Huw Price

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 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

This paper revisits some views about negation I defended in two early papers. Some of the themes of those papers have been developed sympathetically in recent work by Tim Smiley, Lloyd Humberstone and Ian Rumfitt. However, Rumfitt and Peter Gibbard have both criticised arguments I offered in defence of Double Negation Elimination (DNE), against a Dummettian intuitionist. I reconsider those arguments, arguing that although they survive Rumfitt’s and Gibbard’s attacks, the case against Dummett is for other reasons less straightforward than I took it to be. With reference to Rumfitt’s own defence of DNE, I call attention to the attractions of the view defended in my second paper that negation has dialectical origins. I also point out some difficulties for this view which seem to have been overlooked by previous writers, including me

I distinguish three views, a defence of any one of which would go some way towards vindicating the view that there is something objective about the passage of time: the view that the present moment is objectively distinguished; the view that time has an objective direction – that it is an objective matter which of two non-simultaneous events is the earlier and which the later; the view that there is something objectively dynamic, flux-like, or "flow-like" about time. I argue that each of these views is not so much false as doubtfully coherent. In each case, it turns out to be hard to make sense of what the view could be, at least if it is to be non-trivial, and of use to a friend of objective passage. I conclude with some remarks about avenues that seem worth exploring in the philosophy of time, when we are done with trying to make sense of passage

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.

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.

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.