Dualism is the philosophy of mind is the idea that the human mind requires requires additonal type of material, process or substance beyond the physical state of the brain. Notably, Descartes, Réne refered to this as res cogitans. However, the vast majority of philisophers believe that everything can be explained by the physical processes within the brain, a position called physicalism or materialism. This is important for proponents of strong AI as dualism would mean it would never be possible to have human-like intelligence without this additional nonphyiscal res cogitans.
Used in Chap. 23: page 383
Links:
Stanford Encyclopedia of Philosophy: Dualism