René Descartes (1596-1650) was a French philosopher who is often studied as the first great philosopher in the era of “modern philosophy.” He is the most famous proponent of a view called “substance dualism,” which states that the mind and the body are two different substances. While the body is material (corporeal), the mind is immaterial (incorporeal). This view leaves room for human souls, which are usually understood as immaterial. Descartes argued on the basis of the Christian views that souls are immaterial and can exist separate from the body, but he emphasized that the mind alone is immaterial, whereas the other traditional functions of the souls can be explained as corporeal operations. His view and arguments were so influential that after him many philosophers referred to substance dualism under Descartes’ name as “Cartesian dualism.” In his explanation of the mind, the soul, and the ability of humans to understand the world around them through the powers of their minds, Descartes remains one of the most influential figures not just in modern philosophy, but throughout the history of philosophy. Even in the contemporary era, philosophers such as Gilbert Ryle (1900-1976) found worth in writing about and arguing against Descartes’ views to set up their own theories. Ryle questioned whether the mind and body are in fact distinct and argued that they would not communicate with each other if they were. Ryle states:
Body and mind are ordinarily harnessed together….[T]he things and events which belong to the physical world…are external, while the workings of [a person’s] own mind are internal….[This results in the] partly metaphorical representation of the bifurcation of a person’s two lives. (1945, 11-16)
Ryle stated that, if Descartes’ theory were correct, the mind would be a mere “ghost in a machine,” inactive and unable to cause actions in the body (the machine). Ryle did not term Decartes’ theory “substance dualism” but “Descartes’ myth.” Descartes’ arguments for substance dualism and the immaterial nature of the mind and soul are therefore paramount to any investigation of the philosophy of mind, and are still being debated in present-day theories. On the other hand, with his interpretation of what he calls passions (most operations of a living body), he also provides incentives for a non-dualistic physicalism of the mind.