The standard $\mathbb{U}(1)$ “gauge principle” or “gauge argument” produces an exact potential A=dλ and a vanishing field F=d 2 λ=0. Weyl (in Z. Phys. 56:330–352, 1929; Rice Inst. Pam. 16:280–295, 1929) has his own gauge argument, which is sketchy, archaic and hard to follow; but at least it produces an inexact potential A and a nonvanishing field F=dA≠0. I attempt a reconstruction.

The paper first sketches out a reply to the underdetermination challenge and the incommensurability challenge that rebuts the sceptical conclusions of these challenges and that is sufficient to lay the ground for the project of a metaphysics of nature. That metaphysics is as hypothetical as are our scientific theories. The paper then explains how can one can argue for certain views in the metaphysics of nature based on our current fundamental physical theories, namely the commitments to a tenseless theory of (...) time and existence instead of a tensed one, to events instead of substances, and to relations instead of intrinsic properties. Finally, the paper mentions the themes of causation, laws and dispositions. (shrink)

The logic of gauge theory is considered by tracing its development from general relativity to Yang-Mills theory, through Weyl's two gauge theories. A handful of elements---which for want of better terms can be called \emph{geometrical justice}, \emph{matter wave}, \emph{second clock effect}, \emph{twice too many energy levels}---are enough to produce Weyl's second theory; and from there, all that's needed to reach the Yang-Mills formalism is a \emph{non-Abelian structure group} (say $\mathbb{SU}\textrm{(}N\textrm{)}$).

An overview of the German philosophy of science community is given for the years 1992–2012, based on a survey in which 159 philosophers of science in Germany participated. To this end, the institutional background of the German philosophy of science community is examined in terms of journals, centers, and associations. Furthermore, a qualitative description and a quantitative analysis of our survey results are presented. Quantitative estimates are given for: (a) academic positions, (b) research foci, (c) philosophers’ of science most important (...) publications, and (d) externally funded projects, where for (c) all survey participants had indicated their five most important publications in philosophy of science. In addition, the survey results for (a)–(c) are also qualitatively described, as they are interesting in their own right. With respect to (a), we estimated the gender distribution among academic positions. Concerning (c), we quantified philosophers’ of science preference for (i) journals and publishers, (ii) publication format, (iii) language, and (iv) coauthorship for their most important publications. With regard to research projects, we determined their (i) prevalence, (ii) length, and (iii) trend (an increase in number?) as well as their most frequent (iv) research foci and (v) funding organizations. We also distinguished between German-based and non-German-based journals, publishers, and funding institutions, making it thereby possible to evaluate the involvement of the German philosophy of science community in the international research landscape. Finally, we discuss some implications of our findings. (shrink)

During his whole scientific life Hermann Weyl was fascinated by the interrelation of physical and mathematical theories. From the mid 1920s onward he reflected also on the typical difference between the two epistemic fields and tried to identify it by comparing their respective automorphism structures. In a talk given at the end of the 1940s he gave the most detailed and coherent discussion of his thoughts on this topic. This paper presents his arguments in the talk and puts it in (...) the context of the later development of gauge theories. (shrink)

Structural realism is sometimes said to undermine the theory underdetermination (TUD) argument against realism, since, in usual TUD scenarios, the supposed underdetermination concerns the object-like theoretical content but not the structural content. The paper explores the possibility of structural TUD by considering some special cases from modern physics, but also questions the validity of the TUD argument itself. The upshot is that cases of structural TUD cannot be excluded, but that TUD is perhaps not such a terribly serious anti-realistic argument.

Did Goethe devise an empirically viable theory of classical ray optics? Or can we at least make use of his ideas to propose one? And if so, does this confront us with an intriguing case of theory underdetermination? In this paper, which is mainly a comment on the recent work of Olaf Müller, I shall address these three questions and argue for ‘no, yes, no’. This is in contrast to Müller, who has recently launched a vivid defense of Goethe-style ray (...) optics :569–573, 2015b; Z Philos Forsch 69:588–598, 2015c; Br J Hist Philos 24:322–346, 2016). Müller aims to give an almost positive answer to all three questions: ‘perhaps, yes, yes’. My overall line of argument will be that the rather restricted regime of classical geometrical optics of spectral colors allows at best for a weak form of transient theory underdetermination that, in turn and more straightforwardly, also allows for a structuralist reading in terms of two structurally equivalent formulations of one and the same theory. However, extending any of the rivaling models of ray optics other than Newton’s beyond the mentioned regime and embedding them into physics in total—especially in view of thermodynamics—leads to a contradiction. Hence, Newton’s theory is confirmed as the only consistent theoretical interpretation of ray optics. (shrink)

In 1768 Immanuel Kant presented an argument showing the necessity of absolute space, i.e. substantivalism in contrast to relationalism, based on the property of handedness. While there is large consensus about the fallacy of Kant’s argument, a more recent debate exists – mainly stimulated by John Earman – about the status of the Kantian argument in view of modern physics and its fundamentally built-in parity violation, which leads to a preferred handedness. According to Earman the relationalist has no means to (...) distinguish one handedness in the cosmos without reference to an absolute structure of space. After recapitulating the historical background of the Newton/Leibniz debate on the ontological status of space as well as the Kantian argument, this paper offers a systematic consideration of arguments about handedness in modern physics. The goal is to show that “Earman’s challenge” can be rejected. (shrink)

In der modernen Physik spielen Symmetrien eine herausragende Rolle zur Identifikation und Klassifizierung der fundamentalen Theorien und Entitäten. Symmetrien dienen der Darstellung invarianter Strukturen, das geeignete mathematische Werkzeug hierfür ist die Gruppentheorie. Eine Struktur lässt sich als eine Menge von Relationen verstehen, die einer Menge von Objekten aufgeprägt sind. Strukturell charakterisierte Objekte sind daher wesentlich über ihre relationalen Eigenschaften charakterisiert. Sieht man die theoretischen Entitäten wissenschaftlicher Theorien vornehmlich in dieser strukturellen Weise an, vertritt man eine moderate Variante eines wissenschaftlichen Realismus, (...) die als Strukturenrealismus bekannt ist. Im Umfeld dieser drei Konzepte – Symmetrien, Strukturen, Realismus – bewegt sich der folgende Aufsatz. (shrink)

The ''gauge argument'' is often used to 'deduce' interactions from a symmetry requirement. A transition---whose justification can take some effort---from global to local transformations is typically made at the beginning of the argument. But one can spare the trouble by \emph{starting} with local transformations, as global ones do not exist in general. The resulting economy seems noteworthy.

The paper is a kind of opinionated review paper on current issues in the debate about Structural Realism, roughly the view that we should be committed in the structural rather than object-like content of our best current scientific theories. The major thesis in the first part of the paper is that Structural Realism has to take structurally derived intrinsic properties into account, while in the second part key elements of aligning Structural Realism with a Humean framework are outlined.

In discussions of the Aharonov-Bohm effect, Healey and Lyre have attributed reality to loops $\sigma_0$ (or hoops $[\sigma_0]$), since the electromagnetic potential $A$ is currently unmeasurable and can therefore be transformed. I argue that $[A]=[A+d\lambda]_{\lambda}$ and the hoop $[\sigma_0]$ are related by a meaningful duality, so that however one feels about $[A]$ (or any potential $A\in[A]$), it is no worse than $[\sigma_0]$ (or any loop $\sigma_0\in[\sigma_0]$): no ontological firmness is gained by retreating to the loops, which are just as flimsy (...) as the potentials. And one wonders how the unmeasurability of one entity can invest another with physical reality; would an eventual observation of $A$ dissolve $\sigma_0$, consigning it to a realm of incorporeal mathematical abstractions? The reification of loops rests on the potential's ''gauge dependence''; which in turn rests on its unmeasurability; which is too shaky and arbitrary a notion to carry so much weight. (shrink)

In discussions of the Aharonov-Bohm effect, Healey and Lyre have attributed reality to loops $\sigma_0$ (or hoops $[\sigma_0]$), since the electromagnetic potential $A$ is currently unmeasurable and can therefore be transformed. I argue that $[A]=[A+d\lambda]_{\lambda}$ and the hoop $[\sigma_0]$ are related by a meaningful duality, so that however one feels about $[A]$ (or any potential $A\in[A]$), it is no worse than $[\sigma_0]$ (or any loop $\sigma_0\in[\sigma_0]$): no ontological firmness is gained by retreating to the loops, which are just as flimsy (...) as the potentials. And one wonders how the unmeasurability of one entity can invest another with physical reality; would an eventual observation of $A$ dissolve $\sigma_0$, consigning it to a realm of incorporeal mathematical abstractions? The reification of loops rests on the potential's ''gauge dependence''; which in turn rests on its unmeasurability; which is too shaky and arbitrary a notion to carry so much weight. (shrink)

The paper deals with an attempt to present an “abductive-transcendental” argument in favour of a particular version of structural realism (SR), dubbed Intermediate SR. In the first part of the paper the general structure of transcendental arguments is scrutinized with a close view on Kant’s original version and the prospect of their abductive variation. Then the role of symmetries in modern physics, especially symmetries without real instantiations and in particular gauge symmetries is discussed. This is combined with a presentation of (...) SR as a promising current version of scientific realism. The discussion is supported by various arguments form gauge theories in modern physics. Intermediate SR, a realist position about all and only structurally derivable entities located between the extremes of Epistemic and Ontic SR turns out as the best fit to our current fundamental gauge physics and this finally leads to an abductive-transcendental reasoning concerning this position. (shrink)