The Birth of Modern Science — Descartes to Nietzsche (Lecture 2)

Lecture 2 of "From Descartes to Nietzsche: The Birth of Science and the Death of God." Watch the full lecture series:    • From Descartes to Nietzsche: The Birth of ...   Presented by Ergo, a nonprofit that publishes structured philosophical lectures online, free to anyone. https://ergo.org About this lecture 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. Primary Source: Descartes, R. (1993). Meditations on first philosophy (D. A. Cress, Trans.; 3rd ed.). Hackett Publishing Company. About this course Lee Braver leads a tour through four of the most influential philosophers in Western history, asking a single question: how do we know anything at all? Beginning with Descartes, who rebuilt knowledge from scratch, the course follows Hume's challenge to cause and effect, Kant's claim that our minds shape the world we experience, and Nietzsche's confrontation with a universe drained of meaning. Across seven lectures, this introductory course traces one unfolding argument about truth, knowledge, meaning, and human freedom, showing how each thinker built on and challenged those before. About Lee Braver Lee Braver is a Courtesy Professor of Philosophy at the University of South Florida, where he was a Professor of Philosophy from 2012 to 2025. His interests include continental philosophy, especially Heidegger and Foucault, Wittgenstein, realism, and dialogue between continental and analytic philosophy. He is the author of A Thing of This World: A History of Continental Anti-Realism, Groundless Grounds: A Study of Wittgenstein and Heidegger, and Heidegger: Thinking of Being, and editor of Division III of Being and Time: Heidegger's Unanswered Question of Being. Chapters 00:00 Three Bulletproof Beliefs as Foundation 00:38 What Is a Clear and Distinct Perception? 03:33 Proving 2+2=4 From Scratch 07:25 Why Only A Priori Knowledge Qualifies 08:57 Killing the Evil Demon by Proving God Exists 13:15 Ideas Have Essences Even Without Existence 15:40 Essences Entail Necessary Properties 18:09 The Ontological Proof of God's Existence 21:48 Why You Can't Just Reject the Conclusion 24:06 Objections: Thinking Things Into Existence? 27:24 God's Goodness Defeats the Evil Demon 30:33 Human Responsibility for Error 31:45 Restoring A Priori and Empirical Beliefs 33:12 Why the Senses Are Poor Scientific Tools 34:56 Quantification: Turning Experience Into Numbers 38:53 The Moment That Changed Everything