Abstract

Objects persist; objects last over time. According to some, this amounts to the claim that objects perdure, that is, that objects are four-dimensional, having temporal, as well as spatial, parts. A perduring object exists at two different times by having a distinct temporal part existing at each time. The rival view is that objects endure and are three-dimensional. ;In the first chapter, I explain the endurantist ontology and provide an account of what it is for an object to be "wholly present" at a time. I also develop an endurantist semantics for expression like 'Ralph yesterday' and, more generally, 'O at t'. Finally, I defend endurance against the objection that, combined with change, endurance violates the indiscernibility of identicals. ;In Chapter Two, I establish the methodological point that investigations into whether there are criteria, i.e., informative necessary and sufficient conditions, for lasting cannot proceed neutrally with regard to perdurance or endurance. A commitment to either endurance or perdurance must precede any successful investigation into criteria for identity over time. ;In the third chapter I explain the sense in which criteria are informative. I then argue in Chapter Four that the endurantist ought to deny that there are criteria for lasting through time. This conclusion rests on two claims which are also defended in the fourth chapter: the lack of informative necessary and sufficient conditions for identity over time raises no new epistemic problems for our judgments of identity over time, and identity over time cannot be reduced to, or analyzed in terms of, some other relation. ;There are arguments for rejecting, or drastically revising, an endurance ontology from the possibility of objects dividing, or undergoing "fission." In the final chapter I show that such arguments fail. In criticizing these arguments, I make use of the claim that no informative necessary and sufficient conditions are available for identity over time. Any problems fission raises for the endurantist are, I argue, purely epistemic, not ontological