This paper presents the leading idea of my doctoral dissertation and thus has been shaped by the reactions of all the members of my thesis committee: Charles Chastain, Walter Edelberg, W. Kent Wilson, Dorothy Grover, and Charles Marks. I am especially grateful for the help of Professors Chastain, Edelberg, and Wilson; each worked closely with me at one stage or another in the development of the ideas contained in the present work. Shorter versions of this paper were presented at the (...) 47th Annual Northwest Conference on Philosophy (1995), the 1996 Mid-South Philosophy Conference, the 1997 meeting of the Central Division of the American Philosophical Association, and at the University of Washington, Seattle; thanks to all audiences for their insightful comments and questions and also to my conference commentators, Eric Gampel, Jonathan Cohen, and Bruce Glymour, respectively, each of whom offered a thoughtful critique. Lastly, I extend my gratitude to anonymous referees, including two from Mind and Language, whose remarks led to significant improvements in the paper. Address for correspondence: 13416, 4th Ave. S., Seattle, WA 98168, USA E-mail: [email protected].. (shrink)