: Aristotle struggles with two basic tensions in his understanding of reality or substance that have parallels in Indian metaphysical speculation. The first of these tensions, between the understanding of reality as the underlying substrate (to hupokeimenon) and as the individual "this" (tode ti), finds a parallel in the concept of dravya in Patañjali's Mahābhāsa. The second tension, between the understanding of reality as the individual this and as the intelligible essence of the individual this (to ti ēn einai), corresponds (...) to an ambiguity in the concept of vastu in Kumārila's Ślokavārttika. (shrink)

R.I.G. Hughes presents a series of eight philosophical essays on the theoretical practices of physics. The first two essays examine these practices as they appear in physicists' treatises and journal articles. By treating these publications as texts, Hughes casts the philosopher of science in the role of critic. This premise guides the following six essays which deal with various concerns of philosophy and physics such as laws, disunities, models and representation, computer simulation, explanation, and the discourse of physics.

R.I.G Hughes offers the first detailed and accessible analysis of the Hilbert-space models used in quantum theory and explains why they are so successful.

R.I.G. Hughes presents a series of eight philosophical essays on the theoretical practices of physics. The first two essays examine these practices as they appear in physicists' treatises (e.g. Newton's Principia and Opticks ) and journal articles (by Einstein, Bohm and Pines, Aharonov and Bohm). By treating these publications as texts, Hughes casts the philosopher of science in the role of critic. This premise guides the following 6 essays which deal with various concerns of philosophy of physics such as laws, (...) disunities, models and representation, computer simulation, explanation, and the discourse of physics. (shrink)

This volume of recent writings, some previously unpublished, follows the sequence of a typical intermediate or upper-level logic course and allows teachers to enrich their presentations of formal methods and results with readings on corresponding questions in philosophical logic.

Probability kinematics is the theory of how subjective probabilities change with time, in response to certain constraints . Rules are classified by the imposed constraints for which the rules prescribe a procedure for updating one's opinion. The first is simple conditionalization , and the second Jeffrey conditionalization . It is demonstrated by a symmetry argument that these rules are the unique admissible rules for those constraints, and moreover, that any probability kinematic rule must be equivalent to a conditionalization preceded by (...) a determination of the values x i to be given to the members of such a partition. Next two rival rules which can go beyond such conditionalization are described. INFOMIN and MTP . Their properties are investigated and compared. (shrink)

Embryonic development combines paradoxical properties: it has great precision, it is usually conducted at breakneck speed and it is flexible on relatively short evolutionary time scales, particularly at early stages. While these features appear mutually exclusive, we consider how they may be reconciled by the properties of key early regulatory networks. We illustrate these ideas with the network that controls development of endoderm progenitors. We argue that this network enables precision because of its intrinsic stability, self propagation and dependence on (...) signalling. The network enables high developmental speed because it is rapidly established by maternal inputs at multiple points. In turn these properties confer flexibility on an evolutionary time scale because they can be initiated in many ways, while buffering essential progenitor cell populations against changes in their embryonic environment on both evolutionary and developmental time scales. Although stable, these networks must be capable of rapid dissolution as cell differentiation progresses. While we focus on the core early endodermal network of vertebrates, we argue that these properties are likely to be general in early embryonic stem cell populations, such as mammalian ES cells. BioEssays 30:757–765, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Wallace became a full-time naturalist in 1848, the year when he and Bates set out on their journey to South America. Wallace was twenty-five at the time and over half of his life had been spent in various parts of Wales, the land of his birth. Commentators have tended to gloss over or ignore any formative influences from this early period of his life or even to dismiss them as non-existent. This is surprising as it was during the eight or (...) so years in Wales leading up to 1848 that Wallace's interest in natural history emerged. ‘The importance of this early period in Wallace's life can scarcely be over-emphasized’ wrote Durant in his account of the development of the Wallace personality, but he omitted any specific reference to the significance of the early period in Wales. Those seeking a simple unitary cause for Wallace's conversion to natural history usually locate this in his visit to Leicester in 1844 and his meeting there with H. W. Bates. ‘The odyssey began … in 1844, in Leicester’ wrote Brooks, adding that ‘the more remote parts of … southern Wales had offered little reading material…’ This, and similar claims, are presumably founded primarily on Wallace's belief—expressed sixty years later—that it was at Leicester that he first familiarized himself with Malthus'Essay on the Principles of Populationand Humboldt'sPersonal Narrative of Travels in South America.There is, however, evidence that Wallace was probably familiar with at least one of these books some time before his visit to Leicester and that it was during his period in southern Wales that his interest in natural history emerged and developed. (shrink)

W. E. Hocking has written recently that Whitehead's descriptive generalization of concrete fact, namely, his actual occasion, is “… not a term of description in the direct sense. It is an hypothesis. It cannot be kept in place by pointing to its presence as a datum: it can only hold its own if it proves to be a valuable conceptual tool.” I further advance the thesis that all generality is hypothetical, and holds it own only if it proves to be (...) conceptually useful. This is in accord with Whitehead's statement, the full implications of which have not been taken seriously enough, that metaphysical categories are not dogmatic statements of the obvious; they are tentative formulations of the ultimate generalities. But when these tentative formulations prove conceptually useful or are conceptually employed, they lose their “hypothetical air,” and often pass into what Whitehead calls a false state of “sober obviousness:”“An old established metaphysical system gains a false air of adequate precision from the fact that its words and phrases have passed into current literature. Thus propositions expressed in its language are more easily correlated to our flitting intuitions into metaphysical truth. When we trust these verbal statements and argue as though they adequately analysed meaning, we are led into difficulties which take the shape of negations of what in practice is presupposed. But when they are proposed as first principles they assume an unmerited air of sober obviousness.”. (shrink)

The ontological argument, as understood by the first interpretation, runs as follows: The concept of God is the concept of a being than which nothing greater can be conceived. This latter concept includes the concept of a being which exists necessarily, for necessary existence is one of the perfections of an absolutely perfect being; that is, the concept of God is the concept of a being which exists necessarily. God then must conceived as existing necessarily, and hence we must attribute (...) to his essence necessary existence. According to the first interpretation, this inference from concepts alone constitutes the whole of the ontological argument. The argument is thus analytic and purely rational. (shrink)

One problem with assessing quantum logic is that there are considerable differences between its practitioners. In particular they offer different versions of the set of sentences which the logic governs. On some accounts the sentences involved describe events, on others they are ascriptions of properties. In this paper a framework is offered within which to discuss different quantum logical interpretations of quantum theory, and then the works of Jauch, Putnam, van Fraassen and Kochen are located within it.

The pair (A, Δ ), where A is a physical quantity (an observable) and Δ a subset of the reals, may be called an 'experimental question'. The set Q of experimental questions is, in classical mechanics, a Boolean algebra, and in quantum mechanics an orthomodular lattice (and also a transitive partial Boolean algebra). The question is raised: can we specify a priori what algebraic structure Q must have in any theory whatsoever? Several proposals suggesting that Q must be a lattice (...) are discussed, and rejected in favor of the weak claim that Q must be a Boolean atlas. (shrink)

Quite rightly, philosophers of physics examine the theories of physics, theories like Quantum Mechanics, Quantum Field Theory, the Special and General Theories of Relativity, and Statistical Mechanics. Far fewer, however, examine how these theories are put to use; that is to say, little attention is paid to the practices of theoretical physicists. In the early 1950s David Bohm and David Pines published a sequence of four papers, collectively entitled, ‘A Collective Description of Electron Interaction.’ This essay uses that quartet as (...) a case study in theoretical practice. In Part One of the essay, each of the Bohm-Pines papers is summarized, and within each summary an overview is given, framing a more detailed account. In Part Two theoretical practice is broken into six elements: (a) the use of models, (b) the use of theory, (c) modes of description and narrative, (d) the use of approximations, (e) experiment and theory, (f) the varied steps employed in a deduction. The last element is the largest, drawing as it does from the earlier ones. Part Three enlarges on the concept of ‘theoretical practice,’ and briefly outlines the subsequent theoretical advances which rendered the practices of Bohm and Pines obsolete, if still respected. (shrink)