The Birth of Modern Science

How does Descartes move from doubting everything to building the foundations of modern science? In this lecture, Lee Braver walks through the crucial middle steps of Descartes' philosophical project. Starting with the "clear and distinct perception" truth rule, the idea that we can know something fully when we grasp it completely, with no hidden corners where error could lurk, Braver shows how Descartes applies this standard first to mathematical and geometrical truths, then confronts a devastating problem: the evil demon hypothesis threatens even our most certain reasoning. This forces Descartes to prove God's existence through the ontological argument, borrowed from Saint Anselm, which reasons from the very idea of a supremely perfect being to its necessary existence. With God secured as a guarantor against deception, Descartes can finally return to the empirical world, but on new terms. Braver concludes by revealing how Cartesian coordinates exemplify Descartes' revolutionary insight: by quantifying sensory experience through measurement, we transform vague perception into precise, replicable knowledge, laying the groundwork for modern science.