Huw Price

argues that the success of the backward causation hypothesis in quantum mechanics would provide strong support for a version of Reichenbach's account of the direction of causal processes, which takes the direction of causation to rest on the fork asymmetry. He also criticises my perspectival account of the direction of causation, which takes causal asymmetry to be a projection of our own temporal asymmetry as agents. In this reply I take issue with Dowe's argument at three main points: his claim that the backward causation hypothesis in QM is incompatible with my perspectival approach to the direction of causation; his defence of the fork asymmetry approach against a general criticism of mine based on the time-symmetry of microphysics; and his application of his preferred account of the direction of causal processes to the relevant cases in QM.

Can an agent deliberating about an action A hold a meaningful credence that she will do A? 'No', say some authors, for 'Deliberation Crowds Out Prediction' (DCOP). Others disagree, but we argue here that such disagreements are often terminological. We explain why DCOP holds in a Ramseyian operationalist model of credence, but show that it is trivial to extend this model so that DCOP fails. We then discuss a model due to Joyce, and show that Joyce's rejection of DCOP rests on terminological choices about terms such as 'intention', 'prediction', and 'belief'. Once these choices are in view, they reveal underlying agreement between Joyce and the DCOP-favouring tradition that descends from Ramsey. Joyce's Evidential Autonomy Thesis (EAT) is effectively DCOP, in different terminological clothing. Both principles rest on the so-called 'transparency' of first-person present-tensed reflection on one's own mental states.

The best case for thinking that quantum mechanics is nonlocal rests on Bell's Theorem, and later results of the same kind. However, the correlations characteristic of Einstein–Podolsky–Rosen (EPR)–Bell (EPRB) experiments also arise in familiar cases elsewhere in quantum mechanics (QM), where the two measurements involved are timelike rather than spacelike separated; and in which the correlations are usually assumed to have a local causal explanation, requiring no action-at-a-distance (AAD). It is interesting to ask how this is possible, in the light of Bell's Theorem. We investigate this question, and present two options. Either (i) the new cases are nonlocal too, in which case AAD is more widespread in QM than has previously been appreciated (and does not depend on entanglement, as usually construed); or (ii) the means of avoiding AAD in the new cases extends in a natural way to EPRB, removing AAD in these cases too. There is a third option, viz., that the new cases are strongly disanalogous to EPRB. But this option requires an argument, so far missing, that the physical world breaks the symmetries which otherwise support the analogy. In the absence of such an argument, the orthodox combination of views—action-at-a-distance in EPRB, but local causality in its timelike analogue—is less well established than it is usually assumed to be. 1 Introduction1.1 Background1.2 Outline of the argument2 The Experiments2.1 Standard EPRB2.2 Sideways EPRB2.3 Comparing the experiments2.4 The need for beables3 The Symmetry Considerations3.1 The action symmetry3.2 Time-symmetry in SEPRB4 The Basic Trilemma4.1 An intuitive defence of Option III?5 Avoiding the Trilemma?6 The Classical Objection7 Defending Option III7.1 The free will argument7.2 Independence and consistency8 Entanglement and Epistemic Perspective

The dustjacket of The Common Mind bears a photograph of the traffic at a Sydney intersection on a wet winter’s evening in 1938. It is rush hour, and the homeward traffic conveys a fine sense of common purpose. The scene has a special resonance for me, for I stood at that very spot with my parents and brothers one similar evening in 1966, on the day we first arrived in Australia. There was a marked pedestrian crossing there then, which we set out to negotiate, taking it for granted that the relevant conventions were those we were used to in rural England. But pedestrians and rush hour traffic were both under the control of a policeman—one of his predecessors can be seen in the photograph—who had just given the traffic priority. He loudly familiarised us with the local customs, and the kind of emotions we felt play an important part in Philip Pettit’s vision of the possibility and grounds of a satisfactory human society: the approval and disapproval of the community provides an intangible hand that guides defaulters into line.

Causalists and Evidentialists can agree about the right course of action in an (apparent) Newcomb problem, if the causal facts are not as initially they seem. If declining $1,000 causes the Predictor to have placed $1m in the opaque box, CDT agrees with EDT that one-boxing is rational. This creates a difficulty for Causalists. We explain the problem with reference to Dummett's work on backward causation and Lewis's on chance and crystal balls. We show that the possibility that the causal facts might be properly judged to be non-standard in Newcomb problems leads to a dilemma for Causalism. One horn embraces a subjectivist understanding of causation, in a sense analogous to Lewis's own subjectivist conception of objective chance. In this case the analogy with chance reveals a terminological choice point, such that either (i) CDT is completely reconciled with EDT, or (ii) EDT takes precedence in the cases in which the two theories give different recommendations. The other horn of the dilemma rejects subjectivism, but now the analogy with chance suggests that it is simply mysterious why causation so construed should constrain rational action.

There is a long-standing disagreement in the philosophy of probability and Bayesian decision theory about whether an agent can hold a meaningful credence about an upcoming action, while she deliberates about what to do. Can she believe that it is, say, 70% probable that she will do A, while she chooses whether to do A? No, say some philosophers, for Deliberation Crowds Out Prediction (DCOP), but others disagree. In this paper, we propose a valid core for DCOP, and identify terminological causes for some of the apparent disputes.

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.

Proponents of causal decision theories argue that classical Bayesian decision theory (BDT) gives the wrong advice in certain types of cases, of which the clearest and commonest are the medical Newcomb problems. I defend BDT, invoking a familiar principle of statistical inference to show that in such cases a free agent cannot take the contemplated action to be probabilistically relevant to its causes (so that BDT gives the right answer). I argue that my defence does better than those of Ellery Eells and Richard Jeffrey; and that it applies, where necessary, to other types of Newcomb problem.

The so-called Canberra Plan is a grandchild of the Ramsey-Carnap treatment of theoretical terms. In its original form, the Ramsey-Carnap approach provided a method for analysing the meaning of scientific terms, such as “electron”, “gene” and “quark”—terms whose meanings could plausibly be delineated by their roles within scientific theories. But in the hands of David Lewis (1970, 1972), the original approach begat a more ambitious descendant, generalised and extended in two distinct ways: first, Lewis applied the technique to analyse the meaning of terms introduced not just by explicit scientific theories, but also by implicit folk theories such as folk psychology; second, he supplemented the theory to provide an account of the way in which the referents of the analysed terms might be identified on the basis of empirical investigation.

The status and respectability of alethic modality was always a point of contention and divergence between naturalism and empiricism. It poses no problems in principle for naturalism, since modal vocabulary is an integral part of all the candidate naturalistic base vocabularies. Fundamental physics is above all a language of laws; the special sciences distinguish between true and false counterfactual claims; and ordinary empirical talk is richly dispositional. By contrast, modality has been a stumbling-block for the empiricist tradition ever since Hume forcefully formulated his epistemological and ultimately semantic objections to the concepts of law and necessary connection. (, Lecture , §).

It has often been suggested that retrocausality offers a solution to some of the puzzles of quantum mechanics: e.g., that it allows a Lorentz-invariant explanation of Bell correlations, and other manifestations of quantum nonlocality, without action-at-a-distance. Some writers have argued that time-symmetry counts in favour of such a view, in the sense that retrocausality would be a natural consequence of a truly time-symmetric theory of the quantum world. Critics object that there is complete time-symmetry in classical physics, and yet no apparent retrocausality. Why should the quantum world be any different? This note throws some new light on these matters. I call attention to a respect in which quantum mechanics is different, under some assumptions about quantum ontology. Under these assumptions, the combination of time-symmetry without retrocausality is unavailable in quantum mechanics, for reasons intimately connected with the differences between classical and quantum physics (especially the role of discreteness in the latter). Not all interpretations of quantum mechanics share these assumptions, however, and in those that do not, time-symmetry does not entail retrocausality.

In a recent paper, Richard Rorty begins by telling us why pragmatists such as himself are inclined to identify truth with justification: ‘Pragmatists think that if something makes no difference to practice, it should make no difference to philosophy. This conviction makes them suspicious of the distinction between justification and truth, for that distinction makes no difference to my decisions about what to do.’ (1995, p. 19) Rorty goes on to discuss the claim, defended by Crispin Wright, that truth is a normative constraint on assertion. He argues that this claim runs foul of this principle of no difference without a practical difference: ‘The need to justify our beliefs to ourselves and our fellow agents subjects us to norms, and obedience to these norms produces a behavioural pattern that we must detect in others before confidently attributing beliefs to them. But there seems to be no occasion to look for obedience to an additional norm – the commandment to seek the truth. For – to return to the pragmatist doubt with which I began – obedience to that commandment will produce no behaviour not produced by the need to offer justification.’ (1995, p. 26) Again, then, Rorty appeals to the claim that a commitment to a norm of truth rather than a norm of justification makes no behavioural difference. This is an empirical claim, testable in principle by comparing the behaviour of a community of realists (in Rorty’s sense) to that of a community of pragmatists. In my view, the experiment would show that the claim is unjustified, indeed false. I think that there is an important and widespread behavioural pattern that depends on the fact that speakers do take themselves to be subject to such an additional norm. Moreover, it is a..

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.

A number of writers have been attracted to the idea that some of the peculiarities of quantum theory might be manifestations of 'backward' or 'retro' causality, underlying the quantum description. This idea has been explored in the literature in two main ways: firstly in a variety of explicit models of quantum systems, and secondly at a conceptual level. This note introduces a third approach, intended to complement the other two. It describes a simple toy model, which, under a natural interpretation, shows how retrocausality can emerge from simple global constraints. The model is also useful in permitting a clear distinction between the kind of retrocausality likely to be of interest in QM, and a different kind of reverse causality, with which it is liable to be confused. The model is proposed in the hope that future elaborations might throw light on the potential of retrocausality to account for quantum phenomena.