What is a major problem with Descartes' theory of the mind located in the pineal gland?

Descartes' theory posited that the pineal gland was the point of interaction between the mind and the body, suggesting a dualistic approach where the immaterial mind could influence the physical body through this gland. A major problem with this view is that it inherently contradicts his definition of the mind as a non-material substance. By attributing a specific physical location to the mind, Descartes undermined his own argument for dualism, which maintains a strict separation between the mental and the physical realms.

This creates a philosophical dilemma regarding how a non-physical substance can interact with a physical one, highlighting inconsistencies in his own reasoning. While issues such as lack of empirical evidence or failure to explain consciousness are relevant critiques, the core problem lies in the fundamental contradiction between the immaterial aspect of the mind and the physical location he assigned to it. Therefore, the identification of the pineal gland as the seat of the mind directly challenges the coherence of Descartes' dualistic framework.