This paper draws attention to a proof of the necessity of identity given by Arthur Prior. In its simplicity, it is comparable to a proof of Quine's, popularised by Kripke, but it is slightly different. Prior's Polish notation is transcribed into a more familiar idiom. Prior's proof is followed by a proof of the necessity of difference, possibly the first such proof in the literature, which is also repeated here and transcribed. The paper concludes with a brief discussion of Prior's (...) views on identity and difference over time. (shrink)

This paper elaborates the problem of temporal unity for dynamic presentism and diagnoses the source of that problem in the dynamic presentist’s discarding the traditional C-series in its avoidance of McTaggart’s A-series paradox. This C-series provided the fixed structure of time which the transitory aspects of time then followed, and thereby unify those transitory aspects. It then considers ersatzer presentism as an ostensible solution to the problem of temporal unity by providing a new abstract C-series for dynamic presentism. However, after (...) a closer examination of the details of this proposal, it is found that the ersatz-B-series itself needs to be temporally variable to capture the transitory aspects of time that it is meant to track. Consequently, it cannot provide the fixed structure of time required to unify the transitory aspects of time into a temporal series. It is therefore suggested that dynamic presentists look for a more course-grained determiner of temporal progression to construct the presentist-friendly C-series required to unify their transitory aspects of time. (shrink)

There are several intertwined debates in the area of contemporary philos- ophy of time. One field of inquiry is the nature of time itself. Presentists think that only the present moment exists whereas eternalists believe that all of (space-)time exists on a par. The second main field of inquiry is the question of how objects persist through time. The endurantist claims that objects are three-dimensional wholes, which persist by being wholly1 present, whereas the perdurantist thinks that objects are four- dimensional (...) and that their temporal parts are the bearers of properties. The third debate in the field of contemporary philosophy of time is about tense- versus tenseless theory. Tensers are at odds with detensers about the status of the linguistic reference to the present moment. These are only very crude characterizations and it is even disputed by some ad- vocates of the corresponding positions that they are accurate. However this very sketchy picture already reveals a fundamental difference: The eternalism/presentism and endurance/perdurance discussions belong to the field of metaphysics, whereas tense is in the first instance a linguistic phenomenon. (shrink)

Composition as Identity is the view that an object is identical to its parts taken collectively. I elaborate and defend a theory based on this idea: composition is a kind of identity. Since this claim is best presented within a plural logic, I develop a formal system of plural logic. The principles of this system differ from the standard views on plural logic because one of my central claims is that identity is a relation which comes in a variety of (...) forms and only one of them obeys substitution unrestrictedly. I justify this departure from orthodoxy by showing some problems which result from attempts to avoid inconsistencies within plural logic by means of postulating other non-singular terms besides plural terms. Thereby, some of the main criticisms raised against Composition as Identity can be addressed. Further, I argue that the way objects are arranged is relevant with respect to the question which object they compose, i.e. to which object they are identical to. This helps to meet a second group of arguments against Composition as Identity. These arguments aim to show that identifying composite objects on the basis of the identity of their parts entails, contrary to our common sense view, that rearranging the parts of a composite object does not leave us with a different object. Moreover, it allows us to carve out the intensional aspects of Composition as Identity and to defend mereological universalism, the claim that any objects compose some object. Much of the pressure put on the latter view can be avoided by distinguishing the question whether some objects compose an object from the question what object they compose. Eventually, I conclude that Composition as Identity is a coherent and plausible position, as long as we take identity to be a more complex relation than commonly assumed. (shrink)

According to three-dimensionalism, objects persist in time by being wholly present at each time they exist; on the contrary, four-dimensionalism asserts that objects persist by having different temporal parts at different times or that they are instantaneous temporal parts of four-dimensional aggregates. Le Poidevin has argued that four-dimensionalism better accommodates two common assumptions concerning persistence and continuity; namely, that time itself is continuous and that objects persist in time in a continuous way. To this purpose, he has offered two independent (...) arguments, each of which moves from a different understanding of continuity. In this paper, both of Le Poidevin’s arguments will be discussed and rejected. (shrink)

This essay outlines an explanatory virtue of presentism: its unique ability amongst temporal metaphysics to deliver a partial explanation of the conservational character of natural laws. That explanation relies on presentism, uniquely amongst temporal metaphysics, being able to support an endurantist account of persistence. In particular, after reconsidering a former argument for endurantism entailing presentism by Merricks, a new argument for this entailment, is expounded. Before delivering the explanation of the conservational character of natural laws, a brief account of that (...) explanandum is given, followed by an elaboration of the wider significance of an explanation for the conservational character for natural laws, particularly for the dispositional essentialist project of nomic reductionism, and explaining the non-simultaneity of causation. (shrink)

This paper elaborates the problem of temporal unity for dynamic presentism and diagnoses the source of that problem in the dynamic presentist’s discarding the traditional C-series in its avoidance of McTaggart’s (1908, 1927) A-series paradox. This C-series provided the fixed structure of time which the transitory aspects of time then followed, and thereby unify those transitory aspects. It then considers ersatzer presentism as an ostensible solution to the problem of temporal unity by providing a new abstract C-series (namely an ersatz-B-series) (...) for dynamic presentism. However, after a closer examination of the details of this proposal, it is found that the ersatz-B-series itself needs to be temporally variable to capture the transitory aspects of time that it is meant to track. Consequently, it cannot provide the fixed structure of time required to unify the transitory aspects of time into a temporal series. It is therefore suggested that dynamic presentists look for a more course-grained determiner of temporal progression to construct the presentist-friendly C-series required to unify their transitory aspects of time. (shrink)

This essay outlines an explanatory virtue of presentism: its unique ability amongst temporal metaphysics to deliver a partial explanation of the conservational character of natural laws. That explanation relies on presentism, uniquely amongst temporal metaphysics, being able to support an endurantist account of persistence. In particular, after reconsidering a former argument for endurantism entailing presentism by Merricks (Noûs 33:421-438, 1999), a new argument for this entailment, is expounded. Before delivering the explanation of the conservational character of natural laws, a brief (...) account of that explanandum is given, followed by an elaboration of the wider significance of an explanation for the conservational character for natural laws, particularly for the dispositional essentialist project of nomic reductionism, and explaining the non-simultaneity of causation. (shrink)

My topic is the question 'Does time pass?'. Although much has been written in attempts to answer this question, not enough attention has been paid to the asking of the question itself. As a result, it has not been clear exactly what is at issue in this matter, and, consequently, it has not been clear just what are the different views available to one who wishes to give an answer to the question. I hope to ameliorate this situation. ;The aims (...) of my essay are: to state the issues involved in the controversy over temporal passage in a fruitful way; to formulate what I see as the leading candidates among the possible responses to those issues; and to consider the best arguments relevant to the choice among these alternative views. ;Roughly one-quarter of the essay is devoted to linguistic questions about time and tense. Another quarter is devoted to metaphysical matters involving the status of such putative properties as pastness, presentness and futurity. What emerge are not just two but, rather, five distinct views about whether or not time passes: one view, which I call the 4D view, to the effect that time does not pass, and four different views, which I call the 3D views, to the effect that time does pass. Each of these five views consists of a package of linguistic and metaphysical components. ;Once I have formulated these five different views, I present, for each of the five views, a formal language, with semantics, that would be appropriate for that view. Next, various arguments that have been suggested in the literature against the claim that time passes are considered as arguments against the 3D views; each such argument is found to be defective. Similarly, various arguments that have been suggested in the literature against the claim that time does not pass are considered as arguments against the 4D view; each of these arguments is also found to be defective. ;Finally, I explain why I prefer a certain one of the 3D views over its four rivals, and I consider some possible objections to that view. (shrink)

When we begin to investigate the persistence of objects through time, we find immediately that the sort of concerns embodied in Leibniz's Law cause philosophers to divide themselves into the two major camps of Purdurantists and Endurantists. What is required according to each for a given object at a given time to be identified with a given object at another time is held to be dramatically different, even while both often look to the same general sort of indicators for their (...) answers to identity questions: identity or similarity of physical properties, including relational properties like spatial location. I believe, however, that logically prior to the problem of the persistence of objects through time will be questions regarding the composition of objects--we must have coherent notions of what an object is, what it means for parts to compose an object, and what is required for an object to be considered to exist at a single time before we can discuss the continued existence of objects at other times. I believe that posing the problem of temporal gaps for both the Perdurantist and Endurantist to solve can help us uncover reasonable answers to these more basic questions, and thereby help us judge the comparative coherence of the parent theories. Towards this goal, we investigate here some of the assumptions of persistence theories--that Perdurantists are four-dimensionalists and Endurantists are Presentists, for example--before moving on to find reasonable explanations of the composition of objects from within each theory. Important at this stage is clarifying such concepts as parthood and the present. When we at length turn our attention to the problem of gaps, it becomes useful to distinguish two sorts of gaps, each with their own difficulties: a 'gap' as a length of time during which the proper parts of an object are scattered through space, and a 'gap' as a length of time during which the proper parts of an object do not exist in space at all. My contention here is that Perdurantism, paired with four-dimensional spacetime, provides the most coherent answers to the challenges presented throughout. (shrink)