René Descartes, a central figure in Western philosophy and a key architect of modern thought, formulated one of the most influential theories in the philosophy of mind: mind-body dualism. His dualism, often referred to as Cartesian dualism, is a metaphysical framework that distinguishes between two fundamentally different kinds of substances: the mental and the physical. Descartes’ investigation into the nature of reality and knowledge led him to a radical distinction between the mind (res cogitans) and the body (res extensa), claiming that the essence of the mind is thought, while the essence of the body is extension in space. This distinction has shaped the trajectory of modern philosophy, influencing debates in metaphysics, epistemology, psychology, and neuroscience. Descartes’ path to dualism begins with his method of radical doubt, introduced in his seminal work *Meditations on First Philosophy*. He sought a foundation for certain knowledge by doubting everything that could be doubted. This methodological skepticism led him to the famous declaration “Cogito, ergo sum” (“I think, therefore I am”). Here, Descartes identifies the mind as the undeniable foundation of knowledge; even if one doubts the existence of the body or the external world, the act of thinking affirms the existence of the self as a thinking entity. The cogito demonstrates that the mind is self-aware, immaterial, and distinct from the physical world. In contrast, the body, as perceived through the senses, is subject to doubt and deception. This separation