The empirical basis of equilibrium: Mach, Vailati, and the lever

About a century ago, Ernst Mach argued that Archimedes’s deduction of the principle of the lever is invalid, since its premises contain the conclusion to be demonstrated. Subsequently, many scholars defended Archimedes, mostly on historical grounds, by raising objections to Mach’s reconstruction of Archimedes’s deduction. In the debate, the Italian philosopher and historian of science Giovanni Vailati stood out. Vailati responded to Mach with an analysis of Archimedes’s deduction which was later quoted and praised by Mach himself. In this paper, my objective is to show that the debate can be further advanced, as Mach indicated, by reframing it in terms of the empirical vs. the logical dimensions of mechanics. In this way, I will suggest, the debate about Archimedes’s deduction can be resolved in Mach’s favour.     

Fantastic Beasts and where (not) to find them: Local gravitational energy and energy conservation in general relativity

This paper critically examines energy-momentum conservation and local (differential) notions of gravitational energy in General Relativity (GR). On the one hand, I argue that energy-momentum of matter is indeed locally (differentially) conserved: Physical matter energy-momentum 4-currents possess no genuine sinks/sources. On the other hand, global (integral) energy-momentum conservation is contingent on spacetime symmetries. Local gravitational energy-momentum is found to be a supererogatory notion. Various explicit proposals for local gravitational energy-momentum are investigated and found wanting. Besides pseudotensors, the proposals considered include those of Lorentz and Levi-Civita, Pitts and Baker. It is concluded that the ontological commitment we ought to have towards gravitational energy in GR mimics the natural anti-realism/eliminativism towards apparent forces in Newtonian Mechanics.     

The Ontology of the Questionnaire: Max Weber on Measurement and Mass Investigation

Although contemporary sociologists of science have sometimes claimed Max Weber as a methodological precursor, they have not examined Weber's own writings about science. Between 1908 and 1912 Weber published a series of critical studies of the extension of scientific authority into public life. The most notable of these concerned attempts to implement the experimental psychology or psycho-physics laboratory in factories and other real-world settings. Weber's critique centered on the problem of social measurement. He emphasized the discontinuities between the space of the laboratory and that of the factory, showing how several qualitative and historically conditioned differences between the two settings rendered the transfer of instruments and methods between them highly problematic. Weber's critical arguments prepared the ground for his greatest foray into empirical sociology, a survey he directed for the Verein für Sozialpolitik investigating the conditions and attitudes affecting the lives and performance of industrial workers. Using a different measuring instrument — the questionnaire — Weber tried to implement a concept of social measurement which implied a different ontology, drawn not from natural sciences but from the historical sciences.     

专家系统在切割机故障诊断中的理论与应用

本文介绍了一个用于切割机电气故障的专家诊断系统。专家诊断系统与切割机控制系统通过信号联络线同步运行,能够实时地在线地检测和诊断步进电机的驱动电路。专家诊断系统以单片机8031为核心,采用产生式规则建立知识库,用广度优先搜索法进行向后推理,运用并行推理方式提高搜索速度。样机运行结果表明,专家诊断系统达到了设计要求。     

Realism,functions, and the a priori: Ernst Cassirer's philosophy of science

This paper presents the main ideas of Cassirer's general philosophy of science, focusing on the two aspects of his thought that—in addition to being the most central ideas in his philosophy of science—have received the most attention from contemporary philosophers of science: his theory of the a priori aspects of physical theory, and his relation to scientific realism.     

The co-discovery of conservation laws and particle families

This paper presents an epistemological analysis of the search for new conservation laws in particle physics that was especially prominent in the 1950s and 1960s. Discovering conservation laws has posed various challenges concerning the underdetermination of theory by evidence, to which physicists have found various responses. These responses include an appeal to a plenitude principle, a maxim for inductive inference, looking for a parsimonious system of generalizations, and unifying particle ontology and particle dynamics. The connection between conservation laws and ontological categories is a major theme in my analysis: While there are infinitely many conservation law theories that are empirically equivalent to the laws physicists adopted for the fundamental standard model of particle physics, I show that the standard family laws are the only ones that determine and are determined by the simplest division of particles into families.     

The algorithmic turn in conservation biology: Characterizing progress in ethically-driven sciences

As a discipline distinct from ecology, conservation biology emerged in the 1980s as a rigorous science focused on protecting biodiversity. Two algorithmic breakthroughs in information processing made this possible: place-prioritization algorithms and geographical information systems. They provided defensible, data-driven methods for designing reserves to conserve biodiversity that obviated the need for largely intuitive and highly problematic appeals to ecological theory at the time. But the scientific basis of these achievements and whether they constitute genuine scientific progress has been criticized. We counter by pointing out important inaccuracies about the science and rejecting the apparent theory-first focus. More broadly, the case study reveals significant limitations of the predominant epistemic-semantic conceptions of scientific progress and the considerable merits of pragmatic, practically-oriented accounts.     

Helmholtz,the conservation of force and the conservation of vis viva

This paper investigates the relationship between Helmholtz's formulation of the principle of the conservation of force and the two principles well known in rational mechanics as the principle of vis viva and the principle of the conservation of vis viva. An examination of the relevant literature from Leibniz to Duhamel reveals both Helmholtz's indebtedness to that tradition and his creative refashioning of it as he endeavoured to craft an argument that would both prohibit the construction of a perpetuum mobile and the efficacy of a supposed vital force and demonstrate the necessity of an ontology of mass points subject to attractive and repulsive central forces depending solely on distance.     

Preludes to dark energy: zero-point energy and vacuum speculations

According to modern physics and cosmology, the universe expands at an increasing rate as the result of a “dark energy” that characterizes empty space. Although dark energy is a modern concept, some elements in it can be traced back to the early part of the twentieth century. I examine the origin of the idea of zero-point energy, and in particular how it appeared in a cosmological context in a hypothesis proposed by Walther Nernst in 1916. The hypothesis of a zero-point vacuum energy attracted some attention in the 1920s, but without attempts to relate it to the cosmological constant that was discussed by Georges Lemaître in particular. Only in the late 1960s, was it recognized that there is a connection between the cosmological constant and the quantum vacuum. As seen in retrospect, many of the steps that eventually led to the insight of a kind of dark energy occurred isolated and uncoordinated.     

Population biology of figs: Applications for conservation

Summary The flowering phenology typical of at least monoecious figs-intra-tree synchrony and inter-tree asynchrony-poses problems for persistence of the pollinator population, and hence of the fig population itself, when fig population size is small. Establishment and maintenance of a population of the short-lived, species-specific wasp pollinator require that the fig population include a critical minimum number of trees (critical population size: CPS). Below CPS, temporal gaps between flowering trees occur that are unbridgeable by the pollinator, leading to its local extinction. This has implications for conservation in two contexts: human-aided invasions of introduced fig/wasp pairs, in which initial populations of figs and/or wasps may be small, and the persistence of figs and wasps in fragmented forest, in which initially large populations may be drastically reduced. Long-distance range extension by fig/wasp pairs is problematical for two reasons: 1) the fig species must first attain CPS, most likely through repeated seed dispersal events, before the wasp can establish; and 2) long-distance transit should be difficult for the tiny, short-lived wasp pollinators. I review the biology of natural and human-aided range extension by figs and fig wasps, and show that in human-aided range extensions these two difficult steps are circumvented. Once introduced into an area where hosts are abundant, fig wasps should readily establish from a small number of initial colonists, since they mate before dispersal and are highly tolerant of inbreeding. They are thus less subject than many insects to the genetic and demographic hazards of small population size. Of 5–6 fig/wasp pairs that have performed human-aided long-distance range extensions, one Asian pair,Ficus microcarpa and its pollinatorParapristina verticillata, is established in numerous areas in the northern neotropics, and the plant may become a serious weed. In tropical forests, figs may provide keystone resources for frugivores, providing fruit during seasons when other resources are scarce. Figs pose difficult problems for conservation biology, since minimum viable populations appear to be large, and since many species of tropical rainforests occur at low densities. This means that minimum areas required for persistence of a fig population- and for those of other species that would be affected were figs to be removed from the system-may often be large.     

Gender and philosophy of science: The case of Mary Hesse

This article is composed of two intertwining narratives. The first is a discussion of the concept of gender in relation to philosopher of science Mary Hesse's theoretical contributions and academic experiences. The second narrative takes issue with the gender concept at a more general level and particularly to discuss its strengths and limits. The article alternates between a discussion of different claims from gender theorists and a presentation of Mary Hesse's academic experiences. I conclude that although the gender concept has, until now, only been used in an asymmetrical sense, i.e., negatively linked to women's careers and positively to men's, it will not necessarily be identically used in the future. Both empirical findings and conceptual changes may make room for a more differentiated understanding of gender.     

The chatfield-prothero case study: Another look

The Chatfield-Prothero case study in time series, ‘Sales of a company X’, is analysed from a perspective different to that of the authors. More accurate forecasting performance for these data is obtained by adopting the following two tactics: (1) shifting from a problem in transformation of the original series to one of seasonality adjustment; (2) assuming a mixed seasonality type model in contrast to employing a multiplicative assumption.     

Computer simulations and experiments: The case of the Higgs boson

Simulations have been at the center of an important literature that has debated the extent to which they count as epistemologically on a par with traditional experiments. Critics have raised doubts about simulations being genuine experiments, on the ground that simulations seem to lack a distinctive feature of traditional experiments: i.e., the ability to causally interact with a target system. In this paper, we defend the view that simulations are indeed epistemologically on a par with traditional experiments. We first identify three possible ways of understanding the causal interaction claim. We then focus on the use of simulation in the discovery of the Higgs boson to show that in this paradigmatic case, simulations satisfy all three possible readings of the causal interaction claim.     

Forecast accuracy and effort: The case of US inflation rates

This paper investigates the relationship between forecast accuracy and effort, where effort is defined as the number of times the model used to generate forecasts is recursively estimated over the full sample period. More specifically, within a framework of costly effort, optimal effort strategies are derived under the assumption that the dynamics of the variable of interest follow an autoregressive‐type process. Results indicate that the strategies are fairly robust over a wide range of linear and nonlinear processes (including structural break processes), and deliver forecasts of transitory, core and total inflation that require less effort to generate and are as accurate as (that is, are insignificantly different from) those produced with maximum effort. Copyright © 2010 John Wiley & Sons, Ltd.