The past hypothesis is that the entropy of the universe was very low in the distant past. It is put forward to explain the entropic arrow of time but it has been suggested (e.g. [Penrose, R. (1989a). The emperor’s new mind. London:Vintage Books; Penrose, R. (1989b). Annals of the New York Academy of Sciences, 571, 249–264; Price, H. (1995). In S. F. Savitt (Ed.), Times’s arrows today. Cambridge: Cambridge University Press; Price, H. (1996). Time’s arrow and Archimedes’ point. Oxford: Oxford (...) University Press; Price, H. (2004). In C. Hitchcock (Ed.), Contemporary debates in philosophy of science. Oxford: Blackwell]) that it is itself in need of explanation. It has also been suggested that cosmic inflation could provide the explanation, but Price (2004) raises a serious objection to this suggestion, which has otherwise received very little attention in the philosophical literature. Price points out that the standard inflationary explanation involves a double standard: although the evolution of the universe described by the inflationary model seems natural from the standard temporal perspective it looks highly unnatural from the reversed temporal perspective. The main purpose of this paper is to propose a novel form of the inflationary explanation that avoids this objection. It is argued that the inflationary model would not involve a double standard (but would still explain the past hypothesis) if we construct the model with a global “boundary” condition instead of a conventional boundary condition: if we assume that the universe is as generic as possible overall, rather than as generic as possible at some given point (e.g. the Big Bang) as is assumed in the standard inflationary model. This novel form of the inflationary explanation is then compared with Price’s 1996 preferred explanation, a version of the so-called “Weyl hypothesis”. (shrink)

The frequencies with which photons pass through half-silvered mirrors in the forward direction of time is always approximately 1/2, whereas the frequencies with which photons pass through mirrors in the backward direction in time can be highly time-dependent. I argue that whether one should infer from this time-asymmetric phenomenon that time has an objective direction will depend on one's interpretation of quantum mechanics.

Many phenomena in the world display a striking time-asymmetry: the forwards transition frequencies are approximately invariant while the backwards ones are not. I argue in this paper that theories of such phenomena will entail that time has a direction, and that quantum mechanics in particular entails that the future is objectively different from the past.

Causation is a central topic in many areas of philosophy, including metaphysics, epistemology, philosophy of mind, ethics, history of philosophy, and philosophy ...

In Book IV, Chapter 11 of the Physics, Aristotle claims that ‘the before and after’ exists in time because it also exists in change, and it exists in change because it also exists in magnitude, and, further, that ‘time follows change’ and ‘change follows magnitude’.1 This is usually taken to mean that moments of time correspond to momentary stages of changes, and that momentary stages of changes correspond to points in magnitudes, so that time derives its ‘before and after’ from (...) that of change, and change from that of magnitude.2 But this is widely thought to land Aristotle in the following diffi culty: If Socrates walks between points A and C, for instance, he can either proceed from point A to point.. (shrink)

Suppose that God or a demon informs you of the following future fact: despite recent cosmological evidence, the universe is indeed closed and it will have a ‘final’ instant of time; moreover, at that final moment, all 49 of the world’s Imperial Faberge eggs will be in your bedroom bureau’s sock drawer. You’re absolutely certain that this information is true. All of your other dealings with supernatural powers have demonstrated that they are a trustworthy lot.

Thermodynamics is the science that describes much of the time asymmetric behavior found in the world. This entry's first task, consequently, is to show how thermodynamics treats temporally ‘directed’ behavior. It then concentrates on the following two questions. (1) What is the origin of the thermodynamic asymmetry in time? In a world possibly governed by time symmetric laws, how should we understand the time asymmetric laws of thermodynamics? (2) Does the thermodynamic time asymmetry explain the other temporal asymmetries? Does it (...) account, for instance, for the fact that we know more about the past than the future? The discussion thus divides between thermodynamics being an explanandum or explanans. In the former case the answer will be found in philosophy of physics; in the latter case it will be found in metaphysics, epistemology, and other fields, though in each case there will be blurring between the disciplines. (shrink)

This paper searches for an explicit expression of the so-called problem of the direction of time. I argue that the traditional version of the problem is an artifact of a mistaken view in the foundations of statistical mechanics, and that to the degree it is a problem, it is really one general to all the special sciences. I then search the residue of the traditional problem for any remaining difficulty particular to time's arrow and find that there is a special (...) puzzle for some types of scientific realist. (shrink)

Since the nineteenth century, the problem of the arrow of time has been traditionally analyzed in terms of entropy by relating the direction past-to-future to the gradient of the entropy function of the universe. In this paper, we reject this traditional perspective and argue for a global and non-entropic approach to the problem, according to which the arrow of time can be defined in terms of the geometrical properties of spacetime. In particular, we show how the global non-entropic arrow can (...) be transferred to the local level, where it takes the form of a non-spacelike local energy flow that provides the criterion for breaking the symmetry resulting from time-reversal invariant local laws. (shrink)

The thesis that a temporal asymmetry of counterfactual dependence characterizes our world plays a central role in Lewis’s philosophy, as. among other things, it underpins one of Lewis most renowned theses—that causation can be analyzed in terms of counterfactual dependence. To maintain that a temporal asymmetry of counterfactual dependence characterizes our world, Lewis committed himself to two other theses. The first is that the closest possible worlds at which the antecedent of a counterfactual conditional is true is one in which (...) a small miracle occurs—i.e. one whose laws differ from the actual laws in a small spatiotemporal region. The second is that our world is characterized by a temporal asymmetry of miracles. In this paper, I will argue, first, that the latter thesis is either false or incompatible with the picture of the relations among temporal asymmetries endorsed by Lewis and, second, that former thesis conflicts with some of the intuitions which seem to guide us when engaging in counterfactual reasoning. If there is any fact of the matter as to which possible worlds in which the antecedent of a counterfactual conditional is true are closest to the actual world, these are not worlds at which a small miracle occurs. (shrink)

The impression is frequently given that the static description of the 4-dimensional world given by a tenseless theory of time adequately accounts for the world and that a tensed theory of time has nothing to offer. In fact, the tenseless theory of time leaves us incapable of specifying the direction of time, whereas a tensed theory of time enables us to do so. Thus, the tensed theory enjoys a considerable advantage over the tenseless view.

Process theories of causality seek to explicate causality as a property of individual causal processes. This paper examines the capacity of such theories to account for the asymmetry of causation. Three types of theories of asymmetry are discussed; the subjective, the temporal, and the physical, the third of these being the preferred approach. Asymmetric features of the world, namely the entropic and Kaon arrows, are considered as possible sources of causal asymmetry and a physical theory of asymmetry is subsequently developed (...) with special reference to the questions of objectivity and backwards causation. (shrink)

It is argued that the main problem with "the problem of the direction of time" is to figure out what the problem is or is supposed to be. Towards this end, an attempt is made to disentangle and to classify some of the many issues which have been discussed under the label of 'the direction of time'. Secondly, some technical apparatus is introduced in the hope of producing a sharper formulation of the issues than they have received in the philosophical (...) literature. Finally, some tentative suggestions about the central issues are offered. In particular, it is suggested that entropy and irreversibility are much less crucial to the central issues than most philosophers would have us believe. This suggestion is not made because of any firm conviction of its correctness but rather because it helps to focus the discussion on some basic but long neglected assumptions which underlie traditional approaches. (shrink)

This paper assesses branching spacetime theories in light of metaphysical considerations concerning time. I present the A, B, and C series in terms of the temporal structure they impose on sets of events, and raise problems for two elements of extant branching spacetime theories—McCall’s ‘branch attrition’, and the ‘no backward branching’ feature of Belnap’s ‘branching space-time’—in terms of their respective A- and B-theoretic nature. I argue that McCall’s presentation of branch attrition can only be coherently formulated on a model with (...) at least two temporal dimensions, and that this results in severing the link between branch attrition and the flow of time. I argue that ‘no backward branching’ prohibits Belnap’s theory from capturing the modal content of indeterministic physical theories, and results in it ascribing to the world a time-asymmetric modal structure that lacks physical justification. (shrink)

This paper provides a survey of several philosophical issues arising in classical electrodynamics arguing that there is a philosophically rich set of problems in theories of classical physics that have not yet received the attention by philosophers that they deserve. One issue, which is connected to the philosophy of causation, concerns the temporal asymmetry exhibited by radiation fields in the presence of wave sources. Physicists and philosophers disagree on whether this asymmetry reflects a fundamental causal asymmetry or is due to (...) statistical or thermodynamic considerations. I suggest that an explanation appealing to the asymmetry of causation is more promising. Another issue concerns the conceptual structure of the theory. Despite its empirical success, classical electrodynamics faces serious foundational problems. Models of charged particles involve what by the theory's own lights are idealizations, I maintain, and this is a feature that is not readily captured by traditional philosophical accounts of scientific theories. Other issues I discuss concern (i) the relation between Lorentz's theory of the electron and Einstein's Theory of Special Relativity; (ii) the notion of the domain of a theory, the question of theory reduction, and the relation between classical and more fundamental quantum theories; and (iii) the role of locality constraints, their relation to the concept of causation; and the status of locality conditions in the semi-classical theory of the Aharanov-Bohm effect. (shrink)

In this paper I propose a reasonably sharp formulation of the temporal asymmetry of radiation. I criticize accounts that propose to derive the asymmetry from a low-entropy assumption characterizing the state of the early universe and argue that these accounts fail, since they presuppose the very asymmetry they are intended to derive. r 2006 Elsevier Ltd. All rights reserved.

Roger Penrose, in _The Emperor's New Mind_ (1989), writes about the way Mozart perceived music. Mozart did not play a piece in his mind in real time, or even speeded up, but could hold it before him all at once. We all do this, although usually for much shorter riffs than entire symphonies. I have argued that the all-at-onceness of our thoughts and perceptions is at least as inexplicable as what it is like to see red; I think the aural/temporal (...) all-at-onceness makes the point at least as vividly as the visual/spatial all-at-onceness of the curl of smoke in an art nouveau poster. (shrink)

I argue that in the many worlds interpretation of quantum mechanics time has no fundamental direction. I further discuss a way to recover thermodynamics in this interpretation using decoherence theory (Zurek and Paz 1994). Albert's proposal to recover thermodynamics from the collapse theory of Ghirardi et al. (1986) is also considered.

I consider the question of the direction of time in the context of the Everett interpretation of quantum mechanics. I focus on the special role of decoherence in the recovery of time asymmetric behaviour, such as the collapse of the quantum state and the thermodynamic regularities. The discussion is based on results in the consistent histories approach (Gell-Mann and Hartle 1993) and in decoherence theory (Zurek and Paz 1994). Finally, I compare the status of the direction of time in Everett (...) and in a recent proposal by Albert (2001) based on the collapse theory of Ghirardi, Rimini and Weber (1986). (shrink)

Why is our knowledge of the past so much more ‘expansive’ (to pick a suitably vague term) than our knowledge of the future, and what is the best way to capture the difference(s) (i.e., in what sense is knowledge of the past more ‘expansive’)? One could reasonably approach these questions by giving necessary conditions for different kinds of knowledge, and showing how some were satisfied by certain propositions about the past, and not by corresponding propositions about the future. I take (...) it that such is the approach of Chapter 6 of Time and Chance (T&C). Here’s another such a proposal, similar to that of, but significantly different from T&C; my purpose in this section is to highlight the differences, by showing how this account fails. (shrink)

I conduct an empirical analysis of the temporally asymmetric character of our epistemic access to the world by providing an experimental scheme whose results represent the core empirical content of the epistemic asymmetry. I augment this empirical content by formulating a gedanken experiment inspired by a proposal from David Albert. This second experiment cannot be conducted using any technology that is likely to be developed in the foreseeable future, but the expected results help us to state an important constraint on (...) our ability to know the future. Finally, I show that a third experiment concerning precognition, described by Michael Scriven and John Mackie, does not characterize any additional empirical content but does help to illustrate why it is unlikely that any precognition exists. (shrink)

I provide a comprehensive metaphysics of causation based on the idea that fundamentally things are governed by the laws of physics, and that derivatively difference-making can be assessed in terms of what fundamental laws of physics imply for hypothesized events. Highlights include a general philosophical methodology, the fundamental/derivative distinction, and my mature account of causal asymmetry.

Backtracking influence is influence that zigzags in time. For example, backtracking influence exists when an event E_1 makes an event E_2 more likely by way of a nomic connection that goes from E_1 back in time to an event C and then forward in time to E_2. I contend that in our local region of spacetime, at least, backtracking influence is redundant in the sense that any existing backtracking influence exerted by E_1 on E_2 is equivalent to E_1's temporally direct (...) influence on E_2. I prove the redundancy of backtracking influence using several plausible physical principles without assuming any fundamental temporal or causal asymmetry. This explanation can play a prominent role in an account of why causation appears to be objectively asymmetric regardless of whether the fundamental laws are symmetric. (shrink)

An explanation of our seeming inability to influence the past.

We use two logical resources, namely, the notion of recursively defined function and the Benardete-Yablo paradox, together with some inherent features of causality and time, as usually conceived, to derive two results: that no ungrounded causal chain exists and that time has a beginning.

The structure of Yablo’s paradox is analysed and generalised in order to show that beginningless step-by-step determination processes can be used to provoke antinomies, more concretely, to make our logical and our on-tological intuitions clash. The flow of time and the flow of causality are usually conceived of as intimately intertwined, so that temporal causation is the very paradigm of a step-by-step determination process. As a conse-quence, the paradoxical nature of beginningless step-by-step determina-tion processes concerns time and causality as usually (...) conceived. (shrink)

A probabilistic theory of causation is a theory which holds that the central feature of causation is that causes (usually) raise the probability of their effects. In this dissertation, I defend Hans Reichenbach's original (1953) version of the probabilistic theory of causation, which analyses causal relations in terms of a three place statistical betweenness relation. Unlike most discussions of this theory, I hold that the statistical relation should be taken as a sufficient, but not as necessary, condition for causal betweenness. (...) With this difference in interpretation, Reichenbach's theory is shown to be immune to all of the criticisms which have been raised against it in the last.. (shrink)

This article argues that the causal loops that occur in some time-travel scenarios and in certain solutions of the theory of relativity are no more mysterious than the infinitely descending causal chains familiar from Newtonian mechanics.

Tenseless theories of time entail that the only temporal properties exemplified by events are earlier than, simultaneous with, and later than. Such an account seems to conflict with our common experience of time, which suggests that the present moment is ontologically unique and that time flows. Some have argued that only a tensed account of time, one in which past, present and future are objective properties, can do justice to our experience. Any theory that claims that the world is different (...) from how we experience it must nonetheless be consistent with the having of that experience. Accordingly, in this essay I defend the tenseless theory by arguing that it can indeed account for certain key features of our experience of time without recourse to tensed properties. (shrink)

Or better: time asymmetry in thermodynamics. Better still: time asymmetry in thermodynamic phenomena. “Time in thermodynamics” misleadingly suggests that thermodynamics will tell us about the fundamental nature of time. But we don’t think that thermodynamics is a fundamental theory. It is a theory of macroscopic behavior, often called a “phenomenological science.” And to the extent that physics can tell us about the fundamental features of the world, including such things as the nature of time, we generally think that only fundamental (...) physics can. On its own, a science like thermodynamics won’t be able to tell us about time per se. But the theory will have much to say about everyday processes that occur in time; and in particular, the apparent asymmetry of those processes. The pressing question of time in the context of thermodynamics is about the asymmetry of things in time, not the asymmetry of time, to paraphrase Price ( , ). I use the title anyway, to underscore what is, to my mind, the centrality of thermodynamics to any discussion of the nature of time and our experience in it. The two issues—the temporal features of processes in time, and the intrinsic structure of time itself—are related. Indeed, it is in part this relation that makes the question of time asymmetry in thermodynamics so interesting. This, plus the fact that thermodynamics describes a surprisingly wide range of our ordinary experience. We’ll return to this. First, we need to get the question of time asymmetry in thermodynamics out on the table. (shrink)

Can a present or future event bring about a past event? An answer to this question is demanded by many other interesting questions. Can anybody, even a god, do anything about what has already occurred? Should we plan for the past, as well as for the future? Can anybody precognise the future in a way quite different from normal prediction? Do the causal laws and the past jointly preclude free action? Does current physical theory entail a consistent version of backwards (...) causation? Recent articles on the problem of backwards causation have drawn attention to the importance of the principle of the fixity of the past: that the past is now fixed. It can be shown that the standard argument against backwards causation (the bilking experiment) simply builds in the assumption of past fixity. A fixed past deprives future events of past efficacy. This has naturally led to the speculation that by abandoning past fixity real power over the past may be possible.In this paper I show that in order to have an interesting thesis of backwards causation it is not enough simply to drop past fixity. More must go. In particular, to ensure what could be called future-to-past efficacy we must abandon two entrenched principles of permanence: the principle of permanent fixity, and the principle of permanent truth. The only alternative for backwards causal theorists is to embrace real contradictions in nature. (shrink)

In 1963 a group of physicists, mathematicians and philosophers of science assembled in Cornell to discuss the arrow of time. One of them was Richard Feynman, who drew attention to his comments in the published discussions by insisting that they not be attributed to him. (They appeared as the remarks of "Mr. X".) Twenty-eight years later Feynman was gone, but the mysteries of time asymmetry in physics remained as deep as ever. At the end of September, 1991, forty-five physicists and (...) mathematicians assembled in Mazagon, Spain, for a second meeting on the arrow of time. This book is the proceedings of that meeting. (shrink)

Does not the theory of a general tendency of entropy to diminish [sic1] take too much for granted? To a certain extent it is supported by experimental evidence. We must accept such evidence as far as it goes and no further. We have no right to supplement it by a large draft of the scientific imagination. (Burbury 1904, 49).

For more than a century, physics has known of a puzzling conflict between the T- asymmetry of thermodynamic phenomena and the T-symmetry of the underlying microphysics on which these phenomena depend. This paper provides a guide to the current status of this puzzle, distinguishing the central issue from various issues with which it may be confused. It is shown that there are two competing conceptions of what is needed to resolve the puzzle of the thermodynamic asymmetry, which differ with respect (...) to the number of distinct T-asymmetries they take to be manifest in the physical world. On the preferable one-asymmetry conception, the remaining puzzle concerns the ordered distribution of matter in the early universe. The puzzle of the thermodynamic arrow thus becomes a puzzle for cosmology. (shrink)

Summary: Contemporary writers often claim that chaos theory explains the thermodynamic arrow of time. This paper argues that such claims are mistaken, on two levels. First, they underestimate the difficulty of extracting asymmetric conclusions from symmetric theories. More important, however, they misunderstand the nature of the puzzle about the temporal asymmetry of thermodynamics, and simply address the wrong issue. Both of these are old mistakes, but mistakes which are poorly recognised, even today. This paper aims to lay bare the mistakes (...) in their classical (pre-chaos theory) manifestations, in order to make it clear that chaos theory cannot possibly do better. (shrink)

Can physics explain the difference between past and future? The laws of physics seem to be time-symmetric. If they allow a process with one temporal orientation, they allow it in reverse. Yet many ordinary pro– cesses seem to be irreversible. Ilya Prigogine calls this the time paradox, and argues that the solution lies in chaos theory, and related methods pioneered by himself and his Brussells colleagues—a radical alternative, he thinks, to a tradition dating from Boltzmann.

The arrow of time is one of the big unclaimed prizes of modern physics. The problem is to reconcile the temporal asymmetry of thermodynamics with the apparent temporal symmetry of fundamental physical theories. Some major players have wrestled with the issue over the past century or so, but is still up for grabs--and very much in the air of late, having been discussed in recent books by Stephen Hawking..

In many physical systems, coupling forces provide a way of carrying the energy stored in adjacent harmonic oscillators from place to place, in the form of waves. The wave equations governing such phenomena are time-symmetric: they permit the opposite processes, in which energy arrives at a point in the form of incoming concentric waves, to be lost to some external system. But these processes seem rare in nature. What explains this temporal asymmetry, and how is it related to the thermodynamic (...) asymmetry? This paper attempts to clarify these old issues, in the light of recent contributions. After brief introductory remarks (§1), the paper is in three main parts. §2 examines the so-called ‘Sommerfeld Radiation Condition’, arguing that its link to the observed asymmetry is much less direct than commonly supposed. §3 begins with Zeh's proposal to make the Sommerfeld condition an ingredient in an explanation of the observed asymmetry, and makes explicit a useful distinction between two ways in which the thermodynamic asymmetry might connect to the radiation asymmetry. §4 reviews a proposal I have defended in earlier work about the relation of the radiative asymmetry to that of thermodynamics, and defends it against recent objections by Zeh and Frisch. I also distinguish it from a recent proposal due to North. I agree with North that the observed asymmetry of radiation stems from the low entropy history, but argue that she mis-characterises the asymmetry, and hence misses a crucial element in a proper account of the role of the low entropy past. (shrink)

Since the late nineteenth century, physics has been puzzled by the time-asymmetry of thermodynamic phenomena in the light of the apparent T-symmetry of the underlying laws of mechanics. However, a compelling solution to this puzzle has proved elusive. In part, I argue, this can be attributed to a failure to distinguish two conceptions of the problem. According to one, the main focus of our attention is a time-asymmetric lawlike generalisation. According to the other, it is a particular fact about the (...) early universe. This paper aims (i) to distinguish these two different conceptions of the time-asymmetric explanandum in thermodynamics; (ii) to argue in favour of the latter; and (iii) to show that whichever we choose, our rational expectations about the thermodynamic behaviour of the future must depend on what we know about the past: contrary to the common view, statistical arguments alone do not give us good reason to expect that entropy will always continue to increase. (shrink)

Physics takes for granted that interacting physical systems with no common history are independent, before their interaction. This principle is time-asymmetric, for no such restriction applies to systems with no common future, after an interaction. The time-asymmetry is normally attributed to boundary conditions. I argue that there are two distinct independence principles of this kind at work in contemporary physics, one of which cannot be attributed to boundary conditions, and therefore conflicts with the assumed T (or CPT) symmetry of microphysics. (...) I note that this may have interesting ramifications in quantum mechanics. (shrink)

One of the most striking features of causation is that causes typically precede their effects – the causal arrow is strongly aligned with the temporal arrow. Why should this be so? We offer an opinionated guide to this problem, and to the solutions currently on offer. We conclude that the most promising strategy is to begin with the de facto asymmetry of human deliberation, characterised in epistemic terms, and to build out from there. More than any rival, this subjectivist approach (...) promises to demystify the asymmetry, temporal orientation, and deliberative relevance of causal judgements. (shrink)

“We are always already thrown into concrete factual circumstances, facing possibilities that we need to come to grips with. By choosing some we exclude others, thus making them no longer possible. What we are thrown into is the past and present, and the possibilities loom ahead of us, though we may try to turn our back on them. The future is the home of the possibilities while the present and past define the circumstances in which we make our choices, circumstances (...) we can no longer affect.” Or so we might say, and there is something right about this way of talking. Our basic conception of ourselves as agents is radically temporally asymmetric. And so we adopt asymmetric metaphors for time: we talk of time having a direction, as flowing from the future, through the present, to the past, closing possibilities that once were open; or perhaps we think of time as a measure of our own movement from the past to the future. Such metaphors are of very limited value. To think of time as having a direction spatializes time; to think of time as flowing or of ourselves as moving in time is to invite the question of how fast it is flowing or how fast we are moving (at one second per second, perhaps, one might quip, thereby inviting the question of why it cannot flow at two seconds per second instead).             Although the metaphors are flawed, we need to come to grips with an inextricable asymmetry between past and future in them. As agents, we deliberate about the future, while the past we can only bewail or rejoice over. We know the future not only through theoretical knowledge, but also through the intentional knowledge that the agent has of the effects she intends to produce. We think a life that started in years of sorrow but ended in great joy is preferable to one that started with a great joy and ended in years of sorrow.. (shrink)

David Lewis (1979) has argued that according to his possible worlds analysis of counterfactuals, “backtracking” counterfactuals of the form “If event A were to happen at tA, then event B would happen at tB” where tB precedes tA, are usually false if B does not actually happen at tB. On the other..

The final work of a distinguished physicist, this remarkable volume examines the emotive significance of time, the time order of mechanics, the time direction of thermodynamics and microstatistics, the time direction of macrostatistics, and the time of quantum physics. Coherent discussions include accounts of analytic methods of scientific philosophy in the investigation of probability, quantum mechanics, the theory of relativity, and causality. "[Reichenbach’s] best by a good deal."—Physics Today. 1971 ed.

I revise J L Mackie's first account of casual direction by replacing his notion of "fixity" by a newly defined notion of "sufficing" that is designed to accommodate indeterminism. Keeping Mackie's distinction between casual order and casual direction, I then consider another revision that replaces "fixity" with "one-way conditionship". In response to the charge that all such accounts of casual priority beg the question by making an unjustified appeal to temporal priority, i maintain that one-way conditionship explains rather that assumes (...) objective temporal dependence as well as objective casual dependence. (shrink)

The aim of this essay is to introduce philosophers of science to some recent philosophical discussions of the nature and origin of the direction of time. The essay is organized around books by Hans Reichenbach, Paul Horwich, and Huw Price. I outline their major arguments and treat certain critical points in detail. I speculate at the end about the ways in which the subject may continue to develop and in which it may connect with other areas of philosophy.

In a recent book, Asymmetries in Time, Paul Horwich presents a systematic account of various temporal asymmetries, including a neo-Reichenbachian account of the (apparent) fact that we know more about the past than the future, the epistemological time asymmetry. I find some obscurities in Horwich's presentation, however, and I argue that when his view is understood in a way that I shall propose, it does represent an advance on Reichenbach's, but it fails to vindicate Horwich's "main point...that our special knowledge (...) of the past derives from the fork asymmetry. (shrink)

While experience tells us that time flows from the past to the present and into the future, a number of philosophical and physical objections exist to this commonsense view of dynamic time. In an attempt to make sense of this conundrum, philosophers and physicists are forced to confront fascinating questions, such as: Can effects precede causes? Can one travel in time? Can the expansion of the Universe or the process of measurement in quantum mechanics define a direction in time? In (...) this book, researchers from both physics and philosophy attempt to answer these issues in an interesting, yet rigorous way. This fascinating book will be of interest to physicists and philosophers of science and educated general readers interested in the direction of time. (shrink)

Despite over one-hundred years of effort, the origin of temporal asymmetry in the physical world still eludes us. While much has been learned about the role played by fundamental instabilities in microdynamics, by the imperfect isolation of systems and by cosmological facts in the origin of the behavior described by kinetic theory and thermodynamics, important puzzles still remain which continue to make the origins of asymmetric thermal behavior out of dynamically time symmetric underlying laws mysterious to us.

Joe Campbell has identified an apparent flaw in van Inwagen’s Consequence Argument. It apparently derives a metaphysically necessary conclusion from what Campbell argues is a contingent premise: that the past is in some sense necessary. I criticise Campbell’s examples attempting to show that this is not the case (in the requisite sense) and suggest some directions along which an incompatibilist could reconstruct her argument so as to remain immune to Campbell’s worries.

A system whose expected state changes with time cannot have both a forward-directed translationally invariant probabilistic law and a backward-directed translationally invariant law. When faced with this choice, science seems to favor the former. An asymmetry between cause and effect may help to explain why temporally oriented laws are usually forward-directed.

The ancient problem of whether our asymmetrical attitudes towards time are justified (or normatively required) remains a live one in contemporary philosophy. Drawing on themes in the work of McTaggart, Parfit, and Heidegger, I argue that this problem is also a key concern of Kierkegaard’s Either/Or (1843). Part I of Either/Or presents the “aesthete” as living a temporally volatilized form of life, devoid of temporal location, sequence and direction. Like Parfit’s character “Timeless,” these aesthetes are indifferent to the direction of (...) time and seemingly do not experience McTaggart’s “A-Series” mode of temporality. The “ethical” conception of time that Judge William offers in Part II contains an attempt to normativize the direction of time, by re-orienting the aesthete towards an awareness of time’s finitude. However, the form of life Judge William articulates gives time sequentiality but not necessarily the robust directionality necessary to justify (and make normative) our asymmetrical attitudes to time. Hence while Either/Or raises this problem it remains unanswered until The Concept of Anxiety (1844). Only with the eschatological understanding of time developed in The Concept of Anxiety does Kierkegaard answer the question of why directional and asymmetrical conative and affective attitudes towards time are normative. (shrink)

 The three alternative ontological theories of time are introduced as well as the three basic temporal phenomena. The different ontological analyses by the different theories are compared and examined. A relational theory of time is advocated as a result of the examination, and an influential misrepresentation and emendation of it by McTaggart is criticized and diagnosed as hyperdynamism. Finally, the problem of the direction of time is addressed. The physicist’s solutions are rejected, and an ontological solution is offered.

Is the common cause principle merely one of a set of useful heuristics for discovering causal relations, or is it rather a piece of heavy duty metaphysics, capable of grounding the direction of causation itself? Since the principle was introduced in Reichenbach’s groundbreaking work The Direction of Time (1956), there have been a series of attempts to pursue the latter program—to take the probabilistic relationships constitutive of the principle of the common cause and use them to ground the direction of (...) causation. These attempts have not all explicitly appealed to the principle as originally formulated; it has also appeared in the guise of independence conditions, counterfactual overdetermination, and, in the causal modelling literature, as the causal markov condition. In this paper, I identify a set of difficulties for grounding the asymmetry of causation on the principle and its descendents. The first difficulty, concerning what I call the vertical placement of causation, consists of a tension between considerations that drive towards the macroscopic scale, and considerations that drive towards the microscopic scale—the worry is that these considerations cannot both be comfortably accommodated. The second difficulty consists of a novel potential counterexample to the principle based on the familiar Einstein Podolsky Rosen (EPR) correlations in quantum mechanics. (shrink)