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.

Reductive accounts of the direction of time are often paired with Humean accounts of laws, while non-reductive accounts of time are often paired with anti-Humean accounts of laws. The traditional pairing of views has recently come under question. This paper aims to clarify what sorts of anti-Humean views motivate anti-reductionism about the direction of time. It is argued that those who think (i) that the laws are metaphysically fundamental, and (ii) that the laws contain time-asymmetric contents, should treat the arrow (...) of time as metaphysically fundamental. (shrink)

Some argue that time’s causal arrow is grounded in an underlying thermodynamic asymmetry. Often, this is tied to Humean skepticism that causes produce their effects, in any robust sense of ‘produce’. Conversely, those who advocate stronger notions of natural necessity often reject thermodynamic reductions of time’s causal arrow. Against these traditional pairings, I argue that ‘reduction-plus-production’ is coherent. Reductionists looking to invoke robust production can insist that there are metaphysical constraints on the signs of objects’ velocities in any state, given (...) other—including far later—states’ properties. The Past Hypothesis may thus be a metaphysical condition, not a physical law. (shrink)

The aim of this doctoral dissertation is to closely explore the nature of Einstein’s block universe and to tease out its implications for the nature of time and human freedom. Four questions, in particular, are central to this dissertation, and set out the four dimensions of this philosophical investigation: (1) Does the block universe view of time follow inevitably from the theory of special relativity? (2) Is there room for the passage of time in the block universe? (3) Can we (...) distinguish past from future in the block universe? (4) Is there room for human freedom in the block universe? Although the answer of most philosophers would be yes, triple no, my own answer, controversially, is no, triple yes. -/- I thereby challenge the status quo with respect to each of these metaphysical questions, and argue that none of these questions can be answered from looking at physics alone. Physics may constrain our metaphysics, but it certainly does not settle it. What is needed in order to answer these questions, are additional metaphysical assumptions that fall outside the scope of modern physics. My primary goal in this dissertation, therefore, is not to settle the debates on the nature of time and human freedom, but to clarify them by expliciting the metaphysical assumptions that are otherwise left implicit. (shrink)

Can the second law of thermodynamics explain our mental experience of the direction of time? According to an influential approach, the past hypothesis of universal low entropy also explains how the psychological arrow comes about. We argue that although this approach has many attractive features, it cannot explain the psychological arrow after all. In particular, we show that the past hypothesis is neither necessary nor sufficient to explain the psychological arrow on the basis of current physics. We propose two necessary (...) conditions on the workings of the brain that any account of the psychological arrow of time must satisfy. And we propose a new reductive physical account of the psychological arrow of time compatible with time-symmetric physics, according to which these two conditions are also sufficient. Our proposal has some radical implications, for example, that the psychological arrow of time is fundamental, whereas the temporal direction of entropy increase in the second law of thermodynamics and the past hypothesis is derived from it, rather than the other way around. 1Introduction2A Physical Account of the Psychological Arrow of Time3Necessary Conditions for the Psychological Arrow of Time4The Psychological Arrow of Time via the Second Law of Thermodynamics and the Past Hypothesis5Why the Past Hypothesis Is Insufficient for the Psychological Arrow of Time5.1Stage 1, Version 1: From the past hypothesis to the psychological arrow via typicality5.2Stage 1, Version 2: From the past hypothesis to the psychological arrow via dynamical or causal considerations5.3Stage 2: From entropy gradient in the brain to the psychological arrow of time6Why the Past Hypothesis Is Unnecessary for the Psychological Arrow of Time7A New Reductive Account of the Psychological Arrow of Time. (shrink)

This paper claims that, to the extent that temporal direction figures in physics at all, it is found there as part of the extra-scientific language science employs. The asymmetry between “before” and “after” is not captured by the mathematics of any theory, nor can it be derived from the laws of any theory. This, I argue, is true even of theories whose laws are not time reversal invariant. Recognizing that physics does not yield temporal direction but receives it from the (...) background in which physics develops and operates does not, however, expose any hitherto unknown limitations or deficiencies of physics. The claim is not about physics, but about metaphysical stances regarding physics, specifically, physicalism, which requires from physics to deliver more than it does, or should. Once the place of temporal direction in physics is understood, infamous difficulties can be addressed in a novel way. Issues emerging from the 2nd law of thermodynamics, such as the minimum problem, and the worry that the law generates outlandish predictions, are removed. A side benefit is the recognition that the past hypothesis is superfluous. A final conclusion of the paper is that the relationship between physics and everyday language, far from being a source of difficulties, is healthy and beneficial to both. (shrink)

The aim of this article is to analyse the relation between the second law of thermodynamics and the so-called arrow of time. For this purpose, a number of different aspects in this arrow of time are distinguished, in particular those of time-reversal (non-)invariance and of (ir)reversibility. Next I review versions of the second law in the work of Carnot, Clausius, Kelvin, Planck, Gibbs, Caratheodory and Lieb and Yngvason, and investigate their connection with these aspects of the arrow of time. It (...) is shown that this connection varies a great deal along with these formulations of the second law. According to the famous formulation by Planck, the second law expresses the irreversibility of natural processes. But in many other formulations irreversibility or even time-reversal non-invariance plays no role. I therefore argue for the view that the second law has nothing to do with the arrow of time. (shrink)

This article argues that time-asymmetric processes in spacetime are enantiomorphs. Subsequently, the Kantian puzzle concerning enantiomorphs in space is reviewed to introduce a number of positions concerning enantiomorphy, and to arrive at a dilemma: one must either reject that orientations of enantiomorphs are determinate, or furnish space or objects with orientation. The discussion on space is then used to derive two problems in the debate on the direction of time. First, it is shown that certain kinds of reductionism about the (...) direction of time are at variance with the claim that orientation of enantiomorphic objects is intrinsic. Second, it is argued that reductive explanations of time-asymmetric processes presuppose that enantiomorphic processes do not have determinate orientation. (shrink)

The conceptual relation between objective becoming and the direction of time is explored by discussing an ontologically asymmetric notion of causation. It is claimed that such a notion, in terms of which Stein defined objective becoming in Minkowski spacetime, has either a purely metaphysical status or is reducible to physical concepts. In the former case, it is adequate for Stein's purpose but irrelevant to physical theories. In the latter, the causal asymmetry can be related to irreversible physical processes only in (...) an extrinsic way. This dilemma creates additional difficulties both to a unified theory of the direction of time and to the project of making room for becoming in the physical world. (shrink)

In this thesis I will examine the philosophy of the physicist Max Born. As well as his scientific work, Born wrote on a number of philosophical topics: causation, realism, determinism, and probability. They appear as an interest throughout his career, but he particularly concentrates on them from the 1940s onwards. Born is a significant figure in the development of quantum mechanics whose philosophical work has been left largely unexamined. It is the aim of this thesis to elucidate and to critically (...) examine that work. I will give a defence of presentist historiography in the history and philosophy of science and a brief biography of Born. With regards to causation, the thesis will argue that he holds that there exist principles regarding causal relations that have guided the development of physics and have, in the modern formulation of the subject, been confirmed as having an empirical status. I will argue that he is a selective realist, initially with regards to invariant properties and, later on, a structural realist. With regards to determinism, I will argue that Born has produced an argument, compatible with modern philosophical definitions of determinism, that we were never entitled to conclude from the success of classical mechanics that the world was deterministic. Finally, I will argue that Born holds an objective interpretation of probabilities in quantum mechanics which, due to his strong belief in the physical reality of quantum-mechanical probabilities and his apparent disbelief in the superposition of the wave-function, is most likely a long-run propensity theory. (shrink)

This is an extensive review of recent work on the foundations of statistical mechanics.

In this course we will examine several philosophical puzzles concerning time. We all seem to experience time in a very fundamental and direct way. Yet once we begin to reflect on what time really is, it is easy to feel as puzzled as St Augustine was, who wrote: “If no one asks me, I know what [time] is. If I wish to explain it to him who asks me, I do not know.” The first set of issues we will discuss (...) concern the question whether time is ‘real.’ Time appears to consist of past, present and future. But do the past and the future exist in the same way as the present or is only the present real? Does time ‘flow’? In what ways is time different from space? What would it be to ‘spatialize’ time? Next we will ask whether certain views of time imply that there can be no freedom of the will. One might worry that if facts about the future (including facts about what I will do tomorrow) already existed in the same way as facts about the present exist, then I could not be free to choose what I will do. After all, how can I be free to decide to skip class tomorrow, if it is ‘already’ a fact today that I will attend class? What, if anything, is the connection between various views of time and ‘fatalism’? The third topic we will discuss is time travel. First we will ask whether time travel is a conceptual possibility. As we will see, there are certain conceptual puzzles associated with the possibility of time travel. For example, one might think that if time travel is possible, then I should be able to travel back in time and kill my father before the date of my conception. But this scenario seems to lead to a contradiction. Some have taken considerations such as these to argue that the very idea of time travel is incoherent. Is this right? If not, why not? Then we will look at what the theory of relativity says about the nature of time in general and about the physical possibility of time travel more specifically. Finally we will examine several issues concerning the asymmetry of time.. (shrink)

This article argues that time‐asymmetric processes in spacetime are enantiomorphs. Subsequently, the Kantian puzzle concerning enantiomorphs in space is reviewed to introduce a number of positions concerning enantiomorphy, and to arrive at a dilemma: one must either reject that orientations of enantiomorphs are determinate, or furnish space or objects with orientation. The discussion on space is then used to derive two problems in the debate on the direction of time. First, it is shown that certain kinds of reductionism about the (...) direction of time are at variance with the claim that orientation of enantiomorphic objects is intrinsic. Second, it is argued that reductive explanations of time‐asymmetric processes presuppose that enantiomorphic processes do not have determinate orientation. (shrink)