Holger Lyre

The paper aims to spell out the relevance of the Berry phase in view of the question what the minimal mathematical structure is that accounts for all observable quantum phenomena. The question is both of conceptual and of ontological interest. While common wisdom tells us that the quantum structure is represented by the structure of the projective Hilbert space, the appropriate structure rich enough to account for the Berry phase is the U(1) bundle over that projective space. The Berry phase is ultimately rooted in the curvature of this quantum bundle, it cannot be traced back to the Hamiltonian dynamics alone. This motivates the ontological claim in the final part of the paper that, if one strives for a realistic understanding of quantum theory including the Berry phase, one should adopt a form of ontic structural realism.

Structural Realism (SR) is typically rated as a moderate realist doctrine about the ultimate entities of nature described by fundamental physics. Whether it must be extended to the higher-level special sciences is not so clear. In this short paper I argue that there is no need to ‘structuralize’ the special sciences. By mounting concrete examples I show that structural descriptions and structural laws certainly play a role in the special sciences, but that they don’t play any exclusive role nor that they give us any reason to believe that all that there is on the various levels is structure. I fortify my points by arguing that structures are global entities (in order for SR not to collapse into a bundle ontology) and that the assumption of higher-level structures as genuinely global or holistic entities is even more arcane.

The paper presents and discusses the “which-is-which content of handedness,” the meaning of left as left and right as right, as a possible candidate for the idea of a genuine embodied cognitive content. After showing that the Ozma barrier, the non-transferability of the meaning of left and right, provides a kind of proof of the non-descriptive, indexical nature of the which-is-which content of handedness, arguments are presented which suggest that the classical representationalist account of cognition faces a perplexing problem of underdetermination of reference of left and right in the which-is-which sense. By way of contrast, no such problems occur in a framework were embodied contents are not mediated by some extra body model which carries the representational power, but are instead directly represented.

Der Aufsatz lotet den zeitgenössischen Reduktionismus aus. Im ersten Teil wird in zentrale Stationen der wissenschaftstheoretischen Debatte um Theorien-Reduktion eingeleitet, wobei das Schaffner-Hooker-Modell und die Bedeutung von Näherungsbegriffen hervorgehoben werden. Der zweite Teil behandelt die multiple Realisierbarkeit als eines der nach wie vor zentralen anti-reduktionistischen Argumente. Die Analyse soll zeigen, dass es sich hierbei nicht um ein einheitliches Phänomen handelt, sondern dass sehr verschiedene Kategorien von Multirealisierbarkeit zu unterscheiden sind. In einem vereinfachten Slogan: multiple Realisierbarkeit ist ihrerseits multirealisiert. Der Aufsatz entwickelt eine rohe Taxonomie von Typen multipler Realisierbarkeit und möglicher reduktionistischer Strategien, wobei genuine Fälle von Multirealisierbarkeit auf geteilte Eigenschaften zurückgeführt werden. Im letzten Teil wird die besondere Rolle von Näherungen im Zusammenhang mit der explanatorischen Spannung zwischen ontischem Reduktionismus und epistemischen Anti-Reduktionismus verdeutlicht.

I give a response to Adrian Wüthrich’s critical review of my analysis of the Higgs mechanism, in which I try to clarify some possible misunderstandings. I concede that, as Wüthrich points out, many physicists see the Higgs mechanism as the roll-over from a symmetrical potential in the initial Lagrangian to a symmetry-breaking potential, while my former analysis had basically focused on the gauge-invariant transformation of the initial Lagrangian into the intended form. My main contention, however, still is that neither Higgs story has (as yet) much explanatory power

Recent developments under the keywords dynamicism, embodiment and situated cognition suggest the view that cognitive systems are not confined to the neural sys‐tem but leak into the world beyond the traditional system boundaries. This is the thesis of extended cognition. Such an extension of the cognitive vehicles leads to a new kind of content externalism, known as active externalism. The essay pursues three objectives: firstly, to distinguish the theses of extended cognitive and active externalism. Secondly, to delineate active externalism from its various passive-externalist precursors in the form of physical, historical and social externalism and to scrutinize its special position, which amounts to a comprehensive discussion and analysis of all variants of mental externalism. And thirdly, to show that social externalism as opposed to physical and historical externalism allows for a gradual transition from passive to active mental externalism.

This supplement serves a double purpose. It presents, on the one hand, a selection of papers devoted to the title question “How much philosophy in the philosophy of science?”. On the other hand, it signalizes the newly established cooperation between the German Society for the Philosophy of Science and the Journal for General Philosophy of Science .The GWP was founded in Hannover in 2011 and had its inaugural conference in March 2013 [for a report on the “GWP.2013” by H. Lyre see EPSA Newsletter 2 2013]. The society was launched for several reasons. Albeit the German community of philosophers of science is quite large , it is at the same time a rather distributed and dispersed community. This has to do with the university landscape in Germany, which is dispersed rather t ..

NEUER TEXT!!! Holger Lyre unternimmt den grenzüberschreitenden Versuch, sowohl in die philosophisch-begrifflichen als auch physikalisch-mathematischen Zusammenhänge von Informations- und Quantentheorie einzudringen. Ausgehend von Carl Friedrich von Weizsäckers "Quantentheorie der Ur-Alternativen" wird eine abstrakte Theorie der Information in transzendentalphilosophischer Perspektive entworfen und werden die begrifflichen Implikationen einer konsequenten Quantentheorie der Information umfassend diskutiert. Der Autor präsentiert eine Fülle von Material aus den Bereichen Informations- und Komplexitätstheorie, Quantentheorie und Raum-Zeit-Physik sowie der Philosophie der Physik. Aufgrund der verständlichen Darstellung des Formalismus (mit umfangreichem mathematischen Appendix) stellt das Buch auch für jeden interessierten Nicht-Spezialisten eine gewinnbringende Lektüre dar.

Four empirically equivalent versions of general relativity, namely standard GR, Lorentz-invariant gravitational theory,and the gravitational gauge theories of the Lorentz and translation groups, are investigated in the form of a case study for theory underdetermination. The various ontological indeterminacies (both underdetermination and inscrutability of reference) inherent in gravitational theories are analyzed in a detailed comparative study. The concept of practical underdetermination is proposed, followed by a discussion of its adequacy to describe scientific progress.

Im ersten Abschnitt illustrierte ich die These der erweiterten Kognition und diskutiere einige mögliche Missverständnisse. Im zweiten Abschnitt werde ich vier Domänen kognitiver Erweiterung auseinanderhalten, nämlich eine Erweiterung in die körperliche, physikalische, 'informatorische' und soziale Umgebung betreffend. Um die These der erweiterten Kognition vor dem Einwand der kognitiven Inflation zu schützen, muss man für jeden dieser Bereiche (und gegebenenfalls noch spezieller) spezifische Bedingungen und Mechanismen der kognitiven Kopplung an die externen Komponenten angeben. Im dritten Abschnitt unterscheide ich die These der erweiterten Kognition, von der sich im ersten Abschnitt bereits zeigen wird, dass sie eine These kognitiver Vehikel ist, von einer externalistischen Gehaltsthese. Letztere bezeichne ich im Anklang an Clark und Chalmers als aktiven Externalismus und illustriere dessen Unterschiede und Besonderheiten gegenüber den bekannten 'passiven' Formen des semantischen oder mentalen Externalismus in der Philosophie des Geistes, die sich mit den Namen Putnam, Millikan und Burge verbinden. Im vierten Abschnitt verfolge ich die spezifische Idee, die Mechanismen geteilter Intentionalität als Kopplungsmechanismen kognitiver Erweiterung in die soziale Umgebung, speziell soziale Interaktionspartner, anzusehen. Dazu mache ich in einigem Detail von Bratmans bekannter Plan-Konzeption geteilter Intentionalität Gebrauch. Anhand der Ergebnisse dieser Analyse wird sich im fünften und letzten Abschnitt zeigen, in welchem Sinne es sich dabei im Keim bereits um einen sozialen Externalismus handelt. Der soziale Externalismus, so der Clou, stellt bereits eine verkappte Variante eines aktiven Externalismus dar.

Multiple Realizability (MR) must still be regarded as one of the principal arguments against type reductionist accounts of higher-order properties and their special laws. Against this I argue that there is no unique MR but rather a multitude of MR categories. In a slogan: MR is itself “multi-realized”. If this is true then we cannot expect one unique reductionist strategy against MR as an anti-reductionist argument. The main task is rather to develop a taxonomy of the wide variety of MR cases and to sketch possible reductionist answers for each class of cases. The paper outlines some first steps in this direction.

In der Debatte um den wissenschaftlichen Realismus gewinnt zunehmend der Strukturenrealismus - dessen Auffassung zufolge der Realgehalt wissenschaftlicher Theorien in deren mathematisch-logischer Struktur liegt - an Bedeutung. Die vorliegende Arbeit untersucht diese These anhand der in unserer fundamentalen Physik bedeutsamsten Klasse von Theorien, den Eichtheorien, die durch spezielle lokale Symmetriestrukturen gekennzeichnet sind. Die Arbeit bietet dem Leser in ihren ersten Kapiteln einen Einstieg in die zentralen Themen Symmetrien, wissenschaftlicher Realismus und Eichtheorien. In den im Mittelteil durchgeführten Analysen werden Quanten- und Gravitations-Eichtheorien in konzeptioneller Hinsicht - vor allem bezüglich der zugrundeliegenden Prinzipien - und ontologischer Hinsicht - mit Blick auf die Unterbestimmtheit der Entitäten und verschiedener Lokalitätsannahmen - im Detail untersucht. Resultierend ergibt sich eine Stützung des Strukturenrealismus, jedoch nicht in dessen radikaler ontischer Variante, sondern in der moderateren epistemischen oder allenfalls intermediären Spielart, bei der sowohl Strukturen als auch deren Träger existieren, wobei letzterer jedoch amorph und und mithin epistemisch unverfügbar ist.

After decades of neglect philosophers of physics have discovered gauge theories--arguably the paradigm of modern field physics--as a genuine topic for foundational and philosophical research. Incidentally, in the last couple of years interest from the philosophy of physics in structural realism--in the eyes of its proponents the best suited realist position towards modern physics--has also raised. This paper tries to connect both topics and aims to show that structural realism gains further credence from an ontological analysis of gauge theories--in particular U(1) gauge theory. In the first part of the paper the framework of fiber bundle gauge theories is briefly presented and the interpretation of local gauge symmetry will be examined. In the second part, an ontological underdetermination of gauge theories is carved out by considering the various kinds of non-locality involved in such typical effects as the Aharonov-Bohm effect. The analysis shows that the peculiar form of non-separability figuring in gauge theories is a variant of spatiotemporal holism and can be distinguished from quantum theoretic holism. In the last part of the paper the arguments for a gauge theoretic support of structural realism are laid out and discussed.

Since its discovery in 1959 the Aharonov-Bohm effect has continuously been the cause for controversial discussions of various topics in modern physics, e.g. the reality of gauge potentials, topological effects and nonlocalities. In the present paper we juxtapose the two rival interpretations of the Aharonov-Bohm effect. We show that the conception of nonlocality encountered in the Aharonov-Bohm effect is closely related to the nonseparability which is common in quantum mechanics albeit distinct from it due to its topological nature. We propose a third alternative interpretation based on the loop space of holonomies which serves to solve some of the problems and we trace back the topological nonlocality and thereby the Aharonov-Bohm effect to their quantum mechanical origin. All three discussed interpretations are, of course, empirically equivalent. In fact, they present us with an instructive case study for the thesis of theory underdetermination by empirical data.

Quantum theory is a tremendously successful physical theory, but nevertheless suffers from two serious problems: the measurement problem and the problem of interpretational underdetermination. The latter, however, is largely overlooked as a genuine problem of its own. Both problems concern the doctrine of realism, but pull, quite curiously, into opposite directions. The measurement problem can be captured such that due to scientific realism about quantum theory common sense anti-realism follows, while theory underdetermination usually counts as an argument against scientific realism. I will also consider the more refined distinctions of ontic and epistemic realism and demonstrate that quantum theory in its most viable interpretations conflicts with at least one of the various realism claims. A way out of the conundrum is to come to the bold conclusion that quantum theory is, possibly, wrong (in the realist sense).

The paper has three parts. In the first part ExtOSR, an extended version of Ontic Structural Realism, will be introduced. ExtOSR considers structural properties as ontological primitives, where structural properties are understood as comprising both relational and structurally derived intrinsic properties or structure invariants. It is argued that ExtOSR is best suited to accommodate gauge symmetry invariants and zero value properties. In the second part, ExtOSR will be given a Humean shape by considering structures as categorical and global. It will be laid out how such structures serve to reconstruct non-essential structural kinds and laws. In the third part Humean structural realism will be defended against the threat of quidditism.

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

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.