Wes Morriston contends that William Lane Craig's argument for the impossibility of a beginningless past results in an equally good argument for the impossibility of an endless future. Craig disagrees. I show that Craig's reply reveals a commitment to an unmotivated position concerning the relationship between actuality and the actual infinite. I then assess alternative routes to the impossibility of a beginningless past that have been offered in the literature, and show that, contrary to initial appearances, these routes similarly seem (...) to support the impossibility of an endless future. (shrink)

This paper brings two fresh perspectives on Lewis’s theory of time travel. First: many key aspects and theoretical desiderata of Lewis’s theory can be captured in a framework that does not commit to eternalism about time. Second: implementing aspects of Lewisian time travel in a non-eternalist framework provides theoretical resources for a better treatment of time travel to the future. While time travel to the past has been extensively analyzed, time travel to the future has been comparatively underexplored. I make (...) progress on this topic. Along the way, I discuss Lewis’s lesser-known time travel oeuvre, especially his volume of correspondence and lectures on the topic collected in Beebee and Fisher (2020) and Janssen-Lauret & MacBride (forthcoming). Lewis’s body of unpublished work on time travel yields fruitful insights into his broader thinking on the subject. (shrink)

Spatial models dominated memory research throughout much of the 20th century, but in recent decades, the concept of memory as a form of mental time travel (MTT) to the past has gained prominence. Initially introduced as a metaphor, the MTT perspective shifted the focus from internal memory processes to the subjective conscious experience of remembering. Despite its significant impact on empirical and theoretical memory research, there has been limited discussion regarding the meaning and adequacy of the MTT metaphor in accounting (...) for memory. While previous work has addressed the general limitations of the MTT metaphor in explaining memory (Trakas, 2022), the objective of this article is more focused and modest: to gain a better understanding of what constitutes MTT to the past. To achieve this objective, a detailed analysis of the characteristics of MTT to the past is presented through a comparison with time travel (TT) to the past. Although acknowledging that TT does not refer to an existing physical phenomenon, it is an older concept extensively discussed in the philosophical literature and provides commonly accepted grounds, particularly within orthodox theories of time, that can offer insights into the nature of MTT. Six specific characteristics serve as points of comparison: (1) a destination distinct from the present, (2) the distinction between subjective time and objective time, (3) the subjective experience of the time traveler, (4) their differentiation from the past self, (5) the existence of the past, and (6) its unchangeability. Through this research, a detailed exploration of the phenomenal and metaphysical aspects of MTT to the past is undertaken, shedding light on the distinct features that mental time travel to the past acquires when it occurs within the realm of the mind rather than as a physical phenomenon. By examining these characteristics, a deeper understanding of the nature of mental time travel is achieved, offering insights into how it operates in relation to memory and the past. (shrink)

About the possibility of time traveling based on several specialized works, including those of Nicholas J. J. Smith ("Time Travel"), William Grey (”Troubles with Time Travel”), Ulrich Meyer (”Explaining causal loops”), Simon Keller and Michael Nelson (”Presentists should believe in time-travel”), Frank Arntzenius and Tim Maudlin ("Time Travel and Modern Physics"), and David Lewis (“The Paradoxes of Time Travel”). The article begins with an Introduction in which I make a short presentation of the time travel, and continues with a History (...) of the concept of time travel, main physical aspects of time travel, including backward time travel in the past in general relativity and quantum physics, and time travel in the future, then a presentation of the Grandfather paradox that is approached in almost all specialized works, followed by a section dedicated to the Philosophy of time travel, and a section in which I analyze Causal loops for time travel. I finish my work with Conclusions, in which I sustain my personal opinions on the time travel, and the Bibliography on which the work is based. -/- ISSN 978-606-033-195-7, DOI: 10.58679/TW82554. (shrink)

În această lucrare analizez posibilitatea călătoriei în timp pe baza mai multor lucrări de specialitate, printre care cele ale lui Nicholas J.J. Smith ("Time Travel", The Stanford Encyclopedia of Philosophy”), William Grey (”Troubles with Time Travel”), Ulrich Meyer (”Explaining causal loops”), Simon Keller și Michael Nelson (”Presentists should believe in time-travel”), Frank Arntzenius și Tim Maudlin ("Time Travel and Modern Physics") și David Lewis (“The Paradoxes of Time Travel”). Lucrarea începe cu o Introducere în care fac o scurtă prezentare a (...) călătoriei în timp, și continuă cu o Istoria conceptului de călătorie în timp, prezentarea principalelor Aspecte fizice ale călătoriei în timp, inclusiv călătoria în timp în trecut în relativitatea generală și în fizica cuantică și călătoria în timp în viitor, apoi o prezentare a Paradoxul bunicului care este abordat în aproape toate lucrările de specialitate, urmat de o secțiune dedicată Filosofiei călătoriei în timp, și o secțiune în care analizez Buclele cauzale pentru călătoria în timp. Finalizez lucrarea cu Concluzii, în care expun opiniile personale privind călătoria în timp, și Bibliografia pe care se bazează lucrarea. (shrink)

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.. (shrink)

This paper argues for the following disjunction: either we do not live in a world with a branching temporal structure, or backwards time travel is nomologically impossible, given the initial state of the universe, or backwards time travel to our space-time location is impossible given large-scale facts about space and time. A fortiori, if backwards time travel to our location is possible, we do not live in a branching universe.

One objection to the thesis that multilocation is possible claims that, when combined with a preference for parsimonious theories, it leads to the absurd result that we ought to believe the material universe is composed of just one simple particle. I argue that this objection fails.

It has sometimes been suggested that backwards time travel always incurs causal loops. I show that this is mistaken, by describing worlds where backwards time travel occurs and yet no causal loops occur. Arguments that backwards time travel can occur without causal loops have been given before in the literature, but I show that those arguments are unconvincing.

It is often thought that presentism is incompatible with time travel. I will argue that this common view is incorrect. Specifically, I will argue that presentism is compatible with some stories that involve closed timelike curves, and that some of these stories are time-travel stories.

Future-biased individuals systematically prefer positively valenced events to be in the future (positive future-bias) and negatively valenced events to be in the past (negative future-bias). The most extreme form of future-bias is absolute future-bias, whereby we completely discount the value of past events when forming our preferences. Various authors have thought that we are absolutely future-biased (Sullivan (2018:58); Parfit (1984:173) and that future-bias (absolute or otherwise) is at least rationally permissible (Prior (1959), Hare (2007; 2008), Kauppinen (2018), Heathwood (2008)). The (...) permissibility of future-bias is often held to be grounded in the structure of the temporal dimension. In this paper I consider several proposals for grounding the permissibility of such preferences and evaluate these in the light of the preferences we would have, and judge that we should have, in various time-travel scenarios. I argue that what we learn by considering these scenarios is that these preferences really have nothing to do with temporal structure. So if something grounds their permissibility, it is not temporal structure. (shrink)

We direct different attitudes towards states of affairs depending on where in time those states of affairs are located. Call this the type asymmetry. The type asymmetry appears fitting. For instance, it seems fitting to feel guilt or regret only about states of affairs that are past, and anticipation only of states of affairs that are future. It has been argued that the type asymmetry could only be fitting if there are tensed facts, and hence that since it is fitting, (...) there are tensed facts. In this paper I argue that tensed facts are not necessary to ground the fittingness of the type asymmetry, and thus we have no reason, arising from the fittingness of the asymmetry, to posit such facts. I also argue for a stronger conclusion: even if these facts obtain they are no part of what grounds the fittingness of the type asymmetry. These facts are explanatorily redundant. (shrink)

I argue that time travel to the past is impossible, given a certain metaphysical theory, namely, The Dynamic Theory of Time. I first spell out my particular way of capturing the difference between The Dynamic Theory of Time and its rival, The Static Theory of Time. Next I offer four different arguments for the conclusion that The Dynamic Theory is inconsistent with the possibility of time travel to the past. Then I argue that, even if I am wrong about this, (...) it will still be true that The Dynamic Theory entails that you should not want to travel back to the past. Finally, I conclude by considering a puzzle that arises for those who believe that time travel to the past is metaphysically impossible: What exactly are we thinking about when we seem to be thinking about traveling back in time? For it certainly does not feel like we are thinking about something that is metaphysically impossible. (shrink)

After defining presentism, I consider four arguments that presentism and divine atemporality are incompatible. I identify an assumption common to the four, ask what reason there is to consider it true, and argue against it.

Thinking about time travel is an entertaining way to explore how to understand time and its location in the broad conceptual landscape that includes causation, fate, action, possibility, experience, and reality. It is uncontroversial that time travel towards the future exists, and time travel to the past is generally recognized as permitted by Einstein’s general theory of relativity, though no one knows yet whether nature truly allows it. Coherent time travel stories have added flair to traditional debates over the metaphysical (...) status of the past, the reality of temporal passage, and the existence of free will. Moreover, plausible models of time travel and time machines can be used to investigate the subtle relation between space-time structure and causality. -/- It surveys some philosophical issues concerning time travel and should serves as a quick introduction. It includes a new and improved way to define a time machine. (shrink)

Three arguments for the conclusion that objects cannot endure in B-time even if they remain intrinsically unchanged are examined: Carter and Hestevolds enduring-objects-as-universals argument (American Philosophical Quarterly 31(4):269-283, 1994) and Barker and Dowe's paradox 1 and paradox 2 (Analysis 63(2):106-114, 2003, Analysis 65(1):69-74, 2005). All three are shown to fail.

In the present paper, I offer a new argument to show that presentism about time is incompatible with time travel. Time travel requires leaving the present, which, under presentism, contains all of reality. Therefore to leave the present moment is to leave reality entirely; i.e. to go out of existence. Presentist “time travel” is therefore best seen as a form of suicide, not as a mode of transportation. Eternalists about time do not face the same difficulty, and time travel is (...) compossible with eternalism. (shrink)

In this paper I defend the compossibility of presentism and time travel from two objections. One objection is that the presentist’s model of time leaves nowhere to travel to; the second objection attempts to equate presentist time travel with suicide. After targeting some misplaced scrutiny of the first objection, I show that presentists have the resources to account for the facts that make for time travel on the traditional Lewisian view. In light of this ability, I argue that both of (...) the objections fail. (shrink)

How is the debate between endurantism and perdurantism affected by the transition from pre-relativistic spacetimes to relativistic ones? After suggesting that the endurance vs. perdurance distinction may run together a pair of cross-cutting distinctions, I discuss two recent attempts to show that the transition in question does serious damage to endurantism.

‘Past vacillators’ believe that what was once the case may change over time. This has obvious applications to the possibility of changing the past via time travel. ‘Future vacillators’ believe that some things will happen and yet, later, will not. Further to issues in time travel, future vacillation has applications when it comes to ‘Geachian’ views about the open future. This paper argues that if you deny that the ‘earlier than’ and ‘later than’ relations are converses of one another then (...) you can develop metaphysical systems underpinning the possibility of such vacillation. (shrink)

ABSTRACT Closed time is possible in several senses of ‘possible’. One might like to know, therefore, whether closed time is possible in the sense that it is compatible with standard metaphysical theories of time. In this paper I am concerned with whether closed time is compatible with A and/or B theories of time. A common enough view amongst philosophers is that B theories do but A theories do not allow closed time. However, I show that prima-facie neither approach allows closed (...) time, but that with a little work standard versions of both approaches do. This shows that there’s no special problem with the notion of eternal return. (shrink)

Endurantists have recently faced a mereological puzzle in various forms. Here I argue that, instead of presenting a genuine worry, the puzzle actually reveals a common misunderstanding about the endurantist ontology. Furthermore, through this discussion of the alleged problem and the misunderstanding which motivates it, I reveal metaphysical commitments the endurantist has that may not be widely recognized. For instance, she is committed to interesting and perhaps controversial views about shape and location. I highlight these commitments and what they mean (...) for the endurantist. (shrink)

Here I defend the compatibility of presentism and time travel against a few objections. Keller and Nelson argue that, if presentism is at all plausible, presentism and time travel are as compatible as eternalism and time travel. But Miller and Sider are not convinced. I reply that for their concerns to have merit, Miller and Sider must assume presentists are committed to positions they need not be; I explain why presentists are not so committed and, in the process, defend Keller (...) and Nelson’s position that there is no roadblock to presentist time travel that does not also apply to eternalist time travel. (shrink)

The philosophy of time travel is a sub-field of metaphysics – the study of what there is and what things are like – that considers questions about the possibility of time travel and what a world in which time travel is possible looks like. These questions range from whether time travel is actually possible, to how time travellers can act in the past or future. This thesis delves into a particularly interesting, yet historically undertreated theme: the abilities of time travellers (...) and relatedly their freedom as well. The abilities and freedom of time travellers has been the source of a lot of recent discussion with some polarising views. The minority (which includes Lewis (1976), but also Ted Sider (2002)) argue for the affirmative – that time travellers are free and have the same (or perhaps more) abilities as non-time travellers. The majority (which includes Kadri Vihvelin (1996), Michael Rea (2005), Stephanie Rennick (2015), Alison Fernandes (2020), amongst others) argue for the negative, that time travellers do not have exactly the same freedoms and abilities as non-time travellers. I think that it is a mistake to be so pessimistic about the abilities and freedom of time travellers. I treat concerns about the freedom of time travellers and concerns about the abilities of time travellers as two sides of the same coin. Therefore, in what follows, I argue for two related conclusions. First, I argue that time travellers have all sorts of abilities. Second, I argue that time travellers are just as free as non-time travellers. In arguing for these conclusions, I first produce a novel analysis of ability which reveals important details about how abilities track inputs rather than outputs. Second, I use this new analysis of ability to present a new compatibilist account of free will. If I am right in arguing positively for the abilities and freedoms of time travellers, then this has large implications for both the current time travel discourse and the general debate surrounding freedom. Significantly, I am arguing against some prominent views about time travel and in suggesting that these views are mistaken, I am presenting new ideas about ability and freedom: specifically, that time travellers have the ability and are free to do impossible things. (shrink)

Ted Sider aptly and concisely states the self-visitation paradox thus: 'Suppose I travel back in time and stand in a room with my sitting 10-year-old self. I seem to be both sitting and standing, but how can that be?' (2001, 101). I will explore a relativist resolution of this paradox offered by, or on behalf of, endurantists.1 It maintains that the sitting and the standing are relative to the personal time or proper time of the time traveler and is intended (...) to yield the result that Ted is sitting at a certain initial personal/proper time but is not standing relative to that time. Similarly, it is also supposed to yield that Ted is standing relative to a later personal/proper time, but not sitting relative to that .. (shrink)

We argue that a certain variety of presentist time travel ends up significantly undermining the motivational foundations which lead some, but not all, presentists to their view. We suggest that if presentism is motivated by phenomenology, and part of that phenomenology is that it’s an experiential datum that we experience temporal passage, then the basis for believing presentism is less secure than we might have thought.

In this chapter I articulate the threat that time travel to the past allegedly poses to the free will of the time traveler, and I argue that on the traditional way of thinking about free will, the incompatibilist about time travel and free will wins the day. However, a residual worry about the incompatibilist view points the way toward a novel way of thinking about free will, one that I tentatively explore toward the end of the chapter.

Discussions of the nature of time, and of various issues related to time, have always featured prominently in philosophy, but they have been especially important since the beginning of the 20th Century. This article contains a brief overview of some of the main topics in the philosophy of time — Fatalism; Reductionism and Platonism with respect to time; the topology of time; McTaggart's arguments; The A Theory and The B Theory; Presentism, Eternalism, and The Growing Universe Theory; time travel; and (...) the 3D/4D controversy — together with some suggestions for further reading on each topic, and a bibliography. (shrink)

The standard definition of an instantaneous temporal part cannot properly deal with cases involving time travel. This paper provides a new definition of an instantaneous temporal part by appealing to David Lewis's distinction between external time and personal time. The new definition avoids the problems because it does not allow more than one instantaneous temporal part of an object at each moment of its personal time. We argue that this new definition, combined with our new perdurantist semantic thesis, deals with (...) cases of time travel successfully. (shrink)

À propos de la possibilité de voyager dans le temps sur la base de plusieurs ouvrages spécialisés, notamment ceux de Nicholas J. J. Smith (« Time Travel »), William Grey (« Troubles with Time Travel »), Ulrich Meyer (« Explaining causal loops »), Simon Keller and Michael Nelson (« Presentists should believe in time-travel »), Frank Arntzenius and Tim Maudlin (« Time Travel and Modern Physics »), et David Lewis (« The Paradoxes of Time Travel »). L'article commence par une (...) Introduction dans laquelle je fais une brève présentation du voyage dans le temps et poursuit par une Histoire du concept de voyage dans le temps, les principaux aspects physiques du voyage dans le temps, y compris les voyages dans le temps dans le passé dans la relativité générale et la physique quantique , et les voyages dans le temps dans le futur, puis une présentation du Paradoxe du grand-père abordé dans presque toutes les œuvres spécialisées, suivie d’une section consacrée à la Philosophie du voyage dans le temps et d’une section dans laquelle j’analyse les Boucles causales pour le voyage dans le temps. Je termine mon travail avec Conclusions, dans laquelle je maintiens mes opinions personnelles sur le voyage dans le temps et la Bibliographie sur laquelle repose le travail. -/- TABLE: -/- Abstract Introducere Istoria conceptului de călătorie în timp Paradoxul bunicului Filosofía călătoriei în timp Buclele cauzale Concluzii Note Bibliografie -/- DOI: 10.13140/RG.2.2.27116.51841. (shrink)

There is, among some scientists and philosophers, the idea that any theory that would allow the time travel would introduce causal issues. These types of temporal paradoxes can be avoided by the Novikov self-consistency principle or by a variation in the interpretation of many worlds with interacting worlds. The world in which we live has, according to David Lewis, a Parmenidean ontology: "a manifold of events in four dimensions," and the occupants of the world are the 4-dimensional aggregates of the (...) stages - "temporal lines". The causal loops in backwards time travel involve events that appear to "come from nowhere," paradoxical "self-existent" objects or information, resulting in a bootstrap paradox. Many believe that causality loops are not impossible or unacceptable, but only inexplicable. DOI: 10.13140/RG.2.2.28792.70407. (shrink)

Famously, David Lewis argued that we can avoid the apparent paradoxes of time travel by introducing a notion of personal time, which by and large follows the causal flow of the time traveler's life history. This paper argues that a related approach can be adapted for use by three-dimensionalists in response to Ted Sider's claim that three-dimensionalism is inconsistent with time travel. In contrast to Lewis (and others who follow him on this point), however, this paper argues that the order (...) of events captured by so-called "personal time" should be thought of as causal, rather than temporal. (shrink)

This chapter argues for a notion of time that allows time travel. In order to time traveling to happen, in contrast to Presentism, the chapter demonstrates that we can change the past and we have some place where to travel. It shows the advantages of a non-presentist ontology that advocates for indeterminacy of future facts based not on its absence of truth-value, but on the overdetermination of future facts. The conclusion is that to break the causal chain is impossible in (...) we are placed in the same causal line. But if we rethink the time traveling as a trans-world traveling, it is possible to open a new causal line anytime that someone travel in time, to the past as well as to the future. (shrink)

A recent account of presentist time travel involves a causal relation between events at two different and discontiguous times, and presentists cannot have such causal relations because presentism rules out the existence of at least one of the two relata in such a relation due to it being non-present. Additionally, presentists cannot have parodies of such causal relations for use in time travel stories because parodies are subject, at least, to the same limitations as the things being parodied. So, the (...) presentist has not successfully given an internally consistent account of presentist time travel. (shrink)

Newton a susținut ideea timpului absolut, spre deosebire de Leibniz pentru care timpul este doar o relație între evenimente și nu poate fi exprimat în mod independent, afirmație în concordanță ci relativitatea spațiu-timpului. Eternismul susține că trecutul și viitorul există într-un sens real, mergându-se până la ideea că timpul este o dimensiune similară cu dimensiunile spațiale, că evenimentele viitoare și trecute sunt "prezente" pe axa timpului, dar această opinie este contestată. Cel mai cunoscut exemplu de imposibilitate a călătoriei în timp (...) este paradoxul bunicului sau argumentul auto-infanticidului: o persoană care călătorește în trecut și își ucide propriul bunic, împiedicând astfel existența unuia din părinți, și deci propria sa existență. DOI: 10.13140/RG.2.2.12629.47843. (shrink)

Newton supported the idea of absolute time, unlike Leibniz, for which time is only a relation between events and cannot be expressed independently, a statement in concordance with the relativity of space-time. Eternalism claims that the past and the future exist in a real sense, going to the idea that time is a dimension similar to spatial dimensions, that future and past events are "present" on the axis of time, but this view is challenged. On four-dimensional vision, the universe is (...) an existing space-time topology, containing everything that has happened, everything that happens and everything that's going to happen. It follows that there is no singular moment to be considered as insignificant as present. Time travel is possible if the four-dimensional vision including the time is correct, but it is not possible if presentism is true. William Godfrey-Smith says that "the metaphysical image underlying the discussion of time travel is that of the universe block, in which the world is conceived as extended in time as it is in space." DOI: 10.13140/RG.2.2.18575.64163. (shrink)