Introduction: Structuralists of the world unite

Key arguments and claims in Steven French's The Structure of the World are articulated and assessed. Differences between different forms of ontic structural realism are articulated, and some problems raised for some aspects of French's version.     

Holism and structuralism in U(1) gauge theory

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.     

Ramsey sentences, structural realism and trivial realization

Several recent authors identify structural realism about scientific theories with the claim that the content of a scientific theory is expressible using its Ramsey sentence. Many of these authors have also argued that so understood, the view collapses into empiricist anti-realism, since an argument originally proposed by Max Newman in a review of Bertrand Russell’s The analysis of matter demonstrates that Ramsey sentences are trivially satisfied, and cannot make any significant claims about unobservables. In this paper I argue against both of these claims. Structural realism and Ramsey sentence realism are, in their most defensible versions, importantly different doctrines, and neither is committed to the premises required to demonstrate that they collapse into anti-realism.     

Looking for structure in all the wrong places: Ramsey sentences, multiple realisability, and structure

‘Epistemic structural realism’ (ESR) insists that all that we know of the world is its structure, and that the ‘nature’ of the underlying elements remains hidden. With structure represented via Ramsey sentences, the question arises as to how ‘hidden natures’ might also be represented. If the Ramsey sentence describes a class of realisers for the relevant theory, one way of answering this question is through the notion of multiple realisability. We explore this answer in the context of the work of Carnap, Hintikka and Lewis. Both Carnap and Hintikka offer clear structuralist perspectives which, crucially, accommodate the openness inherent in theory change. Unfortunately there is little purchase for a viable form of realism in either case. Lewis’s approach, on the other hand, offers more scope for realism but, as we shall see, concerns arise as to whether a relevant form of structuralism can be maintained. In particular his thesis of Ramseyan humility undermines certain conceptions of scientific laws that the structural realist might naturally cleave to. Our overall conclusion is that the representational device of Ramsey sentence plus multiple realisability can accommodate either the structuralist or realist aspects of ESR but has difficulties capturing both.     

Structural realism versus deployment realism: A comparative evaluation

In this paper I challenge and adjudicate between the two positions that have come to prominence in the scientific realism debate: deployment realism and structural realism. I discuss a set of cases from the history of celestial mechanics, including some of the most important successes in the history of science. To the surprise of the deployment realist, these are novel predictive successes toward which theoretical constituents that are now seen to be patently false were genuinely deployed. Exploring the implications for structural realism, I show that the need to accommodate these cases forces our notion of “structure” toward a dramatic depletion of logical content, threatening to render it explanatorily vacuous: the better structuralism fares against these historical examples, in terms of retention, the worse it fares in content and explanatory strength. I conclude by considering recent restrictions that serve to make “structure” more specific. I show however that these refinements will not suffice: the better structuralism fares in specificity and explanatory strength, the worse it fares against history. In light of these case studies, both deployment realism and structural realism are significantly threatened by the very historical challenge they were introduced to answer.     

Introduction: Reappraising Paul Feyerabend

This volume is devoted to a reappraisal of the philosophy of Paul Feyerabend. It has four aims. The first is to reassess his already well-known work from the 1960s and 1970s in light of contemporary developments in the history and philosophy of science. The second is to explore themes in his neglected later work, including recently published and previously unavailable writings. The third is to assess the contributions that Feyerabend can make to contemporary debate, on topics such as perspectivism, realism, and political philosophy of science. The fourth and final aim is to reconsider Feyerabend's place within the history of philosophy of science in the light of new scholarship.     

Realism without tears II: The structuralist legacy of sensory physiology

This paper examines the implications of the Doctrine of Specific Nerve Energies for contemporary philosophy and psychology. Part I analyzed Johannes Peter Müller’s canonical formulation of the Doctrine, arguing that it follows from empirical results combined with methodological principles. Here, I argue that these methodological principles remain valid in psychology today, consequently, any naturalistic philosophy of perception must accept the Doctrine’s skeptical conclusion, that the qualities of our perceptual experience are not determined by, and thus do not reveal the nature of, their causes in the world. Nevertheless, this does not mean that we must be global skeptics; rather, I argue that contemporary epistemology of perception should embrace Müller’s own response to the Doctrine: epistemic structural realism. As articulated by Müller’s student, Helmholtz, structural realism follows from the Doctrine once we recognize that active exploration constitutes part of the mechanism that determines perceptual experience, a view congenial to contemporary theories of embodied perception in cognitive science. Structural realists in philosophy of science should likewise heed the lessons of the Doctrine, as it played a critical part in the early history of their view, and may still serve a constructive role as exemplar today.     

Conventionalism,structuralism and neo-Kantianism in Poincaré׳s philosophy of science

Poincaré is well known for his conventionalism and structuralism. However, the relationship between these two theses and their place in Poincaré׳s epistemology of science remain puzzling. In this paper I show the scope of Poincaré׳s conventionalism and its position in Poincaré׳s hierarchical approach to scientific theories. I argue that for Poincaré scientific knowledge is relational and made possible by synthetic a priori, empirical and conventional elements, which, however, are not chosen arbitrarily. By examining his geometric conventionalism, his hierarchical account of science and defence of continuity in theory change, I argue that Poincaré defends a complex structuralist position based on synthetic a priori and conventional elements, the mind-dependence of which precludes epistemic access to mind-independent structures.     

Looking forward,not back: Supporting structuralism in the present

The view that the fundamental kind properties are intrinsic properties enjoys reflexive endorsement by most metaphysicians of science. But ontic structural realists deny that there are any fundamental intrinsic properties at all. Given that structuralists distrust intuition as a guide to truth, and given that we currently lack a fundamental physical theory that we could consult instead to order settle the issue, it might seem as if there is simply nowhere for this debate to go at present. However, I will argue that there exists an as-yet untapped resource for arguing for ontic structuralism – namely, the way that fundamentality is conceptualized in our most fundamental physical frameworks. By arguing that physical objects must be subject to the ‘Goldilock's principle’ if they are to count as fundamental at all, I argue that we can no longer view the majority of properties defining them as intrinsic. As such, ontic structural realism can be regarded as the most promising metaphysics for fundamental physics, and that this is so even though we do not yet claim to know precisely what that fundamental physics is.     

Structural realism,mathematics, and ontology

Over the last two decades structural realism has been given progressively more elaborated formulations. Steven French has been at the forefront of the development of the most conceptually sophisticated and historically sensitive version of the view. In his book, The Structure of the World (French (2014)), French shows how structural realism, the view according to which structure is all there is (ontic structural realism), is able to illuminate central issues in the philosophy of science: underdetermination, scientific representation, dispositions, natural modality, and laws of nature. The discussion consistently sheds novel light on the problems under consideration while developing insightful and provocative views. In this paper, I focus on the status of mathematics within French's ontic structural realism, and I raise some concerns about its proper understanding vis-à-vis the realist components of the view.     

Conventionalism about what? Where Duhem and Poincaré part ways

This paper examines whether, and in what contexts, Duhem's and Poincaré's views can be regarded as conventionalist or structural realist. After analysing the three different contexts in which conventionalism is attributed to them—in the context of the aim of science, the underdetermination problem and the epistemological status of certain principles—I show that neither Duhem's nor Poincaré's arguments can be regarded as conventionalist. I argue that Duhem and Poincaré offer different solutions to the problem of theory choice, differ in their stances towards scientific knowledge and the status of scientific principles, making their epistemological claims substantially different.     

Drawing scales apart: The origins of Wilson's conception of effective field theories

This article traces the origins of Kenneth Wilson's conception of effective field theories (EFTs) in the 1960s. I argue that what really made the difference in Wilson's path to his first prototype of EFT are his long-standing pragmatic aspirations and methodological commitments. Wilson's primary interest was to work on mathematically interesting physical problems and he thought that progress could be made by treating them as if they could be analyzed in principle by a sufficiently powerful computer. The first point explains why he had no qualms about twisting the structure of field theories; the second why he divided the state-space of a toy model field theory into continuous slices by following a standard divide-and-conquer algorithmic strategy instead of working directly with a fully discretized and finite theory. I also show how Wilson's prototype bears the mark of these aspirations and commitments and clear up a few striking ironies along the way.     

Causality and chance in relativistic quantum field theories

Bell appealed to the theory of relativity in formulating his principle of local causality. But he maintained that quantum field theories do not conform to that principle, even when their field equations are relativistically covariant and their observable algebras satisfy a relativistically motivated microcausality condition. A pragmatist view of quantum theory and an interventionist approach to causation prompt the reevaluation of local causality and microcausality. Local causality cannot be understood as a reasonable requirement on relativistic quantum field theories: it is unmotivated even if applicable to them. But microcausality emerges as a sufficient condition for the consistent application of a relativistic quantum field theory.     

Structural realism beyond physics

The main purpose of this paper is to test structural realism against (one example from) the historical record. I begin by laying out an existing challenge to structural realism – that of providing an example of a theory exhibiting successful structures that were abandoned – and show that this challenge can be met by the miasma theory of disease. However, rather than concluding that this is an outright counterexample to structural realism, I use this case to show why it is that structural realism, in its current form, has trouble dealing with theories outside physics. I end by making some concrete suggestions for structural realists to pursue if, indeed, they are serious about extending structural realism to other domains.     

For or against structural realism? A verdict from high energy physics

When it comes to supporting the main ontic structural realist thesis, that we are better off with a metaphysics purged of objects, its proponents have to meet several challenges, three of which are to ensure that objects can be recast in terms of structure alone at both the level of theory and the level of ontology, to justify on physical grounds that structure exists in the world in a way that affects the goings-on in it, and to show that the relation between objects and structure is non-reciprocal, so that structure is ontologically prior to objects but not the converse. Assuming—tacitly or explicitly—that the objects of physics can be thus recast using symmetry group structure, supporters of the thesis have, therefore, to meet the remaining challenges. The present paper discusses and contests two such attempts, which typify arguments in favor of ontic structural realism from high-energy physics.     

The ontology of quantum field theory: Structural realism vindicated?

In this paper I elicit a prediction from structural realism and compare it, not to a historical case, but to a contemporary scientific theory. If structural realism is correct, then we should expect physics to develop theories that fail to provide an ontology of the sort sought by traditional realists. If structure alone is responsible for instrumental success, we should expect surplus ontology to be eliminated. Quantum field theory (QFT) provides the framework for some of the best confirmed theories in science, but debates over its ontology are vexed. Rather than taking a stand on these matters, the structural realist can embrace QFT as an example of just the kind of theory SR should lead us to expect. Yet, it is not clear that QFT meets the structuralist's positive expectation by providing a structure for the world. In particular, the problem of unitarily inequivalent representations threatens to undermine the possibility of QFT providing a unique structure for the world. In response to this problem, I suggest that the structuralist should endorse pluralism about structure.     

Relativities of fundamentality

S-dualities have been held to have radical implications for our metaphysics of fundamentality. In particular, it has been claimed that they make the fundamentality status of a physical object theory-relative in an important new way. But what physicists have had to say on the issue has not been clear or consistent, and in particular seems to be ambiguous between whether S-dualities demand an anti-realist interpretation of fundamentality talk or merely a revised realism. This paper is an attempt to bring some clarity to the matter. After showing that even antecedently familiar fundamentality claims are true only relative to a raft of metaphysical, physical, and mathematical assumptions, I argue that the relativity of fundamentality inherent in S-duality nevertheless represents something new, and that part of the reason for this is that it has both realist and anti-realist implications for fundamentality talk. I close by discussing the broader significance that S-dualities have for structuralist metaphysics and for fundamentality metaphysics more generally.     

Quantum entanglement and a metaphysics of relations

This paper argues for a metaphysics of relations based on a characterization of quantum entanglement in terms of non-separability, thereby regarding entanglement as a sort of holism. By contrast to a radical metaphysics of relations, the position set out in this paper recognizes things that stand in the relations, but claims that, as far as the relations are concerned, there is no need for these things to have qualitative intrinsic properties underlying the relations. This position thus opposes a metaphysics of individual things that are characterized by intrinsic properties. A principal problem of the latter position is that it seems that we cannot gain any knowledge of these properties insofar as they are intrinsic. Against this background, the rationale behind a metaphysics of relations is to avoid a gap between epistemology and metaphysics.     

Physics,metaphysics, dispositions,and symmetries – À la French

Recent philosophy has paid increasing attention to the nature of the relationship between the philosophy of science and metaphysics. In The Structure of the World: Metaphysics and Representation, Steven French offers many insights into this relationship (primarily) in the context of fundamental physics, and claims that a specific, structuralist conception of the ontology of the world exemplifies an optimal understanding of it. In this paper I contend that his messages regarding how best to think about the relationship are mixed, and in tension with one another. The tension is resolvable but at a cost: a weakening of the argument for French's structuralist ontology. I elaborate this claim in a specific case: his assertion of the superiority of a structuralist account of de re modality in terms of realism about laws and symmetries (conceived ontologically) over an account in terms of realism about dispositional properties. I suggest that these two accounts stem from different stances regarding how to theorize about scientific ontology, each of which is motivated by important aspects of physics.