Huw Price

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.

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.

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.

This is my Cambridge PhD thesis, written under the supervision of Hugh Mellor and Richard Healey, and examined by Mary Hesse and Simon Blackburn. It addresses what it takes to be the core of the problem of single case probability, namely, the interpretation of claims such as ‘It is probable that P’ (where the probabilistic component occurs as a sentential or propositional operator). I argue that claims of this form are not genuinely truth-apt, and that such operators modify the force, rather than the sense, of sentences or propositions to which they attach. In contemporary terms, I thus defend a version of what Yalcin (2012) has called ‘credal expressivism’. Some of the core arguments were later published in the following papers: (i) ‘Does “Probably” modify sense?’, Australasian Journal of Philosophy 61(1983), 396–408 and (ii) 'Mellor, chance and the single case', British Journal for the Philosophy of Science 35(1984), 11-23. Other arguments, including an attempt at the Frege-Geach problem, form the basis of an unpublished piece 'The use of force in a theory of meaning' (1983), accessible at PhilPapers.

Is non-cognitivism compatible with minimalism about truth? A contemporary argument claims not, and therefore that moral realists, for example, should take heart from the popularity of semantic minimalism. The same is said to apply to cognitivism about other topics—conditionals, for example—for the argument depends only on the fact that ordinary usage applies the notions of truth and falsity to utterances of the kind in question. Given this much, minimalism about truth is said to leave no room for the view that the utterances concerned are non-cognitive in nature

Carnap was one of the first to use the term 'non-cognitivism'. His linguistic pluralism and voluntarism, and his deflationary views of ontology and semantics, are highly congenial to those of us who want to take non-cognitivism in the direction of global expressivism. In his own case, however, this move is in tension with his continued endorsement of what he calls 'the general thesis of logical empiricism', that 'there is no third kind of knowledge besides empirical and logical knowledge.’ So while Carnap clears a path towards global expressivism, he doesn't seem to appreciate what it requires him to leave behind.

Probabilistic accounts of causality have long had trouble with ‘spurious’ evidential correlations. Such correlations are also central to the case for causal decision theory—the argument that evidential decision theory is inadequate to cope with certain sorts of decision problem. However, there are now several strong defences of the evidential theory. Here I present what I regard as the best defence, and apply it to the probabilistic approach to causality. I argue that provided a probabilistic theory appeals to the notions of agency and effective strategy, it can avoid the problem of spurious causes. I show that such an appeal has other advantages; and argue that it is not illegitimate, even for a causal realist.

One of the outstanding achievements of recent cosmology has been to offer some prospect of a unified explanation of temporal asymmetry. The explanation is in two main parts, and runs something like this. First, the various asymmetries we observe are all thermodynamic in origin – all products of the fact that we live in an epoch in which the universe is far from thermodynamic equilibrium. Second, this thermodynamic disequilibrium is associated with the condition of the universe very soon after the Big Bang – the essential point being that in the rapidly expanding universe of the time, gravity is able to create organisation much faster than other processes can destroy it. The stars, galaxies and other forms of organisation we find in the present universe are all products of this early period. Such concentrated energy sources themselves make possible the kinds of asymmetric phenomena with which we are most familiar, such as life itself. If this explanation proves to be right it will surely rank as one of the most impressive achievements in the whole of natural philosophy. Where else do we find this breathtaking scale, this extraordinary conjunction of fundamental physics, the first moments of Creation, the possibility of life and the basic character of human experience? And it is very much a contemporary achievement: even if its roots go back on one side to the investigation of time asymmetry in nineteenth century statistical mechanics, and on the other to Hubble's discovery in the 1920's of the expansion of the universe, the body of the picture has only begun to be filled in in the last twenty or thirty years. This fascinating story has recently been given some well-deserved publicity in Stephen Hawking's bestseller, A Brief History of Time – well-deserved, not least, because Hawking himself is responsible for a considerable part of the story as it presently stands

In 'General Propositions and Causality' Ramsey rejects his earlier view that universal generalizations are infinite conjunctions, arguing that they are not genuine propositions at all. We argue that his new position is unstable. The issues about infinity that lead Ramsey to the new view are essentially those underlying Wittgenstein's rule-following considerations. If they show that generalizations are not genuine propositions, they show that there are no genuine propositions. The connection raises interesting historical questions about the direction of influence between Ramsey and Wittgenstein, the origin of the rule-following argument, and the influence of writers such as Brouwer.

This piece was written circa 1982–83, drawing in part on material from my PhD thesis (The Problem of the Single Case, Cambridge, 1981). In the thesis I proposed what would now be called an expressivist account of judgements of the form ‘It is probable that p’. One chapter, on which this paper builds, tried to defend the view against the Frege-Geach argument. This piece earned a revise and resubmit from Philosophical Review, but was never resubmitted. Parts of it made their way into my ‘Semantic Minimalism and the Frege Point’, in Tsohatzidis, S.L.(ed.), Foundations of Speech Act Theory: Philosophical and Linguistic Perspectives, Routledge, 1994, pp. 132–55 (reprinted in Naturalism without Mirrors, Oxford, 2011, ch. 3) – though that paper favours a different approach to the Frege-Geach argument, leaning more heavily on semantic minimalism. I’m putting this piece online to facilitate self-citation.

Paul Horwich aims to apply some the lessons of deflationism about truth to the debate about the nature of a theory of meaning. Having pacified the philosophical debate about truth to his satisfaction, he wants to use a bridge between truth and meaning to extend the same peace−making techniques into new territory. His goal is to make the debate about meaning more hospitable for an account based on use, by showing that certain apparent obstacles to such a theory are illusory, given deflationism about truth.

In “A Subjectivist’s Guide to Objective Chance,” David Lewis says that he is “led to wonder whether anyone but a subjectivist is in a position to understand objective chance.” The present essay aims to motivate this same Lewisean attitude, and a similar degree of modest subjectivism, with respect to objective causation. The essay begins with Newcomb problems, which turn on an apparent tension between two principles of choice: roughly, a principle sensitive to the causal features of the relevant situation, and a principle sensitive only to evidential factors. Two-boxers give priority to causal beliefs, and one-boxers to evidential beliefs. The essay notes that a similar issue can arise when the modality in question is chance, rather than causation. In this case, the conflict is between decision rules based on credences guided solely by chances, and rules based on credences guided by other sorts of probabilistic evidence. Far from excluding cases of the latter kind, Lewis’s Principal Principle explicitly allows for them, in the form of the caveat that credences should follow beliefs about chances only in the absence of “inadmissible evidence.” The essay then exhibits a tension in Lewis’s views on these two matters, by presenting a class of decision problems—some of them themselves Newcomb problems—in which Lewis’s view of the relevance of inadmissible evidence seems in tension with his causal decision theory. It offers a diagnosis for this dilemma and proposes a remedy, based on an extension of a proposal due to Ned Hall and others from the case of chance to that of causation. The remedy suggests a new view of the relation between causal decision theory and evidential decision theory, namely, that they stand to each other much as chance stands to credence, being objective and subjective faces of the same practical coin. This has much the same metaphysical benefits as Lewis’s own view of chance and also throws interesting new light on Newcomb problems, providing an irenic resolution of the apparent disagreement between causal and evidential decision rules.

Like coastal cities in the third millennium, important areas of human discourse seem threatened by the rise of modern science. The problem isn't new, of course, or wholly unwelcome. The tide of naturalism has been rising since the seventeenth century, and the rise owes more to clarity than to pollution in the intellectual atmosphere. All the same, the regions under threat are some of the most central in human life--the four Ms, for example: Morality, Modality, Meaning and the Mental. Some of the key issues in contemporary metaphysics concern the place and fate of such concepts in a naturalistic world view.

Speech act theory is one of the more lasting products of the linguistic movement in philosophy of the mid−Twentieth century. Within philosophy itself the movement's products did not in general prove so durable. Particularly striking in this respect is the perceived fate of what was one of the most characteristic applications of the linguistic turn in philosophy, namely the view that many traditional philosophical problems are such as to yield to an understanding of the distinctive function of a particular part of language. Most typically, the crucial insight was held to be that despite appearances, the function of the part of language in question is not assertoric, or descriptive, and that the traditional problems arose at least in part from a failure to appreciate this point. Thus problems in moral philosophy were thought to yield to an appreciation that moral discourse is expressive rather than descriptive, problems in the philosophy of mind to an understanding of distinctive r×le of psychological ascriptions, and so on. The philosophical journals of the 1950s are rich with views like these. (No general term for this approach seems to have become widely accepted at the time. I shall call it "non−factualism", for what it denies, most characteristically, is the fact−stating r×le of language of a certain kind.)

One of the jobs of philosophers of the special sciences is to connect the local concerns of particular disciplines with those of philosophy in general. The two-way complexities of this task are well-illustrated by the case of causation. On the one hand—from the outside, as it were— philosophers interested in general issues about causation are prone to turn to the special sciences for real-life examples of the use of causal notions. On the other hand, from the inside, the special disciplines themselves throw up philosophical puzzles in which the notion of causation plays a role. When does correlation indicate causation, for example? Physics and economics both generate hard cases of this kind

Are the distinctions between past, present and future, and the apparent ‘passage’ of time, features of the world in itself, or manifestations of the human perspective? Questions of this kind have been at the heart of metaphysics of time since antiquity. The latter view has much in common with pragmatism, though few in these debates are aware of that connection, and few of the view’s proponents think of themselves as pragmatists. For their part, pragmatists are often unaware of this congenial application of their methodology; some associate pragmatism with the other side of the old debate in the metaphysics of time. In my view, this link between time and pragmatism only scratches the surface of the deep two-way dependencies between these two topics. The human temporal perspective turns out to be deeply implicated not merely in our temporal notions themselves, but in many other conceptual categories – arguably, in fact, in all of them, and in the nature of language and thought. In this way, reflection on our own temporal character vindicates James’ famous slogan for global pragmatism: ‘The trail of the human serpent is thus over everything.’

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.

This piece was written as my Presidential Address at the Annual Conference of the Australasian Association of Philosophy, held at Melbourne University in July 1999. I discuss the view ‘that we can’t describe or theorise about the world from outside language.’ I call this idea ‘linguistic imprisonment’, and take it to be a platitude, although one that is interpreted very differently by different philosophers. In so far as language does depend on contingencies of our own ‘location’, how should we theorise about such matters? I distinguish two approaches, called ‘backgrounding’ and ‘foregrounding’. Roughly, the latter seeks to incorporate the contingencies into the content of claims that depend on them, whereas the former treats them as use conditions. I argue that linguistic imprisonment implies that not everything can be foregrounded, and apply the framework to a then-recent objection to expressivism by Jackson and Pettit.

The paper criticizes the attempt to account for the direction of causation in terms of objective statistical asymmetries, such as those of the fork asymmetry. Following Ramsey, I argue that the most plausible way to account for causal asymmetry is to regard it as "put in by hand", that is as a feature that agents project onto the world. Its temporal orientation stems from that of ourselves as agents. The crucial statistical asymmetry is an anthropocentric one, namely that we take our actions to be statistically independent of everything except (what we come to call) their effects. I argue that this account explains the intuitive plausibility of Reichenbach's principle of the common cause

In the first chapter of From Metaphysics to Ethics, Frank Jackson begins, as he puts it, ‘by explaining how serious metaphysics by its very nature raises the location problem.’ (1998, p. 1) He gives us two examples of location problems. The first concerns semantic properties, such as truth and reference: Some physical structures are true. For example, if I were to utter a token of the type ‘Grass is green’, the structure I would thereby bring into existence would be true ... How are the semantic properties of the sentence related to the non-semantic properties of the sentence? Where, if anywhere, are the semantic properties of truth, content and reference to be found in the non-semantic, physical or naturalistic account of the sentence?’ (1998, p. 2) Jackson notes two possible answers to questions of this kind. The first denies that there are any such semantic properties

Why is the future so different from the past? Why does the past affect the future and not the other way round? The universe began with the Big Bang - will it end with a `Big Crunch'? Now in paperback, this book presents an innovative and controversial view of time and contemporary physics. Price urges physicists, philosophers, and anyone who has ever pondered the paradoxes of time to look at the world from a fresh perspective, and throws fascinating new light on some of the great mysteries of the universe.