In "Changing the Past" (2010), Peter van Inwagen argues that a time traveler can change the past without paradox in a growing block universe. After erasing the portion of past existence that generates paradox, a new, non-paradox-generating block can be "grown" after the temporal relocation of the time traveler. -/- I articulate and explore the underlying mechanism of Van Inwagen's model: the time traveler's control over the location of the objective present. Van Inwagen's model is aimed at preventing paradox by (...) changing the past, but it achieves something broader than paradox avoidance: it gives tools for a new model of time travel. I use van Inwagen's tools to develop a new kind of time travel in which in which the location of the objective present is shifted by the time traveler. I call this type of time travel Movable Objective Present, or MOP. After defining MOP, I argue that it is compatible with any theory of time that accepts hypertime, including presentism and moving spotlight theory. (shrink)

This paper suggests that time travelling scenarios commonly depicted in science fiction introduce problems and dangers for the time traveller. If time travel takes time, then time travellers risk collision with past objects, relocation to distant parts of the universe, and time travel-specific injuries. I propose several models of time travel that avoid the dangers and risks of time travel taking time, and that introduce new questions about the relationship between time travel and spatial location.

This paper is an enquiry into the logical, metaphysical, and physical possibility of time travel understood in the sense of the existence of closed worldlines that can be traced out by physical objects. We argue that none of the purported paradoxes rule out time travel either on grounds of logic or metaphysics. More relevantly, modern spacetime theories such as general relativity seem to permit models that feature closed worldlines. We discuss, in the context of Gödel's infamous argument for (...) the ideality of time based on his eponymous spacetime, what this apparent physical possibility of time travel means. Furthermore, we review the recent literature on so-called time machines, i.e., of devices that produce closed worldlines where none would have existed otherwise. Finally, we investigate what the implications of the quantum behaviour of matter for the possibility of time travel might be and explicate in what sense time travel might be possible according to leading contenders for full quantum theories of gravity such as string theory and loop quantum gravity. (shrink)

While many aspects of cognition have been shown to be shared between humans and non-human animals, there remains controversy regarding whether the capacity to mentally time travel is a uniquely human one. In this paper, we argue that there are four ways of representing when some event happened: four kinds of temporal representation. Distinguishing these four kinds of temporal representation has five benefits. First, it puts us in a position to determine the particular benefits these distinct temporal representations afford (...) an organism. Second, it provides the conceptual resources to foster a discussion about which of these representations is necessary for an organism to count as having the capacity to mentally time travel. Third, it enables us to distinguish stricter from more liberal views of mental time travel that differ regarding which kind(s) of temporal representation is taken to be necessary for mental time travel. Fourth, it allows us to determine the benefits of taking a stricter or more liberal view of mental time travel. Finally, it ensures that disagreement about whether some species can mentally time travel is not merely the product of unrecognised disagreement about which temporal representation is necessary for mental time travel. We argue for a more liberal view, on the grounds that it allows us to view mental time travel as an evolutionarily continuous phenomenon, and to recognise that differences in the ways that organisms mentally time travel might reflect different temporal representations, or combinations thereof, that they employ. Our ultimate aim, however, is to create the conceptual framework for further discussion regarding what sorts of temporal representations are required for mental time travel. (shrink)

In this paper, I argue that the thesis that time travel is logically possible, is inconsistent with the necessary truth of any of the usual ‘open futureobjective present’ models of the universe. It has been relatively uncontroversial until recently to hold that presentism is inconsistent with the possibility of time travel. I argue that recent arguments to the contrary do not show that presentism is consistent with time travel. Moreover, the necessary truth of other open future-objective present (...) models which we might, prima facie, have supposed to be more amenable to the possibility of time travel, turn out also to be inconsistent with this possibility. (shrink)

It is possible to wholly exist at multiple spatial locations at the same time. At least, if time travel is possible and objects endure, then such must be the case. To accommodate this possibility requires the introduction of a spatial analog of either relativising properties to times—relativising properties to spatial locations—or of relativising the manner of instantiation to times—relativising the manner of instantiation to spatial locations. It has been suggested, however, that introducing irreducibly spatially relativised or spatially adverbialised properties (...) presents some difficulties for the endurantist. I will consider an objection according to which embracing such spatially relativised properties could lead us to reject mereology altogether in favour of a metaphysics according to which objects are wholly present at every space-time point at which they exist. I argue that although such a view is coherent, there are some good reasons to reject it. Moreover, I argue that the endurantist can introduce spatially relativised or adverbialised properties without conceding that objects lack spatial parts. Such a strategy has the additional advantage that it allows the endurantist not only to explain time travel, but also to reconcile our competing intuitions about cases of fission. (shrink)

The goal of this paper is to defend the general tenet that time travelers cannot change the past within B-theoretical models of time, independently of how many temporal dimensions there are. Baron Pacific Philosophical Quarterly, 98, 129–147 offered a strong argument intended to reach this general conclusion. However, his argument does not cover a peculiar case, i.e. a B-theoretical one-dimensional model of time that allows for the presence of internal times. Loss Pacific Philosophical Quarterly, 96, 1–11 used the latter model (...) to argue that time travelers can change the past within such model. We show a way to debunk Loss’s argument, so that the general tenet about the impossibility of changing the past within B-theoretical models is maintained. (shrink)

There is a growing body of scholarship that is addressing the ethics, in particular, the bioethics of space travel and colonisation. Naturally, a variety of perspectives concerning the ethical issues and moral permissibility of different technological strategies for confronting the rigours of space travel and colonisation have emerged in the debate. Approaches ranging from genetically enhancing human astronauts to modifying the environments of planets to make them hospitable have been proposed as methods. This paper takes a look at (...) a critique of human bioenhancement proposed by Mirko Garasic who argues that the bioenhancement of human astronauts is not only functional but necessary and thus morally permissible. However, he further claims that the bioethical arguments proposed for the context of space do not apply to the context of Earth. This paper forwards three arguments for how Garasic’s views are philosophically dubious: (1) when he examines our responsibility towards future generations he refers to a moral principle (which we will call the principle of mere survival) which, besides being vague, is not morally acceptable; (2) the idea that human bioenhancement is not natural is not only debatable but morally irrelevant; and (3) it is not true that the situations that may arise in space travel cannot occur on Earth. We conclude that not only is the (bio)enhancement of humans on Earth permissible but perhaps even necessary in certain circumstances. (shrink)

It is possible to wholly exist at multiple spatial locations at the same time. At least, if time travel is possible and objects endure, then such must be the case. To accommodate this possibility requires the introduction of a spatial analog of either relativising properties to times—relativising properties to spatial locations—or of relativising the manner of instantiation to times—relativising the manner of instantiation to spatial locations. It has been suggested, however, that introducing irreducibly spatially relativised or spatially adverbialised properties (...) presents some difficulties for the endurantist. I will consider an objection according to which embracing such spatially relativised properties could lead us to reject mereology altogether in favour of a metaphysics according to which objects are wholly present at every space-time point at which they exist. I argue that although such a view is coherent, there are some good reasons to reject it. Moreover, I argue that the endurantist can introduce spatially relativised or adverbialised properties without conceding that objects lack spatial parts. Such a strategy has the additional advantage that it allows the endurantist not only to explain time travel, but also to reconcile our competing intuitions about cases of fission. (shrink)

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)

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.

The first section of this article focuses on the treatment of “time travel” in science-fiction literature and film as presented in the secondary literature in that field. The first anthology I will consider has a metaphysical focus, including (a) relating the time travel of science fiction to the banal time travel of all living beings, as we move inexorably toward the future; and (b) arguing for the filmstrip as the ultimate metaphor for time. The second anthology I (...) will consider has a more political focus, arguing that the “special effects” form of science-fiction films, rather than the visual or narrative content of science-fiction-films, is truly imaginative and futural. The second section of this article ties together a variety of concepts and insights between time-travel cinema and Deleuze’s Cinema 1, suggesting (among other things) that (c) time-traveling characters in cinema function as a redoubled phenomenon of the “mobile sections” of Bergsonian duration (in reference to Henri Bergson), and (d) time-travel cinema vividly illustrates the imagistic nature of the entire world. (shrink)

This paper is dedicated to articulating the ethical puzzles that arise from the possibility of time travel. I divide the puzzles into three different categories: permissibility puzzles, obligation puzzles, and conflicts between past and future selves. In each category, I suggest that ethical problems involving time travel are not as dissimilar to parallel “normal” ethical puzzles as one might think.

This article argues that existing approaches to programming ethical AI fail to resolve a serious moral-semantic trilemma, generating interpretations of ethical requirements that are either too semantically strict, too semantically flexible, or overly unpredictable. This paper then illustrates the trilemma utilizing a recently proposed ‘general ethical dilemma analyzer,’ GenEth. Finally, it uses empirical evidence to argue that human beings resolve the semantic trilemma using general cognitive and motivational processes involving ‘mental time-travel,’ whereby we simulate different possible pasts and futures. (...) I demonstrate how mental time-travel psychology leads us to resolve the semantic trilemma through a six-step process of interpersonal negotiation and renegotiation, and then conclude by showing how comparative advantages in processing power would plausibly cause AI to use similar processes to solve the semantic trilemma more reliably than we do, leading AI to make better moral-semantic choices than humans do by our very own lights. (shrink)

This article is divided into three sections. In the first and second, I examine Sartorio’s account of the causal structure of the famous Thirsty Traveler thought experiment. I argue that this account does not withstand critical scrutiny. In the third, I turn to a novel kind of moral luck that Sartorio uses the Thirsty Traveler to expose. I expand the scope of my argument to look also at other recently proposed categories of moral luck. I argue that these proposals are (...) overhasty. (shrink)

In this paper I borrow from Maria Lugones’ work on playful “world-traveling” and W.E.B. Du Bois’ notion of “double consciousness” to make the case that humor can facilitate an openness and cooperative attitude among an otherwise closed, even adversarial audience. I focus on what I call “subversive” humor, that which is employed by or on behalf of those who have been continually marginalized. When effectively used, such humor can foster the inclination and even desire to listen to others and, if (...) only for brief moments, adopt their point of view. To be able to see oneself as others see you can also be a desirable capacity, because along with such multidimensional seeing comes an epistemic advantage lacking in those who have no need nor desire to see as others do, especially if the vision of the others happens to be from below where one perceives that the promises of our explicit ideals are constantly being implicitly broken. Such humor is aesthetic, pleasurable in and of itself, and not amenable to scientific dissection. But it is also a skill that can be honed into a powerful tool of persuasion in circumstances where straightforward arguments are less effective. It can raise consciousness about the lived experiences of those suffering under systemic oppression and foster world travelling. Subversive humor encourages audiences, especially those who contribute to what Jean Harvey calls “civilized oppression”, to playfully travel across worlds and “tarry along” with the perspectives of the marginalized. (shrink)

Episodic memory (memories of the personal past) and prospecting the future (anticipating events) are often described as mental time travel (MTT). While most use this description metaphorically, we argue that episodic memory may allow for MTT in at least some robust sense. While episodic memory experiences may not allow us to literally travel through time, they do afford genuine awareness of past-perceived events. This is in contrast to an alternative view on which episodic memory experiences present past-perceived events (...) as mere intentional contents. Hence, episodic memory is a way of coming into experiential contact with, or being again aware of, what happened in the past. We argue that episodic memory experiences depend on a causal-informational link with the past events being remembered, and that, assuming direct realism about episodic memory experiences, this link suffices for genuine awareness. Since there is no such link in future prospection, a similar argument cannot be used to show that it also affords genuine awareness of future events. Constructivist views of memory might challenge the idea of memory as genuine awareness of remembered events. We explain how our view is consistent with both constructivist and anti-causalist conceptions of memory. There is still room for an interpretation of episodic memory as enabling genuine awareness of past events, even if it involves reconstruction. (shrink)

A testimony is somebody else’s reported experience of what has happened. It is an indispensable source of knowledge. It only gives us historical cognition, however, which stands in a complex relation to rational or philosophical cognition: while the latter presupposes historical cognition as its matter, one needs the architectonic “eye of a philosopher” to select, interpret, and organize historical cognition. Kant develops this rationalist theory of testimony. He also practices it in his own work, especially while theorizing about race as (...) a subject of natural philosophy. In three dedicated essays on this subject, he treats race from the standpoint of a philosophical investigator of nature (Naturforscher), who (as Kant puts it in the first Critique) learns from nature “like an appointed judge who compels witnesses to answer the questions he puts to them.” This view underwrites Kant’s use of travel reports (a type of testimony) in developing and defending his theory of race. (shrink)

I criticize Lockwood’s solution to the “paradoxes” of time travel, thus endorsing Lewis’s more conservative position. Lockwood argues that only in the context of a 5D space-time-actuality manifold is the possibility of time travel compatible with the Autonomy Principle (according to which global constraints cannot override what is physically possible locally). I argue that shifting from 4D space-time to 5D space-time-actuality does not change the situation with respect to the Autonomy Principle, since the shift does not allow us (...) to have a coincidence-free local dynamical theory. (shrink)

The Principle of Alternative Possibilities is the intuitive idea that someone is morally responsible for an action only if she could have done otherwise. Harry Frankfurt has famously presented putative counterexamples to this intuitive principle. In this paper, I formulate a simple version of the Principle of Alternative Possibilities that invokes a course-grained notion of actions. After warming up with a Frankfurt-Style Counterexample to this principle, I introduce a new kind of counterexample based on the possibility of time travel. (...) At the end of the paper, I formulate a more sophisticated version of the Principle of Alternative Possibilities that invokes a certain fine grained notion of actions. I then explain how this new kind of counterexample can be augmented to show that even the more sophisticated principle is false. (shrink)

Continuists maintain that, aside from their distinct temporal orientations, episodic memory and future-oriented mental time travel (FMTT) are qualitatively continuous. Discontinuists deny this, arguing that, in addition to their distinct temporal orientations, there are qualitative metaphysical or epistemological differences between episodic memory and FMTT. This chapter defends continuism by responding both to arguments for metaphysical discontinuism, based on alleged discontinuities between episodic memory and FMTT at the causal, intentional, and phenomenological levels, and to arguments for epistemological discontinuism, based on (...) alleged discontinuities with respect to the epistemic openness of the past and future, the directness or indirectness of our knowledge of past and future, and immunity to error through misidentification. The chapter concludes by sketching a positive argument for continuism. (shrink)

Kadri Vihvelin, in "What time travelers cannot do" (Philos Stud 81: 315-330, 1996), argued that "no time traveler can kill the baby who in fact is her younger self, because (V1) "if someone would fail to do something, no matter how hard or how many times she tried, then she cannot do it", and (V2) if a time traveler tried to kill her baby self, she would always fail. Theodore Sider (Philos Stud 110: 115-138, 2002) criticized Vihvelin's argument, and Ira (...) Kiourti (Philos Stud 139: 343-352, 2008) criticized both Vihvelin's argument and Sider's critique. I present a critique of Vihvelin's argument different from both Sider's and Kiourti's critiques: I argue in a novel way that both V1 and V2 are false. Since Vihvelin's argument might be understood as providing a challenge to the possibility of time travel, if my critique succeeds then time travel survives such a challenge unscathed. (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)

It has been suggested that there is something worrisome, puzzling, or incomprehensible about the sorts of causal loops sometimes involved in backwards time travel. This paper disentangles two distinct puzzles and evaluates whether they provide us reason to find backwards time travel incomprehensible, inexplicable, or otherwise worrisome. The paper argues that they provide no such reason.

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)

The article examines the collaborations between the pensionnaires of the Villa Medici in Rome and the members of the French School of Athens, shedding light on the complex relationships between architecture, art, and archeology. The second half of the 19th century was a period during which the exchanges and collaborations between archaeologists, artists, and architects acquired a reinvented role and a dominant place. Within such a context, Athens was the place par excellence, where the encounter between these three disciplines took (...) place. The main objective of the article is to render explicit how the revelations of archeology, actively disseminated by the members of the French School of Athens—the “Athéniens”—had an important impact on the approach of certain pensionnaires of the Villa Medici in Rome. Particular emphasis is placed on certain pensionnaires, who decided to devote their envois to ancient monuments of Greece. In parallel, the article intends to shed light on the methods that helped the pensionnaires-architects of the Villa Medici in Rome appropriate archaeological discoveries concerning Greek antiquities. The article takes, as a starting point, the following hypothesis: to better understand the figure of the architect-archaeologist, of whom Jacques Ignace Hittorff is an emblematic example, it is pivotal to bear in mind that before the second half of the 19th century neither the figure of Hellenic archeology nor the figure of the architect had yet acquired their autonomy. Taking into account that Johann Joachim Winckelmann, in the middle of the 18th century, forged an ideal Greek model, which was criticized during the second half of the 19th century, the article also sheds light on the fact that the revelations of archaeologists have called into question the Winckelmannian image of Greece. Another aspect that is explored in the article is Jacques Ignace Hittorff’s studies concerning the polychromy of ancient Greek monuments, paying special attention to his Restitution du temple d’Empédocle à Sélinonte ou l’Architecture polychrome chez les Grecs. The article also explores how the shifts of the status of philhellenism are related to the mutations of the meaning of travel to Greece. In parallel, it investigates the impact of Greek independence on the ideals of beauty and nature in arts, as well as how Greek independence is related to the intensification of the interest in the excavations of Greek antiquities. (shrink)

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.

Bringing research on collective memory together with research on episodic future thought, Szpunar and Szpunar :376–389, 2016) have recently developed the concept of collective future thought. Individual memory and individual future thought are increasingly seen as two forms of individual mental time travel, and it is natural to see collective memory and collective future thought as forms of collective mental time travel. But how seriously should the notion of collective mental time travel be taken? This article argues (...) that, while collective mental time travel is disanalogous in important respects to individual mental time travel, the concept of collective mental time travel nevertheless provides a useful means of organizing existing findings, while also suggesting promising directions for future research. (shrink)

Time travel is a recognized concept in philosophy and science, but whose scope is highly disputed, giving rise to numerous paradoxes in both philosophy and science. Time travel is considered by some accepted both in general relativity and quantum mechanics, but there is a unanimous consensus that it is not feasible with current technology. (Hawkins 2010) The raised issues are different for the time travel in the past compared to the time travel in the future.

Emily Thomas's seminal book The Meaning of Travel has brought the philosophy of travel back into the public eye in recent years. Thomas has shown that the topic of travel can be approached from numerous different perspectives, ranging from the historical to the conceptual‐analytical, to the political or even social‐philosophical perspectives. This article introduces another perspective, which Thomas only indirectly addresses, namely the argumentation‐theoretical perspective. It is notable that contemporary philosophy of travel lacks the nineteenth‐century approach (...) of using diagrams and maps to examine arguments for and against travel. Since this approach starts with Schopenhauer, we first introduce his argument maps, discuss their advantages and disadvantages, and argue that a modified version is suitable to visualize and analyze arguments for and against traveling as presented in Thomas's work. (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.

We argue that there is an interesting modal analogue of temporal persistence, namely modal persistence, and an interesting modal analogue of time travel, namely modal travel. We explicate each of these notions and then argue that there are plausible conditions under which some ordinary objects modally persist. We go on to consider whether it is plausible that any modally persistent objects also modally travel.

This chapter discusses several possible reasons why works by women philosophers have traveled significantly less than those written by men, although women’s contributions go back to the start of European history of philosophy. Differentiating between geographic, linguistic, historic and philosophical travels, Tove Pettersen claims that gender is particularly significant with regard to historical and philosophical traveling. As the case of women philosophers clearly demonstrate, gender hampers the circulation of certain texts and inhibit transhistorical exchange of knowledge and ideas. ****** Che (...) chapitre examine plusieurs raisons possibles pour expliquer pourquoi les œuvres de femmes philosophes ont “voyage” beaucoup moins que celle des hommes, bien que la contribution des femmes remonte au début de l´histoire européenne de la philosophie. Distinguant entre plusieurs façons de voyager – géographique, linguistique, historique et philosophique –, Tove Pettersen soutient que le “genre” est un facteur particulièrement significative par rapport au voyage historique et philosophique- Comme le démontre clairement le cas des femmes philosophes, leur genre nuit á la circulation de certains textes ainsi qu’à l’échange transnational du savoir et des idées. (shrink)

Smells seem to offer a great opportunity to restructure the reality of the individual. Yet, the olfactory dimension is rarely part of design strategies in architecture, urban planning or landscape urbanism. As designers, we learn to compose mainly with shapes, shapes whose full scale and effects on our senses we will experience only when constructed. However, we should be primarily concerned with creating spaces that not only open the imagination of the individual but also allow positive moods to thrive. In (...) this scheme, all the senses should be called, not just our vision, as is too often the case. The fields of architecture and environmental design must evolve and train professionals capable of conceptualizing both tangible and intangible forms. In this logic, architectural structures offer a way to call upon our own mindscapes; and within the discipline of design a new field of specialization exists: smellscaping. (shrink)

Military recruitment campaigns emphasize adventure, skills and camaraderie but rarely mention the moral complexities of armed conflict. Enlisting in state armed forces poses the risk of being complicit in unjust wars and associated war crimes. For prospective recruits concerned with morality, the decision is challenging. The probability of wrongdoing alone does not settle the matter; many lawful activities increase risks of future wrongdoing. The permissibility of enlisting depends on weighing expectations of doing good versus wrong. -/- Armed forces provide security (...) and humanitarian aid, so members often do much good. To assess individual decisions, consider whether the institution itself is justified. “Minimal justification” means armed forces cause less wrong than having none. “Full justification” means they cause less wrong than feasible alternatives. If justified, the participation needed for functioning should be permitted; volunteers take risks knowingly. -/- If minimally justified, either participation is permitted as above, or impermissible "dirty hands" roles are required, and either conscription distributes burden fairly or volunteers show "moral courage". The real question is institutional justification, not individual permissibility. To argue enlisting is impermissible implies arguing for disbanding the military. -/- If state armed forces are at least minimally justified, enlisting is likely morally permitted or even praiseworthy. Prospective recruits should consider institutional justification and expectations of contributing to good and wrong before deciding the morality of enlisting. For morally conscientious individuals, complex realities of armed conflict pose difficult questions with no easy answers. (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)

In this paper I give consideration to some apparent impossibilities for the time travelers to the past. After criticizing the views of D. Lewis and K. Vihvelin, I will show in what sense they are really impossible.

The idea that episodic memory is a form of mental time travel has played an important role in the development of memory research in the last couple decades. Despite its growing importance in psychology, philosophers have only begun to develop an interest in philosophical questions pertaining to the relationship between memory and mental time travel. Thus, this paper proposes a more systematic discussion of the relationship between memory and mental time travel from the point of view of (...) philosophy. I start by discussing some of the motivations to take memory to be a form of mental time travel. I call the resulting view of memory the mental time travel view. I then proceed to consider important philosophical questions pertaining to memory and develop them in the context of the mental time travel view. I conclude by suggesting that the intersection of the philosophy of memory and research on mental time travel not only provides new perspectives to think about traditional philosophical questions, but also new questions that have not been explored before. (shrink)

Some philosophers defend the possibility of synchronic multilocation, and have even used it to defend other substantive metaphysical theses. But just how strong is the case for the possibility of synchronic multilocation? The answer to this question depends in part on whether synchronic multilocation is wedded to other controversial metaphysical notions. In this paper, I consider whether the possibility of synchronic multilocation depends on the possibility of time travel, and I conclude that the answer hinges on the nature of (...) time and persistence. (shrink)

I argue that the theory of moral responsibility defended by John Martin Fischer and Mark Ravizza is incompatible with the metaphysical possibility of time travel.

Notoriously, the Einstein equations of general relativity have solutions in which closed timelike curves occur. On these curves time loops back onto itself, which has exotic consequences: for example, traveling back into one's own past becomes possible. However, in order to make time travel stories consistent constraints have to be satisfied, which prevents seemingly ordinary and plausible processes from occurring. This, and several other "unphysical" features, have motivated many authors to exclude solutions with CTCs from consideration, e.g. by conjecturing (...) a chronology protection law. In this contribution we shall investigate the nature of one particular class of exotic consequences of CTCs, namely those involving unexpected cases of indeterminism or determinism. Indeterminism arises even against the backdrop of the usual deterministic physical theories when CTCs do not cross spacelike hypersurfaces outside of a limited CTC-region|such hypersurfaces fail to be Cauchy surfaces. We shall compare this CTC-indeterminism with four other types of indeterminism that have been discussed in the philosophy of physics literature: quantum indeterminism, the indeterminism of the hole argument, non-uniqueness of solutions of differential equations and lack of predictability due to insuffcient data. By contrast, a certain kind of determinism appears to arise when an indeterministic theory is applied on a CTC: things cannot be different from what they already were. Again we shall make comparisons, this time with other cases of determination in physics. We shall argue that on further consideration both this indeterminism and determinism on CTCs turn out to possess analogues in other, familiar areas of physics. CTC- indeterminism is close to the epistemological indeterminism we know from statistical physics, while the "fixedness" typical of CTC-determinism is pervasive in physics. CTC- determinism and CTC-indeterminism therefore do not provide incontrovertible grounds for rejecting CTCs as conceptually inadmissible. (shrink)

Electromagnetic suspension system (EMS) is mostly used in the field of high-speed vehicle. In this paper, a space exploring vehicle quarter electromagnetic suspension system is modelled, designed and simulated using linear quadratic optimal control problem. Linear quadratic Gaussian and linear quadratic integral controllers are designed to improve the body travel of the vehicle using bump road profile. Comparison between the proposed controllers is done and a promising simulation result have been analyzed.

In order to understand the transmission of a disease across a population we will have to understand not only the dynamics of contact infection but the transfer of health-care beliefs and resulting health-care behaviors across that population. This paper is a first step in that direction, focusing on the contrasting role of linkage or isolation between sub-networks in (a) contact infection and (b) belief transfer. Using both analytical tools and agent-based simulations we show that it is the structure of a (...) network that is primary for predicting contact infection—whether the networks or sub-networks at issue are distributed ring networks or total networks (hubs, wheels, small world, random, or scale-free for example). Measured in terms of time to total infection, degree of linkage between sub-networks plays a minor role. The case of belief is importantly different. Using a simplified model of belief reinforcement, and measuring belief transfer in terms of time to community consensus, we show that degree of linkage between sub-networks plays a major role in social communication of beliefs. Here, in contrast to the case of contract infection, network type turns out to be of relatively minor importance. What you believe travels differently. In a final section we show that the pattern of belief transfer exhibits a classic power law regardless of the type of network involved. (shrink)

This paper describes a thought experiment that shows that people can travel faster than the speed of light: we are not bound by Einstein’s speed limit. Of course, any two-bit sci-fi story can describe faster-than-light travel. The difference is that the thought experiment proposed here is consistent with Einstein’s theory. The way to extricate ourselves from this seeming contradiction is to acknowledge that persons are not entirely physical. In other words, the explanation for why faster-than-light travel is (...) possible for persons, yet consistent with our best physics, is that persons are not wholly physical. The thought experiment also has implications for our understanding of death, specifically, the death of the body may not be the death of the person. (shrink)

his article develops a framework for addressing racial ontologies in transnational perspective. In contrast to simple contextualist accounts, it is argued that a globally engaged metaphysics of race needs to address transnational continuities of racial ontologies. In contrast to unificationist accounts that aim for one globally unified ontology, it is argued that questions about the nature and reality of race do not always have the same answers across national contexts. In order address racial ontologies in global perspective, the article develops (...) a framework that accounts for both continuities and discontinuities by looking beyond the referents of narrowly defined core concepts. By shifting the focus from narrow concepts to richer conceptions of race, racial ontologies become comparable through globally related but nonetheless distinct mappings between conceptions and property relations. The article concludes by showing how this framework can generate novel insights in case studies from Asia, Europe, and Latin America. (shrink)

There is a tension between Dispositionalism––the view that all metaphysical modality is grounded in actual irreducible dispositional properties––and the possibility of time travel. This is due to the fact that Dispositionalism makes it much harder to solve a potentiality-based version of the grandfather paradox. We first present a potentiality-based version of the grandfather paradox, stating that the following theses are inconsistent: 1) time travel is possible, 2) powers fully ground modality, 3) self-defeating actions are impossible, 4) time-travellers retain (...) their intrinsic powers upon time-travelling, and 5) time-travellers are ordinary agents with basic intrinsic potentialities. We then consider a number of potential solutions, and find them wanting. We argue that the metaphysical impossibility of performing a self-defeating action acts as a necessary perfect mask––while time-travel lets us “slip” the potentiality under the mask, thus generating the contradiction. We conclude considering what are the options for the dispositionalist. (shrink)

This paper explores what the metaphysics of time travel might teach us about moral responsibility. We take our cue from a recent paper by Yishai Cohen, who argues that if time travel is metaphysically possible, then one of the most influential theories of moral responsibility (i.e., Fischer and Ravizza’s) is false. We argue that Cohen’s argument is unsound but that Cohen’s argument can serve as a lens to bring reasons-responsive theories of moral responsibility into sharper focus, helping us (...) to better understand actual-sequence theories of moral responsibility more generally and showing how actual-sequence theorists should respond to a recent criticism. (shrink)

This article aims to bring some work in contemporary analytic metaphysics to discussions of the Real Presence of Christ in the Eucharist. I will show that some unusual claims of the Real Presence doctrine exactly parallel what would be happening in the world if objects were to time-travel in certain ways. Such time-travel would make ordinary objects multiply located, and in the relevantly analogous respects. If it is conceptually coherent that objects behave in this way, we have a (...) model for the behaviour of the Eucharist which shows the doctrine to be coherent, at least with respect to the issues discussed. (shrink)