Abstract

Chisholm's Paradox and the Four Worlds Paradox are paradoxes about the cross-world identity of artifacts that are made of parts. The paradoxes are described as derivable in S5 modal logic from principles concerning the essentiality of the original matter of an artifact and the Tolerance Principle concerning possible changes in the original matter. On one hand, the original matter is essential to the artifact; on the other hand, bare identity or distinctness with respect to the original matter can be inferred by applying the Tolerance Principle in S5. ;This dissertation analyzes two solutions that have been proposed. Nathan Salmon developed an Intransitive Accessibility Solution that rejects S5 as the logic for metaphysical modality. We show that Salmon's argument for the intransitivity of metaphysical possibility is unsound. The fundamental problem in Salmon's account is his attempt to derive the mode of metaphysical possibility from the accessibility relation between the possible worlds, which, by the theory of possible worlds that Salmon advocates, has to be determined by metaphysical possibilities with a pre-determined mode. The conclusion of Salmon's argument only reiterates a premise of the argument. We also discuss Salmon's other defenses, and show that these defenses are unsuccessful. ;Graeme Forbes proposes a Counterpart Solution. His solution replaces the standard two-valued semantics by a counterpart semantics with infinitely many degrees of truth-value. Our view is that Forbes' solution is unsatisfactory. Forbes avoids the identity problem by formulating the problem in terms of similarity relation. We argue that the similarity relation must not be a semantic device for representing identity. ;Our analysis reveals two versions of tolerance principle that have not been distinguished in literature. The paradoxes are associated with the Strong Tolerance Principle. We argue that the Strong Tolerance Principle is false. The intuition of tolerance is sufficiently described by the Weak Tolerance Principle. Moreover, we argue that the knowing of the possibilities about the origination of an artifact is empirical. The knowledge of the historical background and the origination of the artifact is needed for knowing the possibilities. With this view, S5 as the logic of metaphysical modality can be defended