Ryan Wasserman explores a range of fascinating puzzles raised by the possibility of time travel, with entertaining examples from physics, science fiction, and popular culture, and he draws out their implications for our understanding of time, tense, freedom, fatalism, causation, counterfactuals, laws of nature, persistence, change, and mereology.

The paradoxes of time travel are oddities, not impossibilities. This chapter concerns with the sort of time travel that is recounted in science fiction. It argues that what goes on in a time travel story may be a possible pattern of events in four‐dimensional space‐time with no extra time dimension; that it may be correct to regard the scattered stages of the alleged time traveler as comprising a single person; and that we may legitimately (...) assign to those stages and their surroundings a personal time order that disagrees sometimes with their order in external time. Some might concede all this, but protest that the impossibility of time travel is revealed after all when we ask not what the time traveler does, but what he could do. Finally the chapter provides time travel story about Tim and Tom. (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 Lewis’s body of unpublished work on time travel yields fruitful insights into his broader thinking on the subject.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)

Humans have long been fascinated by the idea of visiting the past and of seeing what the future will bring. Time travel has been one of the most popular themes of science fiction. Most people have seen the TV series ‘Dr Who’ or ‘Quantum Leap’ or ‘Star Trek’. You’ve probably seen one of the ‘Back to the Future’ or ‘Terminator’ movies, or ‘Twelve Monkeys’. Time travel narratives provide fascinating plots, which exercise our imaginations in ever so many ways. (...) But is the idea of travelling forward and backward in time pure fantasy—or can it be done? To be sure, not all time travel scenarios are coherent. But we hope to persuade you that the most common objections to the very idea of time travel have no real force. (shrink)

Augustine established that the distension of the mind is a necessary condition of our perceiving temporal wholes. At the same time, as Teske explains, this condition is unnatural to the rational soul and results from original sin.

_ Paradoxes of Time Travel _ By WassermanRyanOxford University Press, 2018. x + 250 pp.

Most arguments against the possibility of time travel use the same old, familiar objection: If I could travel back in time, then I could kill my earlier (i.e. younger) self. Since I do exist such an action would result in a contradiction. Therefore time travel is impossible. This is a statement of the Principal Paradox of Time Travel. Some philosophers have argued that such actions as attempting to kill one’s earlier self would always fail and (...) that there is nothing especially strange about such failures. Despite these arguments, the problem generally is not viewed as being solved in favour of time travel. The above objection to time travel is also used to dismiss a particular class of cosmological models as being unphysical. This paper provides a solution to the Principal Paradox by exploring both the logical and causal implications of time travel. (shrink)

Time travel and its associated paradoxes are a topic of academic discussion that has historically been of interest only in physics and philosophy. This paper presents a new paradox of time travel that puts psychological issues at the forefront. The new time traveller faces conflicts between agency and agency awareness that are not addressed in other paradoxes. Further, in considering these other paradoxes it is seen how concerns about the time traveller's psychological state can lead (...) to new challenges to the accepted deterministic paradox resolutions. (shrink)

Book review of Wasserman, R. (2017), Paradoxes of Time Travel, OUP.

I argue that Deutsch’s model for the behavior of systems traveling around closed timelike curves relies implicitly on a substantive metaphysical assumption. Deutsch is employing a version of quantum theory with a significantly supplemented ontology of parallel existent worlds, which differ in kind from the many worlds of the Everett interpretation. Standard Everett does not support the existence of multiple identical copies of the world, which the D-CTC model requires. This has been obscured because he often refers to the branching (...) structure of Everett as a “multiverse”, and describes quantum interference by reference to parallel interacting definite worlds. But he admits that this is only an approximation to Everett. The D-CTC model, however, relies crucially on the existence of a multiverse of parallel interacting worlds. Since his model is supplemented by structures that go significantly beyond quantum theory, and play an ineliminable role in its predictions and explanations, it does not represent a quantum solution to the paradoxes of time travel. (shrink)

I distinguish paradoxes and hypodoxes among the conundrums of time travel. I introduce ‘hypodoxes’ as a term for seemingly consistent conundrums that seem to be related to various paradoxes, as the Truth-teller is related to the Liar. In this article, I briefly compare paradoxes and hypodoxes of time travel with Liar paradoxes and Truth-teller hypodoxes. I also discuss Lewis’ treatment of time travel paradoxes, which I characterise as a Laissez Faire theory of time travel. Time (...) travel paradoxes are impossible according to Laissez Faire theories, while it seems hypodoxes are possible. (shrink)

Time travel, it has been argued, leads to paradoxes, and in particular to a problem known as the grandfather paradox. Lewis has famously argued for the now standard view that the grandfather paradox is merely apparent. But underlying Lewis's solution is a faulty account of ability statements – one, according to which ability statements express possibility statements. I argue, contrary to Vihvelin and others, that an ameliorated view of ability statements allows for the same treatment of the (...) seeming paradox. Hence, Lewis's take on the grandfather paradox stands despite the failure of the particular view of ability statements it is built upon. (shrink)

The author examines the so-called paradox of identity through time. As he argues, the paradox is often elaborated by enumeration of several theses which generate a contradiction. According to these conditions, change is paradoxical and even impossible because it seems that objects persist as unchanging, or that every change destroys an object and generates a new one . In the first part of the paper the author discusses Roxanne Marie Kurtz’s version of such a view. Subsequently he (...) analyses typical attempts to resolve the paradox. The third section is devoted to applicability of the relation “=” to the correct formulation of the problem of identity through time. He argues that analytic philosophers too hastily decided that identity through time is a strict logical identity holding between quite mysterious “object before change” and “object after change”. It seems that such a view follows from the unjustified presupposition that logic is prior to ontology, i.e. that logic provides a categorial basis for ontology. Apart from this, the exact ontological status of the states described by expressions “object before change” and “object after change” escape our knowledge. In the fourth section he examines the condition of a-temporal exemplification based on the condition of simple exemplification . He argues that the latter is equivocal because one can distinguish several kinds of dependence . Some of them do not have to imply the extrinsic character of the properties involved in change. Key words IDENTITY, TIME, PARADOX. (shrink)

‘Quiet’ and ‘Disquiet’ are terms which express ways of accounting for time-experience, besides being equally open for a rendering as emotional states. Starting from three existential moods – stress, boredom, and the joy of the present moment – this inquiry aims to put into evidence the structuring features of our existential experience of time itself, both in the daily exercise of our being-in-the-world, and at the level of our being or not being in possession of oneself in such (...) exercise and in its potentially pathological derivates. In this context, which finds its theoretical roots in the Heideggerian analysis of the being-in, quiet and disquiet reveal their paradoxical character in terms of the mutual belonging and tension each of them, respectively, presupposes. At the same time, and with such a basis, we will find the way of understanding ‘quiet’ as a correlate of time as a ‘duration’. (shrink)

The purpose of the present paper is to reply to a misleading paper by M. Sachs entitled “Einstein's later view of the Twin Paradox” (TP) (Found. Phys. 15, 977 (1985)). There, by selecting some passages from Einstein's papers, he tried to convince the reader that Einstein changed his mind regarding the asymmetric aging of the twins on different motions. Also Sachs insinuates that he presented several years ago “convincing mathematical arguments” proving that the theory of relativity does not predict (...) asymmetrical aging in the TP. Here we give a definitive treatment to the clocks problem showing that Sachs' “convincing mathematical arguments” are non sequitur. Also, by properly quoting Einstein, we show that his later view of the TP coincides with the one derived from the rigorous theory of time developed in this paper. (shrink)

This book develops a framework for analysing strategic rationality, a notion central to contemporary game theory, which is the formal study of the interaction of rational agents and which has proved extremely fruitful in economics, political theory and business management. The author argues that a logical paradox lies at the root of a number of persistent puzzles in game theory, in particular those concerning rational agents who seek to establish some kind of reputation. Building on the work of Parsons, (...) Burge, Gaifman and Barwise and Etchemendy, Robert Koons constructs a context-sensitive solution to the whole family of liar-like paradoxes including, for the first time, a detailed account of how the interpretation of paradoxical statements is fixed by context. This analysis provides an understanding of how the rational agent model can account for the emergence of rules, practices and institutions. (shrink)

In normative reasoning one typically refers to intervals of time across which norms are intended to hold, as well as to alternative possibilities representing hypothetical developments of a given scenario. Thus, deontic modalities are naturally intertwined with temporal and metaphysical ones. Furthermore, contemporary debates in philosophy suggest that a proper understanding of fundamental ethical principles, such as the Ought-Implies-Can thesis, requires a simultaneous analysis of these three families of concepts. In the present article we propose a general formal framework (...) which allows for fine-grained multimodal reasoning in the normative domain. We provide an axiomatization for a novel system of propositional logic encoding the way in which possibilities and norms arising from different sources change over intervals of time. The usefulness of our framework is illustrated by analysing an ancient and particularly challenging `cold case', the Paradox of the Court. (shrink)

The contrast between the past-future symmetry of mechanical theories and the time-arrow observed in the behaviour of real complex systems doesn’t have nowadays a fully satisfactory explanation. If one confides in the Laplace-dream that everything be exactly and completely describable by the known mechanical differential equations, the whole experimental evidence of the irreversibility of real complex processes can only be interpreted as an illusion due to the limits of human brain and shortness of human history. In this work it (...) is surmised that in the description of real events it would be more reasonable to renounce exactness and completeness of mechanical differential equations, assuming that also further effects exist in nature, governed by different kinds of rules, in spite of being so weak to be directly unobservable in single motions. This surmise can explain not only the time-arrow, but also why, in particular cases, it can happen that approximate and/or statistical models represent an improvement of mechanical theories instead of an approximation: this happened for Boltzmann gas-model and also for the famous work of Max Planck on blackbody-radiation. And it also appears as a more promising “working hypothesis”, stimulating and guiding us to learn more about limits and origin of the basic equations, and also about the nature of chance and the meaning of probability, which is nowadays not clear in spite of the fundamental role it plays in physics. Particularly that kind of probability which gives the connection between quantum–mechanical differential equations and observable events. (shrink)

Any physical explanation of consciousness seems to leave unresolved the ‘explanatory gap': Isn't it conceivable that all the elements in that explanation could occur, with the same information processing outcomes as in a conscious process, but in the absence of consciousness? E.g. any digital computational process could occur in the absence of consciousness. To resolve this dilemma, we propose a biological-process-oriented physiological- phenomenological characterization of consciousness that addresses three ‘paradoxical’ qualities seemingly incompatible with the empirical realm: The dual location of (...) phenomenal properties ‘out there’ yet ‘in here’ in consciousness; the mysterious ‘thickness’ of the specious present; the feeling of ‘free agency', that we can voluntarily direct our actions, including the act of conscious attention, while at the same time attention and the emotions that direct it seem responsive to physiological substrates with physical causes. These paradoxes are then resolved by relating three elements of consciousness: organismically interested anticipation; sensory and proprioceptive imagery generated by the interested anticipation rather than by sensory input; resonating of these activities with activity stimulated by sensory data, where the interested anticipation precedes the processing of the input. Each of these elements is bridged to physiological processes such that, if they occur in a certain relation to each other, we can understand why they would inevitably be accompanied by the corresponding elements of conscious experience. (shrink)

This is a defense of endurantism against an alleged paradox.

The article deals with the problematic aspects of the concept of identity, the analysis of which helps to point out and to overcome the paradoxes of the “diachronic identity”, the identity of the human person (as identity of its inner cell) and “plural, flexible identity”, and also to clarify the conditions of the legitimate use of these concepts in contemporary philosophy and social science. The article examines two paradigms of identity: the substantive, when the identity of a thing is sought (...) in an invariable property, which provides its synchronous identity, and the formal, when the identity is sought in a form, a structure of the language, which provides its duration in time and helps to understand the diachronic identity. The article shows the importance of the use of “criteria of identity”, introduced by analytical philosophers to find out the way of duration in time of beings which they try to identify, from the material objects to the collective beings, including the identity of the human person. The problem of subjective identity is pointed out as a separate problem. Two main approaches to it are differentiated: mentalist and expressivist. The first is focused on the inner world of the human being, its memories and feelings, creating paradoxes of the «identity for itself» which is not the «identity for the others», whereas the second lets include the social world in the definition of the subjective identity and facilitates the reconsideration of the boundaries of the internal and the external in determining the human self. The article analyses contemporary use of the concept of identity in social science and public discourses and demonstrates the contradiction of the concept of “plural, heterogeneous identity”, which formulates but doesn’t solve the problem of the subjective identity as the identification of an individual with different social groups. (shrink)

The article is an attempt to comprehend the radical changes in the historical self-con­sciousness of the modern era and their impact on modern political practices. The position of the author is that our attitude to the time of history crystallizes deep transformations of the political sphere. It is shown that the historicity regime at the turn of the 20th–21st centuries is characterized by an orientation towards today’s needs and interests (so-called presentism) and at the same time increased attention (...) to the past (“memorial revolution”), which, in the absence of major socio-political projects of the future, plays the role of a consolidating social factor. These changes required, on the one hand, significant efforts by historians to revise the methodological foundations of their science and, on the other hand, philosophical reflection on key historiosophical concepts and mean­ings. The most significant discussions concern, first of all, the concept of the past in its relation to the present, “modernity”. Understanding the ontological and epistemological foundations of these concepts has become today a “bone of contention” in building mod­ern political strategies and practices. The article demonstrates how the past from the con­cept of clear and self-evident, as it appeared within the framework of the historicist con­cepts of the Modern era, has become a philosophical and political problem in our days. There are two approaches to solving this problem. These are, firstly, those philosophers and historians who defend the modernist idea of the past as different in relation to the present, although they significantly modify it with the help of the idea of a “living past”. And secondly, those philosophers who defend the thesis about the “non-past” of the past and the continuation of its existence in the present. It is concluded that, with all the differ­ences, both types of concepts proceed from the concept of “living past”, which implies a non-linear and “multi-layered” understanding of historical time. (shrink)

How can we experience real emotions when viewing a movie or reading a novel or watching a play when we know the characters whose actions have this effect on us do not exist? This is a conundrum that has puzzled philosophers for a long time, and in this book Robert Yanal both canvasses previously proposed solutions to it and offers one of his own. First formulated by Samuel Johnson, the paradox received its most famous answer from Samuel Taylor (...) Coleridge, who advised his readers to engage in a "willing suspension of disbelief." More recently, philosophers have argued that we are irrational in emoting toward fiction, or that we do not emote toward fiction but rather toward factual counterparts, or that we do not have real but only quasi-emotion toward fiction, generated by our playing games of make-believe. All of these proposed solutions are critically reviewed. Finding these answers unsatisfactory, Yanal offers an alternative, providing a new version of what has been dubbed "thought theory." On this theory, mere thoughts not believed true are seen as the functional equivalent of belief at least insofar as stimulating emotion is concerned. The emoter's disbelief in the actuality of components of the thoughts must be rendered relatively inactive. Such emotion is real and typically has the character of being richly generated yet unconsummated. The book extends this theory also to resolving other paradoxes arising from emotional response to fiction: how we feel suspense over what comes next in a story even when we are re-reading it for a second or third time; and how we take pleasure in narratives, such as tragedy, that excite unpleasant emotions such as fear, pity, or horror. (shrink)

Asking “What is time?” can be both a simple and a profound question. In this article we intend to introduce the reader to the philosophy of time. To do so, we will deal with McTaggart's paradox. By explaining it and introducing the basic concepts to understand it, we will be able to get an idea of what this branch of philosophy is all about. The main intention of this article is not to explain anything new but to (...) clarify the background of a debate by explaining its roots. By taking a deep dive into the concept of time, we will see that it is not a simple concept at all. In any subsequent possible definition with regards to concepts such time for education or time for ethics, a logical clarification of what time is important and will color all further predication of the concept of time. Considering the impact of digital transformation in our lives in general, and in education in particular, a philosophy of time brings major elements such as paradoxes, which are not of practical character but important for the semantic of the words, such as “duration”, “temporal position” of events, etc. (shrink)

Paradox of Hedonism Varieties of hedonism have been criticized from ancient to modern times. Along the way, philosophers have also considered the paradox of hedonism. The paradox is a common objection to hedonism, even if they often do not give that specific name to the objection. According to the paradox of hedonism, the pursuit of pleasure … Continue reading Paradox of Hedonism →.

This paper consists of two parts. In the first part, I shall expound the kantian concept of paradox and its three different senses, the anthropological, the rhetorical and the metaphysical. In the second part, I shall examine the presence of these senses of paradox in Kant’s texts about Enlightenment. The paradox of immaturity consists of the fact that we are responsible, as human beings, and non-responsible, as subjects of a State, of the exit from it. Another formulation (...) of the same paradox, but in dynamical and metaphysical terms, is that of heautocracy, the paradox of self-constraint, which implies that the subject is at the same time active and passive. Finally, the opposition between public and private use of reason also seems paradoxical, since private use seems to be a prejudiced use while public use seems to be free and reasonable as such. (shrink)

arratives, fictional and factual, commonly raise in their audience suspense. A narrative lays out over time a sequence of events; and because the events of the narrative are not completely told all at once, questions arise for the audience which will be answered only later in the narrative’s telling. Will the transfigured panther-woman pounce on her rival as she walks home alone at night, hearing strange noises around her? Will Sam and Annie ever make their date at the top (...) of the Empire State Building? And the most classic question of all, Who dunnit?, or as it appears in its post-modern form, Who will do it? ‘This is the story of a murder. It hasn’t happened yet. But it will,’ Martin Amis writes at the beginning of London Fields. ‘I know the murderer, I know the murderee,’ and we’re soon told that the murderee is to be Nicola Six.1 But who will kill her? And why? (shrink)

The ultimate success of Hollywood blockbusters is dependent upon repeat viewings. Fans return to theaters to see films multiple times and buy DVDs so they can watch movies yet again. Although it is something of a received dogma in philosophy and psychology that suspense requires uncertainty, many of the biggest box office successes are action movies that fans claim to find suspenseful on repeated viewings. The conflict between the theory of suspense and the accounts of viewers generates a problem known (...) as the paradox of suspense, which we can boil down to a simple question: If suspense requires uncertainty, how can a viewer who knows the outcome still feel suspense? (shrink)

Which modernism or modernisms circulate in Deleuze’s two-volume work on cinema? Can one meaningfully claim that both or either The Movement-Image and The Time-Image maintain connections with literary modernism? What relationship if any may be forged between theoretical debates in the areas of literary and film studies as these have been influenced by engagement with Deleuze’s work on cinema? The first obstacle to any successful negotiation of these questions lies in the absence in the books of any reference to (...) the category of modernism – a fact which is after all hardly surprising in a French author of Deleuze’s generation. A second consideration is summed up well by Joost Raessens when he argues that “For Deleuze the term ‘modernity’ is not a neutral category. In effect modern cinema is a representation of differential thought which is determined [...] as a fundamental critique of the classic thought of Plato and Hegel.” Scholars often assert that Deleuze’s modernity owes much to Nietzsche, in the shape of the latter’s demand for a new approach to questions of truth and knowledge. Once life is no longer judged in the name of a higher authority such as the good or the true, the stage is set for Nietzschean transvaluation. This is a process which subjects “every being, every action and passion, even every value, in relation to the life which they involve” to evaluation. This normative model of a cinema which has the capacity to carry out a Nietzschean total critique by means other than philosophy presides over The Time-Image in particular. In terms of the trajectory of Deleuze’s thought, total critique is opposed, in Nietzsche and Philosophy and Difference and Repetition, to Kantian critique as well as to Hegelian sublation. The thinking images of modern cinema, more specifically of its preeminent auteurs in Deleuze’s pantheon such as Welles, Resnais, Godard, and others, can effectuate this new image of thought. Thus is rendered tangible Deleuze’s claim that films think, that cinema thinks. Thus are linked a modernism of cinema and a project which dates back to Difference and Repetition, namely the challenge to a certain image of thought. In this challenge the allies include the two philosophers who dominate the film books – Bergson and Nietzsche. This chapter assumes the position that it is impossible to consider Deleuze’s modernism as being in any way other than intrinsically linked to his overall philosophical system and therefore that it is only in this context that connections with literary modernism can be explored. (shrink)

Zeno of Elea's motion and infinity paradoxes, excluding the Stadium, are stated (1), commented on (2), and their historical proposed solutions then discussed (3). Their correct solution, based on recent conclusions in physics associated with time and classical and quantum mechanics, and in particular, of there being a necessary trade off of all precisely determined physical values at a time (including relative position), for their continuity through time, is then explained (4). This article follows on from another, (...) more physics orientated and widely encompassing paper entitled "Time and Classical and Quantum Mechanics: Indeterminacy vs. Discontinuity" (Lynds, 2003), with its intention being to detail the correct solution to Zeno's paradoxes more fully by presently focusing on them alone. If any difficulties are encountered in understanding any aspects of the physics underpinning the following contents, it is suggested that readers refer to the original paper for a more in depth coverage. (shrink)

Which modernism or modernisms circulate in Deleuze’s two-volume work on cinema? Can one meaningfully claim that both or either The Movement-Image and The Time-Image maintain connections with literary modernism? What relationship if any may be forged between theoretical debates in the areas of literary and film studies as these have been influenced by engagement with Deleuze’s work on cinema? The first obstacle to any successful negotiation of these questions lies in the absence in the books of any reference to (...) the category of modernism – a fact which is after all hardly surprising in a French author of Deleuze’s generation. A second consideration is summed up well by Joost Raessens when he argues that “For Deleuze the term ‘modernity’ is not a neutral category. In effect modern cinema is a representation of differential thought which is determined [...] as a fundamental critique of the classic thought of Plato and Hegel.” Scholars often assert that Deleuze’s modernity owes much to Nietzsche, in the shape of the latter’s demand for a new approach to questions of truth and knowledge. Once life is no longer judged in the name of a higher authority such as the good or the true, the stage is set for Nietzschean transvaluation. This is a process which subjects “every being, every action and passion, even every value, in relation to the life which they involve” to evaluation. This normative model of a cinema which has the capacity to carry out a Nietzschean total critique by means other than philosophy presides over The Time-Image in particular. In terms of the trajectory of Deleuze’s thought, total critique is opposed, in Nietzsche and Philosophy and Difference and Repetition, to Kantian critique as well as to Hegelian sublation. The thinking images of modern cinema, more specifically of its preeminent auteurs in Deleuze’s pantheon such as Welles, Resnais, Godard, and others, can effectuate this new image of thought. Thus is rendered tangible Deleuze’s claim that films think, that cinema thinks. Thus are linked a modernism of cinema and a project which dates back to Difference and Repetition, namely the challenge to a certain image of thought. In this challenge the allies include the two philosophers who dominate the film books – Bergson and Nietzsche. This chapter assumes the position that it is impossible to consider Deleuze’s modernism as being in any way other than intrinsically linked to his overall philosophical system and therefore that it is only in this context that connections with literary modernism can be explored. (shrink)

Once upon a time, during a large and international conference of the world's leading philosophers, an angel miraculously appeared and said, "I come to you as a messenger from God. You will be permitted to ask any one question you want - but only one! - and I will answer that question truthfully. What would you like to ask?" The philosophers were understandably excited, and immediately began a discussion of what would be the best question to ask. But it (...) quickly became obvious that they needed more time to discuss the matter, so they asked the angel if he could get back to them. The angel was obliging, and said that he would return at the same time the next day. "But be prepared then," he warned them, "for you will only get this one chance." All of the philosophers gathered at the convention worked at a frenzied pace for the next twenty-four hours, proposing and weighing the merits of various questions. Other philosophers from around the world became involved as well, faxing and emailing their suggestions. Some were in favor of asking the kind of practical question that lots of people might like to know the answer to, such as this one: Q1 Is it better to check your oil when the car is hot or when it is cold? But others said they should not squander this rare opportunity, which gave them a chance to learn something about a truly important and intrinsically interesting topic, and after some discussion it was generally agreed that this was right. (shrink)