Descartes' Folly

The pineal gland is an endocrine organ in the brain which secretes melatonin. It always fascinated me because of its fundamental and incontrovertible significance in the history of western philosophy. Nearly every novice philosophy student reads Rene Descartes' Meditations on First Philosophy. In fact, I read that slim book in at least four courses as an undergrad. In Meditations, Descartes proposes his theory of dualism, that mind and body are fundamentally distinct substances. The main problem of dualism involves how mental phenomena interact with physical phenomena if they are fundamentally distinct. How does food satiate my feeling of hunger? Well, Descartes had an answer. He proposed the pineal gland as the "seat of the soul" where mental and physical substances interact. This has, since the 17th century, been debunked, but it was a nice try anyway.