Online research in philosophy

In recent years a number of authors sympathetic to Referentialistaccounts of proper names have argued that utterances containingempty names express `gappy,' or incomplete, propositions. In this paper I want to take issue with this suggestion.In particular, I argue versions of this approach developedby David Braun, Nathan Salmon, Ken Taylor, and by Fred Adams,Gary Fuller, and Robert Stecker.

David Sosa, Michael Nelson, and Jason Stanley have recently offered a series of interesting and provocative challenges to Kripke's modal arguments against Descriptivism. In this paper I explore these challenges and some of the issues to which they give rise. I argue that, in the end, all three challenges fail.

There has recently been considerable interest in accounts of fiction which treat fictional characters as abstract objects. In this paper I argue against this view. More precisely I argue that such accounts are unable to accommodate our intuitions that fictional negative existentials such as “Raskolnikov doesn’t exist” are true. I offer a general argument to this effect and then consider, but reject, some of the accounts of fictional negative existentials offered by abstract object theorists. I then note that some of (...) the sort of data invoked by the abstract object theorist in fact cuts against her position. I concludle that we should not regard fictional characters as abstract objects but rather should adopt a make-believe theoretic account of fictional characters along the lines of those developed by Ken Walton and others. (shrink)

I argue for the existence of intrinsic Finks, Masks, and Mimics, and argue that these undermine certain recent attempts to revive simple conditional analyses of dispositions. I present some examples of intrinsic Finks, Masks, and Mimics, and argue that the example of an intrinsic fink I present has certain advantages over the examples of intrinsic finks recently suggested by Randolph Clarke. I conclude that the existence of such Finks, Masks, and Mimics, undermine a recent attempt by Sungho Choi to distinguish (...) dispositional properties from categorical properties. (shrink)

In this paper I present two arguments against the thesis that we experience qualia. I argue that if we experienced qualia then these qualia would have to be essentially vague entities. And I then offer two arguments, one a reworking of Gareth Evans' argument against the possibility of vague objects, the other a reworking of the Sorites argument, to show that no such essentially vague entities can exist. I consider various objections but argue that ultimately they all fail. In particular (...) I claim that the stock responses to the Sorites argument fail against my reworking of the argument because they require us to make a distinction between a determinate reality and how that reality appears to us, whereas in the case of qualia we can make no such distinction. I conclude that there can be no such things as qualia. (shrink)

Empirical knowledge exists in the form of antiskeptical conditionals, which are propositions like [if I am not undetectably deceived, then I am holding a pen]. Such conditionals, despite their trivial appearance, have the same essential content as the categorical propositions that we usually discuss, and can serve the same functions in science and practical reasoning. This paper sketches out two versions of a general response to skepticism that employs these conditionals. The first says that our ordinary knowledge attributions can safely (...) be replaced by statements using antiskeptical conditionals, which provides a way around the standard sort of skeptical argument while accepting its soundness with respect to the usual targets. The second analyzes the objects of our ordinary knowledge attributions as antiskeptical conditionals, which allows us to refute, not just evade, the skeptic's argument. Both versions compare favorably to the best-knowncurrent approaches to skepticism, including semantic contextualism. (shrink)

In this paper I provide some formal schemas for the analysis of vague predicates in terms of a set of semantic relations other than classical synonymy, including weak synonymy (as between "large" and "huge"), antonymy (as between "large" and "small"), relativity (as between "large" and "large for a dog"), and a kind of supervenience (as between "large" and "wide" or "long"). All of these relations are representable in the simple comparative logic CL, in accordance with the basic formula: the more (...) something is F, the more (or less) it is G. I use Carnapian meaning postulates to define these relations as constraints on interpretations of the formal language of CL. (shrink)

Recent research has suggested that the Pirahã, an Amazonian tribe with a number-less language, are able to match quantities > 3 if the matching task does not require recall or spatial transposition. This finding contravenes previous work among the Pirahã. In this study, we re-tested the Pirahãs’ performance in the crucial one-to-one matching task utilized in the two previous studies on their numerical cognition, as well as in control tasks requiring recall and mental transposition. We also conducted a novel quantity (...) recognition task. Speakers were unable to consistently match quantities > 3, even when no recall or transposition was involved. We provide a plausible motivation for the disparate results previously obtained among the Pirahã. Our findings are consistent with the suggestion that the exact recognition of quantities > 3 requires number terminology. (shrink)

: Many environmentalists criticize as unecological the emphasis that animal liberationists and animal rights theorists place on preventing animal suffering. The strong form of their objection holds that both theories ab-surdly entail a duty to intervene in wild predation. The weak form holds that animal welfarists must at least regard predation as bad, and that this stance reflects an arrogance toward nature that true environmentalists should reject. This paper disputes both versions of the predation critique. Animal welfarists are not committed (...) to protecting the rabbit from the fox, nor do their principles implicitly deprecate nature. (shrink)

Sttrrtmory.— It has been suggested recently that self-awareness is cognitively mediated by inner speech and that this hypothesis could be tested by using the private speech paradigm. This paper describes a study in which the creation of a state of self-awareness was attempted in children to test the viability of a research strategy based on private speech and used to explore the hypothesis of a link between selfawareness and inner speech, and to test directly this hypothesis by comparing the incidence (...) of private speech in self-aware and control conditions. 32 children were asked to evaluate the attractiveness of pictures when in front of a mirror (a widely used self-focusing stimulus) and with no mirror. Reliably more favorable ratings of the images.. (shrink)

I provide an intuitive, semantic account of a new logic forcomparisons (CL), in which atomic statements are assigned both aclassical truth-value and a ``how much'''' value or extension in the range [0, 1]. The truth-value of each comparison is determinedby the extensions of its component sentences; the truth-value ofeach atomic depends on whether its extension matches a separatestandard for its predicate; everything else is computed classically. CL is less radical than Casari''s comparative logics, in that it does not allow for (...) the formation of comparative statements out of truth-functional molecules. I argue that CL provides a betteranalysis of comparisons and predicate vagueness than classicallogic, fuzzy logic or supervaluation theory. CL provides a modelfor descriptions of the world in terms of comparisons only. Thesorites paradox can be solved by the elimination of atomic sentences. (shrink)

Research has shown that men and women are similar in their capabilities and management competence; however, there appears to be a glass ceiling which poses invisible barriers to their promotion to management positions. One explanation for the existence of these barriers lies in stereotyped, biased attitudes toward women in executive positions. This study supports earlier findings that attitudes of men toward women in executive positions are generally negative, while the attitudes of women are generally positive. Additionally, we found that an (...) individual's level of cognitive moral development correlates significantly with attitudes toward women executives. Limitations of the present study and implications for ethics and diversity training in organizations are discussed. (shrink)

This paper extends the discussion of business ethics by examining the issue of corruption, its definition, the solutions being proposed for dealing with it, and the ethical perspectives underpinning these proposals. The paper’s findings are based on a review of association, think-tank, and academic reports, books, and papers dealing with the topic of corruption, as well as the pronouncements, websites, and position papers of a number of important global organizations active in the fight. These organizations include the World Bank, the (...) International Monetary Fund, the Organization for Economic Co-operation and Development, Transparency International, USAID, the United Nations, the International Chamber of Commerce, the Organization of American States, and the Council of Europe. Our discussion departs from prior analyses by adopting a Foucaultian theoretical framing and by incorporating insights found in the virtue ethics literature. Implications are provided for international business organizations. (shrink)

The Mighty Morphin Power Rangers may be the most popular children's program since the inception of television. While the program is a commercial success, it also generates much controversy. For example, with an average of 211 acts of violence per hour, is Power Rangers too violent for children to watch? The show's U.S. producers rebut by claiming that Power Rangers is perhaps the most multicultural children's program available in the United States and should be encouraged. How is this so-called multiculturalism (...) presented to millions of children across America 6 days a week? Can such expression be so valuable that it outweighs the controversy surrounding the program? Through textual analysis this paper concludes that the multiculturalism in Mighty Morphin Power Rangers is, at most, a mirage. The ethical implications of such mirage multicultualism are examined. (shrink)

This article examines four leading multi-stakeholder labour monitoring organizations. All operating in the maquiladora industry, these organizations are viewed in light of the growing global trend toward industry self-regulation, or what has been referred to as the 'global out-sourcing of regulation'. Their Board compositions, codes of conduct and monitoring and enforcement strategies are all examined as a means of tentatively positioning these organizations along an 'egoist-instrumentalist-moralist' ethical culture continuum. Such a framing provides insights into the perceived salience of these organizations' (...) broader stakeholders, the effectiveness of codes of conduct on workplace practices more generally, and the role that ethics plays in the governance and accountability of these increasingly important types of organizations. (shrink)

This study responds to suggestions that business-school faculty are promoting distorted views of human nature and out-dated notions of ethics. Specifically, the paper examines in-depth interviews with a sample of 15 faculty centrally-positioned within the field’s symbolic market, namely, academics who completed their Ph.D. programs in the same institutional space as the editors of five top accounting journals. The paper finds that ethics are for the most part important to these individuals, but that the field’s general adherence to the neoclassical (...) economic model creates pressures that militate against a deeper concern for and more adequate treatment of the topic. (shrink)

The current focus on corporate culture in managerial theory, on character development in business ethics, and on the work—family relationship in family studies calls for an integrating concept to help us explore the relationship of work, family, and fundamental values. The ancient Greek concept of the oikos offers a basic framework for understanding the ensemble of emotional commitments and faith values underlying ethical action in organizational life. Examination of the interrelationships among the arenas of work, family and faith directs us (...) to the importance of ecclesiologies, faith concepts, and family forms for business ethics. (shrink)

The European Legacy, Volume 17, Issue 3, Page 407-408, June 2012.

This article offers a simple technical resolution to the problem of induction, which is to say that general facts are not always inferred from observations of particular facts, but are themselves sometimes defeasibly observed. The article suggests a holistic account of observation that allows for general statements in empirical theories to be interpreted as observation reports, in place of the common but arguably obsolete idea that observations are exclusively particular. Predictions and other particular statements about unobservable facts can then appear (...) as deductive consequences of such general observation statements, rather than inductive consequences of other particular statements. This semantic shift resolves the problem by eliminating induction as a basic form of inference, and folding the justification of general beliefs into the more basic problem of perception. (shrink)

Confucian ethics play a pivotal role in guiding Chinese thinking and behaviour. Aesthetic leadership is emerging as a promising paradigm in leadership studies. This study investigates the practice of aesthetic leadership in Chinese organizations on the basis of Chinese philosophical foundations. We adopt a process perspective to access the aesthetic constellation of meanings present in the Chinese understanding of leadership, linking normative Confucian values to a pragmatic value rational world view, that rests on an ontology of vaguely defined norms that (...) are malleable to different cultural contexts. Value rational pragmatism is explored in order to develop a deeper understanding of normative aesthetic leadership in China and to contrast it to instrumental aesthetic leadership. We empirically demonstrate the contextual specificity of aesthetic leadership in eight Chinese private- and state-owned enterprises (POEs and SOEs) through qualitative case studies. The findings provide a deeper insight into Chinese aesthetic leadership by proposing a dynamic leadership approach, from both ethical and instrumental perspectives, in the Chinese context. (shrink)

This paper attempts an interpretation of Everett's relative state formulation of quantum mechanics that avoids the commitment to new metaphysical entities like ‘worlds’ or ‘minds’. Starting from Everett's quantum mechanical model of an observer, it is argued that an observer's belief to be in an eigenstate of the measurement (corresponding to the observation of a well-defined measurement outcome) is consistent with the fact that she objectively is in a superposition of such states. Subjective states corresponding to such beliefs (...) are constructed. From an analysis of these subjective states and their dynamics it is argued that Everett's pure wave mechanics is subjectively consistent with von Neumann's classical formulation of quantum mechanics. It follows from the argument that the objective state of a system is in principle unobservable. Nevertheless, an adequate concept of empirical reality can be constructed. (shrink)

In the published version of Hugh Everett III’s doctoral dissertation, he inserted what has become a famous footnote, the ‘‘note added in proof’’. This footnote is often the strongest evidence given for any of various interpretations of Everett (the many worlds, many minds, many histories and many threads interpretations). In this paper I will propose a new interpretation of the footnote. One that is supported by evidence found in letters written to and by Everett; one that is (...) suggested by a new interpretation of Everett, an interpretation that takes seriously the central position of relative states in Everett’s pure wave mechanics: the relative facts interpretation. Of central interest in this paper is how to make sense of Everett’s claim in the ‘‘note added in proof’’ that ‘‘all elements of a superposition (all ‘‘branches’’) are ‘‘actual,’’ none any more ‘‘real’’ than the rest.’’. (shrink)

http://dx.doi.org/10.5007/1808-1711.2008v12n2p155 Bas van Fraassen advocates a “Copenhagen variant” of the modal interpretation of quantum mechanics. However, he believes that the Copenhagen approach to measurement is not fully satisfactory, since it seems to rule out the possibility of providing a physical account of the observation process. This was also what John Wheeler had in mind when, in the mid-1950’s, he sponsored the “relative state” formulation proposed by his student Hugh Everett. Wheeler, who considered himself an orthodox Bohrian, tried to convince (...) Bohr to accept the improvement of the Copenhagen approach represented in his eyes by Everett’s proposal. This attempt gave rise to a lively debate, which has been only recently documented, and which provides an interesting framework for the appraisal of van Fraassen’s own programme. (shrink)

Hugh Everett III died of a heart attack in July 1982 at the age of 51. Almost 26 years later, a New York Times obituary for his PhD advisor, John Wheeler, mentioned him and Richard Feynman as Wheeler’s most prominent students. Everett’s PhD thesis on the relative state formulation of quantum mechanics, later known as the “Many Worlds Interpretation”, was published (in its edited form) in 1957, and later (in its original, unedited form) in 1973, and since then (...) has given rise to one of the most radical schools of thought in the foundations of quantum theory. Several years ago two conferences held in Oxford and in the Perimeter Institute celebrated the occasion of 50 years to the first publication of Everett’s thesis. The book Many worlds? grew out from contributions to these conferences, but, as its editors emphasize, it is more than mere conference proceedings. Instead, an attempt was made to assemble an impressive collection of papers which together illustrate the promise of the many worlds interpretation and the obstacles it faces. 23 papers divided into six sections follow an introduction by Simon Saunders, one of Oxford’s fiercest Everettians. The first four sections cover two thorny issues that have been flagged by contemporary opponents to the many worlds interpretation, namely, the problem of ontology and the problem of probability, while the fifth discusses alternatives to Everett such as Bohmian mechanics and information–theoretic approaches to quantum theory. The sixth section seems to be a wild card, hosting several papers unrelated to each other, including one of the most interesting contributions to this volume on the history of Everett’s thesis and his (some may say all too) short academic career. Each section concludes with transcripts of the discussion session that took place after the talks, thus giving an additional emphasis to the points of contention. Apart from general comments on the volume, in what follows I would like to concentrate on few papers I found especially illuminating. Start with ontology.. (shrink)

The Everett (many-worlds) interpretation of quantum mechanics faces a prima facie problem concerning quantum probabilities. Research in this area has been fast-paced over the last few years, following a controversial suggestion by David Deutsch that decision theory can solve the problem. This article provides a non-technical introduction to the decision-theoretic program, and a sketch of the current state of the debate.

Recent work on probability in the Everett interpretation of quantum mechanics yields a decision-theoretic derivation of David Lewis’ Principal Principle, and hence a general metaphysical theory of probability; part 1 is a discussion of this remarkable result. I defend the claim that the ‘subjective uncertainty’ principle is required for the derivation to succeed, arguing that it amounts to a theoretical identification of chance. In part 2, I generalize this account, and suggest that the Everett interpretation, in combination with (...) a plausible view of natural laws, has the potential to provide a reductive theory of metaphysical modality. I defend the resulting naturalistic modal realism, and outline some of its implications for other parts of metaphysics. (shrink)

The Everett interpretation of quantum theory requires either the existence of an infinite number of conscious minds associated with each brain or the existence of one universal consciousness. Reasons are given, and the two ideas are compared.

Much of the evidence for quantum mechanics is statistical in nature. The Everett interpretation, if it is to be a candidate for serious consideration, must be capable of doing justice to reasoning on which statistical evidence in which observed relative frequencies that closely match calculated probabilities counts as evidence in favour of a theory from which the probabilities are calculated. Since, on the Everett interpretation, all outcomes with nonzero amplitude are actualized on different branches, it is not obvious (...) that sense can be made of ascribing probabilities to outcomes of experiments, and this poses a prima facie problem for statistical inference. It is incumbent on the Everettian either to make sense of ascribing probabilities to outcomes of experiments in the Everett interpretation, or to find a substitute on which the usual statistical analysis of experimental results continues to count as evidence for quantum mechanics, and, since it is the very evidence for quantum mechanics that is at stake, this must be done in a way that does not presuppose the correctness of Everettian quantum mechanics. This requires an account of theory confirmation that applies to branching-universe theories but does not presuppose the correctness of any such theory. In this paper, we supply and defend such an account. The account has the consequence that statistical evidence can confirm a branching-universe theory such as Everettian quantum mechanics in the same way in which it can confirm a probabilistic theory. (shrink)

This is a discussion of how we can understand the world-view given to us by the Everett interpretation of quantum mechanics, and in particular the role played by the concept of 'world'. The view presented is that we are entitled to use 'many-worlds' terminology even if the theory does not specify the worlds in the formalism; this is defended by means of an extensive analogy with the concept of an 'instant' or moment of time in relativity, with the lack (...) of a preferred foliation of spacetime being compared with the lack of a preferred basis in quantum theory. Implications for identity of worlds over time, and for relativistic quantum mechanics, are discussed. (shrink)

I address the problem of indefiniteness in quantum mechanics: the problem that the theory, without changes to its formalism, seems to predict that macroscopic quantities have no definite values. The Everett interpretation is often criticised along these lines, and I shall argue that much of this criticism rests on a false dichotomy: that the macroworld must either be written directly into the formalism or be regarded as somehow illusory. By means of analogy with other areas of physics, I develop (...) the view that the macroworld is instead to be understood in terms of certain structures and patterns which emerge from quantum theory (given appropriate dynamics, in particular decoherence). I extend this view to the observer, and in doing so make contact with functionalist theories of mind. (shrink)

How does it come about then, that great scientists such as Einstein, Schrödinger and De Broglie are nevertheless dissatisfied with the situation? Of course, all these objections are levelled not against the correctness of the formulae, but against their interpretation. [...] The lesson to be learned from what I have told of the origin of quantum mechanics is that probable refinements of mathematical methods will not suffice to produce a satisfactory theory, but that somewhere in our doctrine is hidden a (...) concept, unjustified by experience, which we must eliminate to open up the road. (Born [ 1954 ], pp. 8, 11) It is truly surprising how little difference all this makes. Most physicists use quantum mechanics every day in their working lives without needing to worry about the fundamental problem of its interpretation. (Weinberg [ 1992 ], p. 66) I endorse the view that it may be of no relevance to the acceptability of the Everett interpretation of quantum mechanics as a physical theory whether or not an informed observer can be uncertain about the outcome of a quantum measurement prior to its having occurred. However, I suggest that the very possibility of post-measurement, pre-observation uncertainty has an essential role to play in both confirmation theory and decision theory in a branching universe. This is supported by arguments which do not appeal to van Fraassen’s Reflection Principle. (shrink)

I propose, in the context of Everett interpretations of quantum mechanics, a way of understanding how there can be genuine uncertainty about the future notwithstanding that the universe is governed by known, deterministic dynamical laws, and notwithstanding that there is no ignorance about initial conditions, nor anything in the universe whose evolution is not itself governed by the known dynamical laws. The proposal allows us to draw some lessons about the relationship between chance and determinism, and to dispel one (...) source of the tendency among Everettians to introduce consciousness as a primitive element into physical description. (shrink)

The quantum theory of de Broglie and Bohm solves the measurement problem, but the hypothetical corpuscles play no role in the argument. The solution finds a more natural home in the Everett interpretation.

I consider exactly what is involved in a solution to the probability problem of the Everett interpretation, in the light of recent work on applying considerations from decision theory to that problem. I suggest an overall framework for understanding probability in a physical theory, and conclude that this framework, when applied to the Everett interpretation, yields the result that that interpretation satisfactorily solves the measurement problem. Introduction What is probability? 2.1 Objective probability and the Principal Principle 2.2 Three (...) ways of satisfying the functional definition 2.3 Cautious functionalism 2.4 Is the functional definition complete? The Everett interpretation and subjective uncertainty 3.1 Interpreting quantum mechanics 3.2 The need for subjective uncertainty 3.3 Saunders' argument for subjective uncertainty 3.4 Objections to Saunders' argument 3.5 Subjective uncertainty again: arguments from interpretative charity 3.6 Quantum weights and the functional definition of probability Rejecting subjective uncertainty 4.1 The fission program 4.2 Against the fission program Justifying the axioms of decision theory 5.1 The primitive status of the decision-theoretic axioms 5.2 Holistic scepticism 5.3 The role of an explanation of decision theory Conclusion. (shrink)

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. (shrink)

An analysis is made of Deutsch's recent claim to have derived the Born rule from decision-theoretic assumptions. It is argued that Deutsch's proof must be understood in the explicit context of the Everett interpretation, and that in this context, it essentially succeeds. Some comments are made about the criticism of Deutsch's proof by Barnum, Caves, Finkelstein, Fuchs, and Schack; it is argued that the flaw which they point out in the proof does not apply if the Everett interpretation (...) is assumed. (shrink)

Everett's relative-state formulation of quantum mechanics is an attempt to solve the measurement problem by dropping the collapse dynamics from the standard von Neumann-Dirac theory of quantum mechanics. The main problem with Everett's theory is that it is not at all clear how it is supposed to work. In particular, while it is clear that he wanted to explain why we get determinate measurement results in the context of his theory, it is unclear how he intended to do (...) this. There have been many attempts to reconstruct Everett's no-collapse theory in order to account for the apparent determinateness of measurement outcomes. These attempts have led to such formulations of quantum mechanics as the many-worlds, many-minds, many-histories, and relative-fact theories. Each of these captures part of what Everett claimed for his theory, but each also encounters problems. (shrink)

Q0 Why this FAQ? Q1 Who believes in many-worlds? Q2 What is many-worlds? Q3 What are the alternatives to many-worlds? Q4 What is a "world"? Q5 What is a measurement? Q6 Why do worlds split? What is decoherence? Q7 When do worlds split? Q8 When does Schrodinger's cat split? Q9 What is sum-over-histories? Q10 What is many-histories? What is the environment basis? Q11 How many worlds are there? Q12 Is many-worlds a local theory? Q13 Is many-worlds a deterministic theory? Q14 (...) Is many-worlds a relativistic theory? What about quantum field theory? What about quantum gravity? Q15 Where are the other worlds? Q16 Is many-worlds (just) an interpretation? Q17 Why don't worlds fuse, as well as split? Do splitting worlds imply irreversible physics? Q18 What retrodictions does many-worlds make? Q19 Do worlds differentiate or split? Q20 What is many-minds? Q21 Does many-worlds violate Ockham's Razor? Q22 Does many-worlds violate conservation of energy? Q23 How do probabilities emerge within many-worlds? Q24 Does many-worlds allow free-will? Q25 Why am I in this world and not another? Why does the universe appear random? Q26 Can wavefunctions collapse? Q27 Is physics linear? Could we ever communicate with the other worlds? Why do I only ever experience one world? Why am I not aware of the world (and myself) splitting? Q28 Can we determine what other worlds there are? Is the form of the Universal Wavefunction knowable? Q29 Who was Everett? Q30 What are the problems with quantum theory? Q31 What is the Copenhagen interpretation? Q32 Does the EPR experiment prohibit locality? What about Bell's Inequality? Q33 Is Everett's relative state formulation the same as many-worlds? Q34 What is a relative state? Q35 Was Everett a "splitter"? Q36 What unique predictions does many-worlds make? Q37 Could we detect other Everett-worlds? Q38 Why quantum gravity? Q39 Is linearity exact? (shrink)

Simon Saunders and David Wallace attempt to use a modified form of David Lewis's analysis of personal fission to ground the claim that prior to undergoing Everett branching an informed subject can be uncertain about which outcome s/he will observe. I argue that a central assumption of this seductive idea is questionable despite appearing innocuous and that at the very least further argument is needed in support of it. CiteULike Connotea Del.icio.us What's this?

It is often objected that the Everett interpretation of QM cannot make adequate sense of quantum probabilities, in one or both of two senses: either it cannot make sense of probability at all, or cannot 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, and that under reasonable assumptions, the credences of a rational agent (...) in an Everett world should be constrained by the Born rule. David Wallace has recently developed and defended Deutsch's proposal, and greatly clarified its conceptual basis. In this note I outline some concerns about the Deutsch argument, as presented by Wallace, and about related proposals by Hilary Greaves. In particular, I argue that the argument is circular, at a crucial point. (shrink)

In his long 1957 paper, “The Theory of the Universal Wave Function”, Hugh Everett III made some significant preliminary steps towards the application and generalization of Shannon’s information theory to quantum mechanics. In the course of doing so, he conjectured that, for a given wavefunction on a compound space, the Schmidt decomposition maximises the correlation between subsystem bases. This is proved here.

Abstract An argument originated by Brandon Carter presents humankind's imminent extinction as likelier than we should otherwise have judged. We ought to be reluctant to think ourselves among the earliest 0.01 %, for instance, of all humans who will ever have lived; yet we should be in that tiny group if the human race survived long, even at just its present size. While such reasoning attracts many criticisms, perhaps the only grave one is that indeterminism means there is not yet (...) any firm, theoretically predictable fact of how long the human race will survive. This, though, might not save Everett's many?worlds theory from a variant on Carter's point. Everett seemingly pictures observers as splitting into ever more versions, which explains away all apparent indeterminism; but then, absurdly, all except a vanishingly tiny proportion of one's versions would come into existence near one's death, outweighing all apparent evidence that death was not imminent. The need to avoid such a result severely constrains Everett?type theories. We need theories in which observer?versions diverge without increasing their numbers in any straightforward way. (shrink)

The quantum theory of de Broglie and Bohm solves the measurement problem, but the hypothetical corpuscles play no role in the argument. The solution finds a more natural home in the Everett interpretation.

There are currently several versions of Everett's relative state interpretation of quantum mechanics, responding to a number of perceived problems for the original proposal. One of those problems is whether Everett's idea is in accord with the standard 'probabilistic' interpretation implicit in the Born rule. I argue in defence of what appears to be Everett's original view on this. The contribution I aim to make is a more complete discussion of the central issues of the identity of (...) objects and observers over time and how the concept of expectation can be applied when all 'possible' outcomes of a measurement process are regarded as actually occurring. (shrink)

In Part 1, Bell's inequality for a pair of protons starting from a singlet state is briefly described. Since it has not been possible so far to conclusively verify the inequality experimentally, the usual hidden-variables interpretation of quantum mechanics is tentatively abandoned in favour of Everett's ramification (or many-universe) interpretation. Several details need then to be made precise, among them the following: (1) ramification must propagate itself at the velocity of light to satisfy relativistic requirements; (2) the ramification (...) process starts from those atoms of the detection screen where impacts are quantum-mechanically possible. These quantum-mechanically possible impacts become real impacts, while space-time is progressively split into several branches resulting in several copies of the observers and their apparatus. The future-cones (i.e. the spatial spheres growing at light velocity) which are splitting space-time are called ramifiers. In the simple case where both protons are submitted to spin measurements along the same direction, the known minus-one correlation between the measurements is realized. This happens not at the impacts, but only at the intersection of both ramifiers, the common future of the impacts; then the branch of spin + from the first impact is identified with the branch of spin – from the second one, and conversely.Part 2 contains a cursory study of the case of a wave bearing only one particle. We recall the existence, in usual formalisms (e.g., of Gordon-Klein or of Dirac), of a conservative presence quadrivector, consisting of its time component (the presence density) and the current trivector. The screen being a tridimensional hypersurface, the probability of finding the impact is the flux of the presence quadrivector through the screen. According to our point of view, every possible impact does occur, and it becomes the origin of a branch in which this impact alone is observed; the wave is then rubbed out at the velocity of light. Part 2 ends with a comment on the logic specific to ramification, i.e. on the virgin form of the screen and wave: the form they would have if the impact never occurred. (shrink)

Everett wanted a formulation of quantum mechanics that (i) took the linear dynamics to be a complete and accurate description of the time-evolution of all physical systems and (ii) logically entailed the same subjective appearances predicted by the standard formulation of quantum mechanics. While most everyone would agree with this description of Everett’s project, there is little agreement on exactly how his relative-state formulation was supposed to work. In this paper, I consider two very different readings of (...) class='Hi'>Everett: the bare reading and the splitting-worlds reading. What distinguishes these is their interpretation of the wave function and how one accounts for the experiences of observers. The difficulty in interpreting Everett, however, is illustrated by the fact that neither reading is entirely compatible with his own description of his project. (shrink)

Pour résoudre les paradoxes bien connus de la mécanique quantique, on propose une interprétation par ramification (ou univers parallèles) analogue à celle d?Everett, mais avec des différences: (i) on propose une infinité continue de branches, dont les poids (o[ugrave] probabilités) se calculent par intégrale; (ii) les branches sont séparées par des ramifieurs qui se propagent à la vitesse de la lumière. Lorsqu?est négligeable la composante d?énergie négative de la fonction d?onde, le poids de chaque branche en un point donné (...) u est égal au flux du quadrivecteur (courant-densité de présence), soit à travers l'élément d?écran antérieur à u sur lequel l'impact est perçu, soit à travers le cône passé de u si aucun impact n?est perçu. In order to solve well-known paradoxes in quantum mechanics, we propose a reworking of Everett's interpretation with ramified branches (or many worlds), yet somewhat different: (i) branches form an infinity continuum and each weight (probability) is defined by an integral; (ii) branches are separated by ramifiers which propagate themselves with the velocity of light. Assuming we can neglect the negative-energy component in the wave function, then the weight of each branch at a given point u is equal to the flux of the quadrivector (current-presence density), either through the screen element where the impact occurs, or through the past light-cone of u if no impact occurs. (shrink)

Sometimes we learn what the world is like, and sometimes we learn where in the world we are. Are there any interesting differences between the two kinds of cases? The main aim of this article is to argue that learning where we are in the world brings into view the same kind of observation selection effects that operate when sampling from a population. I will first explain what observation selection effects are ( Section 1 ) and how they are relevant (...) to learning where we are in the world ( Section 2 ). I will show how measurements in the Many Worlds Interpretation of quantum mechanics can be understood as learning where you are in the world via some observation selection effect ( Section 3 ). I will apply a similar argument to the Sleeping Beauty Problem ( Section 4 ) and explain what I take the significance of the analogy to be ( Section 5 ). Finally, I will defend the Restricted Principle of Indifference on which some of my arguments depend ( Section 6 ). (shrink)