Achille C. Varzi

Might we some day be in a position to move about in time, just as we can already move about in space? Today, few would question that deliberate change in temporal location is logically possible. There is no contradiction in the thought that Tim could step into a time machine and travel backwards to visit his grandfather, or forwards to visit his grandchildren. That is, there is no contradiction provided that we take time travel to involve influencing the course of history rather than changing it. But is time travel metaphysically possible? Is there a genuinely possible world—as opposed to a merely coherent scenario—in which one can freely change one’s location in time? Here is where puzzlement and bewilderment lead to philosophical controversy. For the answer depends on one’s views concerning a wide range of other matters, and such views are themselves the subject of major philosophical controversy. Consider

In classical topology the only part of a doughnut that matters is the edible part. Here I review some good reasons for reversing the order and focusing on the hole instead. By studying the topology of the hole one can learn interesting things about the morphology of the doughnut (its shape), and by studying the morphology of the hole in turn one can learn a lot about the doughnut’s dynamic properties (its patterns of interaction with the environment). The price--of course--is that one must be serious about reifying voids.

This paper focuses on the semantics of statements of the form ‘x is P at t’ vis-à-vis its metaphysical underpinnings. I begin by considering four main readings, corresponding to the four basic parsings of the temporal modifier ‘at t’: (1) at-t x is P, (2) x-at-t is P, (3) x is-at-t P, and (4) x is P-at-t. Each of these readings—which correspond to different metaphysical conceptions of the nature of temporal change—is found inadequate or otherwise problematic. In the second part of the paper I therefore consider a fifth account whose advantages over (1)–(4), I argue, exceed its revisionary costs. This fifth account is based on a conception of objects as entia successiva held together by a nexus of temporal counterparthood and reads ‘x is P at t’ as ‘the t-counterpart of x is P’.

In ‘Towards a Solution to the Sorites Paradox’, Graham Priest gives us a new account of the sorites based on fuzzy logic. The novelty lies in the suggestion that truth-value assignments should themselves be treated as fuzzy objects, i.e., objects about which we can make fuzzy identity statements. I argue that Priest’s solution does not have the explanatory force that Priest advocates. That is, it does not explain why we find the existence of a cut-off point counter-intuitive. I also argue that this sort of explanation calls for a general theory that goes beyond the special case of linguistic vagueness, for the phenomenon is at bottom not linguistic.