Whether or not mental states turn out to be physical states of the brain is a matter of whether or not cognitive neuroscience eventually succeeds in discovering systematic neural analogs for all of the intrinsic and causal properties of mental states.
Whatever explanation of cognition will in the end prove satisfactory; we can at least suppose that only one kind of existence–the real kind–will be involved. The faith of many today that the mind is wholly physical. But if the mind must be explained in terms of the nonphysical, at least it need not be explained in terms of the nonreal.
Traditionally, especially within the period of Modern Philosophy, when philosophers turned their attention to perception and our knowledge of the external world, a standard set of issues, problems, principles and concepts were invoked, assumed and occasionally modified. A recent statement of the representative theory of perception characterized that theory as holding to two claims: mental operations of the mind arise from causal impingement by the world” and the mind has “mental states and events which represent the world.
Analyses of the representative relation varied and questions were raised about the causal relation. Some writers became uneasy with the notion that mental contents (ideas) could be caused by physical (brain) events. That uneasiness was not due entirely to the acceptance of an ontology in which physical events are assigned to one kind of category or substance, and mental events to another kind of category or substance. There are passages in Descartes, Glanvill, Cudworth and, later, Kant that indicate a two-fold relation between perceiver and the world: a physical causal relation from objects to brain, and a significatory or semantic relation between brain and mind.
It was generally recognized that the way the world appears to us, the world as known, differs qualitatively from the world itself, the world that is known...................
