The technical apparatus of modal semantics--Possible worlds, World-Lines, Counterparts, Etc.--Continues to arouse suspicion among philosophers of various persuasions. A way to dispel at least some of the suspicion is to provide a naturalistic interpretation of the semantical machinery. My goal here is precisely that. More specifically, I provide a behavioristically acceptable interpretation of david lewis' counterpart theory. Reference to worlds and counterparts is construed in sober, Quinean terms. The result is a "metalinguistic" construal of counterpart semantics, And thus, Of modality. (...) Having shown that counterpart theory rests on no dubious philosophical assumptions, I briefly explore some of the metaphysical consequences of the resulting theory of modality. (shrink)

We motivate and formalize the idea of sameness by default: two objects are considered the same if they cannot be proved to be different. This idea turns out to be useful for a number of widely different applications, including natural language processing, reasoning with incomplete information, and even philosophical paradoxes. We consider two formalizations of this notion, both of which are based on Reiter’s Default Logic. The first formalization is a new relation of indistinguishability that is introduced by default. We (...) prove that the corresponding default theory has a unique extension, in which every two objects are indistinguishable if and only if their non-equality cannot be proved from the known facts. We show that the indistinguishability relation has some desirable properties: it is reflexive, symmetric, and, while not transitive, it has a transitive “flavor.” The second formalization is an extension (modification) of the ordinary language equality by a similar default: two objects are equal if and only if their non-equality cannot be proved from the known facts. It appears to be less elegant from a formal point of view. In particular, it gives rise to multiple extensions. However, this extended equality is better suited for most of the applications discussed in this paper. (shrink)

Whether or not the particular view of generic sentences articulated above is correct, it is quite clear that the study of generic terms and the truth-conditions of generic sentences touches on the representation of other parts of the grammar, as well as on how the world around us is reflected in language. I would hope that the problems mentioned above will highlight the relevance of semantic analysis to other apparently distinct questions, and focus attention on the relevance of linguistic problems (...) to other already established areas of inquiry. (shrink)

Traditionally, this puzzle has been solved in various ways. Aristotle, for example, distinguished between “accidental” and “essential” changes. Accidental changes are ones that don't result in a change in an objects' identity after the change, such as when a house is painted, or one's hair turns gray, etc. Aristotle thought of these as changes in the accidental properties of a thing. Essential changes, by contrast, are those which don't preserve the identity of the object when it changes, such as when (...) a house burns to the ground and becomes ashes, or when someone dies. Armed with these distinctions, Aristotle would then say that, in the case of accidental changes, (1) and (2) are both false—a changing thing can really change one of its “accidental properties” and yet literally remain one and the same thing before and after the change. (shrink)

Two closely related issues are addressed in this thesis. The first of these issues is whether Lockean criteria can withstand criticisms based on cases such as Wiggins' brain bisection case. The problem here is that the memory relation, or in general any relation of psychological continuity, seems to be a many-one relation and hence not suitable as a criterion of identity for persons. The second issue involves the question of what we ought to say about such cases. The problem here (...) is that, intuitively, psychological continuity seems to be a very good criterion of personal identity. When one person is psychologically continuous with a future person, we want to say that the one person has survived--as that future person. ;Several contemporary philosophers have addressed themselves to these issues. In Chapter I of the thesis, I consider the theory of identity suggested by Baruch Brody. He rejects Lockean criteria, and instead uses his own perfectly general theory as a criterion of identity. I argue that the theory he suggests is of limited value, and that the arguments he provides against Lockean criteria are question-begging. In Chapter II, I develop a specific Lockean criterion; in Chapter III, I consider and finally reject particular arguments against this criterion which are based on the brain bisection cases. In this chapter, I consider work by David Wiggins, Bernard Williams, and Roland Puccetti. In Chapter IV, I turn to the defense of Lockean criteria suggested by John Perry and David Lewis. Finally, in Chapter V, I develop my own views on the brain bisection case, and concluding that Lockean criteria of a certain sort remain defensible. (shrink)