Abstract

This dissertation examines Wilfrid Sellars' refutation of physical reductive materialism, the thesis that the catalog of theoretical primitives, suitable to describe non-sentient reality completely, is adequate also for depicting the sentient domain. Accordingly, psychic properties, unique features of the sentient world, are reducible to states of purely material entities. There are two forms of physical reductive materialism: the Identity Thesis and eliminative materialism. The Identity Thesis maintains that core persons and their psychic properties are identical with the appropriate systems of neurophysiological objects and their complex states; eliminative materialism denies the existence of irreducible psychic properties of sentient organisms and grants ontological status to the entities of the most adequate theory of sentient reality, current neurophysiology. ;Sellars' grain argument contends that manifest physical objects and their perceptible qualities cannot be identical with micro-physical particle systems and their properties or states, and that manifest core persons and certain of their psychic properties cannot be identical with micro-theoretical neuron systems and their complex states. For the perceptible qualities of manifest physical objects and the quasi-perceptible qualities of sense impressions are ultimately homogeneous, while complex properties or states of micro-theoretical particle systems must lack ultimate homogeneity. Sellars' grain argument thus undermines the Identity Thesis, the first form of physical reductive materialism. ;Sellars rejects eliminative materialism, the second form of physical reductive materialism, on two grounds. First, sense impressions are required to account for the truth of perceptual judgments, especially in non-standard cases. Second, ultimately homogeneous perceptible qualities or their analogs must be present in any theory that is to provide its own independent observation base, since such qualities constitute a necessary condition for the total observability of individuals. Any adequate theoretical picture of the world must incorporate successor analogs to the ultimately homogeneous perceptible qualities, as states of sentient organisms, to meet nomological and methodological requirements for adequacy and independence. The elimination of these qualities from a scientific picture of reality leaves that picture without its own independent observation base, thus sacrificing empirical contact with the world. Thus, eliminative materialism is inadequate