Various formalisms for recasting quantum mechanics in the framework of classical mechanics on phase space are reviewed and compared. Recent results in stochastic quantum mechanics are shown to avoid the difficulties encountered by the earlier approach of Wigner, as well as to avoid the well-known incompatibilities of relativity and ordinary quantum theory. Specific mappings among the various formalisms are given.
Working in stochastic spin space and using POV measures as in the Davies and Lewis measurement scheme, we construct a formalism to describe the simultaneous measurement of incompatible spin components. The methods are illustrated with a new analysis of the Stern-Gerlach experiment, and with a discussion of spin dynamics in stochastic spin space. We also present a new short proof of a theorem on representations of spin-1/2 systems, find a joint spectral family for (noncommuting) spin components, and indicate the connection (...) of our result with the Riesz extension theorem. (shrink)
The notion of superhigh computably enumerable (c.e.) degrees was first introduced by (Mohrherr in Z Math Logik Grundlag Math 32: 5–12, 1986) where she proved the existence of incomplete superhigh c.e. degrees, and high, but not superhigh, c.e. degrees. Recent research shows that the notion of superhighness is closely related to algorithmic randomness and effective measure theory. Jockusch and Mohrherr proved in (Proc Amer Math Soc 94:123–128, 1985) that the diamond lattice can be embedded into the c.e. tt-degrees preserving 0 (...) and 1 and that the two atoms can be low. In this paper, we prove that the two atoms in such embeddings can also be superhigh. (shrink)
In this book, Christopher Evan Franklin develops and defends a novel version of event-causal libertarianism. This view is a combination of libertarianism--the view that humans sometimes act freely and that those actions are the causal upshots of nondeterministic processes--and agency reductionism--the view that the causal role of the agent in exercises of free will is exhausted by the causal role of mental states and events (e.g., desires and beliefs) involving the agent. Franklin boldly counteracts a dominant theory that (...) has similar aims, put forth by well-known philosopher Robert Kane. -/- Many philosophers contend that event-causal libertarians have no advantage over compatibilists when it comes to securing a distinctively valuable kind of freedom and responsibility. To Franklin, this position is mistaken. Assuming agency reductionism is true, event-causal libertarians need only adopt the most plausible compatibilist theory and add indeterminism at the proper juncture in the genesis of human action. The result is minimal event-causal libertarianism: a model of free will with the metaphysical simplicity of compatibilism and the intuitive power of libertarianism. And yet a worry remains: toward the end of the book, Franklin reconsiders his assumption of agency reductionism, arguing that this picture faces a hitherto unsolved problem. This problem, however, has nothing to do with indeterminism or determinism, or even libertarianism or compatibilism, but with how to understand the nature of the self and its role in the genesis of action. Crucially, if this problem proves unsolvable, then not only is event-causal libertarianism untenable, so also is event-causal compatibilism. (shrink)
An attempt to introduce readers "at the eleventh grade level" to some leading principles and practitioners of philosophy in America. This undertaking, admittedly difficult, meets with varying success. The book's most satisfactory part consists of essays by various contributors describing the different fields of philosophy; the rest outlines briefly the philosophical doctrines most influential in American thought, and sketches the lives of a wide assortment of American "philosophers," from Jonathan Edwards to Franklin D. Roosevelt, with a one- or two-paragraph (...) selection from the works of each.--E. T. (shrink)
But Williams had created a field of historical study, where his white counterparts had not. Single-handedly and without the blessing or approval of the academic community, Williams had called attention to the importance of including Afro-Americans in any acceptable and comprehensive history of the nation long before the historians of various groups of European-Americans or Asian-Americans had begun to advocate a similar treatment for their groups. And if Williams did not impress the white professional historians, he gave heart and encouragement (...) to future Afro-American historians. When the History of the Negro Troops appeared in 1887, nineteen-year-old W. E. B. Du Bois was a college senior at Fisk University and editor-in-chief of the student magazine, The Fisk Herald. In the columns of the Herald Du Bois wrote, "At last we have a historian; not merely a Negro historian, but a man who judged by his merits alone has written a splendid narrative. The Herald congratulates George W. Williams, and the race, which may justly be . . . [proud] of him."1 Many years later, Carter G. Woodson, the founder of the Association for the Study of Negro Life and History and of the Journal of Negro History, described Williams' History of the Negro Troops as "one of the most valuable accounts of the Civil War."2 With words like these from Du Bois and Woodson, on whose shoulders much of the second stage of Afro-American historiography would rest, it is not too much to say that George Washington Williams was responsible for the beginnings of Afro-American historiography. · 1. The Fisk Herald, January 1888, p. 8.· 2. Woodson's appraisal of Williams was found among his papers and made available to me by Dr. Charles H. Wesley when he was executive director of the Association for the Study of Negro Life and History, which had been founded by Woodson in 1915. John Hope Franklin, president-elect of the American Historical Society, has written a biography of George Washington Williams. He is the John Matthews Manly Distinguished Service Professor of History at the University of Chicago and the author of, among other works, From Slavery to Freedom: A History of Negro Americans and A Southern Odyssey: Travelers in the Antebellum North. (shrink)
Symmetries are introduced into the convexity approach to physics. This allows one to make connections between classical and quantum theories by exploiting the properties of quantum mechanics on phase space. The measurement problem is discussed and many of the known no-go theorems are shown not to apply. Finally, hidden variable theories exhibiting these physical symmetries are shown to have a certain required group structure, if they exist at all.
The language of manuals may be used to discuss inference in measurement in a general experimental context. Specializing to the context of the frame manual for Hilbert space, this inference leads to state dominance of the inferred state from partial measurements; this in turn, by Sakai's theorem, determines observables which are described by positive operator-valued measures. Symmetries are then introduced, showing that systems of covariance, rather than systems of imprimitivity, are natural objects to study in quantum mechanics. Experiments measuring different (...) polarization components simultaneously are reexamined in this language. Finally, implications of the Naimark extension theorem for the manual approach are investigated. (shrink)
The internal paradoxes in the quantum measurement scheme related to violation of conservation laws, changes in entropy, absence of a dynamic description of collapse, Wigner's friend, as well as the paradox of violation of causality in the EPR experiment are shown to be partially circumvented in the measurement scheme of stochastic quantum mechanics.
Starting from the phase space representation of quantum mechanics we provide an Euclidean system of covariance for the photon. In particular, we consider systems with the Poincaré group as the symmetry group and use a standard procedure in order to build a phase space and a localization observable on the phase space. Then we focus on the massless representations of the Poincaré group that we use to build a space localization observable for the photon.
A challenge of performing research in the paediatric emergency and acute care setting is obtaining valid prospective informed consent from parents. The ethical issues are complex, and it is important to consider the perspective of participants, health care workers and researchers on research without prospective informed consent while planning this type of research. We performed a systematic review according to PRISMA guidelines, of empirical evidence relating to the process, experiences and acceptability of alternatives to prospective informed consent, in the paediatric (...) emergency or acute care setting. Major medical databases and grey sources were searched and results were screened and assessed against eligibility criteria by 2 authors, and full text articles of relevant studies obtained. Data were extracted onto data collection forms and imported into data management software for analysis. Thirteen studies were included in the review consisting of nine full text articles and four abstracts. Given the heterogeneity of the methods, results could not be quantitatively combined for meta-analysis, and qualitative results are presented in narrative form, according to themes identified from the data. Major themes include capacity of parents to provide informed consent, feasibility of informed consent, support for alternatives to informed consent, process issues, modified consent process, child death, and community consultation. Our review demonstrated that children, their families, and health care staff recognise the requirement for research without prior consent, and are generally supportive of enrolling children in such research with the provisions of limiting risk, and informing parents as soon as possible. Australian data and perspectives of children are lacking and represent important knowledge gaps. (shrink)
O presente texto procura acompanhar alguns aspectos da reconstrução sartreana das relações entre indivíduo e história, tentando mostrar que a fenomenologia e o materialismo dialético comparecem nessa proposta de conhecimento e que é a convergência das duas perspectivas que permite, contemplando adequadamente a universalidade e a singularidade, descrever e compreender dialeticamente o modo histórico de produção da identidade individual.
A questão que se tenta construir neste texto é a da convergência entre filosofia, história da filosofia e formação. Tal pergunta se desdobra primeiramente na elucidação das relações entre história e historicidade da filosofia, que remonta à constatação óbvia, mas nem sempre lembrada, de que o fundamento da história da filosofia é o caráter histórico da própria filosofia. A idéia de formação está presente em toda filosofia, já que, antes de ser sistema ou concepção cristalizada da realidade, cada filosofia é (...) sempre um exercício de síntese das possibilidades e das circunstâncias da vida humana, inclusive sob o aspecto do trabalho da reflexão. Nesse sentido, o texto remete a algumas idéias de Bergson acerca de formação e processo, e à noção sartriana de práxis como formação e superação contínua dos momentos estruturais do curso da história. Assim compreendida, a relação entre história da filosofia e filosofia contém inevitavelmente o compromisso com a atualidade, isto é, com a formação atual do pensamento. (shrink)
É bem conhecida a oposição estabelecida por Kant entre experiência possível e dialética, na medida em que esta última é caracterizada como a lógica da ilusão. Ao mesmo tempo, o modo de pensar metafísico, que ocorre dialeticamente, em sentido kantiano, é uma tendência inevitável da razão, expressa na exigência formal de completude das categorias. Como o pensar, enquanto exercício livre da razão, é em si mesmo mais amplo do que a atividade de conhecer, própria do entendimento, o pensar contém o (...) conhecimento, embora este se qualifique pelas regras e pelos limites determinantes da objetividade. A pergunta que tentaremos formular é se essa relação continente-conteúdo não poderia configurar também uma dependência da experiência em relação ao raciocínio dialético, que estaria de algum modo indicada na função reguladora das idéias da razão. Nesse caso, a oposição formal entre conhecer e pensar seria inseparável da inclusão estrutural (dependência) da experiência no âmbito da razão. Na raiz do problema estaria talvez a tensão (dialética) entre a aspiração subjetiva de totalidade e as exigências objetivas de limitação e segmentação da experiência e a forma da experiência teria de ser finalmente concebida a partir de um fundo de inteligibilidade problemática. Dialectics and experienceThe separation of possible experience as objective knowledge and dialetics as a non-objective or non-theoretical knowledge is one of the most important aspects of kantian critical philosophy. But Kant also says that the activity of reason, as a pure thinking, has more amplitude than understanding knowledge. So we could say that theoric knowledge would depend on rational ( and non-theoretical) knowledge, as something contained in it. If we accept that, the consequence would be a relation of dependence between the form of objective knowledge and the background of a problematic even doubtful inteligible knowledge. (shrink)
Esse texto pretende indicar um modo de aproximação da noção d e subjetividade tal como ela aparece especificamente na Critica do Juízo : a especificidade do juízo reﬂe xionant e como ato subjetivo. A fu nção de ajuizar, no seu estrato pre-cate gorial, pode nos fornecer a i ndicação de uma possibilidade interpretativa fundada na conjunção entre mundo natural e mundo prático como o universo da nova fo rm a de juizo.
Este artigo pretende mostrar como, a partir da noção de “vizinhança comunicante” estabelecida por Franklin Leopoldo e Silva, poderemos compreender os principais temas da filosofia sartriana e a relação entre eles, tais como a relação entre metafísica e história, sujeito e objeto, (liberdade) absoluta e concreta, e ética e estética. Ao estender a expressão inicialmente cunhada para a relação entre filosofia e literatura em Sartre, pretendemos evidenciar que as noções de ambiguidade e tensão são fundamentais para termos uma chave (...) de leitura para todo o pensamento de Sartre. (shrink)
En pleno debate sobre qué significa ser liberal y qué no, la editorial Tecnos nos ofrece una colección de textos que ejemplifican una de las configuraciones clásicas de este modo de pensar en el siglo XX: una serie de discursos e intervenciones públicas de Franklin Delano Roosevelt en las que se justifican las particulares medidas adoptadas durante el comienzo de su mandato y que recibieron el nombre de New Deal.
The passing away of Mitchell Franklin has meant not only the loss of a teacher and a friend, but also die dosing of a chapter in intellectual history which, in die U.S., was hardly ever opened. Franklin's persona was certainly “born in the U.S.A.” (he, on die odier hand, was bom in Montreal, Canada). Yet, he belonged to diat European generation of diinkers, who, confronted widi rising 20th century irrationalism, sought to vindicate an updated version of Enlightenment rationalism. (...) In diis, of course, he was in good company: diis is precisely die kind of trajectory one finds traced not only by most of diose intellectuals who came of age between die two World Wars (e.g., Lukács), but also, more recendy, by thinkers still confronted widi irrationalism as a national question (e.g., Habermas). (shrink)