It is widely held that if an object a is identical (or non-identical) to an object b, then it is necessary that a is identical (non-identical) to b. This view is supported an argument from Leibniz's Law and a popular conception of de re modality. On the other hand, there are good reasons to allow for contingent identity. Various alternative accounts of de re modality have been developed to achieve this kind of generality, and to explain what is wrong with (...) the argument from Leibniz's Law. (shrink)

The article deals with the charge of irrelevance levelled against D. Lewis’s modal realism, notably known as a reductionist account of modality. The charge of irrelevance is apparently one of the most popular objections to modal realism though it often seems that the debate surrounding this charge is not very fruitful since in this context it is common to appeal, implicitly or explicitly, to different criteria for theory choice. As a result, the article deals with the problem in a slightly (...) different manner. The article addresses arguments aimed to show that, contrary to what is often stated, modal realism does not violate our pre-theoretical intuitions, as well as arguments aimed to respond to the charge of irrelevance without appealing to criteria for theory choice at all but providing different reasons instead. However, the aim of this article is to show that all these arguments are rather unconvincing. (shrink)

An intuitive objection to modal realism is that merely possible worlds and their inhabitants seem to be irrelevant to an analysis of modality. Kripke originally phrased the objection in terms of being concerned about one’s modal properties without being concerned about the properties one’s other-worldly counterparts have. The author assesses this objection in a variety of forms, and then provides his own formulation that does not beg the question against the modal realist. Finally, the author considers two potential answers to (...) the objection so understood and concludes that only one of them has a chance of succeeding. (shrink)

The aim of this chapter is to explore to some extent the relationship between identity and necessity in logic and metaphysics. First, I provide a historically-based summary of proofs of the necessity of identity, highlighting the importance of the role that self-identity plays. Second, I introduce two examples of metaphysical topics where the necessity of identity has played a pivotal role: the necessary a posteriori, and the coincidence of material objects. I argue that important aspects of these debates rest on (...) how we represent identity. Third, I consider some recent work on generalized identity. This opens up new prospects for explaining why identity is necessary. (shrink)