Everything you always wanted to know about structural realism but were afraid to ask Content Type Journal Article Pages 227-276 DOI 10.1007/s13194-011-0025-7 Authors Roman Frigg, Department of Philosophy, Logic and Scientific Method, London School of Economics and Political Science, Houghton Street, London, WC2A 2AE UK Ioannis Votsis, Philosophisches Institut, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, Geb. 23.21/04.86, 40225 Düsseldorf, Germany Journal European Journal for Philosophy of Science Online ISSN 1879-4920 Print ISSN 1879-4912 Journal Volume Volume 1 Journal Issue Volume 1, Number 2.

I respond to the frequent objection that structural realism fails to sharply state an alternative to the standard predicate-logic, object / property / relation, way of doing metaphysics. The approach I propose is based on what I call a ‘math-first’ approach to physical theories (close to the so-called ‘semantic view of theories') where the content of a physical theory is to be understood primarily in terms of its mathematical structure and the representational relations it bears to physical systems, rather than (...) as a collection of sentences that attempt to make true claims about those systems (a ‘language-first’ approach). I argue that adopting the math-first approach already amounts to a form of structural realism, and that the choice between epistemic and ontic versions of structural realism is then a choice between a language-first and math-first view of metaphysics; I then explore the status of objects (and properties and relations) in fundamental and non-fundamental physics for both versions of math-first structural realism. (shrink)

The paper argues that digital ontology (the ultimate nature of reality is digital, and the universe is a computational system equivalent to a Turing Machine) should be carefully distinguished from informational ontology (the ultimate nature of reality is structural), in order to abandon the former and retain only the latter as a promising line of research. Digital vs. analogue is a Boolean dichotomy typical of our computational paradigm, but digital and analogue are only “modes of presentation” of Being (to paraphrase (...) Kant), that is, ways in which reality is experienced or conceptualised by an epistemic agent at a given level of abstraction. A preferable alternative is provided by an informational approach to structural realism, according to which knowledge of the world is knowledge of its structures. The most reasonable ontological commitment turns out to be in favour of an interpretation of reality as the totality of structures dynamically interacting with each other. The paper is the first part (the pars destruens) of a two-part piece of research. The pars construens, entitled “A Defence of Informational Structural Realism”, is developed in a separate article, also published in this journal. (shrink)

The identity and diversity of individual objects may be grounded or ungrounded, and intrinsic or contextual. Intrinsic individuation can be grounded in haecceities, or absolute discernibility. Contextual individuation can be grounded in relations, but this is compatible with absolute, relative or weak discernibility. Contextual individuation is compatible with the denial of haecceitism, and this is more harmonious with science. Structuralism implies contextual individuation. In mathematics contextual individuation is in general primitive. In physics contextual individuation may be grounded in relations via (...) weak discernibility. (shrink)

Radical ontic structural realism (ROSR) asserts an ontological commitment to ‘free-standing’ physical structures understood solely in terms of fundamental relations, without any recourse to relata that stand in these relations. Bain ([2013], pp.1621–35) has recently defended ROSR against the common charge of incoherence by arguing that a reformulation of fundamental physical theories in category-theoretic terms (rather than the usual set-theoretic ones) offers a coherent and precise articulation of the commitments accepted by ROSR. In this essay, we argue that category theory (...) does not offer a more hospitable environment to ROSR than set theory. We also show that the application of category-theoretic tools to topological quantum field theory and to algebraic generalizations of general relativity do not warrant the claim that these theories describe ‘object-free’ structures. We conclude that category theory offers little if any comfort to ROSR. 1 Introduction: Ridding Structures of Objects2 The Set-theoretic Peril for Radical Ontic Structural Realism3 Bain’s Categorial Strategy to Save Radical Ontic Structural Realism4 Throwing out the Relations with the Relata5 Categorial and Set-theoretical Structures6 Radical Suggestions from Topological Quantum Field Theory?7 Sheaves of Einstein Algebras as Radical Structures?8 Conclusions. (shrink)

More often than not, recently popular structuralist interpretations of physical theories leave the central concept of a structure insufficiently precisified. The incipient causal sets approach to quantum gravity offers a paradigmatic case of a physical theory predestined to be interpreted in structuralist terms. It is shown how employing structuralism lends itself to a natural interpretation of the physical meaning of causal set theory. Conversely, the conceptually exceptionally clear case of causal sets is used as a foil to illustrate how a (...) mathematically informed rigorous conceptualization of structure serves to identify structures in physical theories. Furthermore, a number of technical issues infesting structuralist interpretations of physical theories such as difficulties with grounding the identity of the places of highly symmetrical physical structures in their relational profile and what may resolve these difficulties can be vividly illustrated with causal sets. (shrink)

Ontic Structural Realism is a version of realism about science according to which by positing the existence of structures, understood as basic components of reality, one can resolve central difficulties faced by standard versions of scientific realism. Structures are invoked to respond to two important challenges: one posed by the pessimist meta-induction and the other by the underdetermination of metaphysics by physics, which arises in non-relativistic quantum mechanics. We argue that difficulties in the proper understanding of what a structure is (...) undermines the realist component of the view. Given the difficulties, either realism should be dropped or additional metaphysical components not fully endorsed by science should be incorporated. (shrink)

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.

Carlo Rovelli's relational interpretation of quantum mechanics holds that a system's states or the values of its physical quantities as normally conceived only exist relative to a cut between a system and an observer or measuring instrument. Furthermore, on Rovelli's account, the appearance of determinate observations from pure quantum superpositions happens only relative to the interaction of the system and observer. Jeffrey Barrett ([1999]) has pointed out that certain relational interpretations suffer from what we might call the ‘determinacy problem', but (...) Barrett misclassifies Rovelli's interpretation by lumping it in with Mermin's view, as Rovelli's view is quite different and has resources to escape the particular criticisms that Barrett makes of Mermin's view. Rovelli's interpretation still leaves us with a paradox having to do with the determinacy of measurement outcomes, which can be accepted only if we are willing to give up on certain elements of the ‘absolute’ view of the world. (shrink)

We address an argument by Floridi (Synthese 168(1):151–178, 2009; 2011a), to the effect that digital and analogue are not features of reality, only of modes of presentation of reality. One can therefore have an informational ontology, like Floridi’s Informational Structural Realism, without commitment to a supposedly digital or analogue world. After introducing the topic in Sect. 1, in Sect. 2 we explain what the proposition expressed by the title of our paper means. In Sect. 3, we describe Floridi’s argument. In (...) the following three sections, we raise three difficulties for it, (i) an objection from intuitions: Floridi’s view is not supported by the intuitions embedded in the scientific views he exploits (Sect. 4); (ii) an objection from mereology: the view is incompatible with the world’s having parts (Sect. 5); (iii) an objection from counting: the view entails that the question of how many things there are doesn’t make sense (Sect. 6). In Sect. 7, we outline two possible ways out for Floridi’s position. Such ways out involve tampering with the logical properties of identity, and this may be bothersome enough. Thus, Floridi’s modus ponens will be our (and most ontologists’) modus tollens. (shrink)

Ladyman and Ross argue that quantum objects are not individuals and use this idea to ground their metaphysical view, ontic structural realism, according to which relational structures are primary to things. LR acknowledge that there is a version of quantum theory, namely the Bohm theory, according to which particles do have denite trajectories at all times. However, LR interpret the research by Brown et al. as implying that "raw stuff" or haecceities are needed for the individuality of particles of BT, (...) and LR dismiss this as idle metaphysics. In this paper we note that Brown et al.'s research does not imply that haecceities are needed. Thus BT remains as a genuine option for those who seek to understand quantum particles as individuals. However, we go on to discuss some problems with BT which led Bohm and Hiley to modify it. This modified version underlines that, due to features such as context-dependence and non-locality, Bohmian particles have a very limited autonomy in situations where quantum effects are non-negligible. So while BT restores the possibility of quantum individuals, it also underlines the primacy of the whole over the autonomy of the parts. The later sections of the paper also examine the Bohm theory in the general mathematical context of symplectic geometry. This provides yet another way of understanding the subtle, holistic and dynamic nature of Bohmian individuals. We finally briefly consider Bohm's other main line of research, the "implicate order", which is in some ways similar to LR's structural realism. (shrink)

Ontic structural realism claims that all there is to the world is structure. But how can this slogan be turned into a worked-out metaphysics? Here I consider one potential answer: a metaphysical framework known as ‘generalism’. According to the generalist, the most fundamental description of the world is not given in terms of individuals bearing properties, but rather, general facts about which states of affairs obtain. However, I contend that despite several apparent similarities between the positions, generalism is unable to (...) capture the two main motivations for OSR. I suggest instead that OSR should be construed as a meta-metaphysical position. 1Introduction 2Motivations 2.1Theory change 2.2Permutation invariance 3Metaphysics 4Generalism 4.1Quantifier generalism 4.2Algebraic generalism 5Why Generalism Is Not Ontic Structural Realism 6Ontic Structural Realism as Meta-metaphysics 7Conclusion. (shrink)

Ontic structural realism (OSR) claims that all there is to the world is structure. But how can this slogan be turned into a worked-out metaphysics? Here I consider one potential answer: a metaphysical framework known as generalism (Dasgupta, 2009, 2016). According to the generalist, the most fundamental description of the world is not given in terms of individuals bearing properties, but rather, general facts about which states of affairs obtain. However, I contend that despite several apparent similarities between the positions, (...) generalism is unable to capture the two main motivations for OSR. I suggest instead that OSR should be construed as a meta-metaphysical position. (shrink)

Recently, there has been a debate as to whether or not the principle of the identity of indiscernibles (the PII) is compatible with quantum physics. It is also sometimes argued that the answer to this question has implications for the debate over the tenability of ontic structural realism (OSR). The central aim of this paper is to establish what relationship there is (if any) between the PII and OSR. It is argued that one common interpretation of OSR is undermined if (...) the PII turns out to be false, since it is committed to a version of the bundle theory of objects, which implies the PII. However, if OSR is understood as the physical analogue of (sophisticated) mathematical structuralism then OSR does not imply the PII. It is further noted that it is (arguably) a virtue of OSR that it is compatible with a version of the PII for possible worlds. (shrink)

Starting from the sixties of the past century theory change has become a main concern of philosophy of science. Two of the best known formal accounts of theory change are the post-Popperian theories of verisimilitude (PPV for short) and the AGM theory of belief change (AGM for short). In this paper, we will investigate the conceptual relations between PPV and AGM and, in particular, we will ask whether the AGM rules for theory change are effective means for approaching the truth, (...) i.e., for achieving the cognitive aim of science pointed out by PPV. First, the key ideas of PPV and AGM and their application to a particular kind of propositional theories - the so called "conjunctive propositions" - will be illustrated. Afterwards, we will prove that, as far as conjunctive propositions are concerned, AGM belief change is an effective tool for approaching the truth. (shrink)

The idea that there is some fundamental “level” or “ground” where our description of the world bottoms out has acquired the status of ‘the received view’ in metaphysics ; for a more recent critical defense, see Cameron, 2008). Typically this view is cashed out in terms of some set of ‘basic building blocks’ populating this level, which sits at the bottom of a hierarchy ordered according to some set of compositional principles. These fundamental building blocks are thus taken to have (...) some form of “ultimate” ontological priority with regard to everything else in the hierarchy. In this chapter I shall consider two kinds of threats to this view: the first comes from arguments against the idea of such a level in general, whereas the second concerns the nature of these occupants. As we’ll see, both these threats become entwined in the context of modern physics but I’ll conclude with a suggestion as to how this “received view” may be maintained in this context. (shrink)

In this paper, we argue that formal ontological relations avoid Bradley's reductio of relations, including his famous relation regress.

This unpublished paper, written in 2005 in the PhD philosophy program at Notre Dame, argues that algebraic structural realism faces a potentially fatal difficulty raised by the existence of inequivalent representations in quantum field theory.

'Structural realism' is a buzzword in the scientific realism debate. Various positions with diverse motivations fall under this label. A much advertised distinction is between epistemic and ontological forms of structuralism. This paper scrutinizes the alleged dichotomy between these two 'alternatives', and criticises the considerations that have been taken to motivate the ontic variety over the epistemic. I will argue that ontological structural realism is not called for within the traditional realism debate.

The objective of this thesis is to present a naturalised metaphysics of information, or to naturalise information, by way of deploying a scientific metaphysics according to which contingency is privileged and a-priori conceptual analysis is excluded (or at least greatly diminished) in favour of contingent and defeasible metaphysics. The ontology of information is established according to the premises and mandate of the scientific metaphysics by inference to the best explanation, and in accordance with the idea that the primacy of physics (...) constraint accommodates defeasibility of theorising in physics. This metametaphysical approach is used to establish a field ontology as a basis for an informational structural realism. This is in turn, in combination with information theory and specifically mathematical and algorithmic theories of information, becomes the foundation of what will be called a source ontology, according to which the world is the totality of information sources. Information sources are to be understood as causally induced configurations of structure that are, or else reduce to and/or supervene upon, bounded (including distributed and non-contiguous) regions of the heterogeneous quantum field (all quantum fields combined) and fluctuating vacuum, all in accordance with the above-mentioned quantum field-ontic informational structural realism (FOSIR.) Arguments are presented for realism, physicalism, and reductionism about information on the basis of the stated contingent scientific metaphysics. In terms of philosophical argumentation, realism about information is argued for primarily by way of an indispensability argument that defers to the practice of scientists and regards concepts of information as just as indispensable in their theories as contingent representations of structure. Physicalism and reductionism about information are adduced by way of the identity thesis that identifies the substance of the structure of ontic structural realism as identical to selections of structure existing in re to combined heterogeneous quantum fields, and to the total heterogeneous quantum field comprised of all such fields. Adjunctly, an informational statement of physicalism is arrived at, and a theory of semantic information is proposed, according to which information is intrinsically semantic and alethically neutral. (shrink)

Quantum entanglement poses a challenge to the traditional metaphysical view that an extrinsic property of an object is determined by its intrinsic properties. So structural realists might be tempted to cite quantum entanglement as evidence for structural realism. I argue, however, that quantum entanglement undermines structural realism. If we classify two entangled electrons as a single system, we can say that their spin properties are intrinsic properties of the system, and that we can have knowledge about these intrinsic properties. Specifically, (...) we can know that the parts of the system are entangled and spatially separated from each other. In addition, the concept of supervenience neither illuminates quantum entanglement nor helps structural realism. (shrink)

This project investigates naturalized metaphysics as a recent trend in analytic metaphysics originating in the naturalist attitude of James Ladyman and Don Ross in their seminal work Everything must Go: Metaphysics Naturalized (2007). The primary focus, however, will be the more recent article “Neo-Positivist Metaphysics” (2012) by Alyssa Ney that originates in this tradition. The project will conclude that naturalized metaphysics is an unsuccessful attempt at an answer to the question ’how is metaphysics possible’. More precisely, the project will establish (...) that any answer to this question must instruct how to succeed at attempts at assertions about the Kantian thing in itself. This requirement is the result of an argument that no other conception of ’reality’ is robust enough to accommodate an ambitious metaphysics. Subsequently, it will be argued that naturalized metaphysics is conceived by its proponents as an attempt at such an answer, but that naturalized metaphysics does not provide the required instruction. This problem occurs because of Carnap’s challenge to metaphysics. Carnap observes that no assertion can be made outside a linguistic framework which has the consequence that metaphysical assertions must be about the conceptual conventions of the linguistic framework rather than the thing in itself. It is the view of Ney and the other proponents of naturalized metaphysics that metaphysics is possible as a naturalized metaphysics; a metaphysics that appropriately defers or yields to the findings of science. The project argues that this requirement does nothing to ensure that Carnap’s challenge is avoided. The challenge is equally significant to naturalized and non-naturalized metaphysics, so long as both require that successful attempts at metaphysics must be assertions about the thing in itself. -/- The project concludes that until or unless Carnap’s challenge is refuted, naturalized metaphysics remain impossible, just like the metaphysics it is supposed to replace. (shrink)

It has been argued that in the context of Bohm’s approach to quantum mechanics, the postulation of a three-dimensional ontology (as opposed to a high-dimensional one) is presumed to be the only interpretation that may reliably support object-oriented realism by virtue of the fact that this ontology is approximately preserved through scientific change, at least in the classical–quantum transition. Based on an interpretative analysis of the Bohmian formulation, I shall critically evaluate the tenability of this argument. In so doing, I (...) shall argue that this formulation admits the postulation of an alternative ontology that is properly defined in a high-dimensional space, and is approximately preserved among this transition. As a result, both the three-dimensional and the high-dimensional worldviews shall form the basis of an equally reliable endorsement of object-oriented realism in the context of the Bohmian framework. I shall conclude that this argument becomes a problem of metaphysical underdetermination between a three and a high-dimensional Bohmian interpretation. (shrink)

Recent developments in the scientific realism debate have resulted in a form of ‘exemplar driven’ realism that eschews general ‘recipes’ and instead focuses on the specific, ‘local’ reasons for adopting a realist stance in particular theoretical contexts. Here I suggest that such a move highlights even more sharply the need for the realist to incorporate a health dose of metaphysics in her position, particularly when it comes to the theories associated with modern physics. Turning to another set of recent developments, (...) having to do with the relationship between metaphysics and science, I argue that the exemplar driven realist can appropriate certain current metaphysical devices to help make concrete her commitments. Specifically I focus on a kind of exemplar based structural realism and examine the adequacy of, first, the determinables-determinate relationship as presented by Wilson and, second, Paul’s ‘one category ontology, as such devices within this framework. (shrink)

Ontic structural realism constitutes a promising take on scientific realism, one that avoids the well‐known issues that realist stances have with underdetermination and theory change. In its most radical versions, ontic structural realism proposes a type of eliminativism about theoretical entities, ascribing ontological commitment only to the structures, and not to the objects appearing in our theories. More moderate versions of ontic structural realism have also been proposed, allowing for ‘thin’ objects in the ontology. This work connects these takes on (...) structural realism with the independent notion that there are two categorically different kinds of scientific theories, namely those that deal with interactions and those that deal with structural constraints – what are known as interaction and framework theories, respectively. By taking this classification seriously, one can arrive at a selective version of ontic structural realism which is better adapted to our scientific knowledge, in which eliminativist ontic structural realism constitutes a natural fit to framework theories, whereas the moderate version is connected to interaction theories. (shrink)

Scientific progress in the 20th century has shown that the structure of the world is hierarchical. A philosophical analysis of the hierarchy will bear obvious significance for metaphysics and philosophy in general. Jonathan Schaffer’s paper, “Is There a Fundamental Level?”, provides a systematic review of the works in the field, the difficulties for various versions of fundamentalism, and the prospect for the third option, i.e., to treat each level as ontologically equal. The purpose of this paper is to provide an (...) argument for the third option. The author will apply Aristotle’s theory of matter and form to the discussion of the hierarchy and develop a theory of form realism, which will grant every level with “full citizenship in the republic of being.” It constitutes an argument against ontological and epistemological reductionism. A non-reductive theory of causation is also developed against the fundamental theory of causation. (shrink)

The composition of objects is a much discussed issue in metaphysics. In this paper I look at various approaches to this issue in the context of two examples: the relationship between ‘everyday’ objects, such as tables, and their constituent physical entities, and the relationship between structures and objects, from the perspective of structural realism. My aims are first, to defend forms of eliminativism in both cases, whereby one can still make statements about the entities to be eliminated ; and second, (...) to highlight some of the metaphysical moves that are available to the structuralist in articulating their ontology. In doing so I hope also to indicate how metaphysics and the philosophy of science can be brought into a more productive relationship. (shrink)

Aristotle’s main objection to Pythagorean number ontology is that it posits as a basic subject what can exist only as inherent in a subject. I then show how contemporary structural realists posit an ontology much like that of Aristotle’s Pythagoreans. Both take the objects of knowledge to be structure, not the subject of structure. I discuss both how pancomputationalists such as Edward Fredkin approach the Pythagorean account insofar as on their account all reality can in principle be expressed as one (...) (very big) number, made up of discrete units, and even more moderate varieties of structural realism, like that of Floridi, share with pancomputationalism the aspect of “Pythagorean” ontology that Aristotle finds so objectionable: positing structure or form with no substrate. I conclude by arguing that Aristotle himself is drawn to something close or (identical) to a structural realist ontology in Metaphysics 7.3. (shrink)

I discuss some problems related to extreme mathematical realism, focusing on a recently proposed “shut-up-and-calculate” approach to physics. I offer arguments for a moderate alternative, the essence of which lies in the acceptance that mathematics is a human construction, and discuss concrete consequences of this—at first sight purely philosophical—difference in point of view.

This thesis introduces the Problem of Consciousness as an antinomy between Physicalism and Primitivism about the phenomenal. I argue that Primitivism is implausible, but is supported by two conceptual gaps. The ‘–tivity gap’ holds that physical states are objective and phenomenal states are subjective, and that there is no entailment from the objective to the subjective. The ‘–trinsicality gap’ holds that physical properties are extrinsic and phenomenal qualities are intrinsic, and that there is no entailment from the extrinsic to the (...) intrinsic. Stoljar’s Epistemic View (EV) suggests that we have a limited conception of the physical world, and that the apparent inexplicability of consciousness is merely a symptom of our ignorance. I argue that EV must satisfy two conditions which require it to specify the content of our ignorance. EV’s best hope is a Russellian appeal to our ignorance of intrinsic physical properties. After arguing in favour of this ignorance claim, I show how it undermines the –trinsicality gap. However, I suggest that the –tivity gap cannot be dealt with by the Russellian ignorance hypothesis, nor by any other version of EV. However, I then argue that the Russellian ignorance hypothesis can still be deployed as half of a hybrid account of the phenomenal. Representationalist theories of consciousness have difficulty with the –trinsicality gap, but show promise with the –tivity gap. Specifically, Kriegel’s Self-Representationalism indicates that there can indeed be an entailment from objective physical states to subjective phenomenal states. This paves the way for my hybrid account of consciousness: the subjectivity of a phenomenal state is the product of its self-representational structure, and the qualitative character of a phenomenal state is the product of the epistemically inaccessible intrinsic physical properties involved in its implementation. (shrink)