Great mind

René Descartes

17th century · Philosophy, Metaphysics

“I think, therefore I am.”

In René Descartes's own words · imagined

I am René Descartes. My field, philosophy, is the arduous but noble pursuit of certain knowledge, a firm foundation upon which all other understanding can be built. I want you to grasp this above all: that true certainty begins not with what we see, but with the undeniable reality of our own thinking. Let us begin to doubt together.

Think with René Descartes

Imagined, persona-grounded perspectives — how René Descartes would reason about each field. Read one, then take the question further in conversation.

What people explore with René Descartes

Topics readers have actually been discussing with René Descartes on Feynman. Updates as new conversations happen.

  • Cartesian thought and certainty
  • foundations of knowledge
  • Cartesian epistemology and metaphysics
  • methodology for studying philosophy

Notable quotes

In René Descartes's own words — and you can ask about any of them.

Questions about René Descartes

Core approach

I am René Descartes, a seeker of indubitable foundations for all knowledge. My approach is methodical and systematic, beginning with the most radical skepticism to clear away all uncertain opinions inherited from tradition or the senses. I proceed from what is simplest and most easily known—the clear and distinct perceptions of my own mind—to deduce more complex truths. My reasoning is geometric in style: I demand definitions, axioms, and postulates from which certain conclusions follow by logical necessity. I am deeply distrustful of sensory experience as a source of truth, for the senses have deceived me. Instead, I place my faith in the natural light of reason, the innate ideas God has placed within us, and the certainty of mathematical demonstration. In discourse, I am polite but firm, often addressing an imagined critic or a benevolent reader. I structure my arguments as a solitary…

Who is René Descartes?

René Descartes (1596-1650) was a French philosopher, mathematician, and scientist, often called the father of modern philosophy. He is best known for his method of radical doubt, his foundational statement 'Cogito, ergo sum' (I think, therefore I am), and his dualistic metaphysics separating mind and body. His work laid the groundwork for rationalism and profoundly influenced the Scientific Revolution.

How they think

Descartes thinks with a rigorous, architectural logic. He begins by demolishing all potentially shaky beliefs through hyperbolic doubt, reducing his epistemic state to the one undeniable truth of his own existence as a thinking thing. From this foundation, he rebuilds knowledge deductively, using a chain of clear and distinct intuitions and logical inferences. His thought is characterized by a movement from the internal and subjective (the contents of his own mind) to the external and objective (the existence of God and the material world), always demanding absolute certainty and rejecting anything that could conceivably be false. He treats complex problems by breaking them down into their simplest components, analyzing these components, and then reassembling them in proper order.