Huw Price

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.

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..

It has been suggested that some of the puzzles of QM are resolved if we allow that there is retrocausality in the quantum world. In particular, it has been claimed that this approach offers a path to a Lorentz-invariant explanation of Bell correlations, and other manifestations of quantum "nonlocality", without action-at-a-distance. Some writers have suggested that this proposal can be supported by an appeal to time-symmetry, claiming that if QM were made "more time-symmetric", retrocausality would be a natural consequence. Critics object that there is complete time-symmetry in classical physics, and yet no apparent retrocausality. Why should QM be any different? In this note I call attention to a respect in which QM is different, under some assumptions about quantum ontology. Under these assumptions, the option of time-symmetry without retrocausality is not available in QM, for reasons intimately connected with the fundamental differences between classical and quantum physics (especially the role of discreteness in the latter).

It is often objected that the Everett interpretation of QM cannot make sense of quantum probabilities, in one or both of two ways: either it can’t make sense of probability at all, or it can’t explain why probability should be governed by the Born rule. David Deutsch has attempted to meet these objections. He argues not only that rational decision under uncertainty makes sense in the Everett interpretation, but also that under reasonable assumptions, the credences of a rational agent in an Everett world should be constrained by the Born rule. David Wallace has developed and defended Deutsch’s proposal, and greatly clarified its conceptual basis. In particular, he has stressed its reliance on the distinguishing symmetry of the Everett view, viz., that all possible outcomes of a quantum measurement are treated as equally real. The argument thus tries to make a virtue of what has usually been seen as the main obstacle to making sense of probability in the Everett world. In this note I outline some objections to the Deutsch-Wallace argument, and to related proposals by Hilary Greaves about the epistemology of Everettian QM. (In the latter case, my arguments include an appeal to an Everettian analogue of the Sleeping Beauty problem.) The common thread to these objections is that the symmetry in question remains a very significant obstacle to making sense of probability in the Everett interpretation.

In the opening line of his essay ‘On Truth’, Francis Bacon ticks off Pontius Pilate for not giving the subject its due time and gravity—‘“What is truth?”, said jesting Pilate, and would not stay for an answer.’ If Pilate had stayed for an answer, he would have been waiting a long time—four centuries after Bacon, and twenty after Christ, the jury is still out. But things do seem to have been moving along quite nicely, this past century or so; and as Pilate might note with satisfaction, he himself has been getting a better press. Perhaps Nietzsche’s extravagant compliment was a mixed blessing: Nietzsche declared (‘as offensively as possible’, as Will Durant [1929: 25] put it) that..

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

Bertrand Russell’s celebrated essay “On the Notion of Cause” was first delivered to the Aristotelian Society on 4 November 1912, as Russell’s Presidential Address. The piece is best known for a passage in which its author deftly positions himself between the traditional metaphysics of causation and the British crown, firing broadsides in both directions: “The law of causality”, Russell declares, “Like much that passes muster in philosophy, is a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm.” To mark the lecture’s centenary, I offer a contemporary view of the issues Russell here puts on the table, and of the health or otherwise, at the end of the essay’s first century, of his notorious conclusion.

Lecture I begins with a distinction between two themes in philosophical naturalism. The first theme takes science to be our best guide to what there is, the second takes it to be our best guide to the nature of our own thought and talk. Thus the first theme ('object naturalism') motivates a scientifically-constrained metaphysics, while the second ('subject naturalism') motivates a scientifically-constrained philosophy of language and philosophical psychology. The lecture discusses a sense in which these two themes may conflict: in particular, a sense in which subject naturalism may undermine a presupposition of object naturalism. The presupposition in question is the assumption that belief, judgement and assertion are 'referential', or 'representational', in some theoretically robust sense. In showing that this assumption is itself open to naturalistic challenge, the lecture identifies a little-recognised vulnerability in popular forms of (object) naturalism. The remaining lectures aim to show, first, what conception(s) of representation might replace the assumption in question; and second, what the project of philosophical naturalism looks like, in the light of these changes. Lecture II begins with the so-called bifurcation thesis -- the view that speech acts into descriptive and non-descriptive categories. The lecture advocates a different bifurcation, between two notions of representation: an 'external', world-tracking notion, and an 'internal', inferentialist notion. I argue that traditional representationalism confuses these notions. Lecture III outlines a conception of the project of naturalistic philosophy, in the light of this new bifurcation thesis. The recognition that not all representations in the inferential sense need be representation in the world-tracking sense permits a new pluralism within the former class: a pluralism about the functions of representation (in the former sense) in the lives of natural creatures in a natural environment. I emphasise that this kind of pluralism is orthogonal to familiar programs for pluralism in the philosophy of science. It involves a new dimension of variability, that conventional representationalism simply hides from view.