Structure in Ontology – 22/11/2007 The Identity of Material Objects

Given that there are so different competing theories of the metaphysical structure of material objects, we may expect them to provide different characterization of their identity conditions: the conditions under which an entity counts as one, it is articulated from the rest of reality overall as one single thing. Material objects, as we know, have among their fundamental features an unrepeatable location in space, and in time. So the problem of identity conditions can be divided into two: (1) Synchronic identity: we want our theory to provide us with criteria to count how many objects there are, and in particular how many of them occupy a certain place at one time. Questions of synchronic identity are often intermingled with questions concerning the material and mereological constitution of material objects. (2) Diachronic identity: we want our theory to tell us under which conditions a material object keeps its identity through time, it remains “the same ” object (it keeps existing) while undergoing minor or major changes. Questions of diachronic identity typically involve the classic problem of accounting for the phenomenon of becoming