Macroscopic ontology in Everettian quantum mechanics

Simon Saunders and David Wallace have proposed an appealing candidate semantics for interpreting linguistic communities embedded in an Everettian multiverse. It provides a charitable interpretation of our ordinary talk about the future, and allows us to retain a principle of bivalence for propositions and to retain the Law of Excluded Middle in the logic of propositions about the future. But difficulties arise when it comes to providing an appropriate account of the metaphysics of macroscopic objects and events. In this paper, I evaluate various metaphysical frameworks which might be combined with the Saunders-Wallace semantics. I conclude that the most appropriate metaphysics to underwrite the semantics renders Everettian quantum mechanics a theory of non-overlapping worlds

Everettian quantum mechanics without branching time

In this paper I assess the prospects for combining contemporary Everettian quantum mechanics (EQM) with branching-time semantics in the tradition of Kripke, Prior, Thomason and Belnap. I begin by outlining the salient features of ‘decoherence-based’ EQM, and of the ’consistent histories’ formalism that is particularly apt for conceptual discussions in EQM. This formalism permits of both ‘branching worlds’and ‘parallel worlds’ interpretations; the metaphysics of EQM is in this sense underdetermined by the physics. A prominent argument due to David Lewis [1986] supports the non-branching interpretation. Belnap et al. [2001] refer to Lewis’ argument as the ’Assertion problem’, and propose a pragmatic response to it. I argue that their response is unattractively ad hoc and complex, and that it prevents an Everettian who adopts branching-time semantics from making clear sense of objective probability. The upshot is that Everettians are better off without branching-time semantics. I conclude by discussing and rejecting an alternative possible motivation for branching time

The human story behind Everettian quantum mechanics

Hugh Everett III was an unappealing character with a remarkable mind. His Princeton doctoral thesis on the foundations of physics transformed our understanding of quantum-mechanical reality, and he made original contributions to military operations research and to game theory. His domestic life was less inspiring; he died young after a lifetime of over-indulgence in food, alcohol, tobacco and sex, leaving behind a somewhat dysfunctional family with which he had little emotional connection

Disagreement, equal weight and commutativity

How should we respond to cases of disagreement where two epistemic agents have the same evidence but come to different conclusions? Adam Elga has provided a Bayesian framework for addressing this question. In this paper, I shall highlight two unfortunate consequences of this framework, which Elga does not anticipate. Both problems derive from a failure of commutativity between application of the equal weight view and updating in the light of other evidence

Why Is Fairness ‘Grubby’? - Semantics, Etymology, and Perspectives in Dispute Resolution

Delivering judgment in the House of Lords in the case of White v White (subsequently a leading legal precedent in this jurisdiction) Lord Nicholls of Birkenhead famously opined: Features which are important when assessing fairness differ in each case. And, sometimes, different minds can reach different conclusions on what fairness requires. Then fairness, like beauty, lies in the eye of the beholder. His Lordship\u27s comment in this landmark divorce appeal is interesting in the context of this paper, which is written from the perspective of alternative dispute resolution (ADR) practice, specifically that of family mediation. The authors set out to provide a very brief overview of certain relevant case law, considerations of ideologies of law and ADR, and some of the concerns around mediation. Whether what constitutes fairness and justice is influenced-or even deter mined-by the etymology of these terms is then considered. The paper concludes that, incorporating this and earlier academic work related to group processes, clients\u27 perceptions of fairness can be addressed and maximized within the mediation process. An increased understanding of these concepts might in turn benefit mediation practitioners in the conduct of their work. Following in part the earlier lead of Birke and Fox, who alerted practitioners and legal scholars to the psychological principles most relevant to legal negotiation, this paper also offers synthesized elements which may inform negotiation, specifically mediation or ADR practice. The elements discussed are drawn from the linguistics field as well as from certain psychological perspectives and data. In this our purpose is to offer material which may assist and inform practitioners while recognizing, along with Birke and Fox, the necessarily speculative nature of some aspects of a work of this nature