My interest in gathering together a collection of this sort was generated by a fortuitous combination of historical studies under Professor Keith Lehrer and studies in cognitive science under Professor R. Michael Harnish at the University of Arizona. Work on the volume began there while I was an instructor in the Department of Linguistics and was greatly encouraged by participants in the Faculty Seminar on Cognitive Science chaired by Professor Lance J. Rips. I wish to express my appreciation to all of these and to many other individuals with whom I discussed the possibility of contribution...