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The prosaic content of these sayings is that events change from future to present and from present to past. Your next birthday is in the future, but with the passage of time it draws nearer and nearer until it is present. 24 hours later it will be in the past, and then lapse forever deeper into history. And things get older: even if they don’t wear out or lose their hair or change in any other way, their chronological age is always increasing. These changes are universal and inescapable: no event could ever fail to be first future, then present, then past, and no persisting thing can avoid growing older. We call this process time’s passage.

Some say that presentism precludes time travel into the past since it implies that the past does not exist, but this is a bad argument. Presentism says that only currently existing entities exist, and that the only properties and relations those entities instantiate are those that they currently instantiate. This does in a sense imply that the past does not exist. But if that precluded time travel into the past, it would also preclude the one-second-per-second “time travel” into the future that is ordinary persistence, for presentism accords the future the same ontological status as the past. Instead of quantifying over past and future objects and events, presentists speak a tensed language, regimented with primitive sentential tense operators. For a presentist, a persisting person is one who did exist, and who will exist. Regimented, these claims become: it was the case that she exists, and it will be the case that she exists. The presentist may then apply the same strategy to time travel proper. Suppose Katy travels back to the time of the dinosaurs. The presentist can say that it was the case two hundred million years ago that Katy exists. This claim, which consists of a present-tense statement “Katy exists” embedded within the past tense operator it was the case two hundred million years ago that, is exactly the sort of statement about time that a presentist is free to accept. This has all been made clear by Simon Keller and Michael Nelson ( ). In addition to rebutting the bad argument against the consistency of presentism and time travel, Keller and Nelson argue positively in favor of consistency by showing how to translate David Lewis’s ( ) account of time travel into the presentist’s tensed language. The appearance of con ict between presentism and time travel, they argue, is due only to the fact that most defenders of time travel (for example Lewis) have tended to phrase their defenses in nonpresentist terms. As much as I applaud their rebuttal of the bad argument, I wish to sound a note of caution..

Presentism—the thesis that only those things that are present exist—seems to face an insurmountable barrier in the Special Theory ofRelativity (STR). For the STR entails that simultaneity, and so the present, are relative to inertial frame. But if the present is the real and the present is relative, so too is in the real relative. But this cannot be. The real is absolute. But what is the Presentist to do? I suggest that she craft an alternative to the STR that is empirically equivalent to it but makes rooms for a present, and a real, that are absolute.

In this paper I argue that the debate between the so-called “presentists” – according to whom only the present is real – and the “eternalists”, according to whom past present and future are equally real, has no ontological significance. In particular, once we carefully distinguish between a tensed and a tenseless sense of existence, it is difficult to find a single ontological claim on which the two parties could disagree. Since the choice of using a tense or a tenseless language is dictated by purely pragmatic reasons, we should abstain from bringing to bear pseudo-debates generated by the “tensed” or the “tenseless theories” of time on the question of understanding the philosophical implications of contemporary spacetime theories, or notions like becoming, change and persistence in time.

The A-theory of time says that it is an objective, non-perspectival fact about the world that some events are present , while others were present or will be present. I shall argue that the A-theory has some implausible consequences for inductive reasoning. In particular, the presentist version of the A-theory, which holds that the difference between the present and the non-present consists in the present events being the only ones that exist, is very much in trouble.

If reality is temporary, then reality changes, and if reality changes, the past has explanatory work to do, and it cannot do that work unless it is no longer real. This tells against the Moving Now Theory, the Growing Block Theory, and any form of Presentism that attempts to understand the past in terms of the present, including Tensed Properties Presentism and Tensed Facts Presentism. It tells in favor of a form Presentism that allows us to appeal to unreal past facts. I suggest that Priorian Presentism, conjoined with a certain way of understanding the role played by tense operators, is one such view.

In this paper I discuss an unconventional form of presentism which, I claim, captures better than all other versions of the doctrine the fundamental notion underpinning it, namely, the notion that 'only what is present is real'. My proposal is to take this maxim as stating, not the rather uncontroversial view that past things are not real now, but the more radical idea that they never were. This rendition of presentism is, I argue, the only one that is neither trivial nor absurd. I examine this proposal by considering it against a sceptical hypothesis that bears similarities to it, viz., the hypothesis that the world was created five minutes ago. On this hypothesis, the past, all but five minutes of it, is unreal, in precisely the sense in which the presentism I discuss claims it is. I show that, assuming semantic externalism, this sceptical hypothesis cannot be sustained, but that a somewhat weaker hypothesis, the Creationist hypothesis that the world is 5,768 years old, cannot be refuted. Together, these conclusions enable a demarcation of those presentist intuitions that language and thought tolerate and those they do not.

According to the moving spotlight theory of time, the property of being present moves from earlier times to later times, like a spotlight shone on spacetime by God. In more detail, the theory has three components. First, it is a version of eternalism: all times, past present and future, exist. (Here I use “exist” in its tenseless sense.) Second, it is a version of the A-theory of time: there are nonrelative facts about which times are past, which time is present, and which times are future. That is, it is not just that the year 1066 is past relative to 2007. The year 1066 is also past full-stop, not relative to any other time. (The A-theory is opposed to the B-theory of time, which says that facts about which times are past are relative to other times.) And third, on this view the passage of time is a real phenomenon. Which moment is present keeps changing. As I will sometimes put it, the NOW moves from the past toward the future.1 And this does not mean that relative to different times, different times are present. Even the B-theory can say that 1999 is present relative to 1999 but is not present relative to 2007. No, according to the moving spotlight theory, the claim that which moment is present keeps changing is supposed to be true, even from a perspective outside time.

This is an expanded and revised discussion of the argument briefly put forward in my 'A New Problem for the A-Theory of Time', where it is claimed that it is impossible to experience real temporal passage and that no such phenomenon exists. In the first half of the paper the premises of the argument are discussed in more detail than before. In the second half responses are given to several possible objections, none of which were addressed in the earlier paper. There is also some discussion of some related epistemic arguments against the passage of time given by Huw Price and David Braddon-Mitchell along with objections raised against them recently by Tim Maudlin and Peter Forrest respectively.