Eventually, Kuhlmann proposes a dispositional trope ontology, according to which particularized properties and not things are the most basic entities.

Quantum field theory provides the framework for many fundamental theories in modern physics, and over the last few years there has been growing interest in its historical and philosophical foundations. This anthology on the foundations of QFT brings together 15 essays by well-known researchers in physics, the philosophy of physics, and analytic philosophy.Many of these essays were first presented as papers at the conference?Ontological Aspects of Quantum Field Theory?, held at the Zentrum fr interdisziplin„re Forschung, Bielefeld, Germany. The essays contain (...) cutting-edge work on ontological aspects of QFT, including: the role of measurement and experimental evidence, corpuscular versus field-theoretic interpretations of QFT, the interpretation of gauge symmetry, and localization.This book is ideally suited to anyone with an interest in the foundations of quantum physics, including physicists, philosophers and historians of physics, as well as general readers interested in philosophy or science. (shrink)

Das sogenannte „Messproblem“ ist das zentrale Problem der Quantenmechanik, dessen Lösung das Potenzial hat, unsere Sicht der physischen Welt fundamental zu verändern. Das Problem besteht darin, dass die Quantenmechanik (QM) nicht zu dem passen will, was wir tatsächlich beobachten. Nach einer qualitativen und einer formalen Darstellung des Messproblems der QM werden in diesem Beitrag die Ansätze von Ghirardi, Rimini und Weber (GRW), von de Broglie und Bohm (dBB) sowie von Everett (Vielweltendeutung) besprochen und auf der Grundlage wissenschaftsphilosophischer Bewertungskriterien miteinander verglichen.

Quantum Field Theory (QFT) is the mathematical and conceptual framework for contemporary elementary particle physics. In a rather informal sense QFT is the extension of quantum mechanics (QM), dealing with particles, over to fields, i.e. systems with an infinite number of degrees of freedom. (See the entry on quantum mechanics.) In the last few years QFT has become a more widely discussed topic in philosophy of science, with questions ranging from methodology and semantics to ontology. QFT taken seriously in its (...) metaphysical implications seems to give a picture of the world which is at variance with central classical conceptions of particles and fields, and even with some features of QM. -/- The following sketches how QFT describes fundamental physics and what the status of QFT is among other theories of physics. Since there is a strong emphasis on those aspects of the theory that are particularly important for interpretive inquiries, it does not replace an introduction to QFT as such. One main group of target readers are philosophers who want to get a first impression of some issues that may be of interest for their own work, another target group are physicists who are interested in a philosophical view upon QFT. (shrink)

Advocates of the New Mechanicism in philosophy of science argue that scientific explanation often consists in describing mechanisms responsible for natural phenomena. Despite its successes, one might think that this approach does not square with the ontological strictures of quantum mechanics. New Mechanists suppose that mechanisms are composed of objects with definite properties, which are interconnected via local causal interactions. Quantum mechanics calls these suppositions into question. Since mechanisms are hierarchical it appears that even macroscopic mechanisms must supervene on a (...) set of “objects” that behave non-classically. In this paper we argue, in part by appeal to the theory of quantum decoherence, that the universal validity of quantum mechanics does not undermine neo-mechanistic ontological and explanatory claims as they occur within in classical domains. Additionally, we argue that by relaxation of certain classical assumptions, mechanistic explanatory strategies can sometimes be carried over into the quantum domain. (shrink)

Large changes of financial market prices without exogenous causes deviate significantly from the Gaussian behavior of random variables. This indicates that financial markets should be treated as complex systems, for which nonlinear interactions of its subunits/agents are crucial. I focus on how the complex systems perspective impacts the notion of explanations in economics. The mechanistic model seems to fit the bill, but problems surface on closer scrutiny. One characteristic of complex systems is that their behavior is surprisingly independent from microscopic (...) details. Thus, mechanistic explanations in the microreductionist manner seem unavailable. Despite these conflicts, I defend a modified structural mechanistic approach. (shrink)

Agent-based models derive the behavior of artificial socio-economic entities computationally from the actions of a large number of agents. One objection is that highly idealized ABMs fail to represent the real world in any reasonable sense. Another objection is that they at best show how observed patterns may have come about, because simulations are easy to produce and there is no evidence that this is really what happens. Moreover, different models may well yield the same result. I will rebut these (...) objections by focusing on an often neglected, but crucial function of ABMs. Building on Gelfert’s account of the exploratory uses of scientific models I show that, in the absence of an accepted underlying theory, successful ABMs lend inductive support to assumptions concerning certain structural feutures of the behavioral rules employed. One core step towards this goal is what I call multiple-model robustness analysis. (shrink)

In recent debates mechanisms are often discussed in the context of ‘complex systems’ which are understood as having a complicated compositional structure. I want to draw the attention to another, radically different kind of complex system, in fact one that many scientists regard as the only genuine kind of complex system. Instead of being compositionally complex these systems rather exhibit highly non-trivial dynamical patterns on the basis of structurally simple arrangements of large numbers of non-linearly interacting constituents. The characteristic dynamical (...) patterns in what I call “dynamically complex systems” arise from the interaction of the system’s parts largely irrespective of many properties of these parts. Dynamically complex systems can exhibit surprising statistical characteristics, the robustness of which calls for an explanation in terms of underlying generating mechanisms. However, I want to argue, dynamically complex systems are not sufficiently covered by the available conceptions of mechanisms. I will explore how the notion of a mechanism has to be modified to accommodate this case. Moreover, I will show under which conditions the widespread, if not inflationary talk about mechanisms in complex systems stretches the notion of mechanisms beyond its reasonable limits and is no longer legitimate. (shrink)

Philosophy of physics is a small but thriving research field situated at the intersection between the natural sciences and the humanities. However, what exactly distinguishes philosophy of physics from physics is rarely made explicit in much depth. We provide a detailed analysis in the form of eleven theses, delineating both the nature of the questions asked in philosophy of physics and the methodology with which they are addressed.

Quantentheorie und Relativitätstheorie haben das Weltbild der Physik revolutioniert. Beide Theorien gelten jedoch als unanschaulich und schwer verständlich. Dieses Sachbuch schafft neue Zugänge und lädt zum Mitdenken ein. Renommierte Experten aus Physik und Philosophie erläutern Grundbegriffe, Erkenntnisfortschritte und Deutungsfragen zu Raum, Zeit und Materie. Dabei kommen typische Themen aus der Philosophie der Physik zur Sprache, wie etwa die Interpretationsdebatte der Quantentheorie oder Modellbildungen in der Kosmologie. Weltbildrelevante Fragen nach dem Verhältnis von Mathematik, Empirie und Anschauung oder nach der Verlässlichkeit physikalischer (...) Erkenntnis erfordern die Verbindung von Physik und Philosophie, von fachwissenschaftlicher Grundlagenforschung und methodenkritischer Reflexion. Der thematische Bogen geht zurück auf ein hochkarätig besetztes Symposium mit populärwissenschaftlicher Ausrichtung. Das Buch enthält Beiträge von Andreas Bartels, Robert Harlander, Paul Hoyningen-Huene, Gert-Ludwig Ingold, Claus Kiefer, Meinard Kuhlmann, Klaus Mainzer, Oliver Passon, Manfred Stöckler, Rüdiger Vaas und Reinhard Werner. (shrink)

Financial theory is in trouble. Market crashes and high volatility are only too familiar to everyone, although the standard theories predict that they hardly ever occur. According to the well-known and (partly due to its simplicity) still widely used random-walk model, the probabilities for price changes of, say, stocks should result in a Gaussian distribution. However, experience tells us that large changes occur far more often than ‘allowed’ by a Gaussian distribution. New models are needed which lead to realistic probability (...) distributions. ‘Econophysicists’ are particularly active in this field by constructing microscopic models of financial markets on the basis of various ideas and tools from physics. But in which sense do these models contribute scientific explanations? In this paper I will investigate what and how one exemplary econophysics model explains. (shrink)

Viele ihrer philosophischen Probleme teilt die Quantenfeldtheorie mit der Quantenmechanik. Dazu gehören der Messprozess und die damit zusammenhängenden Interpretationsprobleme, zu denen die QFT kaum etwas Neues beiträgt. Auch die Frage, wie die Objekte, die die Theorie beschreibt, in den Raum eingebettet sind, wird schon in der Quantenmechanik diskutiert. Die neuen mathematischen Strukturen der QFT lassen allerdings auch neue Antworten erwarten, so dass die raumzeitliche Interpretation der Theorie ein wichtiges Thema wird. In diesem Kapitel werden die mathematischen Besonderheiten der QFT skizziert (...) und es wird gezeigt, dass dadurch sowohl eine Teilchen- wie auch eine Feldinterpretation ausgeschlossen wird. Zum Abschluss werden alternative Interpretationsansätze diskutiert. (shrink)

I argue that algebraic quantum field theory (AQFT) permits an undisturbed view of the right ontology for fundamental physics, whereas standard (or Lagrangian) QFT offers different mutually incompatible ontologies.My claim does not depend on the mathematical inconsistency of standard QFT but on the fact that AQFT has the same concerns as ontology, namely categorical parsimony and a clearly structured hierarchy of entities.

Dieses Buch liefert dem Leser eine aktuelle und fundierte Einführung in die Philosophie der Quantenphysik. Obwohl sich die Quantentheorie durch spektakuläre empirische Erfolge auszeichnet, wird bis heute kontrovers diskutiert, wie sie zu verstehen ist. In diesem Werk geben die Autoren einen Überblick über die zahlreichen philosophischen Herausforderungen: Verletzen Quantenobjekte das Prinzip der Kausalität? Sind gleichartige Teilchen ununterscheidbar und daher keine Individuen? Behalten Quantenobjekte in der zeitlichen Entwicklung ihre Identität? Wie verhält sich ein zusammengesetztes Quantensystem zu seinen Teilen? Diese Fragen werden (...) im Rahmen verschiedener Deutungsansätze der Quantentheorie diskutiert. Ein Ausblick in die Quantenfeldtheorie verschärft das Hauptproblem der Nichtlokalität. Philosophie der Quantenphysik richtet sich an Philosophen mit Interesse für Physik, macht Physiker mit den philosophischen Fragen ihres Faches vertraut und liefert Anregungen für den gymnasialen Physik-Unterricht. Das Buch schließt damit eine Lücke zwischen populären Einführungen und spezialisierten Monografien zur Philosophie der Quantenphysik. In der vorliegenden zweiten Auflage wurde das Kapitel zu Verschränkung und Nicht-Lokalität deutlich erweitert und jedes Kapitel mit Übungsaufgaben und Musterlösungen ergänzt. (shrink)

This book provides a thorough and up-to-date introduction to the philosophy of quantum physics. Although quantum theory is renowned for its spectacular empirical successes, controversial discussion about how it should be understood continue to rage today. In this volume, the authors provide an overview of its numerous philosophical challenges: Do quantum objects violate the principle of causality? Are particles of the same type indistinguishable and therefore not individual entities? Do quantum objects retain their identity over time? How does a compound (...) quantum system relate to its parts? These questions are answered here within different interpretational approaches to quantum theory. Finally, moving to Quantum Field Theory, we find that the problem of non-locality is exacerbated. Philosophy of quantum physics is aimed at philosophers with an interest in physics, while also serving to familiarize physicists with many of the essential philosophical questions of their subject. (shrink)

Die folgende Chronologie legt den Fokus auf die Grundlagen und Deutungen der Quantenphysik, sie ist keine Geschichte der Quantenphysik im Ganzen, insbesondere finden die speziellen Entwicklungen der Quantenfeldtheorie und der sich daraus entwickelnden Teilchenphysik keine Berücksichtigung.

Dieses Buch liefert dem Leser eine aktuelle und fundierte Einführung in die Philosophie der Quantenphysik. Obwohl sich die Quantentheorie durch spektakuläre empirische Erfolge auszeichnet, wird bis heute kontrovers diskutiert, wie sie zu verstehen ist. In diesem Werk geben die Autoren einen Überblick über die zahlreichen philosophischen Herausforderungen: Verletzen Quantenobjekte das Prinzip der Kausalität? Sind gleichartige Teilchen ununterscheidbar und daher keine Individuen? Behalten Quantenobjekte in der zeitlichen Entwicklung ihre Identität? Wie verhält sich ein zusammengesetztes Quantensystem zu seinen Teilen? Diese Fragen werden (...) im Rahmen verschiedener Deutungsansätze der Quantentheorie diskutiert. Ein Ausblick in die Quantenfeldtheorie verschärft das Hauptproblem der Nichtlokalität. Philosophie der Quantenphysik richtet sich an Philosophiestudierende mit Interesse für Physik, macht Physikerinnen und Physiker mit den philosophischen Fragen ihres Faches vertraut und liefert Lehramtsstudierenden und Lehrern Anregungen für den gymnasialen Physik-Unterricht. Das Buch schließt damit eine Lücke zwischen populären Einführungen und spezialisierten Monografien zur Philosophie der Quantenphysik im deutschsprachigen Lehrbuchmarkt. In der vorliegenden zweiten Auflage wurde das Kapitel zu Verschränkung und Nicht-Lokalität deutlich erweitert und jedes Kapitel mit Übungsaufgaben und Musterlösungen ergänzt. cord friebezurzeit="" vertretung="" der="" professur="" für="" analytische="" philosophie="" an="" universität="" des="" saarlandes.p. (shrink)

Reviewed work: Meinard Kuhlmann, Holger Lyre, and Andrew Wayne (eds.), Ontological Aspects of Quantum Field Theory. Singapore: World Scientific (2002), 376 pp.

Biodiversity sciences witness a double dynamic. Whereas the need for interdisciplinary approaches is increasingly appreciated, most disciplinary studies are still confined to developing operational, discipline-specific indices. We show that a reassessment of the general notion of biodiversity is needed to clarify this situation. We advocate a new approach, according to which the main usefulness of this notion is not to capture quantitatively biological objects or processes, but to organize meaningful and coherent interdisciplinary interactions by constructively criticizing disciplinary studies. We apply (...) this approach to ecological-economic models, in the hope of launching more fruitful critical dialogs between economists and biologists. (shrink)

Despite a strong sensitization to the corruption problem and a large body of interdisciplinary research, scientists have only rarely investigated which motivational, volitional, emotional, and cognitive components make decision makers in companies act corruptly. Thus, we examined how their interrelation leads to corruption by proposing an action model. We tested the model using a business simulation game with students as participants. Results of the PLS structural equation modeling showed that both an attitude and subjective norm favoring corruption led to a (...) desire to act corruptly. Given high perceived behavioral control, this desire was transformed into an intention that finally resulted in corrupt action. Components related to general private and professional goals did not allow for any prediction. Based on these results, we discuss preventative measures and methods for combating intra- and inter-organizational corruption. (shrink)

L’analyse de la notion de procéduralisme montre qu’elle est utilisée dans la littérature en deux sens très différents. Nous mettons en évidence une condition suffisante à la mise en cohérence de ces deux idées, basée sur une compréhension pragmatique de la notion d’acceptabilité. Nous montrons alors que l’adoption de cette condition suffisante implique que tout dépassement procéduraliste du welfarisme passe par un travail de formation des préférences.

Environmental economic valuations of biodiversity are an increasingly active field of academic inquiry, often presented as a prominent means to rationalize decision-making on environmental issues. However, the meaning of this argument is unclear, because it uses the term “rationalize” in a loose way. This argument, as it is typically formulated in the literature, makes it look as though economic valuations do not involve any value-judgment by economists: by emphasizing rationalization, this argument silences value-judgements. This blind spot is critical, since environmental (...) inequalities are pervasive in economic valuations and their applications, and environmental decision making hence unavoidably involves value-judgements. In this article, we identify conditions upon which environmental economic valuations can truly contribute to rationalizing decision making, despite environmental inequalities. We review the main arguments found in the literature to entrench the credentials of economic approaches to rationalize decision-making, and argue that these approaches fail, at a fundamental level. We then argue that the key for economic valuations to truly contribute to rationalization is that their usage should be embedded in the deployment of what we will call a justificatory task. We then take advantage of an analysis of the notion of rationality, when applied to decision-aiding processes, to translate this reasoning in the concrete terms of applications of environmental economic valuations. According to the argument that we articulate here, standard economic valuations, just like any other application of economic tools, can indeed play a role in rationalizing environmental decisions, in spite of the inequalities that they produce. But this possibility is conditioned by the requirement that the economist implementing them should produce justifications. (shrink)

Conservation biology is a branch of ecology devoted to conserving biodiversity. Because this discipline is based on the assumption that knowledge should guide actions, it endows experts with a power that should be questioned. The work of the French philosopher Michel Foucault can be seen as a relevant conceptual resource to think these aspects of conservation biology through. I critically analyse the relevance of the Foucauldian approach to conservation. I argue that Foucauldian arguments are deeply ambiguous, and therefore useless for (...) conservation purposes, unless they are supplemented with unsaid assumptions that are, depending on the case at hand, untenable, or at least at odds with basic assumptions underlying conservation biology. In any case, the prospects of using the Foucauldian approach for conservation purposes are deeply undermined. However, the Foucauldian reasoning contains some ideas that can be important and useful for conservation purposes, if they are duly clarified. (shrink)

In einem auf drei Bände angelegten Dokumentationswerk werden Entstehung und Ausbreitung des Paracelsismus in den kontroversen Verflechtungen der Wissenschafts-, Literatur- und Sozialgeschichte des späten 16. Jahrhunderts verankert. Die kritische Edition aufschlußreicher, oft in unbekanntes Terrain führender Texte ist begleitet von umfangreichen Kommentaren sowie von biographischen Darstellungen der Urheber, Adressaten, Gegner bzw. Sympathisanten der paracelsistischen Reform und Protestbewegung. Der zweite Band des »Corpus Paracelsisticum« erschließt das weitläufige Oeuvre von Michael Toxites und Gerhard Dorn, wirkmächtige Gründergestalten des oberrheinischen Paracelsismus. Von da aus (...) fällt der Blick quer über die Konfessionsgrenzen auf andere kulturelle Zentren in Bayern, Sachsen, Schlesien, Böhmen und am Niederrhein. Mit Verfassern wie G. Fedro, M. Ambrosius, L. Span, B. Flöter, G. Etschenreutter, B. Scultetus, P. Perna, Th. Zwinger und J. Albrecht eröffnet sich ein epochaler, äußerst weitläufiger Diskurszusammenhang. In ihm lassen sich doxographische, methodische, hermeneutische, sprachtheoretische und überlieferungsspezifische Auseinandersetzungen ebenso beobachten wie Tendenzen einer theosophischen Spiritualisierung und heterodoxen Aufladung der in Paracelsus' Namen entwickelten Anthropologie und Kosmologie. Direkte Verbindungen ergeben sich unter anderem zu führenden Vertretern der sogenannten Schwenckfelder, damit auch zu Fraktionen aktiver protestantischer Dissidenten. Der Band wird neben dem weiterführenden Kommentar begleitet von einer ausführlichen Einleitung und erschlossen nicht nur durch mehrere Register, sondern auch durch wissenschaftshistorische Zusammenfassungen zu jedem Autorcorpus. (shrink)

To investigate whether making performance predictions affects prospective memory processing, we asked one group of participants to predict their performance in a PM task embedded in an ongoing task and compared their performance with a control group that made no predictions. A third group gave not only PM predictions but also ongoing-task predictions. Exclusive PM predictions resulted in slower ongoing-task responding both in a nonfocal and in a focal PM task. Only in the nonfocal task was the additional slowing accompanied (...) by improved PM performance. Even in the nonfocal task, however, was the correlation between ongoing-task speed and PM performance reduced after predictions, suggesting that the slowing was not completely functional for PM. Prediction-induced changes could be avoided by asking participants to additionally predict their performance in the ongoing task. In sum, the present findings substantiate a role of metamemory for attention-allocation strategies of PM. (shrink)

We extend the characterization of extremal valued fields given in [2] to the missing case of valued fields of mixed characteristic with perfect residue field. This leads to a complete characterization of the tame valued fields that are extremal. The key to the proof is a model theoretic result about tame valued fields in mixed characteristic. Further, we prove that in an extremal valued field of finitep-degree, the images of all additive polynomials have the optimal approximation property. This fact can (...) be used to improve the axiom system that is suggested in [8] for the elementary theory of Laurent series fields over finite fields. Finally we give examples that demonstrate the problems we are facing when we try to characterize the extremal valued fields with imperfect residue fields. To this end, we describe several ways of constructing extremal valued fields; in particular, we show that in every ℵ1saturated valued field the valuation is a composition of extremal valuations of rank 1. (shrink)

We propose a new masking technique for masking word stimuli. Drawing on the phenomena of metacontrast and paracontrast, we alternately presented two prime displays of the same word with the background color in one display matching the font color in the other display and vice versa. The sequence of twenty alterations was sandwich-masked by structure masks. Using this masking technique, we conducted evaluative priming experiments with positive and negative target and prime words. Significant priming effects were found – for primes (...) and targets drawn from the same as well as from different word sets. Priming effects were independent of prime discrimination performance in direct tests and they were still significant after the sample was restricted to those participants who showed random responding in the direct test. (shrink)

While the philosophical literature has extensively studied how decisions relate to arguments, reasons and justifications, decision theory almost entirely ignores the latter notions. In this article, we elaborate a formal framework to introduce in decision theory the stance that decision-makers take towards arguments and counter-arguments. We start from a decision situation, where an individual requests decision support. We formally define, as a commendable basis for decision-aid, this individual’s deliberated judgment, a notion inspired by Rawls’ contributions to the philosophical literature, and (...) embodying the requirement that the decision-maker should carefully examine arguments and counter-arguments. We explain how models of deliberated judgment can be validated empirically. We then identify conditions upon which the existence of a valid model can be taken for granted, and analyze how these conditions can be relaxed. We then explore the significance of our framework for the practice of decision analysis. Our framework opens avenues for future research involving both philosophy and decision theory, as well as empirical implementations. (shrink)

In [F.-V. Kuhlmann, S. Kuhlmann, S. Shelah, Exponentiation in power series fields, Proc. Amer. Math. Soc. 125 3177–3183] it was shown that fields of generalized power series cannot admit an exponential function. In this paper, we construct fields of generalized power series with bounded support which admit an exponential. We give a natural definition of an exponential, which makes these fields into models of real exponentiation. The method allows us to construct for every κ regular uncountable cardinal, 2κ (...) pairwise non-isomorphic models of real exponentiation , but all isomorphic as ordered fields. Indeed, the 2κ exponentials constructed have pairwise distinct growth rates. This method relies on constructing lexicographic chains with many automorphisms. (shrink)

Transcendental pragmatics is the attempt to make Kants transcendental philosophy philosophically defensible by means of a reconstruction in terms of semiotics and the theory of communication. The central theses of transcendental pragmatics are: philosophical final justification is possible. The claim of radical fallibilism: "all propositions are fallible, therefore final justification is impossible" is false. Both theses are defended against H. Keuths critique, recently published in this journal. Radical fallibilism, which admits the application of the principle of fallibility to itself entangles (...) itself pecisely for this reason in a whole raw of contradictions. Keuths objections rest upon a misunderstanding. His critique does not demonstrate the invalidity of reflexive final justification arguments because he misses the essential feature of such arguments namely that they are intended as strictly reflexive arguments. (shrink)

Zusammenfassung. Das Arzt-Patient-Verhältnis wird zunehmend von ökonomischen Interessen überlagert. Diese explorative Studie fragt nach konsensfähigen Lösungsstrategien für die Vermittlung dieser ökonomischen Hintergründe an Patienten und nach der ärztlichen Aufklärungspraxis im klinischen Alltag. Methodisch wird eine Kombination aus einer Fragebogenstudie mit Vertretern relevanter Organisationen im Gesundheitswesen (n=132) und Interviews mit Ärztinnen und Ärzten aus unterschiedlichen klinischen Bereichen (n=15) gewählt. Ergebnisse: Trotz einer mehrheitlichen Präferenz für die wahrheitsgemäße Aufklärung über ökonomische Aspekte erfährt dieses Prinzip vielfältige Relativierungen. In der klinischen Praxis dominiert das (...) Bestreben, ökonomische Motive hinter medizinischen Begründungen zu verschweigen. Die ärztliche Informationspolitik weist eine völlig uneinheitliche und für Patienten undurchschaubare Praxis sowie eine extreme Spannbreite subjektiver Wertpräferenzen auf. (shrink)

We explain how the field of logarithmic-exponential series constructed in 20 and 21 embeds as an exponential field in any field of exponential-logarithmic series constructed in 9, 6, and 13. On the other hand, we explain why no field of exponential-logarithmic series embeds in the field of logarithmic-exponential series. This clarifies why the two constructions are intrinsically different, in the sense that they produce non-isomorphic models of Thequation image; the elementary theory of the ordered field of real numbers, with the (...) exponential function and restricted analytic functions. (shrink)

We study the algebraic implications of the non-independence property and variants thereof on infinite fields, motivated by the conjecture that all such fields which are neither real closed nor separably closed admit a henselian valuation. Our results mainly focus on Hahn fields and build up on Will Johnson’s “The canonical topology on dp-minimal fields” :1850007, 2018).

Given an ordered fieldK, we compute the natural valuation and skeleton of the ordered multiplicative group (K >0, ·, 1, <) in terms of those of the ordered additive group (K,+,0,<). We use this computation to provide necessary and sufficient conditions on the value groupv(K) and residue field $\bar K$ , for theL ∞ε-equivalence of the above mentioned groups. We then apply the results to exponential fields, and describev(K) in that case. Finally, ifK is countable or a power series field, (...) we derive necessary and sufficient conditions onv(K) and $\bar K$ forK to be exponential. In the countable case, we get a structure theorem forv(K). (shrink)