Dualism and monism are the two central schools of thought on the mind–body problem, although nuanced views have arisen that do not fit one or the other category neatly. Dualism is seen even in the Eastern tradition, in the Sankhya and Yoga schools of Hindu philosophy, and Plato, but its entry into Western philosophy was thanks to René Descartes in the 17th century. Substance dualists like Descartes argue that the mind is an independently existing substance, whereas property dualists maintain that the mind is a group of [nonphysical in category] properties that emerge from and cannot be reduced to the brain, but that it is not a distinct substance.
Why these two—substance and property? What a crock! This injects a contingent mechanism of interior/phenomenological making that pretends to be a making of (real) being. But is the making of an analysis of predicates. Predicates have no real being. They are not in spacetime. Qualia are—reds and muscle resisting mass. Things are not linked as predicates through logical combination influenced solely by thinkability. “Red and triangle” is only as rich as “not red and green.” This cannot be the glue of the real. The truth-and-being of predication, the under-stuff that makes “This (S) is P,” is logical containment. This has no real analog; it is entirely projection. The truth (and, so, being, for the object) of “This leaf of green” unpacks into a model of class containment—this leaf is under “green” whose reality is extension. Green is a class, and this leaf is a member. The grammar of general logic (summarize: predication as subsumption and analysis and the part/whole relation, whose generative power is PNC) thus projects a whole world and its unique emergent metaphysics: (1) the web of inference based on cognizing identity or difference, and (2) hierarchies of kind based on subsumption, which is finally (3) a calculable world of facts serving as the object domain for the exercise of our calculus ratiocinator by an intellect for whom intelligibility is total and analytic. This is the dream of rationalism, the generative priority of axiom over theory/world, fulfilled. Though it is incomplete. Kant calls is intellectualism (Kant says that “Leibniz intellectualized appearances, just as Locke … sensualize all of the concepts of understanding” [A271/B327].)
It is incomplete because it leaves out mathematics—just as. For Kant, a complete world-making system (of the phenomenal) must include FOL and Peano arithmetic.
Thus we impute a metaphysics—that of propositional judgment—onto the real. And here, in the above passage, philosophy of mind has produced a false-problem playground by theorizing the world through one of its own secretions. Is mind a distinct subject term, or just a distinct predicate term? Why would mind conform to our grammar? Matter does not—position and momentum are not separable to the grade assumed by logic, which is total, thanks to identity resting on the almighty PNC.