A critical review of gravitational wave theory is made. It is pointed out that the usual linear approach to the gravitational wave theory is neither conceptually consistent nor mathematically justified. Relying upon that analysis it is argued that—analogously to a Yang-Mills propagating field, which must be nonlinear to carry its gauge charge—a gravitational wave must necessarily be nonlinear to transport its own charge—that is, energy-momentum.

The Poincaré group generalizes the Galilei group for high-velocity kinematics. The de Sitter group is assumed to go one step further, generalizing Poincaré as the group governing high-energy kinematics. In other words, ordinary special relativity is here replaced by de Sitter relativity. In this theory, the cosmological constant Λ is no longer a free parameter, and can be determined in terms of other quantities. When applied to the whole universe, it is able to predict the value of Λ and to (...) explain the cosmic coincidence. When applied to the propagation of ultra-high energy photons, it gives a good estimate of the time delay observed in extragalactic gamma-ray flares. It can, for this reason, be considered a new paradigm to approach the quantum gravity problem. (shrink)

A solution of the sourceless Einstein's equation with an infinite value for the cosmological constant Λ is discussed by using Inönü–Wigner contractions of the de Sitter groups and spaces. When Λ→∞, spacetime becomes a four-dimensional cone, dual to Minkowski space by a spacetime inversion. This inversion relates the four-cone vertex to the infinity of Minkowski space, and the four-cone infinity to the Minkowski light-cone. The non-relativistic limit c→∞ is further considered, the kinematical group in this case being a modified Galilei (...) group in which the space and time translations are replaced by the non-relativistic limits of the corresponding proper conformal transformations. This group presents the same abstract Lie algebra as the Galilei group and can be named the conformal Galilei group. The results may be of interest to the early Universe Cosmology. (shrink)

A precise fomulation of the strong Equivalence Principle is essential to the understanding of the relationship between gravitation and quantum mechanics. The relevant aspects are reviewed in a context including General Relativity but allowing for the presence of torsion. For the sake of brevity, a concise statement is proposed for the Principle: An ideal observer immersed in a gravitational field can choose a reference frame in which gravitation goes unnoticed. This statement is given a clear mathematical meaning through an accurate (...) discussion of its terms. It holds for ideal observers (time-like smooth non-intersecting curves), but not for real, spatially extended observers. Analogous results hold for gauge fields. The difference between gravitation and the other fundamental interactions comes from their distinct roles in the equation of force. (shrink)

By considering the irreducible representations of the Lorentz group, an analysis of the different spin-2 waves is presented. In particular, the question of the helicity is discussed. It is concluded that, although from the point of view of representation theory there are no compelling reasons to choose between spin-2 waves with helicity σ=±1 or σ=±2, consistency arguments of the ensuing field theories favor waves with helicity σ=±1.

In order to study early human development while avoiding the burdens associated with human embryo research, scientists are redirecting their efforts towards so-called human embryo-like structures (hELS). hELS are created from clusters of human pluripotent stem cells and seem capable of mimicking early human development with increasing accuracy. Notwithstanding, hELS research finds itself at the intersection of historically controversial fields, and the expectation that it might be received as similarly sensitive is prompting proactive law reform in many jurisdictions, including the (...) Netherlands. However, studies on the public perception of hELS research remain scarce. To help guide policymakers and fill this gap in the literature, we conducted an explorative qualitative study aimed at mapping the range of perspectives in the Netherlands on the creation and research use of hELS. This article reports on a subset of our findings, namely those pertaining to (the degrees of and requirements for) confidence in research with hELS and its regulation. Despite commonly found disparities in confidence on emerging biotechnologies, we also found wide consensus regarding the requirements for having (more) confidence in hELS research. We conclude by reflecting on how these findings could be relevant to researchers and (Dutch) policymakers when interpreted within the context of their limitations. (shrink)

The geometric system of deduction called N-Graphs was introduced by de Oliveira in 2001. The proofs in this system are represented by means of digraphs and, while its derivations are mostly based on Gentzen's sequent calculus, the system gets its inspiration from geometrically based systems, such as the Kneales' tables of development, Statman's proofs-as-graphs, Buss' logical flow graphs, and Girard's proof-nets. Given that all these geometric systems appeal to the classical symmetry between premises and conclusions, providing an intuitionistic version of (...) any of these is an interesting exercise in extending the range of applicability of the geometric system in question. In this article we produce an intuitionistic version of N-Graphs, based on Maehara's LJ' system, as described by Takeuti. Recall that LJ' has multiple conclusions in all but the essential intuitionistic rules, e.g., implication right and negation right. We show soundness and completeness of our intuitionistic N-Graphs with respect to LJ'. We also discuss how we expect to extend this work to a version of N-Graphs corresponding to the intuitionistic logic system FIL (Full Intuitionistic Logic) of de Paiva and Pereira and sketch future developments. (shrink)

The first English translation of Fichte’s second set of 1804 lectures on the Wissenschaftslehre.

This book explores the relationship between schizophrenia and common sense. It approaches this theme from a multidisciplinary perspective. Coverage features contributions from phenomenology, cognitive neuroscience, philosophy of mind, psychology, and social cognition. The contributors address the following questions: How relevant is the loss of common sense in schizophrenia? How can the study of schizophrenia contribute to the study of common sense? How to understand and explain this loss of common sense? They also consider: What is the relationship of practical reasoning (...) and logical formal reasoning with schizophrenia? What is the relationship between the person with a diagnosis of schizophrenia and social values? Chapters examine such issues as rationality, emotions, self, and delusion. In addition, one looks at brain structure and neurotransmission. Others explore phenomenological and Wittgensteinian theories. The book features papers from the Schizophrenia and Common Sense International Workshop, held at New University of Lisbon, November 2015. It offers new insights into this topic and will appeal to researchers, students, as well as interested general readers. (shrink)

This paper examines the debate between permissive and impermissive forms of Bayesianism. It briefly discusses some considerations that might be offered by both sides of the debate, and then replies to some new arguments in favor of impermissivism offered by Roger White. First, it argues that White’s (Oxford studies in epistemology, vol 3. Oxford University Press, Oxford, pp 161–186, 2010) defense of Indifference Principles is unsuccessful. Second, it contends that White’s (Philos Perspect 19:445–459, 2005) arguments against permissive views do not (...) succeed. (shrink)

Representation theorems are often taken to provide the foundations for decision theory. First, they are taken to characterize degrees of belief and utilities. Second, they are taken to justify two fundamental rules of rationality: that we should have probabilistic degrees of belief and that we should act as expected utility maximizers. We argue that representation theorems cannot serve either of these foundational purposes, and that recent attempts to defend the foundational importance of representation theorems are unsuccessful. As a result, we (...) should reject these claims, and lay the foundations of decision theory on firmer ground. (shrink)

Several variants of Lewis's Best System Account of Lawhood have been proposed that avoid its commitment to perfectly natural properties. There has been little discussion of the relative merits of these proposals, and little discussion of how one might extend this strategy to provide natural property-free variants of Lewis's other accounts, such as his accounts of duplication, intrinsicality, causation, counterfactuals, and reference. We undertake these projects in this paper. We begin by providing a framework for classifying and assessing the variants (...) of the Best System Account. We then evaluate these proposals, and identify the most promising candidates. We go on to develop a proposal for systematically modifying Lewis's other accounts so that they, too, avoid commitment to perfectly natural properties. We conclude by briefly considering a different route one might take to developing natural property-free versions of Lewis's other accounts, drawing on recent work by Williams. (shrink)

In Reasons and Persons, Parfit (1984) posed a challenge: provide a satisfying normative account that solves the Non-Identity Problem, avoids the Repugnant and Absurd Conclusions, and solves the Mere-Addition Paradox. In response, some have suggested that we look toward person-affecting views of morality for a solution. But the person-affecting views that have been offered so far have been unable to satisfy Parfit's four requirements, and these views have been subject to a number of independent complaints. This paper describes a person-affecting (...) account which meets Parfit's challenge. The account satisfies Parfit's four requirements, and avoids many of the criticisms that have been raised against person-affecting views. (shrink)

At the heart of the Bayesianism is a rule, Conditionalization, which tells us how to update our beliefs. Typical formulations of this rule are underspecified. This paper considers how, exactly, this rule should be formulated. It focuses on three issues: when a subject’s evidence is received, whether the rule prescribes sequential or interval updates, and whether the rule is narrow or wide scope. After examining these issues, it argues that there are two distinct and equally viable versions of Conditionalization to (...) choose from. And which version we choose has interesting ramifications, bearing on issues such as whether Conditionalization can handle continuous evidence, and whether Jeffrey Conditionalization is really a generalization of Conditionalization. (shrink)

In “Bayesianism, Infinite Decisions, and Binding”, Arntzenius et al. (Mind 113:251–283, 2004 ) present cases in which agents who cannot bind themselves are driven by standard decision theory to choose sequences of actions with disastrous consequences. They defend standard decision theory by arguing that if a decision rule leads agents to disaster only when they cannot bind themselves, this should not be taken to be a mark against the decision rule. I show that this claim has surprising implications for a (...) number of other debates in decision theory. I then assess the plausibility of this claim, and suggest that it should be rejected. (shrink)

In recent work, Adlam (2022b), Chen & Goldstein (2022), and Meacham (2023) have defended accounts of laws that take laws to be primitive global constraints. A major advantage of these accounts is that they’re able to accommodate the many different kinds of laws that appear in physical theories. In this paper I’ll present these three accounts, highlight their distinguishing features, and note some key differences that might lead one to favor one of these accounts over the others. I’ll conclude by (...) briefly discussing a version of a “constraint” account that I think is especially attractive. (shrink)

It is proved that the relevance logic \ has no structurally complete consistent axiomatic extension, except for classical propositional logic. In fact, no other such extension is even passively structurally complete.

Descartes nimmt in Anspruch, daß sein Argument des Deus malignus über die Einwände der Skeptiker hinausgehe. Was fügt es dem Traumargument hinzu? Die verbreitete Ansicht, der Dämon stelle die Erkenntnis mathematischer und logischer Wahrheiten in Frage, wird im folgenden diskutiert und zurückgewiesen. Die richtige Interpretation lautet: Die Annahme des Dämons unterstützt den Skeptizismus und verstärkt die Zweifel an der Existenz äußerer Objekte. Es werden drei Einwände gegen diese Interpretation erörtert und zurückgewiesen. Eine andere Auffassung vertritt Frankfurt: Die Rolle des Traumarguments (...) sei wesentlich begrenzt; die durch den Dämon aufgeworfenen Zweifel seien umfassender. Eine genaue Analyse der Entwicklung des Traumarguments in der Ersten Meditation führt zur Widerlegung dieser Interpretation. (shrink)

This essay is written on the following premises and argues for them. “Enlightenment” is a word or signifier, and not a single or unifiable phenomenon which it consistently signifies. There is no single or unifiable phenomenon describable as “the Enlightenment,” but it is the definite article rather than the noun which is to be avoided. In studying the intellectual history of the late seventeenth century and the eighteenth, we encounter a variety of statements made, and assumptions proposed, to which the (...) term “Enlightenment” may usefully be applied, but the meanings of the term shift as we apply it. The things are connected, but not continuous; they cannot be reduced to a single narrative; and we find ourselves using the word “Enlightenment” in a family of ways and talking about a family of phenomena, resembling and related to one another in a variety of ways that permit of various generalizations about them. We are not, however, committed to a single root meaning of the word “Enlightenment,” and we do not need to reduce the phenomena of which we treat to a single process or entity to be termed “the” Enlightenment. It is a reification that we wish to avoid, but the structure of our language is such that this is difficult, and we will find ourselves talking of “the French” or “the Scottish,” “the Newtonian” or the “the Arminian” Enlightenments, and hoping that by employing qualifying adjectives we may constantly remind ourselves that the keyword “Enlightenment” is ours to use and should not master us. (shrink)

Originally published in 1913. Author: Henri Lichtenberger Language: English Keywords: History Many of the earliest books, particularly those dating back to the 1900s and before, are now extremely scarce and increasingly expensive. Obscure Press are republishing these classic works in affordable, high quality, modern editions, using the original text and artwork.Keywords: English Keywords 1900s Language English Artwork.

Logics that do not have a deduction-detachment theorem (briefly, a DDT) may still possess a contextual DDT —a syntactic notion introduced here for arbitrary deductive systems, along with a local variant. Substructural logics without sentential constants are natural witnesses to these phenomena. In the presence of a contextual DDT, we can still upgrade many weak completeness results to strong ones, e.g., the finite model property implies the strong finite model property. It turns out that a finitary system has a contextual (...) DDT iff it is protoalgebraic and gives rise to a dually Brouwerian semilattice of compact deductive filters in every finitely generated algebra of the corresponding type. Any such system is filter distributive, although it may lack the filter extension property. More generally, filter distributivity and modularity are characterized for all finitary systems with a local contextual DDT, and several examples are discussed. For algebraizable logics, the well-known correspondence between the DDT and the equational definability of principal congruences is adapted to the contextual case. (shrink)