René Descartes is spoken of as the father of modern philosophy, and his seventeenth-century contributions to the discipline as the most significant since Aristotle. While in his lifetime he was primarily known as a mathematician and scientific theorist—in contemporaneous terms a “natural philosopher”—the works of his that we’d today consider to be philosophy are those that continue to command attention. Of these, collected here are the “Discourse on the Method of Rightly Conducting One’s Reason and of Seeking Truth in the Sciences,” the “Meditations on the First Philosophy,” and selections from the “Principles of Philosophy.”
The “Discourse on the Method” was first published as a lengthy introduction to treatises on optics, meteorology, and geometry, in which the titular method of seeking truth in the sciences was applied. Unlike Descartes’ other major works, it was originally composed in French in the hope of reaching a wider audience than scholarly Latin would allow. It’s written in the first person, and Descartes introduces it as a sort of intellectual autobiography. In the second part he outlines the method for right ratiocinative conduct in the form of four precepts; later parts cover issues in morality, metaphysics, medicine, and scientific progress in general.
In the “Meditations on the First Philosophy” Descartes takes up the metaphysical issues he says were only touched on “in passing” in the “Discourse,” namely “the existence of God and the nature of the human soul,” including what it can and cannot doubt. In the second Meditation he arrives at his most famous idea, which he’d later call the “first principle” of his thought, a proposition he argues is indubitable: “ cogito ergo sum ”—“I think, therefore I am.” From the cogito he goes on to deduce the existence of God and God’s non-deceiving nature—and then from these two conclusions, eventually the distinction between mind and body and the existence of material objects, foundations on which all other truths about the world may be based.
Descartes’ arguments in the “Meditations” were controversial—the book was originally published with objections from seven of his contemporaries, and his replies to them—but its reputation remains that of one of the finest pieces of philosophical writing ever produced, and it’s still in wide use today as an introduction to philosophy. His discussion of the mind-body distinction in the “Meditations” is perhaps the most influential treatment of the subject since Plato, even if “Cartesian dualism” now functions as a pejorative. His solutions have since been rejected, but the problem he raised is still considered a problem.