In this innovative study E.J. Lowe demonstrates the inadequacy of physicalism, even in its mildest, nonreductionist guises, as a basis for a scientifically and philosophically acceptable account of human beings as subjects of experience, thought and action. He shows how an attribution of independent causal powers to the mental states of human subjects is perfectly consistent with a thoroughly natural world view, and examines the role that conscious mental states play in the human subject’s exercise of its most central capacities for perception, action, thought and self-knowledge.