? Descartes drew a sharp line between thinking mind and extended matter: the „mind-body problem“ still debated today.

Discourse on the Method

So that anyone could read it: even 'women and artisans', as Descartes stressed.

💡 Did you know? He deliberately wrote it in French rather than Latin so non-scholars could read it too: unusual for his time.

Cartesian coordinate system

It joins algebra and geometry: every curve becomes an equation: the foundation of analytic geometry.

💡 Did you know? The „Cartesian“ coordinate system (after his Latin name Cartesius) first united algebra and geometry.

modern philosophy

No longer authorities but one's own reason is the source of certain knowledge.

💡 Did you know? With doubt as his starting point, Descartes is regarded as the founder of modern philosophy.

in the stove-heated room

In winter quarters near Ulm or Neuburg: there he conceived the plan to refound all knowledge.

💡 Did you know? That same night he had three dreams, which he took as his calling.

Netherlands

The tolerant country offered shelter from church persecution: yet after Galileo's condemnation he still withheld one work.

💡 Did you know? In the tolerant Netherlands Descartes found, for over 20 years, the calm to write his most important works.

Christina of Sweden

She demanded lessons at five in the morning: torture for the notorious late riser.

💡 Did you know? The queen insisted on lessons at five in the morning: a torment for the late-rising Descartes.

pneumonia

The icy winter and the five-a.m. lessons with the queen are considered the trigger.

💡 Did you know? The early mornings in cold Stockholm probably brought on the fatal pneumonia.

thinking in bed

As a frail schoolboy he was allowed to stay in bed in the mornings: he kept the habit for life.

💡 Did you know? Legend has it the idea of coordinates came to him watching a fly on the ceiling.

Meditations

Six meditations from doubt to the proof of God: published with objections by eminent contemporaries and his replies.

💡 Did you know? In the „Meditations“ he pushes methodical doubt to the famous „evil demon“ who might be deceiving us.

René Descartes

René Descartes was a French philosopher and mathematician who founded modern philosophy with „I think, therefore I am“.

💡 Did you know? The Cartesian coordinate system, which links algebra and geometry, is named after him.