I argue that it follows from a very plausible principle concerning understanding that the truth of an ascription of understanding is context-relative. I use this to defend an account of lexical meaning according to which full understanding of a natural kind term or name requires knowing informative, uniquely identifying information about its referent. This point undermines Putnam-style 'elm-beech' arguments against the description theory of names and natural kind terms.
This paper develops the treatment of vague predicates begun in my "Vagueness Without Paradox" (Philosophical Review 103, 1 ). In particular, I show how my account of vague words dissolves an "eternal" version of the sorites paradox, i.e., a version in which the paradox is generated independently of any particular run of judgments of the items in a sorites series. In so doing I refine the notion of an internal contest, introduced in the earlier paper, and draw a distinction within (...) the class of internal contexts between contexts of judgment and contexts of consideration. (shrink)
Existing models of strategic decision making typically assume that only the attributes of the currently played game need be considered when reaching a decision. The results presented in this article demonstrate that the so-called “cooperativeness” of the previously played prisoner’s dilemma games influence choices and predictions in the current prisoner’s dilemma game, which suggests that games are not considered independently. These effects involved reinforcement-based assimilation to the previous choices and also a perceptual contrast of the present game with preceding games, (...) depending on the range and the rank of their cooperativeness. A. Parducci’s (1965) range frequency theory and H. Helson’s (1964) adaptation level theory are plausible theories of relative judgment of magnitude information, which could provide an account of these context effects. (shrink)
According to what I will call a contextualist solution to the sorites paradox, vague terms are context-sensitive, and one can give a convincing dissolution of the sorites paradox in terms of this context-dependency. The reason, according to the contextualist, that precise boundaries for expressions like “heap” or “tall for a basketball player” are so difficult to detect is that when two entities are sufficiently similar (or saliently similar), we tend to shift the interpretation of the vague expression so that if (...) one counts as falling in the extension of the property expressed by that expression, so does the other. As a consequence, when we look for the boundary of the extension of a vague expression in its penumbra, our very looking has the effect of changing the interpretation of the vague expression so that the boundary is not where we are looking. This accounts for the persuasive force of sorites arguments. (shrink)
Hans Reichenbach introduced two seemingly separate sets of distinctions in his epistemology at different times. One is between the axioms of coordination and the axioms of connections. The other distinction is between the context of discovery and the context of justification. The status and nature of each of these distinctions have been subject-matter of an ongoing debate among philosophers of science. Thus, there is a significant amount of works considering both distinctions separately. However, the relevance of Reichenbach's two distinctions to (...) each other does not seem to have enjoyed the same amount of interest so far. This is what I would like to consider in this paper. In other words, I am concerned with the question: what kind of relationship is there between his two distinctions, if there is any? (shrink)
This paper presents a precise semantics for incomplete predicates such as “ready”. Incomplete predicates have distinctive logical properties that a semantic theory needs to accommodate. For instance, “Tipper is ready” logically implies “Tipper is ready for something”, but “Tipper is ready for something” does not imply “Tipper is ready”. It is shown that several approaches to the semantics of incomplete predicates fail to accommodate these logical properties. The account offered here defines contexts as structures containing an element called a proposition (...) set, which contains atomic propositions and negations of atomic propositions. The condition under which “Tipper is ready” is true in a context is defined in terms of the contents of the proposition set for the context. On this account, the content of the context pertinent to a conversation must be determined not by what speakers have in mind but by relations of objective relevance. (shrink)
Recanati takes for granted the conveyance conception of linguistic communica- tion, although it is not very clear exactly where he lies on the spectrum of possible variations. Even if we disavow all such conceptions of linguistic communication, there will be a place for semantic theory in articulating normative concepts such as logical consistency and logical validity. An approach to semantics focused on such normative concepts is illustrated using the example of “It’s raining”. It is argued that Recanati’s conception of semantics (...) as involving the pragmatics of saturation and modulation cannot account for the logical properties of “It’s raining. (shrink)
It is often assumed that, though we may speak in sentences that express propositions only inexplicitly, our thoughts must express their propositional contents explicitly. This paper argues that, on the contrary, thoughts too may be inexplicit. Inexplicit thoughts may effectively drive behavior inasmuch as they rest on a foundation of imagistic cognition. The paper also sketches an approach to semantic theory that accommodates inexplicitness in mental representations as well as in spoken sentences.
Universally recognized as bringing about a revolutionary transformation of the notions of space, time, and motion in physics, Einstein's theory of gravitation, known as "general relativity," was also a defining event for 20th century philosophy of science. During the decisive first ten years of the theory's existence, two main tendencies dominated its philosophical reception. This book is an extended argument that the path actually taken, which became logical empiricist philosophy of science, greatly contributed to the current impasse over realism, whereas (...) new possibilities are opened in revisiting and reviving the spirit of the more sophisticated tendency, a cluster of viewpoints broadly termed transcendental idealism, and furthering its articulation. It also emerges that Einstein, while paying lip service to the emerging philosophy of logical empiricism, ended up siding de facto with the latter tendency. Ryckman's work speaks to several groups, among them philosophers of science and historians of relativity. Equations are displayed as necessary, but Ryckman gives the non-mathematical reader enough background to understand their occurrence in the context of his wider philosophical project. (shrink)
Here we briefly review the concept of "prediction" within the context of classical relativity theory. We prove a theorem asserting that one may predict one's own future only in a closed universe. We then question whether prediction is possible at all (even in closed universes). We note that interest in prediction has stemmed from considering the epistemological predicament of the observer. We argue that the definitions of prediction found thus far in the literature do not fully appreciate this predicament. We (...) propose a more adequate alternative and show that, under this definition, prediction is essentially impossible in general relativity. (shrink)
The Special Theory of Relativity and the Theory of the Electron have had an interesting history together. Originally the electron was studied in a non-relativistic context and this opened up the interesting possibility that lead to the conclusion that the mass of the electron could be thought of entirely in electromagnetic terms without introducing inertial considerations. However the application of Special Relativity lead to several problems, both for an extended electron and the point electron. These inconsistencies have, contrary to popular (...) belief not been resolved satisfactorily to date, even within the context of Quantum Theory. Thus they are not merely of historical interest. Nevertheless these and subsequent studies bring out the interesting result that Special Relativity (and the theory of the electron) breaks down within the Compton scale or when the Compton scale is not neglected. This again runs contrary to an uncritical notion that Special Relativity is valid for point particles. Furthermore, it is pointed out that experiments have been recently suggested to test these ideas. These considerations lead to a characterization of the Planck constant in classical terms. (shrink)
That space and time should be integrated into a single entity, spacetime, is the great insight of Einstein's special theory of relativity, and leads us to regard spacetime as a fundamental context in which to make sense of the world around us. But it is not the only one. Causality is equally important and at least as far as the special theory goes, it cannot be subsumed under a fundamentally geometrical form of explanation. In fact, the agent of propagation of (...) causal influence is electromagnetic radiation. In this examination, the authors find support for a rationalist approach to physics, never neglecting experimentation, but rejecting a simple empiricist or positivist view of science. (shrink)
"If you turn left at the next corner, you will see a blue house at the end of the street." That sentence -- a conditional -- might be true even though it is possible that you will not see a blue house at the end of the street when you turn left at the next corner. A moving van may block your view; the house may have been painted pink; a crow might swoop down and peck out your eyes. Still, (...) in some contexts, we might ignore these possibilities and correctly assert the conditional. In this book, Christopher Gauker argues that such context-relativity is the key to understanding the semantics of conditionals. Contexts are defined as objective features of the situation in which a conversation takes place, and the semantic properties of sentences -- conditionals included -- are defined in terms of assertibility in a context. One of the primary goals of a theory of conditionals has to be to distinguish correctly between valid and invalid arguments containing conditionals. According to Gauker, an argument is valid if the conclusion is assertible in every context in which the premises are assertible. This runs counter to what Gauker sees as a systematic misreading of the data by other authors, who judge arguments to be invalid if they can think of a context in which the premises are judged true and some other context in which the conclusion is judged false. Different schools of thought on conditionals reflect fundamentally different approaches to semantics. Gauker offers his theory as a motive and test case for a distinctive kind of semantics that dispenses with reference relations and possible worlds. (shrink)
It is argued that there is much to be said for a fairly standard interpretation of the thesis that colour, unlike shape, is a subjective or phenomenal property of objects. But if this fairly standard thesis fails to do justice to the ‘objective’ aspect of colour, and justice in this regard is called for, then it is argued we can settle for less; we can settle for the strategy of ‘dividing the spoils’ between subjective and objective accounts. But it is (...) also argued that if we do settle for this, we need to realise that the same ‘egalitarian’ division cannot be made in application to the primary properties. And that it is argued is the insight at the heart of the traditional account. (shrink)
Scientific realism has three dimensions: a metaphysical commitment to the existence of a mind-independent world; a semantic commitment to a literal interpretation of scientific claims; and an epistemological commitment to scientific knowledge of both observable and unobservable entities. The semantic dimension is uncontroversial, and the epistemological dimension, though contested, is well articulated in a number of ways. The metaphysical dimension, however, is not even well articulated. In this paper, I elaborate a plausible understanding of mind independence for the realist – (...) plausible in conceding the force of sceptical arguments to the effect that there is no one correct way to carve nature at its joints, but realist in proposing an objective basis for carving nonetheless. Walking this line between implausible realism and full-blown constructivism leads down the path of three forms of relativism or pluralism: one concerning the ways in which scientists “package” properties into entities; another concerning the precise metaphysical natures of these entities; and another concerning the context relativity of their behaviour. (shrink)
Results from two self-paced reading experiments in English are reported in which subject- and object-extracted relative clauses (SRCs and ORCs, respectively) were presented in contexts that support both types of relative clauses (RCs). Object-extracted versions were read more slowly than subject-extracted versions across both experiments. These results are not consistent with a decay-based working memory account of dependency formation where the amount of decay is a function of the number of new discourse referents that intervene between the dependents (Gibson, 1998; (...) Warren & Gibson, 2002). Rather, these results support interference-based accounts and decay-based accounts where the amount of decay depends on the number of words or on the type of noun phrases that intervene between the dependents. In Experiment 2, presentation in supportive contexts was directly contrasted with presentation in null contexts. Whereas in the null context the extraction effect was only observed during the RC region, in a supportive context the extraction effect was numerically larger and persisted into the following region, thus showing that extraction effects are enhanced in supportive contexts. A sentence completion study demonstrated that the rate of SRCs versus ORCs was similar across null and supportive contexts (with most completions being subject-extractions), ruling out the possibility that an enhanced extraction effect in supportive contexts is due to ORCs being less expected in such contexts. However, the content of the RCs differed between contexts in the completions, such that the RCs produced in supportive contexts were more constrained, reflecting the lexical and semantic content of the preceding context. This effect, which we discuss in terms of expectations/lexico-syntactic priming, suggests that the enhancement of the extraction effect in supportive contexts is due to the facilitation of the subject-extracted condition. (shrink)
Some expressions, such as “all” and “might”, must be interpreted differently, relative to a single context, when embedded under “says that” than when unembedded. Egan, Hawthorne and Weatherson have appealed to that fact to argue that utterance-truth is relative to point of evaluation. This paper shows that the phenomena do not warrant this relativistic response. Instead, contexts may be defined as entities that assign other contexts to contextually relevant people, and context-relative truth conditions for indirect discourse sentences can be satisfactorily (...) formulated in terms of such contexts. (shrink)
Moderate relativism -- The framework -- The distribution of content -- Radical vs. moderate relativism -- Two levels of content -- Branch points for moderate relativism -- The debate over temporalism (1) : do we need temporal propositions? -- Modal vs. extensional treatments of tense -- What is at stake? -- Modal and temporal innocence -- Temporal operators and temporal propositions in an extensional framework -- The debate over temporalism (2) : can we believe temporal propositions? -- An epistemic argument (...) against temporalism -- Rebutting Richard's argument -- Relativistic disagreement -- Relativization and indexicality -- Index, context, and content -- The two-stage picture : Lewis vs. Kaplan and Stalnaker -- Rescuing the two-stage picture -- Content, character, and cognitive significance -- Experience and subjectivity -- Content and mode -- Duality and the fallacy of misplaced information -- The content of perceptual judgements -- Episodic memory -- Immunity to error through misidentification -- Implicit self-reference -- Weak and strong immunity -- Quasi-perception and quasi-memory -- Reflexive states -- Relativization and reflexivity -- The (alleged) reflexivity of de se thoughts -- Reflexivity : internal or external? -- What is wrong with reflexivism -- The first person point of view -- De se thoughts and subjectivity -- Memory and the imagination -- Imagination and the self-- Imagination, empathy, and the quasi-de se -- Egocentricity and beyond -- Unarticulated constituents in the lekton? -- The context-dependence of the lekton : how far can we go? -- Unarticulatedness and the 'concerning' relation -- Three (alleged) arguments for the externality principle -- Invariance -- Self-relative thoughts -- The problem of the essential indexical -- Perry against relativized propositions -- Context-relativity -- Implicit and explicit de se thoughts -- Shiftability -- The generalized reflexive constraint -- Parametric invariance and m-shiftability -- Free shiftability -- The anaphoric mode : a Bühlerian perspective. (shrink)
The paper is concerned with the semantics of knowledge attributions(K-claims, for short) and proposes a position holding that K-claims are contextsensitive that differs from extant views on the market. First I lay down the data a semantic theory for K-claims needs to explain. Next I present and assess three views purporting to give the semantics for K-claims: contextualism, subject-sensitive invariantism and relativism. All three views are found wanting with respect to their accounting for the data. I then propose a hybrid (...) view according to which the relevant epistemic standards for evaluating K-claims are neither those at the context of the subject (subject-sensitive invariantism), nor those at the context of the assessor (relativism), but it is itself an open matter. However, given that we need a principled way of deciding which epistemic standards are the relevant ones, I provide a principle according to which the relevant standards are those that are the highest between those at the context of the subject and those at the context of the assessor/attributor. In the end I consider some objections to the view and offer some answers. (shrink)
I argue that truth is relative (in the sense recently defended by some prominent analytical philosophers) by focusing on some semantic issues raised by Einstein's theory of relativity together with our ordinary attributions of truth.
The purpose of this paper is to evaluate the `Lorentzian Pedagogy' defended by J.S. Bell in his essay ``How to teach special relativity'', and to explore its consistency with Einstein's thinking from 1905 to 1952. Some remarks are also made in this context on Weyl's philosophy of relativity and his 1918 gauge theory. Finally, it is argued that the Lorentzian pedagogy---which stresses the important connection between kinematics and dynamics---clarifies the role of rods and clocks in general relativity.
Color adjectives have played a central role in work on language typology and variation, but there has been relatively little investigation of their meanings by researchers in formal semantics. This is surprising given the fact that color terms have been at the center of debates in the philosophy of language over foundational questions, in particular whether the idea of a compositional, truth-conditional theory of natural language semantics is even coherent. The challenge presented by color terms is articulated in detail in (...) the work of Charles Travis. Travis argues that structurally isomorphic sentences containing color adjectives can shift truth value from context to context depending on how they are used and in the absence of effects of vagueness or ambiguity/polysemy, and concludes that a deterministic mapping from structures to truth conditions is impossible. The goal of this paper is to provide a linguistic perspective on this issue, which we believe defuses Travis’ challenge. We provide empirical arguments that color adjectives are in fact ambiguous between gradable and nongradable interpretations, and that this simple ambiguity, together with independently motivated options concerning scalar dimension within the gradable reading accounts for the Travis facts in a simpler, more constrained, and thus ultimately more successful fashion than recent contextualist analyses such as those in Szabó (Perspectives on semantics, pragmatics and discourse: A festschrift for Ferenc Kiefer, 2001) or Rothschild and Segal (Mind Lang, 2009). (shrink)
I discuss a rarely mentioned correspondence between Einstein and Swann on the constructive approach to the special theory of relativity, in which Einstein points out that the attempts to construct a dynamical explanation of relativistic kinematical effects require postulating a fundamental length scale in the level of the dynamics. I use this correspondence to shed light on several issues under dispute in current philosophy of spacetime that were highlighted recently in Harvey Brown’s monograph Physical Relativity, namely, Einstein’s view on the (...) distinction between principle and constructive theories, and the consequences of pursuing the constructive approach in the context of spacetime theories. r 2008 Elsevier Ltd. All rights reserved. (shrink)
Jason Stanley has argued that in order to obtain the desired readings of certain sentences, such as “In most of John’s classes, he fails exactly three Frenchmen”, we must suppose that each common noun is associated with a hidden indexical that may be either bound by a higher quantifier phrase or interpreted by the context. This paper shows that the desired readings can be obtained as well by interpreting nouns as expressing relations and without supposing that nouns are associated with (...) hidden indexicals. Stanley’s theory and the present alternative are not equivalent, however. They differ over the status of sentences such as “Every student is happy and some student is not happy”. On Stanley’s theory, this sentence will be true in some contexts, while on the present alternative it will be true in no context. Considerations in favor of the present theory’s verdict on such sentences are presented. The broader question at issue is the correct way to incorporate context-relativity into formal semantics. (shrink)
In his book, Physical Relativity, Harvey Brown challenges the orthodox view that special relativity is preferable to those parts of Lorentz's classical ether theory it replaced because it revealed various phenomena that were given a dynamical explanation in Lorentz's theory to be purely kinematical. I want to defend this orthodoxy. The phenomena most commonly discussed in this context in the philosophical literature are length contraction and time dilation. I consider three other phenomena of this kind that played a role in (...) the early reception of special relativity in the physics literature: the Fresnel drag effect in the Fizeau experiment, the velocity dependence of electron mass in beta-ray deflection experiments by Kaufmann and others, and the delicately balanced torques on a moving charged capacitor in the Trouton-Noble experiment. I offer historical sketches of how Lorentz's dynamical explanations of these phenomena came to be replaced by their now standard kinematical explanations. I then take up the philosophical challenge posed by the work of Harvey Brown and Oliver Pooley and clarify how those kinematical explanations work. (shrink)
In a comparison of the principles of special relativity and of quantum mechanics, the former theory is marked by its relative economy and apparent explanatory simplicity. A number of theorists have thus been led to search for a small number of postulates - essentially information theoretic in nature - that would play the role in quantum mechanics that the relativity principle and the light postulate jointly play in Einstein's 1905 special relativity theory. The purpose of the present paper is to (...) resist this idea, at least in so far as it is supposed to reveal the fundamental form of the theory. It is argued that the methodology of Einstein's 1905 theory represents a victory of pragmatism over explanatory depth; and that its adoption only made sense in the context of the chaotic state state of physics at the start of the 20th century - as Einstein well knew. (shrink)
Abstract -/- Inclusive nonindexical context-dependence occurs when the preferred interpretation of an utterance implies its lexically-derived meaning. It is argued that the corresponding processes of free or lexically mandated enrichment can be modeled as abductive inference. A form of abduction is implemented in Simple Type Theory on the basis of a notion of plausibility, which is in turn regarded a preference relation over possible worlds. Since a preordering of doxastic alternatives taken for itself only amounts to a relatively vacuous ad (...) hoc model, it needs to be combined with a rational way of learning from new evidence. Lexicographic upgrade is implemented as an example of how an agent might revise his plausibility ordering in light of new evidence. Various examples are given how this apparatus may be used to model the contextual resolution of context-dependent or semantically incomplete utterances. The described form of abduction is limited and merely serves as a proof of concept, but the idea in general has good potential as one among many ways to build a bridge between semantics and pragmatics since inclusive context-dependence is ubiquitous. (shrink)
Contextualism is relativism tamed. Relativism about truth is usually motivated by the idea of no-fault disagreement. Imagine two parties: one (she) says ‘P’; the other (he) says ‘Not P’.1 Apparently, if P then ‘P’ is true and ‘Not P’ false, so she is right and he is wrong; if not P then ‘P’ is false and ‘Not P’ true, so he is right and she is wrong. In both cases, there is an asymmetry between the two parties. Since P or (...) not P (by the law of excluded middle), there is indeed an asymmetry between them, one way or the other. Yet the two parties may strike a neutral observer as on a par, equally intelligent, informed, perceptive and alert. Relativists about truth strive to dissolve the unpleasant asymmetry: ‘”P” is true for her; “Not P” is true for him’. Trouble starts when we ask what the relativists mean by ‘for’ in the construction ‘true for X’. If to call something true ‘for’ X is just to say that X believes that it is true, then the attempted dissolution amounts to this: ‘She believes that “P” is true; he believes that “Not P” is true’. But that is to add no more than that both parties believe that they are right; it does nothing to undermine the argument for an asymmetry between them. Relativists had better mean something else by ‘true for X’. When asked to explain what else they mean, wild relativists bluster incoherently. Contextualists, by contrast, have a clear answer. A sentence is true for X if and only if it is true as uttered by X, true relative to a context in which X is the speaker. Such relativism is tame because the relativity to context in the truth-value of a sentence allows for absoluteness in the truth-value of what the sentence is used to say in a given context. When she says ‘P’, she speaks truly: not just truly for her, but absolutely truly. When he says ‘Not P’, he too speaks truly: not just truly for him, but absolutely truly. The argument for asymmetry 1 assumes that, when she says ‘P’, she speaks truly if and only if P, and when he says ‘Not P’, he speaks truly if and only if not P.. (shrink)
Within the context of general relativity, we consider one definition of a “time machine” proposed by Earman, Smeenk, and Wüthrich. They conjecture that, under their definition, the class of time machine spacetimes is not empty. Here, we prove this conjecture. †To contact the author, please write to: Department of Philosophy, University of Washington, Box 353350, Seattle, WA 98195‐3350; e‐mail: firstname.lastname@example.org.
This survey article is divided into two parts. In the first (section 2), I give a brief account of the structure of classical relativity theory. In the second (section 3), I discuss three special topics: (i) the status of the relative simultaneity relation in the context of Minkowski spacetime; (ii) the ``geometrized" version of Newtonian gravitation theory (also known as Newton-Cartan theory); and (iii) the possibility of recovering the global geometric structure of spacetime from its ``causal structure".
It has been argued that the existence of faster than light particles in the context of special relativity would imply the possibility to influence the past, and that this would lead to paradox. In this paper I argue that such conclusions cannot safely be drawn without consideration of the equations of motion of such particles. I show that such equations must be non-local, that they can be deterministic, and that they can avoid the suggested paradoxes. I also discuss conservation of (...) energymomentum, and how instantaneous action at a distance can avoid similar paradoxes. *I am most grateful for helpful comments made by John Earman, and especially John Norton, who is responsible for anything that makes sense in this paper. I am also grateful for the reception of a Mellon postdoctoral fellowship, which supported me whilst doing the research for this paper. (shrink)
Davies argues that the ontology of artworks as performances offers a principled way of explaining work-relativity of modality. Object oriented contextualist ontologies of art (Levinson) cannot adequately address the problem of work-relativity of modal properties because they understand looseness in what counts as the same context as a view that slight differences in the work-constitutive features of provenance are work-relative. I argue that it is more in the spirit of contextualism to understand looseness as context-dependent. This points to the general (...) problem—the context of appreciation is not robust enough to ground modal intuitions about objective entities. In general, when epistemology dictates ontology there is always a threat of anti-realism, scepticism and relativism. Davies also appeals to the modality principle—an entity’s essential properties are all and only its constitutive properties. Davies understands essentiality in a traditional way: a property P is an essential property of an object o iff o could not exist and lack P. Kit Fine has recently made a convincing case for the view that the notion of essence is not to be understood in modal terms. I explore some of the implications of this view for Davies’ modal argument for the performance theory. (shrink)
Based on the premise that what is relevant, consistent, or true may change from context to context, a formal framework of relevance and context is proposed in which • contexts are mathematical entities • each context has its own language with relevant implication • the languages of distinct contexts are connected by embeddings • inter-context deduction is supported by bridge rules • databases are sets of formulae tagged with deductive histories and the contexts they belong to • abduction and revision (...) are supported by a notion of consistency of formulae and sets of formulae which are relative to a context, and which can, in turn, be seen as constituents of agendas. (shrink)
A substantial part of my reconstruction can aheady be found, in a very condensed form, in the annotauon for the relevant pages of the Einstein-Besso manuscript in Einstein CP4: doc. 14, pp. [41Ã¢â¬â 42]. The letter to Freundlich and other correspondence from the period 1915 Ã¢â¬â 1917 that I drew on for this paper appear in Einstein CPS. I wrote this paper in the context of a larger project of the Maxplanck-Institut flir Wissenschaflsgeschichte which aims at giving the most detailed (...) reconstruction yet of Einstein's path to general relativity. My paper does not necessarily reflect the views of the other members of the group working on this project. See Renn tk Sauer 1996 for a preliminary report on the gmup's findings. (shrink)
I discuss the ontological assumptions and implications of General Relativity. I maintain that General Relativity is a theory about gravitational fields, not about space-time. The latter is a more basic ontological category, that emerges from physical relations among all existents. I also argue that there are no physical singularities in space-time. Singular space-time models do not belong to the ontology of the world: they are not things but concepts, i.e. defective solutions of Einstein’s field equations. I briefly discuss the actual (...) implication of the so-called singularity theorems in General Relativity and some problems related to ontological assumptions of Quantum Gravity. (shrink)
The dark matter problem in astrophysics exposes an underappreciated weakness in the evidential warrant for General Relativity (GR). The "dark matter double bind" entails that GR gets no differential evidential support from dynamical phenomena occurring at scales larger than our solar system, as compared to members of a significant class of rival gravitation theories. These rivals are each empirically indistinguishable from GR for phenomena taking place at solar system scales, but make predictions that may differ radically from GR's at larger (...) scales. Thus the typical confidence in the universal applicability of GR is insufficiently warranted in the present evidential context. (shrink)
In effort to investigate how quantum physics might modify Einstein's Theory of Relativity at speeds v→c, the relationship between space-time coordinates of different reference frames is revisited by introducing only one new parameter xo, a fundamental constant for the quantization of space. The starting point is three criteria: (a) real space-time data are conditioned by standard quantum effects on measurements; (b) since currently used apparatus are only capable of probing the aggregate behavior of these quanta the relevant model is one (...) which maximizes the Entropy subject to certain defining constraints; and (c) the constraints simply involve fixed ensemble averages in the case of an inertial frame, or boundary conditions on running averages in the case of an accelerated frame. In this context it is found that both the Lorentz transformation and a simple scheme for the quantization of space-time which resembles identically Planck's photon picture of radiation are a direct consequence of the Principle of Relativity. Non-inertial behavior corresponds to local Entropy maxima, obtainable by solution of a diffusion equation which gives gradually varying ensemble averages across space-time, as demonstrated by the example of a profile which connects a central region of highly agitated quanta with an asymptotic ambient environment—the outcome is the Schwarzschild metric of General Relativity. Apart from the above, a new feature emerges from the theory: the space-time data of an observer, when referred to the frame of his moving partner, are subject to extra quantum fluctuations which increase indefinitely in severity as v→c, with the Lorentz transformation providing only the mean data values. Thus for fast moving bodies like cosmic rays or matter at the horizon of a black hole, physical processes which affect them may not always be perceived by us to occur at the expected length or time scales. (shrink)
Several recent papers which purport to substantiate or negate arguments in favor of certain theories of absolute space have been based on fallacious principles. In this paper we discuss three related instances, indicating where misconceptions have arisen. We establish, contrary to popular belief, that the classical Lorentz ether theory accounts for all the experimental evidence which supports the special theory of relativity. We demonstrate that the ether theory predicts the null results obtained from pulsar timing and Mössbauer experiments. We conclude (...) that a measurement of the one-way velocity of light has physical meaning within the context of the Lorentz theory, and argue that an adequately designed experiment to measure the one-way velocity of light should be attempted. (shrink)
When do objects at different times compose a further object? This is the question of diachronic composition. The universalist answers, ‘under any conditions whatsoever’. Others argue for restrictions on diachronic composition: composition occurs only when certain conditions are met. Recently, some philosophers have argued that restrictions on diachronic compositions are motivated by our best physical theories. In Persistence and Spacetime and elsewhere, Yuri Balashov argues that diachronic compositions are restricted in terms of causal connections between object stages. In a recent (...) article, Nikk Effingham () argues that the standard objections to views that endorse restrictions on composition do not apply to a view that restricts composition according to compliance with the laws of nature. On the face of it, such restrictions on diachronic composition preserve our common-sense ontology while eliminating from it scientifically revisionary objects that travel faster than the speed of light. I argue that these attempts to restrict diachronic composition by appealing to either causal or nomological constraints face insurmountable difficulties within the context of special relativity. I discuss how the universalist should best respond to Hudson’s argument for superluminal objects, and in doing so, I present and defend a new sufficient condition for motion that does not entail that such objects are in superluminal motion. 1 Introduction2 Diachronic Composition3 Diachronic Composition and Superluminal Objects4 Restricting Diachronic Composition5 Causal and Nomological Restrictions on Composition in a Relativistic Context6 Superluminal Objects and Motion7 Conclusion. (shrink)
The experimental testing of the Lorentz transformations is based on a family of sets of coordinate transformations that do not comply in general with the principle of equivalence of the inertial frames. The Lorentz and Galilean sets of transformations are the only member sets of the family that satisfy this principle. In the neighborhood of regular points of space-time, all members in the family are assumed to comply with local homogeneity of space-time and isotropy of space in at least one (...) free-falling elevator, to be denoted as Robertson'sab initio rest frame [H. P. Robertson,Rev. Mod. Phys. 21, 378 (1949)].Without any further assumptions, it is shown that Robertson's rest frame becomes a preferred frame for all member sets of the Robertson family except for, again, Galilean and Einstein's relativities. If one now assumes the validity of Maxwell-Lorentz electrodynamics in the preferred frame, a different electrodynamics spontaneously emerges for each set of transformations. The flat space-time of relativity retains its relevance, which permits an obvious generalization, in a Robertson context, of Dirac's theory of the electron and Einstein's gravitation. The family of theories thus obtained constitutes a covering theory of relativistic physics.A technique is developed to move back and forth between Einstein's relativity and the different members of the family of theories. It permits great simplifications in the analysis of relativistic experiments with relevant “Robertson's subfamilies.” It is shown how to adapt the Clifford algebra version of standard physics for use with the covering theory and, in particular, with the covering Dirac theory. (shrink)
Prospect Relativity 2 Abstract In many theories of decision under risk (e.g., expected utility theory, rank dependent utility theory, and prospect theory) the utility or value of a prospect is independent of other prospects or options in the choice set. The experiments presented here show a large effect of the available options set, suggesting instead that prospects are valued relative to one another. The judged certainty equivalent is strongly influenced by the options available. Similarly, the selection of a preferred option (...) from a set of prospects is strongly influenced by the prospects available. Alternative theories of decision under risk (e.g., the stochastic difference model, multialternative decision field theory, and range frequency theory), where prospects themselves or prospect attributes are valued relative to one another, can provide an account of these context effects. (shrink)
The relation of the special and the general principle of relativity to the principle of covariance, the principle of equivalence and Mach's principle, is discussed. In particular, the connection between Lorentz covariance and the special principle of relativity is illustrated by giving Lorentz covariant formulations of laws that violate the special principle of relativity: Ohm's law and what we call “Aristotle's first and second laws.” An “Aristotelian” universe in which all motion is relative to “absolute space” is considered. The first (...) law: a free particle is at rest. The second law: force is proportional to velocity. Ohm's law: the current density is proportional to the electrical field strength. Neither of these laws fulfills the principle of relativity. The examples illustrate, in the context of Lorentz covariance and special relativity, Kretschmann's critique of founding Einstein's general principle of relativity on the principle of general covariance. A modification of the principle of covariance is suggested, which may serve as a restricted criterium for a physical law to satisfy Einstein's general principle of relativity. Other objections that have been raised to the validity of Einstein's general principle of relativity are based upon the preferred state of inertial frames in the general, as well as in the special theory, the existence of tidal effects in “true” gravitational fields, doubts as to the validity of Mach's principle, whether electromagnetic phenomena obey the principle, and, finally, the anisotropy of the cosmic background radiation. These objections are reviewed and discussed. (shrink)
Special Relativity can be based on the whole proper group of both ortho- and antichronous Lorentz transformations, and a clear physical meaning can be given also to antichronous (i.e., nonorthochronous) Lorentz transformations. From the active point of view, the latter requires existence, for any particle, of its antiparticle within a purely relativistic, classical context. From the passive point of view, they give rise to frames “dual” to the ordinary ones, whose properties—here briefly discussed—are linked with the fact that in relativity (...) it is impossible to teach another, far observer (by transmitting only instructions, and no physical objects) our own conventions about the choices right/left, matter/antimatter, and positive/negative time direction. Interesting considerations follow, in particular, by considering—as it is the case—theCPT operation as an actual (even if antichronous) Lorentz transformation. (shrink)