John Locke discusses the notions of identity and diversity in Book 2, Chapter 27 of An Essay Concerning Human Understanding. At the beginning of this much-discussed chapter, Locke posits the place-time-kind principle. According to this principle, no two things of the same kind can be in the same place at the same time . Just what Locke means by this is unclear, however. So too is whether this principle causes problems for Locke, and whether these problems can be resolved. This (...) is significant because the place-time-kind principle is foundational to Locke's discussion of identity. Moreover, the place-time-kind principle stands at the center of a number of lively and long-standing debates in Locke scholarship. These include the debates over the ontological status of Lockean persons, and whether Locke is a relative identity theorist, to name just two. In this paper, I offer a survey of how Locke's place-time-kind principle has been interpreted in the secondary literature. The aim of this taxonomy is to clarify where the differences between competing interpretations lie, and additionally show just how challenging it is to determine which reading is best. (shrink)

A.J. Cotnoir has argued that we should distinguish between two notions of proper parthood: outstripped part and non-identical part. Outstripped parthood is an asymmetric relation, but non-identical parthood is not. We argue, first, that the intuitions Cotnoir uses to motivate these notions do not always give the right verdict; and, second, that systematic reasons for distinguishing these two notions of parthood have further counter-intuitive consequences. This means the distinction between two notions of proper parthood currently lacks adequate motivation.

In dicephalus conjoined twinning, it appears that two heads share a body; in cephalopagus, it appears that two bodies share a head. How many human animals are present in these cases? One answer is that there are two in both cases—conjoined twins are precisely that, conjoined twins. Another is that the number of humans corresponds to the number of bodies—so there is one in dicephalus and two in cephalopagus. I show that both of these answers are incorrect. Prominent accounts of (...) biological individuation, which treat the organism as an integrated whole, reveal that in these and other cases of conjoined twinning the ‘twins’ share a single human animal. This has a number of consequences for the debate about what we are. First, if animalism is true, individuals of our kind can be—and are—profoundly psychologically divided. Second, cephalopagus twinning does not divide animalism from its rivals, as has been claimed. Finally, animalists can reply to a vicious species of the ‘too many thinkers’ problem to which they are allegedly uniquely vulnerable. (shrink)

An encyclopedia entry which covers various revisionary conceptions of which macroscopic objects there are, and the puzzles and arguments that motivate these conceptions: sorites arguments, the argument from vagueness, the puzzles of material constitution, arguments against indeterminate identity, arguments from arbitrariness, debunking arguments, the overdetermination argument, and the problem of the many.

An annotated bibliography of important works on material constitution.