Each of our sensory modalities—vision, touch, taste, etc.—works on a slightly different timescale, with differing temporal resolutions and processing lag. This raises the question of how, or indeed whether, these sensory streams are co-ordinated or ‘bound’ into a coherent multisensory experience of the perceptual ‘now’. In this paper I evaluate one account of how temporal binding is achieved: the temporal windows hypothesis, concluding that, in its simplest form, this hypothesis is inadequate to capture a variety of multisensory phenomena. Rather, the (...) evidence suggests the existence of a more complex temporal structure in which multiple overlapping windows support distinct functional mechanisms. To aid in the precise formulation of such views, I propose a taxonomy of temporal window types and their characteristics that in turn suggests promising avenues for future empirical and philosophical research. I conclude by examining some philosophical implications of multi-window models for the metaphysics of perception and perceptual experience more generally. (shrink)

In a quantum universe with a strong arrow of time, it is standard to postulate that the initial wave function started in a particular macrostate---the special low-entropy macrostate selected by the Past Hypothesis. Moreover, there is an additional postulate about statistical mechanical probabilities according to which the initial wave function is a ''typical'' choice in the macrostate. Together, they support a probabilistic version of the Second Law of Thermodynamics: typical initial wave functions will increase in entropy. Hence, there are (...) two sources of randomness in such a universe: the quantum-mechanical probabilities of the Born rule and the statistical mechanical probabilities of the Statistical Postulate. I propose a new way to understand time's arrow in a quantum universe. It is based on what I call the Thermodynamic Theories of Quantum Mechanics. According to this perspective, there is a natural choice for the initial quantum state of the universe, which is given by not a wave function but by a density matrix. The density matrix plays a microscopic role: it appears in the fundamental dynamical equations of those theories. The density matrix also plays a macroscopic / thermodynamic role: it is exactly the projection operator onto the Past Hypothesis subspace. Thus, given an initial subspace, we obtain a unique choice of the initial density matrix. I call this property "the conditional uniqueness" of the initial quantum state. The conditional uniqueness provides a new and general strategy to eliminate statistical mechanical probabilities in the fundamental physical theories, by which we can reduce the two sources of randomness to only the quantum mechanical one. I also explore the idea of an absolutely unique initial quantum state, in a way that might realize Penrose's idea of a strongly deterministic universe. (shrink)

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)

On one popular view, the general covariance of gravity implies that change is relational in a strong sense, such that all it is for a physical degree of freedom to change is for it to vary with regard to a second physical degree of freedom. At a quantum level, this view of change as relative variation leads to a fundamentally timeless formalism for quantum gravity. Here, we will show how one may avoid this acute ‘problem of time’. Under our (...) view, duration is still regarded as relative, but temporal succession is taken to be absolute. Following our approach, which is presented in more formal terms in, it is possible to conceive of a genuinely dynamical theory of quantum gravity within which time, in a substantive sense, remains. 1 Introduction1.1 The problem of time1.2 Our solution2 Understanding Symmetry2.1 Mechanics and representation2.2 Freedom by degrees2.3 Voluntary redundancy3 Understanding Time3.1 Change and order3.2 Quantization and succession4 Time and Gravitation4.1 The two faces of classical gravity4.2 Retaining succession in quantum gravity5 Discussion5.1 Related arguments5.2 Concluding remarks. (shrink)

I advocate Time-Slice Rationality, the thesis that the relationship between two time-slices of the same person is not importantly different, for purposes of rational evaluation, from the relationship between time-slices of distinct persons. The locus of rationality, so to speak, is the time-slice rather than the temporally extended agent. This claim is motivated by consideration of puzzle cases for personal identity over time and by a very moderate form of internalism about rationality. Time-Slice Rationality (...) conflicts with two proposed principles of rationality, Conditionalization and Reflection. Conditionalization is a diachronic norm saying how your current degrees of belief should fit with your old ones, while Reflection is a norm enjoining you to defer to the degrees of belief that you expect to have in the future. But they are independently problematic and should be replaced by improved, time-slice-centric principles. Conditionalization should be replaced by a synchronic norm saying what degrees of belief you ought to have given your current evidence and Reflection should be replaced by a norm which instructs you to defer to the degrees of belief of agents you take to be experts. These replacement principles do all the work that the old principles were supposed to do while avoiding their problems. In this way, Time-Slice Rationality puts the theory of rationality on firmer foundations and yields better norms than alternative, non-time-slice-centric approaches. (shrink)

Two of the most difficult problems in the foundations of physics are (1) what gives rise to the arrow of time and (2) what the ontology of quantum mechanics is. I propose a unified 'Humean' solution to the two problems. Humeanism allows us to incorporate the Past Hypothesis and the Statistical Postulate into the best system, which we then use to simplify the quantum state of the universe. This enables us to confer the nomological status to the quantum state (...) in a way that adds no significant complexity to the best system and solves the ''supervenient-kind problem'' facing the original version of the Past Hypothesis. We call the resultant theory the Humean unification. It provides a unified explanation of time asymmetry and quantum entanglement. On this theory, what gives rise to time's arrow is also responsible for quantum phenomena. The new theory has a separable mosaic, a best system that is simple and non-vague, less tension between quantum mechanics and special relativity, and a higher degree of theoretical and dynamical unity. The Humean unification leads to new insights that can be useful to Humeans and non-Humeans alike. (shrink)

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 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)

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)

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)

The epistemology of self-locating belief concerns itself with how rational agents ought to respond to certain kinds of indexical information. I argue that those who endorse the thesis of Time-Slice Rationality ought to endorse a particular view about the epistemology of self-locating belief, according to which ‘essentially indexical’ information is never evidentially relevant to non-indexical matters. I close by offering some independent motivations for endorsing Time-Slice Rationality in the context of the epistemology of self-locating belief.

Branching time is a popular theory of time that is intended to account for the openness of the future. Generally, branching-time models the openness of the future by positing a multiplicity of concrete alternative futures mirroring all the possible ways the future could unfold. A distinction is drawn in the literature among branching-time theories: those that make use of moment-based structures and those that employ history-based ones. In this paper, I introduce and discuss a particular kind (...) of openness relative to the possibility that time ends (doomsday). I then show that whereas moment-based branching structures cannot represent this kind of openness, history-based structures can account for it. The conclusion is that history-based structures have an advantage over moment-based ones. (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)

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)

It is often thought that there is little that seems more obvious from experience than that time objectively passes, and that time is, in this respect, quite unlike space. Yet nothing in the physical picture of the world seems to correspond to the idea of such an objective passage of time. In this paper, I discuss some attempts to explain this apparent conflict between appearance and reality. I argue that existing attempts to explain the conflict as the (...) result of a perceptual illusion fail, and that it is, in fact, the nature of memory, rather than perception, that explains why we are inclined to think of time as passing. I also offer a diagnosis as to why philosophers have sometimes been tempted to think that an objective passage of time seems to figure directly in perceptual experience, even though it does not. (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.

According to the No Alternate Possibilities argument, if time passes then the rate at which it passes could be different. Thus, time cannot pass, since if time passes, then necessarily it passes at a rate of 1 second per second. One response to this argument is to posit hypertime, and to argue that at different worlds, time passes at different rates when measured against hypertime. Since many A-theorists think we can make sense of temporal passage without (...) positing hypertime, we pursue a different response. We describe several worlds that do not contain hypertime, but do contain differential passage: worlds where time passes at different rates in different subregions within the same world. Hence we argue that even if we focus just on the set of worlds that do not contain hypertime (whether this is all, or only some of the worlds) we find that not all these worlds are such that time passes at a rate of 1 second per second. Thus the No Alternate Possibilities argument fails even when restricted to just this set of worlds. (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)

The idea of a moving present or ‘now’ seems to form part of our most basic beliefs about reality. Such a present, however, is not reflected in any of our theories of the physical world. I show in this article that presentism, the doctrine that only what is present exists, is in conflict with modern relativistic cosmology and recent advances in neurosciences. I argue for a tenseless view of time, where what we call ‘the present’ is just an emergent (...) secondary quality arising from the interaction of perceiving self-conscious individuals with their environment. I maintain that there is no flow of time, but just an ordered system of events. (shrink)

‘One’ and ‘Two.’ (Zero and one). Are, technically, circumference and diameter.

In English, discourse reference to time involves grammatical tenses interpreted as temporal anaphors. Recently, it has been argued that conditionals involve modal discourse anaphora expressed by a parallel grammatical system of anaphoric modals. Based on evidence from Kalaallisut, this paper argues that temporal and modal anaphora can be just as precise in a language that does not have either grammatical category. Instead, temporal anaphora directly targets eventualities of verbs, without mediating tenses, while modal anaphora involves anaphoric moods and/or attitudinal (...) verbs. (shrink)

This paper argues that all of the standard theories about the divisions of space and time can benefit from, and may need to rely on, parsimony considerations. More specifically, whether spacetime is discrete, gunky or pointy, there are wildly unparsimonious rivals to standard accounts that need to be resisted by proponents of those accounts, and only parsimony considerations offer a natural way of doing that resisting. Furthermore, quantitative parsimony considerations appear to be needed in many of these cases.

What would it be for a process to happen backwards in time? Would such a process involve different causal relations? It is common to understand the time-reversal invariance of a physical theory in causal terms, such that whatever can happen forwards in time can also happen backwards in time. This has led many to hold that time-reversal symmetry is incompatible with the asymmetry of cause and effect. This article critiques the causal reading of time (...) reversal. First, I argue that the causal reading requires time-reversal-related models to be understood as representing distinct possible worlds and, on such a reading, causal relations are compatible with time-reversal symmetry. Second, I argue that the former approach does, however, raise serious sceptical problems regarding the causal relations of paradigm causal processes and as a consequence there are overwhelming reasons to prefer a non-causal reading of time reversal, whereby time reversal leaves causal relations invariant. On the non-causal reading, time-reversal symmetry poses no significant conceptual nor epistemological problems for causation. _1_ Introduction _1.1_ The directionality argument _1.2_ Time reversal _2_ What Does Time Reversal Reverse? _2.1_ The B- and C-theory of time _2.2_ Time reversal on the C-theory _2.3_ Answers _3_ Does Time Reversal Reverse Causal Relations? _3.1_ Causation, billiards, and snooker _3.2_ The epistemology of causal direction _3.3_ Answers _4_ Is Time-Reversal Symmetry Compatible with Causation? _4.1_ Incompatibilism _4.2_ Compatibilism _4.3_ Answers _5_ Outlook. (shrink)

An extended examination of Libet's works led to a comprehensive reinterpretation of his results. According to this reinterpretation, the Minimum Train Duration of electrical brain stimulation should be considered as the time needed to create a brain stimulus efficient for producing conscious sensation and not as a basis for inferring the latency for conscious sensation of peripheral origin. Latency for conscious sensation with brain stimulation may occurafterthe Minimum Train Duration. Backward masking with cortical stimuli suggests a 125-300 ms minimum (...) value for the latency for conscious sensation of threshold skin stimuli. Backward enhancement is not suitable for inferring this latency. For determining temporal relations between stimuli that correspond to subjects' reports, theendof cerebral Minimum Train Duration should be used as reference, rather than its onset. Results of coupling peripheral and cortical stimuli are explained by a latency after the cortical Minimum Train Duration, having roughly the same duration as the latency for supraliminal skin stimuli. Results of coupling peripheral stimuli and stimuli to medial lemniscus (LM) are explained by a shorter LM latency and/or a longer peripheral latency. This interpretation suggests a 230 ms minimum value for the latency for conscious sensation of somatosensory near-threshold stimuli. The backward referral hypothesis, as formulated by Libet, should not be retained. Long readiness potentials preceding spontaneous conscious or nonconscious movements suggest that both kinds of movement are nonconsciously initiated. The validity of Libet's measures of W and M moments (Libet et al., 1983a) is questionable due to problems involving latencies, training, and introspective distinction of W and M. Veto of intended actions may be initially nonconscious but dependent on conscious awareness. (shrink)

This essay aims to provide a self-contained introduction to time in relativistic cosmology that clarifies both how questions about the nature of time should be posed in this setting and the extent to which they have been or can be answered empirically. The first section below recounts the loss of Newtonian absolute time with the advent of special and general relativity, and the partial recovery of absolute time in the form of cosmic time in some (...) cosmological models. Section II considers the beginning and end of time in a broader class of models in which there is not an analog of Newtonian absolute time. As we will see, reasonable physical assumptions imply that the universe is finite to the past, and Section III turns to consideration of the “beginning” itself. We critically review conventional wisdom that a “singularity” reveals flaws in general relativity and briefly assess ways of avoiding the singularity. (shrink)

According to the No Alternate Possibilities argument, if time passes then the rate at which it passes could be different but time cannot pass at different rates, and hence time cannot pass. Typically, defenders of the NAP argument have focussed on defending premise, and have taken the truth of for granted: they accept the orthodox view of rate necessitarianism. In this paper we argue that the defender of the NAP argument needs to turn her attention to. We (...) describe a series of worlds that appear to contain differential passage: worlds where time passes at different rates in different subregions. If the NAP argument is to succeed, rate necessitarians must show that each of these worlds is either metaphysically impossible, or does not contain differential passage. (shrink)

Several areas of welfare economics seek to evaluate states of affairs as a function of interpersonally comparable individual utilities. The aim is to map each state of affairs onto a vector of individual utilities, and then to produce an ordering of these vectors that can be represented by a mathematical function assigning a real number to each. When this approach is used in intertemporal contexts, a central theoretical question concerns the evaluative weight to be applied to utility coming at different (...) times. This question concerns the rate of pure time preference, which is one key determinant of the social discount rate. This article argues that the standard philosophical account of pure time preference is mistaken, because it ascribes to economists a methodological commitment they need not, and often do not, accept. This in turn undercuts the most common philosophical objection to pure time preference, which traces at least to Rawls’s A Theory of Justice. The article then evaluates three further objections to pure time preference, concluding that it might still be defensible under certain circumstances. The article closes by articulating a final argument that is suggested by the “Social, Economic and Ethical Concepts and Methods” chapter of the most recent Intergovernmental Panel on Climate Change report. If this further argument is sound, it would constitute a decisive objection to pure time preference as it currently figures in much intertemporal welfare economics. (shrink)

In ‘from times to worlds and back again: a transcendentist theory of persistence’ (henceforth TTP) Alessandro Giordani outlines five competitor views regarding the manner in which objects occupy regions along a dimension. These are: (1) classical uni-location (2) bare uni-location (3) multi-location (4) counterpart presence and (5) transcendent presence. Each view comes in both a temporal and modal version and Giordani argues that one ought to prefer transcendentism (i.e. 5) along both dimensions. According to temporal transcendentism, necessarily, no object is (...) exactly located at any region along the temporal dimension. Instead, any object, O, is derivatively present at some region, R, along the temporal dimension in virtue of bearing certain relations to something (according to TTP an event) that occupies R along that dimension. According to modal transcendentism, no object is exactly located at any region along the modal dimension. Instead, any object, O, is derivatively present at some region, R, along the modal dimension in virtue of bearing certain relations to something (according to TTP an event) that occupies R along that dimension. I argue that such a view is under motivated, and, at any rate, may not in fact offer a distinct view. (shrink)

In what sense is the direction of time a matter of convention? In 'The Direction of Time', Hans Reichenbach makes brief reference to parallels between his views about the status of time’s direction and his conventionalism about geometry. In this article, I: (1) provide a conventionalist account of time direction motivated by a number of Reichenbach’s claims in the book; (2) show how forwards and backwards time can give equivalent descriptions of the world despite the (...) former being the ‘natural’ direction of time; and (3) argue that this offers an important middle-ground position between existing realist and antirealist accounts of the direction of time. (shrink)

Readers familiar with the workhorse of cosmology, the hot big bang model, may think that cosmology raises little of interest about time. As cosmological models are just relativistic spacetimes, time is understood just as it is in relativity theory, and all cosmology adds is a few bells and whistles such as inflation and the big bang and no more. The aim of this chapter is to show that this opinion is not completely right...and may well be dead wrong. (...) In our survey, we show how the hot big bang model invites deep questions about the nature of time, how inflationary cosmology has led to interesting new perspectives on time, and how cosmological speculation continues to entertain dramatically different models of time altogether. Together these issues indicate that the philosopher interested in the nature of time would do well to know a little about modern cosmology. (shrink)

This paper is a brief (and hopelessly incomplete) non-standard introduction to the philosophy of space and time. It is an introduction because I plan to give an overview of what I consider some of the main questions about space and time: Is space a substance over and above matter? How many dimensions does it have? Is space-time fundamental or emergent? Does time have a direction? Does time even exist? Nonetheless, this introduction is not standard because (...) I conclude the discussion by presenting the material with an original spin, guided by a particular understanding of fundamental physical theories, the so-called primitive ontology approach. (shrink)

It is often assumed that believing that p for a normative reason consists in nothing more than (i) believing that p for a reason and (ii) that reason’s corresponding to a normative reason to believe that p, where (i) and (ii) are independent factors. This is the Composite View. In this paper, we argue against the Composite View on extensional and theoretical grounds. We advocate an alternative that we call the Prime View. On this view, believing for a normative reason (...) is a distinctive achievement that isn’t exhausted by the mere conjunction of (i) and (ii). Its being an achievement entails that (i) and (ii) are not independent when one believes for a normative reason: minimally, (i) must hold because (ii) holds. Apart from its intrinsic interest, our discussion has important upshots for central issues in epistemology, including the analysis of doxastic justification, the epistemology of perception, and the place of competence in epistemology. (shrink)

In a quantum universe with a strong arrow of time, we postulate a low-entropy boundary condition to account for the temporal asymmetry. In this paper, I show that the Past Hypothesis also contains enough information to simplify the quantum ontology and define a unique initial condition in such a world. First, I introduce Density Matrix Realism, the thesis that the quantum universe is described by a fundamental density matrix that represents something objective. This stands in sharp contrast to Wave (...) Function Realism, the thesis that the quantum universe is described by a wave function that represents something objective. Second, I suggest that the Past Hypothesis is sufficient to determine a unique and simple density matrix. This is achieved by what I call the Initial Projection Hypothesis: the initial density matrix of the universe is the normalized projection onto the special low-dimensional Hilbert space. Third, because the initial quantum state is unique and simple, we have a strong case for the \emph{Nomological Thesis}: the initial quantum state of the universe is on a par with laws of nature. This new package of ideas has several interesting implications, including on the harmony between statistical mechanics and quantum mechanics, the dynamic unity of the universe and the subsystems, and the alleged conflict between Humean supervenience and quantum entanglement. (shrink)

I argue that the following theses are both popular among evidentialists but also jointly inconsistent with evidentialism: 1) Time-Slice Mentalism: one’s justificational properties at t are grounded only by one’s mental properties at t; 2) Experience Ultimacy: all ultimate evidence is experiential; and 3) Sleep Justification: we have justified beliefs while we have dreamless, nonexperiential sleep. Although I intend for this paper to be a polemic against evidentialists, it can also be viewed as an opportunity for them to clarify (...) their views. Furthermore, the paper is not only relevant to evidentialists. For example, the arguments of this paper could give Time-Slice Mentalists a reason to deny evidentialism. (shrink)

Many philosophers hold that ‘one-instant worlds’—worlds that contain a single instant—fail to contain time. We experimentally investigate whether these worlds satisfy the folk concept of time. We found that ~50% of participants hold that there is time in such worlds. We argue that this suggests one of two possibilities. First, the population disagree about whether at least one of the A-, B-, or C-series is necessary for time, with there being a substantial sub-population for whom the (...) presence of neither an A-, B-, nor C-series, is necessary for time, and hence those folk have a radically more minimal concept of time than has been attributed to them by philosophers. Or, second, the population do not disagree about whether at least one of the A-, B-, or C-series is necessary for time, but disagree about what it takes for a world to fail to contain even a C-series. (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)

This paper proffers an account of why interdisciplinary research on, inter alia, the nature of time can be fruitful even if the disciplines in question have different explanatory pro-jects. We suggest that the special sciences perform a subject setting role for lower-level disciplines such as physics. In essence, they tell us where, amongst a theory of the physical world, we should expect to locate phenomena such as temporality; they tell us what it would take for there to be (...) class='Hi'>time. Physical theory tells us whether there is anything like that in the world and what its hidden nature is. Only working in tandem can physics and the special sciences locate and describe the phenomenon that is time. (shrink)

Metaphysics is the part of philosophy that asks questions about the nature of reality – about what there is, and what it is like. The metaphysics of time is the part of the philosophy of time that asks questions about the nature of temporal reality. One central such question is that of whether time passes or flows, or whether it has a dynamic aspect.

One of the most difficult problems in the foundations of physics is what gives rise to the arrow of time. Since the fundamental dynamical laws of physics are (essentially) symmetric in time, the explanation for time's arrow must come from elsewhere. A promising explanation introduces a special cosmological initial condition, now called the Past Hypothesis: the universe started in a low-entropy state. Unfortunately, in a universe where there are many copies of us (in the distant ''past'' or (...) the distant ''future''), the Past Hypothesis is not enough; we also need to postulate self-locating (de se) probabilities. However, I show that we can similarly use self-locating probabilities to strengthen its rival---the Fluctuation Hypothesis, leading to in-principle empirical underdetermination and radical epistemological skepticism. The underdetermination is robust in the sense that it is not resolved by the usual appeal to 'empirical coherence' or 'simplicity.' That is a serious problem for the vision of providing a completely scientific explanation of time's arrow. (shrink)

Until recently, an almost perfect parallelism seemed to hold between theories of identity through time and across possible worlds,as every account in the temporal case(endurantism,perdurantism, exdurantism) was mirrored by a twin account in the modal case (trans-world identity, identity-via-parts, identity-via-counterparts). Nevertheless, in the recent literature, this parallelism has been broken because of the implementation in the debate of the relation of location. In particular, endurantism has been subject to a more in-depth analysis, and different versions of it, corresponding to (...) different ways an entity can be located in time, emerged. In this article, we provide a precise map of the conceptions at stake, complete the debate by introducing a version of endurantism not yet considered in the debate — we call transcendentism — and show that it allows us to provide an effective interpretation of the relation of trans-world identity and an intuitive solution in the temporal case. (shrink)

Time has multiple aspects and is difficult to define as one unique entity, which therefore led to multiple interpretations in physics and philosophy. However, if the perception of time is considered as a composite time concept, it can be decomposed into basic invariable components for the perception of progressive and support-fixed time and into secondary components with possible association to unit-defined time or tense. Progressive time corresponds to Bergson’s definition of duration without boundaries, which (...) cannot be divided for measurements. Time periods are already lying in the past and fixed on different kinds of support. The human memory is the first automatic support, but any other support suitable for time registration can also be considered. The true reproduction of original time from any support requires conditions identical to the initial conditions, if not time reproduction becomes artificially modified as can be seen with a film. Time reproduction can be artificially accelerated, slowed down, extended or diminished, and also inverted from the present to the past, which only depends on the manipulation of the support, to which time is firmly linked. Tense associated to progressive and support fixed time is a psychological property directly dependent on an observer, who judges his present as immediate, his past as finished and his future as uncertain. Events can be secondarily associated to the tenses of an observer. Unit-defined time is essential for physics and normal live and is obtained by comparison of support-fixed time to systems with regular motions, like clocks. The association of time perception to time units can also be broken. Einstein’s time units became relative, in quantum mechanics, some physicist eliminated time units, others maintained them. Nevertheless, even the complete elimination of time units is not identical to timelessness, since the psychological perception of progressive and support-fixed time still remains and cannot be ignored. It is not seizable by physical methods, but experienced by everybody in everyday life. Contemporary physics can only abandon the association of time units or tenses to the basic components in perceived time. (shrink)

Argues that standard interpretations of Merleau-Ponty's criticisms of Sartrean freedom fail and presents an alternative interpretation that argues that the fundamental issue concerns their different theories of time.

We develop a theory about the metaphysics of time and modality that combines the conceptual resources devised in recent sympathetic work on ontological pluralism (the thesis that there are fundamentally distinct kinds of being) with the thought that what is past, future, and merely possible is less real than what is present and actual (albeit real enough to serve as truthmakers for statements about the past, future, and merely possible). However, we also show that despite being a coherent, distinctive, (...) and prima facie appealing position, the theory succumbs to what we call the “problem of mixed ontological status”. We conclude that the proponents of the theory can only evade these problems by developing ontological pluralism in a radically different way than it has been by its recent sympathizers. (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)

It is a remarkable fact that all processes occurring in the observable universe are irre- versible, whereas the equations through which the fundamental laws of physics are formu- lated are invariant under time reversal. The emergence of irreversibility from the funda- mental laws has been a topic of consideration by physicists, astronomers and philosophers since Boltzmann's formulation of his famous \H" theorem. In this paper we shall discuss some aspects of this problem and its connection with the dynamics of (...) space-time, within the framework of modern cosmology. We conclude that the existence of cosmological horizons allows a coupling of the global state of the universe with the local events deter- mined through electromagnetic processes. (shrink)

“The universe is expanding, not contracting.” Many statements of this form appear unambiguously true; after all, the discovery of the universe’s expansion is one of the great triumphs of empirical science. However, the statement is time-directed: the universe expands towards what we call the future; it contracts towards the past. If we deny that time has a direction, should we also deny that the universe is really expanding? This article draws together and discusses what I call ‘C-theories’ of (...) time — in short, philosophical positions that hold time lacks a direction — from different areas of the literature. I set out the various motivations, aims, and problems for C-theories, and outline different versions of antirealism about the direction of time. (shrink)

Modern physics has provided a range of motivations for holding time to be fundamentally undirected. But how does a temporally adirectional metaphysics, or ‘C-theory’ of time, fit with the time of experience? In this chapter, I look at what kind of problem human time poses for C-theories. First, I ask whether there is a ‘hard problem’ of human time: whether it is in principle impossible to have the kinds of experience we do in a temporally (...) adirectional world. Second I consider the ‘easy problem’: how specific directed aspects of our temporal experience are to be explained by C-theorists. This leads to a greater issue: is there such a thing as an experience of time direction at all to even be explained? I show how the kinds of experience we have that we typically associate with the idea of time being directed can be accommodated within a directionless picture of time. (shrink)

Recent research (Latham, Miller and Norton, forthcoming) reveals that a majority of people represent actual time as dynamical. But do they, as suggested by McTaggart and Gödel, represent time as essentially dynamical? This paper distinguishes three interrelated questions. We ask (a) whether the folk representation of time is sensitive or insensitive: i.e., does what satisfies the folk representation of time in counterfactual worlds depend on what satisfies it actually—sensitive—or does is not depend on what satisfies it (...) actually—insensitive, and (b) do those who represent actual time as dynamical, represent time in all possible worlds as dynamical—what we call insensitive dynamism—or do they represent time in all possible worlds as dynamical only conditional on the actual world in fact being dynamical—what we call sensitive dynamism and (c) do dynamists and non-dynamists deploy two different representations of time, or deploy the same representation, but disagree about what actually satisfies that representation? We found no evidence that the folk representation of time is sensitive, or that the folk representation of time is essentially dynamical in either sense, though we did find evidence of a shared representation, on which dynamical features are sufficient, but not necessary, for time. (shrink)