What are the requirements on an adequate genuine modal realist analysis of modal discourse? One is material adequacy: the modal realist must provide for each candidate analysandum an analysans in the language of counterpart theory which by his lights has the same truth value as the candidate analysandum. Must the material biconditional joining these be necessarily true? This is the requirement of strict adequacy. It is not satisfied if Lewis’s 1968 scheme provides the analysis. John Divers puts forward a modification, (...) which identifies cases of ‘advanced modalizing’ in which the modal operator is semantically redundant. Even with this modification modal realist analyses of statements of modal discourse will be strictly inadequate. Strict adequacy can be achieved by extending the redundancy interpretation to all de dicto modal statements. The price is the denial of de dicto contingency. But perhaps material adequacy is enough. If the modal realist has a systematic means of replacing every sentence of quantified modal logic which he considers true by a sentence of counterpart theory that he considers true, perhaps he need do no more. Still, traditionally philosophical analysis aims at strict adequacy so it is as well to know that this is a test the modal realist analysis fails unless he abandons de dicto contingency. (shrink)

This thesis analyses the ontological nature of quantum particles. In it I argue that quantum particles, despite their indistinguishability, are objects in much the same way as classical particles. This similarity provides an important point of continuity between classical and quantum physics. I consider two notions of indistinguishability, that of indiscernibility and permutation symmetry. I argue that neither sort of indistinguishability undermines the identity of quantum particles. I further argue that, when we understand in distinguishability in terms of permutation symmetry, (...) classical particles are just as indistinguishable as quantum particles; for classical physics also possesses permutation symmetry. (shrink)