It is often claimed that the debate between presentism and eternalism is merely verbal, because when we use tensed, detensed or tenseless notions of existence, there is no difference in the accepted metaphysical statements between the adherents of both views. On the contrary, it is shown in this paper that when we express their positions making use, in accordance with intentions of the presentists and the eternalists, of the tensed notion of existence (in the case of the presentists) and the (...) detensed or tenseless notion (in the case of the eternalists), the controversy remains deep and very important for us, because both ontological claims express a different attitude to the existence of the flow of time. It is shown that not only does the proposed approach to presentism and eternalism exactly express the intentions of the adherents of both views but it also offers a better understanding of them joining together seemingly different theses maintained by the presentists and the eternalists, and explaining at the same time the dynamism of the presentists' ontology. The paper takes for granted that we should assess metaphysical theories in a similar way as we assess scientific theories, that is on the basis of their explanatory value. (shrink)

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)

Empirical evidence suggests that a majority of people believe that time robustly passes and that many also report that it seems to them, in experience, as though time robustly passes. Non-dynamists deny that time robustly passes, and many contemporary non-dynamists—deflationists—even deny that it seems to us as though time robustly passes. Non-dynamists, then, face the dual challenge of explaining why people have such beliefs and make such reports about their experiences. Several philosophers have suggested the stable-self explanation, according to which (...) what partly explains one or both of the explananda is that people believe themselves to have a stable persisting self that is imagined either as moving through time or as being stationary with time moving around it. This paper empirically investigates this explanation. We found, however, no evidential support for the stable-self explanation, leaving the non-dynamist but also, we will argue, the dynamist with an extant explanatory challenge. (shrink)

Empirical evidence suggests that people naïvely represent time as dynamical (i.e. as containing robust temporal passage). Yet many contemporary B-theorists deny that it seems to us, in perceptual experience, as though time robustly passes. The question then arises as to why we represent time as dynamical if we do not have perceptual experiences which represent time as dynamical. We consider two hypotheses about why this might be: the temporally aperspectival replacement hypothesis and the moving open future hypothesis. We then empirically (...) test the moving open future hypothesis. According to that hypothesis, we represent the past as objectively fixed and the future open. And we represent that this objective openness moves as events that were open become fixed, such that in doing so, we represent a privileged moving present. We found no evidence for the moving open future hypothesis, which suggests that further investigation of the temporally aperspectival replacement hypothesis is called for. Our results also shed further light on our understanding of the respects in which we represent the future to be open, which, in turn, has implications for our theorising about the open future. (shrink)

This paper aims to determine whether we can locate temporal passage in a non-dynamical (block universe) world. In particular, we seek to determine both whether temporal passage can be located somewhere in our world if it is non-dynamical, and also to home in on where in such a world temporal passage can be located, if it can be located anywhere. We investigate this question by seeking to determine, across three experiments, whether the folk concept of temporal passage can be satisfied (...) in our world if it is non-dynamical, and, if it can, what sort of thing in our world satisfies that concept. In particular, we focus on the question of whether that concept (if satisfied) is satisfied by something mind-dependent or something mind-independent. In other words, we ask, is temporal passage something that is at least partially in the mind, or is it entirely external to the mind? We find, contrary to what is often assumed by dynamists and non-dynamists alike, that the folk concept of temporal passage is satisfied in our world conditional on it being non-dynamical, and that the concept is satisfied by something mind-independent. This provides further ammunition for recent deflationary accounts of temporal passage that attempt to locate passage somewhere in our non-dynamical world. (shrink)

Temporal dynamists typically hold that it seems to us as though time robustly passes, and that its seeming so is explained by the fact that time does robustly pass. Temporal non-dynamists hold that time does not robustly pass. Some non-dynamists nevertheless hold that it seems as though it does: we have an illusory phenomenal state whose content represents robust passage. Call these phenomenal passage illusionists. Other non-dynamists argue that the phenomenal state in question is veridical and represents something other than (...) robust passage. Call this the veridical passage-less view. This paper argues in favour of the latter view over the former, by arguing that we should reject passage illusionism. (shrink)

The notion of time reversal has caused some recent controversy in philosophy of physics. The debate has mainly put the focus on how the concept of time reversal should be formally implemented across different physical theories and models, as if time reversal were a single, unified concept that physical theories should capture. In this paper, I shift the focus of the debate and defend that the concept of time reversal involves at least three facets, where each of them gives rise (...) to opposing views. In particular, I submit that any account of time reversal presupposes (explicitly or implicitly) modal, metaphysical, and heuristic facets. The comprehension of this multi-faceted nature of time reversal, I conclude, shows that time reversal can be coherently said in many ways, suggesting a disunified concept. (shrink)

Philosophical debates about the metaphysics of time typically revolve around two contrasting views of time. On the A-theory, time is something that itself undergoes change, as captured by the idea of the passage of time; on the B-theory, all there is to time is events standing in before/after or simultaneity relations to each other, and these temporal relations are unchanging. Philosophers typically regard the A-theory as being supported by our experience of time, and they take it that the B-theory clashes (...) with how we experience time and therefore faces the burden of having to explain away that clash. In this paper, we investigate empirically whether these intuitions about the experience of time are shared by the general public. We asked directly for people’s subjective reports of their experience of time—in particular, whether they believe themselves to have a phenomenology as of time’s passing—and we probed their understanding of what time’s passage in fact is. We find that a majority of participants do share the aforementioned intuitions, but interestingly a minority do not. (shrink)

A theory is usually said to be time reversible if whenever a sequence of states S 1 , S 2 , S 3 is possible according to that theory, then the reverse sequence of time reversed states S 3 T , S 2 T , S 1 T is also possible according to that theory; i.e., one normally not only inverts the sequence of states, but also operates on the states with a time reversal operator T . David Albert and (...) Paul Horwich have suggested that one should not allow such time reversal operations T on states. I will argue that time reversal operations on fundamental states should be allowed. I will furthermore argue that the form that time reversal operations take is determined by the type of fundamental geometric quantities that occur in nature and that we have good reason to believe that the fundamental geometric quantities that occur in nature correspond to irreducible representations of the Lorentz transformations. Finally, I will argue that we have good reason to believe that space-time has a temporal orientation. (shrink)

In this article I shall defend, against the conventional understanding of the matter, that two coherent and tenable approaches to time reversal can be suitably introduced in standard quantum mechanics: an “orthodox” approach that demands time reversal to be represented in terms of an anti-unitary and anti-linear time-reversal operator, and a “heterodox” approach that represents time reversal in terms of a unitary, linear time-reversal operator. The rationale shall be that the orthodox approach in quantum theories assumes a relationalist metaphysics of (...) time, according to which time reversal is nothing but motion reversal. But, when one shifts gears and turn to a substantivalist metaphysics of time the heterodox approach to time reversal in quantum mechanics comes up in a more natural way. (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)

It has been argued that measurement-induced collapses in Orthodox Quantum Mechanics generates an intrinsic (or built-in) quantum arrow of time. In this paper, I critically assess this proposal. I begin by distinguishing between an intrinsic and non-intrinsic arrow of time. After presenting the proposal of a collapse-based arrow of time in some detail, I argue, first, that any quantum arrow of time in Orthodox Quantum Mechanics is non-intrinsic since it depends on external information about the measurement context, and second, that (...) it cannot be global, but just local. I complement these arguments by assessing some criticisms and considerations about the implementation of time reversal in contexts wherein measurement-induced collapses work. I conclude that the quantum arrow of time delivered by Orthodox Quantum Mechanics is much weaker than usually thought. (shrink)

In the contemporary landscape about temporal experience, debates concerning the “hard question” of the experience of the flow—as opposed to debates concerning more qualitative aspects of temporality, such as change, movement, succession and duration—are gaining more and more attention. The overall dialectics can be thought of in terms of a debate between the realists (who take the phenomenology of the flow of time seriously, and propose various account of it) and deflationists (who take our description of temporal phenomenology as “flowy” (...) to be spurious, and propose various explanation of this spuriousness). In this paper we look inside the realist side. We distinguish primitivist realism, according to which the feeling of time flowing is an irreducible sui generis phenomenology, and various forms of reductionist realism, according to which the experience of the flow is ultimately explainable in terms of a more basic phenomenology. We present reasons to be sceptical against the various reductionist proposals. The conclusion is thus disjunctive: either primitivism or deflationism is the correct account of the purported experience of the flow of time. (shrink)

I attempt a reconstruction of Kant’s version of the causal theory of time that makes it appear coherent. Two problems are at issue. The first concerns Kant’s reference to reciprocal causal influence for characterizing simultaneity. This approach is criticized by pointing out that Kant’s procedure involves simultaneous counterdirected processes—which seems to run into circularity. The problem can be defused by drawing on instantaneous processes such as the propagation of gravitation in Newtonian mechanics. Another charge of circularity against Kant’s causal theory (...) was leveled by Schopenhauer. His objection was that Kant’s approach is invalidated by the failure to deliver non-temporal criteria for distinguishing between causes and effects. I try to show that the modern causal account has made important progress toward a successful resolution of this difficulty. The fork asymmetry, as based on Reichenbach’s principle of the common cause, provides a means for the distinction between cause and effect that is not based on temporal order.Author Keywords: Kant; Causal theory of time; Anisotropy of time; Fork asymmetry; Principle of the common cause; Screening off. (shrink)

Traditional discussions about the arrow of time in general involve the concept of entropy. In the cosmological context, the direction past-to-future is usually related to the direction of the gradient of the entropy function of the universe. But the definition of the entropy of the universe is a very controversial matter. Moreover, thermodynamics is a phenomenological theory. Geometrical properties of space-time provide a more fundamental and less controversial way of defining an arrow of time for the universe as a whole. (...) We will call the arrow defined only on the basis of the geometrical properties of space-time, independently of any entropic considerations, “the global arrow of time.” In this paper we will argue that: (i) if certain conditions are satisfied, it is possible to define a global arrow of time for the universe as a whole, and (ii) the standard models of contemporary cosmology satisfy these conditions. (shrink)

In a recent paper, Malament (2004) employs a time reversal transformation that differs from the standard one, without explicitly arguing for it. This is a new and important understanding of time reversal that deserves arguing for in its own right. I argue that it improves upon the standard one. Recent discussion has focused on whether velocities should undergo a time reversal operation. I address a prior question: What is the proper notion of time reversal? This is important, for it will (...) affect our conclusion as to whether our best theories are time-reversal symmetric, and hence whether our spacetime is temporally oriented. *Received February 2007; revised March 2008. †To contact the author, please write to: Department of Philosophy, Yale University, P.O. Box 208306, New Haven, CT 06520-8306; e-mail: [email protected]. (shrink)

During the last decades the physico-chemical conception of self-organization of chemical systems has been created. The chemical systems in natural-historical processes do not have any creator: they rise up from irreversible processes by self-organization. The issue of self-organization in physics has led to a new interpretation of the laws of nature. As Ilya Prigogine has shown, they do not express certainties but possibilities and describe a world that must be understood in a historical way. In the new philosophical understanding of (...) nature priority is not ascribed to any single type or level of entity, but to historical processes, to processes of endless generation and change. (shrink)

The aim of this article is to argue that a temporal asymmetry may be established within the framework of quantum field theory, independently of any violation of CP, and thereby T, in weak interactions, and independently of the property of time reversal invariance that its dynamical equations instantiate. Particularly, I shall argue that the temporal asymmetry can be stemmed from assessing the links between the proper group of symmetries of the theory and the ontology of the theory: arguments applied to (...) establish which elements and magnitudes remain invariants under group transformations can also be used to establish a temporal asymmetry. (shrink)

In this survey, we discuss and analyze foundational issues of the problem of time and its asymmetry from a unified standpoint. Our aim is to discuss concisely the current theories and underlying notions, including interdisciplinary aspects, such as the role of time and temporality in quantum and statistical physics, biology, and cosmology. We compare some sophisticated ideas and approaches for the treatment of the problem of time and its asymmetry by thoroughly considering various aspects of the second law of thermodynamics, (...) nonequilibrium entropy, entropy production, and irreversibility. The concept of irreversibility is discussed carefully and reanalyzed in this connection to clarify the concept of entropy production, which is a marked characteristic of irreversibility. The role of boundary conditions in the distinction between past and future is discussed with attention in this context. The paper also includes a synthesis of past and present research and a survey of methodology. It also analyzes some open questions in the field from a critical perspective. (shrink)