Philosophy of mind
Dualism is a set of views about the relationship between mind and matter (or body). It begins with the claim that mental phenomena are, in some respects, non-physical. One of the earliest known formulations of mind–body dualism was expressed in the eastern Sankhya and Yoga schools of Hindu philosophy (c. 650 BCE), which divided the world into purusha (mind/spirit) and prakriti (material substance). Specifically, the Yoga Sutra of Patanjali presents an analytical approach to the nature of the mind.
Trialism
Cottingham introduced trialism after citing that Descartes' account of sensation and imagination has opened his official dualism under considerable pressure. He cited that an evaluation of the Cartesian writings on human psychology there is a grouping of not two but three notions - mind, body, sensation, hence the term trialism. According to cottingham, Descartes added the third category or notion " alongside thought and extension without proceeding to reify it as a separate substance." Thinkers such as Daniel Garber and Tad Schmaltz supported this by citing a letter in the correspondence between Descartes and Princess Elizabeth of Bohemia, which indicated that that he changed his mind from a dualistic view.