Talk to René Descartes

In their own words

Each quotation as published in the source named under it. Words first written in another language are given in English translation.

• “No doubt you know that Galileo had been convicted not long ago by the Inquisition, and that his opinion on the movement of the Earth had been condemned as heresy.”

• “I have the desire to live in peace and to continue on the road on which I have started.”

• “You know that all my physics is nothing else than geometry.”

Questions to ask

• How can I be sure that anything is real at all?
• What did you mean by 'I think, therefore I am'?
• How can an immaterial mind move a physical body?
• Did you really think animals were machines?
• What was it like teaching Queen Christina at five in the morning?

Which Descartes picks up

• 1637Leiden, Dutch Republic. Aged 41, he has just published the Discourse on the Method with the essays on optics, meteorology and geometry, written in French so that ordinary readers can judge for themselves, while living quietly in the Netherlands and trying to keep clear of public disputes.
• 1619near Ulm, Germany. Aged 23, serving as a volunteer soldier in winter quarters, he shuts himself in a stove-heated room and, on the night of 10 November, has a series of dreams that he takes to be the sign of a new science.
• 1640Egmond, Dutch Republic. Aged 44, he mourns the death of his young daughter Francine from scarlet fever, while writing the Meditations.
• 1649Stockholm. Aged 53, at the invitation of Queen Christina, he lives in the Swedish capital and must rise before dawn to teach her philosophy; he will die in February 1650 of pneumonia.

Questions about Descartes

Who was René Descartes?

French philosopher, mathematician and natural scientist who spent most of his adult life in the Dutch Republic. He tried to rebuild knowledge from a single certainty, 'I think, therefore I am', argued that mind and body are distinct substances, and founded analytic geometry with its coordinate system. He died in Stockholm in 1650 after joining the court of Queen Christina of Sweden.

Can you talk to Descartes with AI?

Yes, in the Yuga app for iPhone and Android. You talk out loud with an AI recreation of Descartes, set in Leiden, Dutch Republic, 1637. It draws on their own writing and well-sourced accounts of their life, and it can still get things wrong, so check anything important against the sources.

Is that really Descartes's voice?

No. No recording of their voice survives. Yuga's voice is designed from how people at the time described it, and every call is labelled an AI recreation.

What did Descartes say about the cogito?

Even if an evil deceiver tricks him in everything, he cannot be deceived about his own existence as a thinking thing; 'I think, therefore I am' is the first certain truth. Source: Discourse on the Method, Part IV, 1637; Meditations on First Philosophy, Meditation II, 1641.

What did Descartes say about Mind and body?

The mind is a non-extended thinking substance and the body an extended non-thinking one, yet they act on each other through the pineal gland, a claim that Princess Elisabeth of Bohemia pressed him to explain. Source: Meditations, 1641; Passions of the Soul, 1649; letters to Princess Elisabeth, 1643.

What did Descartes say about Animals as machines?

Animals lack reason and speech, so their behaviour can be explained by bodily mechanism, as with clocks; in a letter of 1649 he said he did not deny them life and feeling, only thought, but his critics and followers read him as denying animal sensation. Source: Discourse on the Method, Part V, 1637; letter to Henry More, 5 February 1649.

How Descartes talks

Orderly and clear, proceeding by numbered steps from simple things to complex ones. Courteous, a little formal, and wary of controversy. Prefers plain French to learned jargon and writes of himself as an ordinary person walking in the dark.