Two things about Hilary Putnam have not changed throughout his career: some (including Putnam himself) have regarded him as a “realist” and some have seen him as a philosopherwho changed his positions (certainly with respect to realism) almost continually. Apparently, what realism meant to him in the 1960s, in the late seventies and eighties, and in the nineties, respectively, are quite different things. Putnam indicates this by changing prefixes: scientific, metaphysical, internal, pragmatic, commonsense, but always realism. Encouraged by Putnam’s own (...) attempts to distinguish his views from one time to another, his work is often regarded as split between an early period of “metaphysical realism” (his characterization) and a later and still continuing period of “internal realism”. Late Putnam is understood to be a view that insists on the primacy of our practices, while the early period is taken to be a view from outside these, a “God’s Eye view”. As Putnam himself stresses (1992b), this way of dividing his work obscures continuities, the most important of which is a continuing attempt to understand what is involved in judging practices of inquiry, like science, as being objectively correct. Thus Putnam’s early and his current work appear to have more in common than the division between “early” and “late” suggests. In fact, Putnam’s earlier writings owe much of their critical force to his adopting the pragmatic perspective of an open-minded participant in practices of empirical inquiry, a stance not explicitly articulated in these writings but rather taken simply as a matter of course.1 Thus insofaras Putnam’s early writings defend a form of representational realism, they can be regarded as attempts to articulate a realist position at work inside our ordinary practices of making empirical judgments. For this reason, we begin our review of Putnam’s realisms by extracting from the early writings a core of principles that carries over into his current work but underwent significantly different interpretations over time.. (shrink)

Larry Laudan has challenged the realist to come up with a program that submits realism to "those stringent empirical demands which the realist himself minimally insists on when appraising scientific theories." This paper shows how the realist can go about taking up Laudan on this challenge; and, in such a way that the realist hypothesis actually ends up being confirmed, by any empirical standards. In other words, it is shown that we can test for convergent realism, just as readily as (...) Laudan can test for a connection between theories that are controlled by the cannons of science and their subsequent reliability. (shrink)

There is good reason to suppose that our best physical theories are false: In addition to its own internal problems, the standard formulation of quantum mechanics is logically incompatible with special relativity. I will also argue that we have no concrete idea what it means to claim that these theories are approximately true.

A popular and plausible response against Laudan's “pessimistic induction” has been what I call “preservative realism,” which argues that there have actually been enough elements of scientific knowledge preserved through major theory‐change processes, and that those elements can be accepted realistically. This paper argues against preservative realism, in particular through a critical review of Psillos's argument concerning the case of the caloric theory of heat. Contrary to his argument, the historical record of the caloric theory reveals that beliefs about the (...) properties of material caloric, rejected by subsequent theories, were indeed central to the successes of the caloric theory. Therefore caloric remains a favorable case for Laudan. Further, I argue that even confirmed cases of preservation do not warrant an inference to truth. (shrink)

Against Laudan`s "pessimistic induction", a popular and plausible response has been what I call "preservative realism", which argues that there have actually been enough elements of scientific knowledge preserved through processes of major theory-changes, and that those elements can be accepted realistically. This paper argues against preservative realism, in particular through a critical review of Psillos`s argument concerning the case of the caloric theory of heat. The historical record of the caloric theory reveals that beliefs about the properties of material (...) caloric were indeed central to the successes of the caloric theory, contrary to Psillos`s argument. Therefore caloric remains a favorable case for Laudan. Further, I argue that even confirmed cases of preservation do not warrant an inference to truth. (shrink)

It is often thought that questions of reference are crucial in assessing scientific realism, construed as the view that successful theories are at least approximately true descriptions of the unobservable; realism is justified only if terms in empirically successful theories generally refer to genuinely existing entities or properties. In this paper this view is questioned. First, it is argued that there are good reasons to think that questions of realism are largely decided by convention and carry no epistemic significance. An (...) alternative conception of realism is then proposed, which focuses on the Ramsey sentences of scientific theories, constructed in the manner of David Lewis's 'How to define theoretical terms'. It is argued that because the Ramsey sentence of a theory preserves the epistemically significant part of the theory's content without generating commitments to any particular conclusions about reference, the realism issue is better addressed by asking whether Ramsey sentences of theories, rather than the theories themselves, are approximately true. (shrink)

In his paper "A Confutation of Convergent Realism", Larry Laudan offered one of the most powerful criticisms of scientific realism. I defend here that although Laudan's criticism is right, this does not refute the realist position. The thesis that Laudan confutes is a much stronger thesis than realist needs to maintain. As I will exemplify with Salmon's statistical-relevance model, a less strict notion of explanation would allow us to claim that (approximate) truth is the best explanation for such success, even (...) if it is accepted that there can be cases of unsuccessful (approximately) true theories and cases of successful false theories. (shrink)

Many realists have maintained that the success of scientific theories can be explained only if they may be regarded as approximately true. Laurens Laudan has in turn contended that a necessary condition for a theory's being approximately true is that its central terms refer, and since many successful theories of the past have employed central terms which we now understand to be non-referential, realism cannot explain their success. The present paper argues that a realist can adopt a view of reference (...) according to which a theory might plausibly be said to be approximately true even though its central terms do not refer, or alternatively, he may construe reference in such a way as to assign reference to a range of successful older theories which includes Laudan's purported counterexamples. (shrink)

This essay contains a partial exploration of some key concepts associated with the epistemology of realist philosophies of science. It shows that neither reference nor approximate truth will do the explanatory jobs that realists expect of them. Equally, several widely-held realist theses about the nature of inter-theoretic relations and scientific progress are scrutinized and found wanting. Finally, it is argued that the history of science, far from confirming scientific realism, decisively confutes several extant versions of avowedly 'naturalistic' forms of scientific (...) realism. (shrink)

This paper concerns Jean Piaget's (1896–1980) philosophy of science and, in particular, the picture of scientific development suggested by his theory of genetic epistemology. The aims of the paper are threefold: (1) to examine genetic epistemology as a theory concerning the growth of knowledge both in the individual and in science; (2) to explicate Piaget's view of ‘scientific progress’, which is grounded in his theory of equilibration; and (3) to juxtapose Piaget's notion of progress with Thomas Kuhn's (1922–1996). Issues of (...) scientific continuity, scientific realism and scientific rationality are discussed. It is argued that Piaget's view highlights weaknesses in Kuhn's ‘discontinuous’ picture of scientific change. (shrink)

The pessimistic induction argument, most often associated with Larry Laudan, is now widely considered to be one of the main obstacles for realism. Put simply, the argument holds that since past predictively successful scientific theories have eventually been discarded, we have inductive evidence that our current theories will also be discarded one day. More precisely, Laudan undermines the inference from the explanatory and predictive success of a theory to its approximate truth and referential success. This paper criticises a particular kind (...) of realist reply to Laudan. (shrink)

This paper describes a theory of accuracy or approximate truth and applies it to problems in the realist interpretation of scientific theories. It argues not only that realism requires approximate truth, but that an adequate theory of approximation also presupposes some elements of a realist interpretation of theories. The paper distinguishes approximate truth from vagueness, probability and verisimilitude, and applies it to problems of confirmation and deduction from inaccurate premises. Basic results are cited, but details appear elsewhere. Objections are surveyed, (...) including arguments by Miller, Laymon, and Laudan. Comparison is made with Niiniluoto's theory of verisimilitude, and the utility of his theory for realism assessed. (shrink)

The intuition of the naı¨ve realist, miracle arguments notwithstanding, is countered forcefully by a host of considerations, including the possibility of underdetermination, and criticisms of abductive inferences to explanatory hypotheses. Some have suggested that an induction may be performed, from the perspective of present theories, on their predecessors. Past theories are thought to be false, strictly speaking; it is thus likely that present-day theories are also false, and will be taken as such at an appropriate future time.

I consider two transcendental arguments for realism in the philosophy of science, which are due to Roy Bhaskar (A realist theory of science, 1975) and Nancy Cartwright (The dappled world, 1999). Bhaskar and Cartwright are both influential figures, however there is little discussion of their use of transcendental arguments in the literature. Here I seek to correct this oversight. I begin by describing the role of the transcendental arguments in question, in the context of the broader philosophical theories in which (...) they are embedded, by Bhaskar and Cartwright respectively. I then consider some specific problems that arise for these particular transcendental arguments, in the context of contemporary philosophy of science. I raise two general problems for transcendental arguments for realism and I finish by spelling out what needs to be done to address the criticisms raised in this paper. (shrink)

In the face of argument to the contrary, it is shown that there is defensible middle ground available for entity realism, between the extremes of scientific realism and empiricist antirealism. Cartwright's ([1983]) earlier argument for defensible middle ground between these extremes, which depended crucially on the viability of an underdeveloped distinction between inference to the best explanation (IBE) and inference to the most probable cause (IPC), is examined and its defects are identified. The relationship between IBE and IPC is clarified (...) and a revised version of Cartwright's argument for defensible middle ground, which is free of the identified defects, is presented. (shrink)

The business of Selective Realism, is to distinguish the denoting terms from the nondenoting terms in our best scientific theories. This is no easy matter, and despite agreement amongst many philosophers of science that at least some of our scientific vocabulary denotes and some does not, there is very little agreement about how the demarcation in question is to be affected.1 One strategy that enjoys fairly widespread support, however, is the appeal to a causal test.2 According to this view, the (...) only terms that are taken to denote are those concerning causally active entities. Such an approach rules against the existence of abstracta but maintains realism about theoretical entities such as electrons and the like. In this paper I will consider one important defence of such a test due to David Armstrong. I argue that this defence fails because of its reliance on the assumption that only causally active entities can have explanatory power.. (shrink)

Hacking (1983) introduces an attempt to defend scientific realism on the basis of the reality of theoretical entities. This position, which is called entity realism, is based on disconnecting the reality of theoretical entities from the truth and explanatory power of theories that account for them. In this way, two problems can be avoided. First if theories about theoretical entities are rejected, the entities themselves do not have to go with them, and the realist thesis that we can have knowledge (...) of what exists in the world can be sustained. Second, theoretical entities, which will replace theories as the grounds for the realist position, would be protected from attacks on the validity of the inference to the best explanation which underlies classical or "theory" realism. In other words, theoretical entities would be able to survive the collapse of the inference to the best explanation. The subject of this paper is a critique of this line of defending realism. (shrink)

In its original form due to Ian Hacking, entity realism postulates a criterion of manipulative success which replaces explanatory virtue as the criterion of justified scientific belief. The article analyses the foundations on which this postulate rests and identifies the conditions on which one can derive a form of entity realism from it. It then develops in detail an extensive class of counterexamples, drawing on the notion of quasi-particles in condensed matter physics. While the phenomena associated with quasi-particles pass the (...) entity realist's criterion of manipulative success, quasi-particles themselves are illusions, and can be seen to be so even on the basis of the largely non-theoretical "home truths" that one must be ready to admit as background knowledge. Hence, Hacking's entity realism is shown to be incoherent. (shrink)

This is a lively and clearly written introduction to the philosophy of natural science, organized around the central theme of scientific realism. It has two parts. 'Representing' deals with the different philosophical accounts of scientific objectivity and the reality of scientific entities. The views of Kuhn, Feyerabend, Lakatos, Putnam, van Fraassen, and others, are all considered. 'Intervening' presents the first sustained treatment of experimental science for many years and uses it to give a new direction to debates about realism. Hacking (...) illustrates how experimentation often has a life independent of theory. He argues that although the philosophical problems of scientific realism can not be resolved when put in terms of theory alone, a sound philosophy of experiment provides compelling grounds for a realistic attitude. A great many scientific examples are described in both parts of the book, which also includes lucid expositions of recent high energy physics and a remarkable chapter on the microscope in cell biology. (shrink)

It is widely believed that many of the competing accounts of scientific explanation have ramifications which are relevant to the scientific realism debate. I claim that the two issues are orthogonal. For definiteness, I consider Cartwright's argument that causal explanations secure belief in theoretical entities. In Section I, van Fraassen's anti-realism is reviewed; I argue that this anti-realism is, prima facie, consistent with a causal account of explanation. Section II reviews Cartwright's arguments. In Section III, it is argued that causal (...) explanations do not license the sort of inferences to theoretical entities that would embarass the anti-realist. Section IV examines the epistemic commitments involved in accepting a causal explanation. Section V presents my conclusions: contra Cartwright, the anti-realist may incorporate a causal account of explanation into his vision of science in an entirely natural way. (shrink)

The issue of scientific realism is discussed in terms of the specific details of the practice of experimental meson and baryon spectroscopy in the field of High-Energy Physics (HEP), during the period from 1966 to 1970. The philosophical positions of I. Hacking, A. Fine, J. Leplin, and N. Rescher that concern scientific realism are presented in such a manner as to allow for the evaluation of their appropriateness in the description of this experimental research field. This philosophical analysis focuses on (...) the empirical adequacy of these four philosophical models that purport to describe the process of acquiring knowledge of the physical world. In this specific case, an experiment performed by the HEP research group at the University of Notre Dame to study the scattering interaction. (shrink)

The goal of this paper is to defend the claim that there is such a thing as direct perception, where by ‘direct perception’ I mean perception unmediated by theorizing or concepts. The basis for my defense is a general philosophic perspective which I call ‘empiricist philosophy’. In brief, empiricist philosophy (as I have defined it) is untenable without the occurrence of direct perception. It is untenable without direct perception because, otherwise, one can't escape the hermeneutic circle, as this phrase is (...) used in van Fraassen (1980). The bulk of the paper is devoted to defending my belief in direct perception against various objections that can be posed against it. I discuss various anticipations of my view found in the literature, eventually focusing on Ian Hacking's related conception of `entity realism' (Hacking 1983). Hacking has been criticized by a number of philosophers and my plan is to respond to these criticisms on behalf of entity realism (or more precisely on behalf of the claim that direct perception is a reality) and to then respond to other possible criticisms that can be launched against direct perception. (shrink)

Experimental realism aims at striking a middle ground between scientific realism and anti-realism, between the success of experimental physics it would explain and the realism about scientific theories it would supplant. This middle ground reinstates the engineering idea that belief in scientific entities is justified on purely experimental grounds, without any commitment to scientific theories and laws. This paper argues that there is no defensible middle ground to be staked out when it comes to justifying physicists' belief in colored quarks, (...) and that experimental realism shifts, under analysis, into scientific realism. (shrink)

With the careful use of the polywater episode in the history of chemistry as a case study, I will show that the distinction recently made in the philosophy of science between experimenting on an entity and manipulating that entity is best seen as a distinction between experimenting on, and experimenting with, that entity. The polywater case also reveals that Ian Hacking's 1983 manipulability criterion is not a necessary condition for realism, and that scientists can, and do, justifiably change their minds (...) as to the reality of theoretical entities. (shrink)

A leaf falls to the ground, wafting lazily on the afternoon breeze. Clouds move across the sky, and birds sing. Are these events governed by universal laws of nature, laws that apply everywhere without exception, subsuming events such as the falling of the leaf, the movement of the clouds and the singing of the birds? Are such laws part of a small set of fundamental laws, or descended from such a set, which govern everything there is in the world?

Nancy Cartwright relies upon an inference pattern known as inference to the best causal explanation (IBCE) to support a limited form of entity realism, according to which we are warranted in believing in entities that purportively cause observable effects. IBCE, as usually understood, is valid, even though all other forms of inference to the best explanation (IBE) are usually understood to be invalid. We argue that IBCE and IBE are in the same boat with respect to their ability to support (...) realist conclusions. Either rule can be interpreted as valid, this is a matter of semantic convention. However, doing so deprives the rule of the empirical content the realist needs, requiring the realist to find independent warrant for a strong (theoretical or causal) premise. We then examine the proposed means of obtaining this warrant, and find them as inadequate in the case of IBCE as they are in the case of IBE. (shrink)

In this paper I develop five worries concerning Cartwright’s realism about entities and capacities. The first is that while she was right to insist on the ontic commitment that flows from causal explanation, she was wrong to tie these commitments solely to the entities that do the causal explaining. This move obscured the nature of causal explanation and its connection to laws. The second worry is that when she turned her attention to causal inference, by insisting on the motto of (...) ‘the most likely cause’, she underplayed her powerful argument for realism. For she focused her attention on an extrinsic feature of causal inference (or, indeed, of any ampliative inference), that is the demand of high probability, leaving behind the intrinsic qualities that causal explanation should have in order to provide the required understanding. The third worry is that her objections to Inference to the Best Explanation were unnecessarily tied to her objections about the falsity of fundamental laws. The fourth worry is that though her argument for positing capacities and being realist about them was supposed to take strength from its parallel with Sellars’s powerful argument for the indispensable explanatory role of positing unobservable entities, there are important disanalogies between the two arguments which cast doubt on the indispensability of capacities. The final (fifth) worry is that laws—perhaps brute regularities—might well have to come back from the front door, since they are still the most plausible candidates for explaining why objects have the capacities to do what they can do. (shrink)

As Laudan and Fine show, and Boyd concedes, the attempt to infer the truth of scientific realism from the fact that it putatively provides the best explanation of the instrumental success of science is circular, since what is to be shown is precisely the legitimacy of such abductive inferences. Hacking's "experimental argument for scientific realism about entities" is one of the few arguments for scientific realism that purports to avoid this circularity. We argue that Hacking's argument is as dependent on (...) inference to the best explanation (IBE), and therefore as weak, as the other realist arguments. (shrink)

In Extragalactic Reality: The Case of Gravitational Lensing Hacking resumes the discussion of scientific realism from the last chapter of Representing and Intervening. Since the criterion of manipulability cannot be applied to astronomical objects, experimental entity realism seems to be restricted to terrestrial entities. In fact, Hacking explicitly argues against astronomical realism. The case at issue is the existence of gravitational lenses. In this paper, I question Hacking's chief witness for astronomical antirealism: the gravitational lens system “0957+ (...) 561”. It will be shown that Hacking's argumentation is misleading. Discussing astronomical realism as theory realism, Hacking focuses on the question of how to infer the existence of gravitational lenses from the truth of gravitational lens theory. But neither the reconstruction of gravitational lensing in terms of inference to the best explanation (IBE) nor the argument of underdetermination are tenable under closer inspection. My thesis is that a realist account of gravitational lensing can be given by relying on observation, causal capacities and home truths. (shrink)

Representing and Reconstructing: A Hermeneutical Reply to Ian Hacking. Hacking published in 1983 Representing and Intervening which has provoked, particularly in the US, the so called realism/anti-realism debate which is still alive today. He lays claim to anti-realism for theory and to realism for the experiment. Following him, only that which can be used for manipulating something (e.g., the path of an electon) is realistic. H. Putnam is a severe critic of this dualism. In my paper I am (...) going to take the Hacking-Putnam controversy as a starting-point for the problem about the determination of the relation between theory and experiment in the natural sciences. I shall then follow M. Schlick's discussion of this problem and the current solution to the problem as offered by H. Pietschmann. The differing interpretation of Kant according to the three perspectives shall be the guideline for the argumentation. The goal of my argumentation is that theory and experiment do not live their own lives, that in experimenting one always continues traditional chains of action, and that natural science cannot be regarded independently of the life world it takes place in. This insight into the representing and reconstructing overturns in natural science, due to the necessity of human decisions, opens up their hermeneutical dimension. (shrink)

Hacking argues against van Fraassen's constructive empiricism by appeal to features of microscopic imaging. Hacking relies on both our practices involving imaging instruments and the structure of the images produced by these micropractices. Van Fraassen's reply is formally correct yet fundamentally unsatisfying. I aim to strengthen van Fraassen's reply, but must then extend constructive empiricism, specifically the central notion of "theoretical immersion." I argue that immersion is more analogous to entering a virtual reality than to learning a language. This metaphor (...) assimilates instrument-based practice as well as theoretical debate and explanation, and can provide an anti-realist view of our micro-practices consonant with constructive empiricism. (shrink)

On a purely epistemic understanding of experimental realism, manipulation affords a particularly robust kind of causal warrant, which is – like any other warrant – defeasible. I defend a version of Nancy Cartwright’s inference to the most likely cause, and I conclude that this minimally epistemic version of experimental realism is a coherent, adequate and plausible epistemology for science.

On a purely epistemic understanding of experimental realism, manipulation affords a particularly robust kind of causal warrant, which is – like any other warrant – defeasible. I defend a version of Nancy Cartwright’s inference to the most likely cause, and I conclude that this minimally epistemic version of experimental realism is a coherent, adequate and plausible epistemology for science.

This paper develops a phenomenological defense of Ian Hacking's experimental realism about unobservable entities in physical science, employing historically undervalued resources from the phenomenological tradition in order to clarify the warrant for our ontological commitments in science. Building upon the work of Husserl, Merleau-Ponty and Heelan, the paper provides a phenomenological correction of the positivistic conception of perceptual evidence maintained by antirealists such as van Fraassen, the experimental relevance of which is illustrated through a phenomenological interpretation of the 1974 discovery (...) of the J/ ψ particle generally regarded as evidence for the charmed quark. The argument then turns to address known problems in Hacking's account, demonstrating that his own instrumentalist criterion of the real is inadequately rooted in the phenomenology of perception, and as a result, passes over the true ontological significance of experimental phenomena. The paper maintains that the proper criterion, only indirectly related to instrumentality, is the distinctive style of the real encountered in perception: empirical pregnancy. With this notion and Merleau-Ponty's associated reversibility thesis, I show that the phenomenological tradition provides insights into the warrant for our realist commitments that have yet to be adequately acknowledged by philosophers of science. (shrink)

The paper is focused on some aspects of experimental realism of Ian Hacking, and especially on his manipulability criterion of existence. The problem is here related to chemical molecules, the objects of interest in chemical research. The authors consider whether and to what extent this criterion has been applied in experimental practice of chemistry. They argue that experimentation on is a fundamental criterion of existence of entities in chemistry rather than experimentation with. Some examples regarding studies of structures of complex (...) compounds, taken from organic chemistry, are presented to support the authors' considerations. Chemists' laboratory practice depends strongly on the way that representations of entities on (or with) the experiments are used. The authors show that this point has not been given sufficient attention by the new experimentalists. (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)

Radical Ontic Structural Realism (ROSR) claims that structure exists independently of objects that may instantiate it. Critics of ROSR contend that this claim is conceptually incoherent, insofar as, (i) it entails there can be relations without relata, and (ii) there is a conceptual dependence between relations and relata. In this essay I suggest that (ii) is motivated by a set-theoretic formulation of structure, and that adopting a category-theoretic formulation may provide ROSR with more support. In particular, I consider how a (...) category-theoretic formulation of structure can be developed that denies (ii), and can be made to do work in the context of formulating theories in physics. Keywords: structural realism, category theory, general relativity.. (shrink)

In the debate over scientific realism, attention has been given recently to a realist position referred to as structural realism. In this essay, I offer a version of this position and indicate how it addresses two standard forms of underdetermination argument posed by the anti-realist.

The focus of this paper is the recent revival of interest in structuralist approaches to science and, in particular, the structural realist position in philosophy of science . The challenge facing scientific structuralists is three-fold: i) to characterize scientific theories in ‘structural’ terms, and to use this characterization ii) to establish a theory-world connection (including an explanation of applicability) and iii) to address the relationship of ‘structural continuity’ between predecessor and successor theories. Our aim is to appeal to the notion (...) of shared structure between models to reconsider all of these challenges, and, in so doing, to classify the varieties of scientific structuralism and to offer a ‘minimal’ construal that is best viewed from a methodological stance. (shrink)

Abstract: According to Luciano Floridi (2008) , informational structural realism provides a framework to reconcile the two main versions of realism about structure: the epistemic formulation (according to which all we can know is structure) and the ontic version (according to which structure is all there is). The reconciliation is achieved by introducing suitable levels of abstraction and by articulating a conception of structural objects in information-theoretic terms. In this essay, I argue that the proposed reconciliation works at the expense (...) of realism. I then propose an alternative framework, in terms of partial structures, that offers a way of combining information and structure in a realist setting while still preserving the distinctive features of the two formulations of structural realism. Suitably interpreted, the proposed framework also makes room for an empiricist form of informational structuralism (structural empiricism). Pluralism then emerges. (shrink)

Scientific change has two important dimensions: conceptual change and structural change. In this paper, I argue that the existence of conceptual change brings serious difficulties for scientific realism, and the existence of structural change makes structural realism look quite implausible. I then sketch an alternative account of scientific change, in terms of partial structures, that accommodates both conceptual and structural changes. The proposal, however, is not realist, and supports a structuralist version of van Fraassen’s constructive empiricism (structural empiricism).

Abstract. I argue that pessimistic meta-induction (PMI) seems to point an ontological priority of the relations over the objects of the scientific theories of the kind suggested by French and Ladyman (French and Ladyman 2003). My strategy will involve a critical examination of epistemic structural realism (ESR) and historical case-study: the prediction of Zeeman’s effect in Lorentz’s theory of electron.

Structural realism has recently re-entered mainstream discussions in the philosophy of science. The central notion of structure, however, is contested by both advocates and critics. This paper briefly reviews currently prominent structuralist accounts en route to proposing a metaphysics of structure that is capable of supporting the epistemic aspirations of realists, and that is immune to the charge most commonly levelled against structuralism. This account provides an alternative to the existing epistemic and ontic forms of the position, incorporating elements of (...) both. Structures are here identified with relations between first order, causal properties: properties that confer specific dispositions for relations. This form of structuralism constitutes an explicit proposal for what seem implicit structuralist tendencies in sophisticated but more traditional characterizations of realism. An outline of the proposal's response to the anti-realist's pessimistic induction on the history of scientific theories is considered. (shrink)

This paper explores the consequences of the two most prominent forms of contemporary structural realism for the notion of objecthood. Epistemic structuralists hold that we can know structural aspects of reality, but nothing about the natures of unobservable relata whose relations define structures. Ontic structuralists hold that we can know structural aspects of reality, and that there is nothing else to know—objects are useful heuristic posits, but are ultimately ontologically dispensable. I argue that structuralism does not succeed in ridding a (...) structuralist ontology of objects. (shrink)

The intuition of the naı¨ve realist, miracle arguments notwithstanding, is countered forcefully by a host of considerations, including the possibility of underdetermination, and criticisms of abductive inferences to explanatory hypotheses. Some have suggested that an induction may be performed, from the perspective of present theories, on their predecessors. Past theories are thought to be false, strictly speaking; it is thus likely that present-day theories are also false, and will be taken as such at an appropriate future time.

Ladyman, Ross and their collaborators (Spurrett is a co-author of two chapters, Collier of one) begin their book with a ferocious attack on "analytic metaphysics", as it is currently practiced. Their opening blast claims that contemporary analytic metaphysics 'contributes nothing to human knowledge': its practitioners are 'wasting their talents', and the whole enterprise, although 'engaged in by some extremely intelligent and morally serious people, fails to qualify as part of the enlightened pursuit of objective truth, and should be discontinued' (vii). (...) They set out on a 'mission of disciplinary rescue' in the spirit of Hume and the logical positivists, in which a fair proportion of philosophy as currently practiced -- as they realize, their critique applies far beyond the boundaries of metaphysics proper -- will be consigned to the flames. (shrink)

We first introduce structural realism as a position in the metaphysics of science, pointing out the way in which this position replaces intrinsic properties with relations so that it amounts to a holistic in contrast to an atomistic metaphysics. We argue in favour of a moderate version of structural realism that puts objects and relations on the same ontological footing and assess the general philosophical arguments for this position. The second section shows how structural realism gains support from quantum physics. (...) The third section explains how structural realism can be applied to the metaphysics of space-time. (shrink)

Ontic structural realism is the view that structures are what is real in the first place in the domain of fundamental physics. The structures are usually conceived as including a primitive modality. However, it has not been spelled out as yet what exactly that modality amounts to. This paper proposes to fill this lacuna by arguing that the fundamental physical structures possess a causal essence, being powers. Applying the debate about causal vs categorical properties in analytic metaphysics to ontic structural (...) realism, I show that the standard argument against categorical and for causal properties holds for structures as well. Structural realism, as a position in the metaphysics of science that is a form of scientific realism, is committed to causal structures. The metaphysics of causal structures is supported by physics, and it can provide for a complete and coherent view of the world that includes all domains of empirical science. (shrink)

This paper sets out a moderate version of metaphysical structural realism that stands in contrast to both the epistemic structural realism of Worrall and the—radical—ontic structural realism of French and Ladyman. According to moderate structural realism, objects and relations (structure) are on the same ontological footing, with the objects being characterized only by the relations in which they stand. We show how this position fares well as regards philosophical arguments, avoiding the objections against the other two versions of structural realism. (...) In particular, we set out how this position can be applied to space-time, providing for a convincing understanding of space-time points in the standard tensor formulation of general relativity as well as in the fibre bundle formulation. (shrink)

The paper spells out five different accounts of the relationship between objects and relations three of which are versions of ontic structural realism (OSR). We argue that the distinction between objects and properties, including relations, is merely a conceptual one by contrast to an ontological one: properties, including relations, are modes, that is the concrete, particular ways in which objects exist. We then set out moderate OSR as the view according to which irreducible relations are central ways in which the (...) fundamental physical objects exist. Physical structures thus consist in objects for whom it is essential that they are related in certain ways. There hence are objects, but they do not possess an intrinsic identity. This view can also admit intrinsic properties as ways in which objects exist provided that these do not amount to identity conditions for the objects. Finally, we indicate how this view can take objective modality into account. (shrink)

This is the revised version of an invited keynote lecture delivered at the 1st Australian Computing and Philosophy Conference (CAP@AU; the Australian National University in Canberra, 31 October–2 November, 2003). The paper is divided into two parts. The first part defends an informational approach to structural realism. It does so in three steps. First, it is shown that, within the debate about structural realism (SR), epistemic (ESR) and ontic (OSR) structural realism are reconcilable. It follows that a version of OSR (...) is defensible from a structuralist-friendly position. Second, it is argued that a version of OSR is also plausible, because not all relata (structured entities) are logically prior to relations (structures). Third, it is shown that a version of OSR is also applicable to both sub-observable (unobservable and instrumentally-only observable) and observable entities, by developing its ontology of structural objects in terms of informational objects. The outcome is informational structural realism, a version of OSR supporting the ontological commitment to a view of the world as the totality of informational objects dynamically interacting with each other. The paper has been discussed by several colleagues and, in the second half, ten objections that have been moved to the proposal are answered in order to clarify it further. (shrink)

According to ‘Ontic Structural Realism’ (OSR), physical objects—qua metaphysical entities—should be reconceptualised, or, more strongly, eliminated in favour of the relevant structures. In this paper I shall attempt to articulate the relationship between these putative objects and structures in terms of certain accounts of metaphysical dependence currently available. This will allow me to articulate the differences between the different forms of OSR and to argue in favour of the ‘eliminativist’ version. A useful context is provided by Floridi’s account of the (...) relationship between ‘ontic’ and ‘epistemic’ structural realisms and I shall conclude with some brief remarks on possible extensions of OSR into other scientific domains. (shrink)

Within the philosophy of science, the realism debate has been revitalised by the development of forms of structural realism. These urge a shift in focus from the object oriented ontologies that come and go through the history of science to the structures that remain through theory change. Such views have typically been elaborated in the context of theories of physics and are motivated by, first of all, the presence within such theories of mathematical equations that allow straightforward representation of the (...) relevant structures; and secondly, the implications of such theories for the individuality and identity of putative objects. My aim in this talk is to explore the possibility of extending such views to biological theories. An obvious concern is that within the context of the latter it is typically insisted that we cannot find the kinds of highly mathematised structures that structural realism can point to in physics. I shall indicate how the model-theoretic approach to theories might help allay such concerns. Furthermore, issues of identity and individuality also arise within biology. Thus Dupre has recently noted that there exists a ‘General Problem of Biological Individuality’ which relates to the issue of how one divides ‘massively integrated and interconnected’ systems into discrete components. In response Dupre advocates a form of ‘Promiscuous Realism’ that holds, for example, that there is no unique way of dividing the phylogenetic tree into kinds. Instead I shall urge serious consideration of those aspects of the work of Dupre and others that lean towards a structuralist interpretation. By doing so I hope to suggest possible ways in which a structuralist stance might be extended to biology. (shrink)

Howard argues that the existence of unitarily inequivalent representations in Quantum Field Theory presents a problem for structural realism in this context. I consider two potential ways round this problem: 1), follow Wallace in adopting the 'naive' Lagrangian form of QFT with cut-offs; 2), adapt Ruetsche's 'Swiss Army Knife' approach. The first takes us into the current debate between Wallace and Fraser on conventional vs. algebraic QFT. The second involves consideration of the role of inequivalent representations in understanding spontaneous symmetry (...) breaking and quantum statistics. In both cases, I suggest, the structural realist has sufficient room to manoeuvre. (shrink)

We outline Ladyman's 'metaphysical' or 'ontic' form of structuralrealism and defend it against various objections. Cao, in particular, has questioned theview of ontology presupposed by this approach and we argue that by reconceptualisingobjects in structural terms it offers the best hope for the realist in thecontext of modern physics.

The central concern of this paper is whether the Semantic Approach to theories has the resources to appropriately capture the core tenets of structural realism. Chakravartty, for example, has argued that a realist notion of correspondence cannot be accommodated without introducing a linguistic component which undermines the Approach itself. We suggest first of all, that this worry can be addressed by an appropriate understanding of the role of language with respect to the Semantic Approach. Secondly, we argue that an appropriately (...) structuralist account of representation can serve the structural realist’s needs. However, the real challenge, we feel, is whether a core notion of ‘explanatory approximate truth’ can be incorporated into this account and in such a way that the emphasis on structure is retained. The extent to which this challenge can be met is something on which even the authors are divided! (shrink)

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.

According to the semantic view of scientific theories, theories are classes of models. I show that this view -- if taken seriously as a formal explication -- leads to absurdities. In particular, this view equates theories that are truly distinct, and it distinguishes theories that are truly equivalent. Furthermore, the semantic view lacks the resources to explicate interesting theoretical relations, such as embeddability of one theory into another. The untenability of the semantic view -- as currently formulated -- threatens to (...) undermine scientific structuralism. (shrink)

In this article I discuss a recent argument due to Dan McArthur, who suggests that the charge that Michael Friedman?s relativised a priori leads to irrationality in theory change can be avoided by adopting structural realism. I provide several arguments to show that the conjunction of Friedman?s relativised a priori with structural realism cannot make the former avoid the charge of irrationality. I also explore the extent to which Friedman?s view and structural realism are compatible, a presupposition of McArthur?s argument. (...) This compatibility is usually questioned, due to the Kantian aspect of Friedman?s view, which clashes with the metaphysical premise of scientific realism. I argue that structural realism does not necessarily depend on this premise and as a consequence can be compatible with Friedman?s view, but more importantly I question whether Friedman?s view really implies mind dependence. (shrink)

Structural realism has been proposed as an epistemological position interpolating between realism and sceptical anti-realism about scientific theories. The structural realist who accepts a scientific theory Theta thinks that Theta is empirically correct, and furthermore is a realist about the ‘structural content’ of Theta. But what exactly is ‘structural content’? One proposal is that the ‘structural content’ of a scientific theory may be associated with its Ramsey sentence R(Theta). However, Demopoulos and Friedman argued, using ideas drawn from Newman’s earlier criticism (...) of Russell’s structuralism, that this move fails to achieve an interesting intermediate position between realism and anti-realism. Rather, R(Theta) adds little content beyond the instrumentalistically acceptable claim that the theory Theta is empirically adequate. Here, we formulate carefully the crucial claim of Demopoulos and Friedman, and show that the Ramsey sentence R(Theta) is true just in case Theta possesses a full model which is empirically correct and satisfies a certain cardinality condition on its theoretical domain. This suggests that structural realism is not a position significantly different from the anti-realism it attempts to distinguish itself from. (shrink)

After sorting different structuralist claims, I argue that structural realist ideas are instantiated in the social sciences, providing both clarification of social science research and support for some components of structural realism. My main focus is on three distinct ways that the social sciences can be about structural relations—exemplified by claims about social structure, reduced form structures in causal modeling, and equilibrium explanations—and on the implication of structuralist ideas for thinking about issues concerning causal explanation and nonreductive pictures of the (...) unity of the science. †To contact the author, please write to: Department of Philosophy, 900 13th Street South, University of Alabama at Birmingham, Birmingham, AL 35294; e‐mail: kincaid@uab.edu. (shrink)

The 'ontic' form of structural realism (OSR), roughly speaking, aims at a complete elimination of objects of the discourse of scientific theories, leaving us with structures only. As put by the defenders of such a claim, the idea is that all there is are structures and, if the relevant structures are to be set theoretical constructs, as it has also been claimed, then the relations which appear in such structures should be taken to be 'relations without the relata'. As far (...) as we know, there is not a definition of structure in standard mathematics which fits their intuitions, and even category theory seems do not correspond adequately to the OSR claims. Since OSR is also linked to the semantic approach to theories, the structures to be dealt with are (at least in principle) to be taken as set theoretical constructs. But these are 'relational' structures where the involved relations are built from basic objects (in short, the rank of the relation is greater than the rank of the relata), and so no elimination of the relata is possible, although it would be interesting for characterizing OSR. In this paper we present a definition of a relation which does not depend on the particular objects being related in the sense that the 'relation' continues to hold even if the relata are exchanged by other suitable ones. Although there is not a 'complete' elimination of the relata, there is an elimination of 'particular' relata, and so our definition might be viewed as an alternative way of finding adequate mathematical 'set-theoretical' frameworks for describing at least some of the intuitions regarding OSR. (shrink)

Structural realism is considered by many realists and antirealists alike as the most defensible form of scientific realism. There are now many forms of structural realism and an extensive literature about them. There are interesting connections with debates in metaphysics, philosophy of physics and philosophy of mathematics. This entry is intended to be a comprehensive survey of the field.

The aim of this paper is to revisit the phlogiston theory to see what can be learned from it about the relationship between scientific realism, approximate truth and successful reference. It is argued that phlogiston theory did to some extent correctly describe the causal or nomological structure of the world, and that some of its central terms can be regarded as referring. However, it is concluded that the issue of whether or not theoretical terms successfully refer is not the key (...) to formulating the appropriate form of scientific realism in response to arguments from theory change, and that the case of phlogiston theory is shown to be readily accommodated by ontic structural realism. (shrink)

The primacy of physics generates a philosophical problem that the naturalist must solve in order to be entitled to an egalitarian acceptance of the ontological commitments he or she inherits from the special sciences and fundamental physics. The problem is the generalized causal exclusion argument. If there is no genuine causation in the domains of the special sciences but only in fundamental physics then there are grounds for doubting the existence of macroscopic objects and properties, or at least the concreteness (...) of them. The aim of this paper is to show that the causal exclusion problem derives its force from a false dichotomy between Humeanism about causation and a notion of productive or generative causation based on a defunct model of the physical world. †To contact the author, please write to: Department of Philosophy, University of Bristol, 9 Woodland Rd., Bristol BS8 1TB, UK. (shrink)

Recent semantic approaches to scientific structuralism, aiming to make precise the concept of shared structure between models, formally frame a model as a type of set-structure. This framework is then used to provide a semantic account of (a) the structure of a scientific theory, (b) the applicability of a mathematical theory to a physical theory, and (c) the structural realist’s appeal to the structural continuity between successive physical theories. In this paper, I challenge the idea that, to be so used, (...) the concept of a model and so the concept of shared structure between models must be formally framed within a single unified framework, set-theoretic or other. I first investigate the Bourbaki-inspired assumption that structures are types of set-structured systems and next consider the extent to which this problematic assumption underpins both Suppes’ and recent semantic views of the structure of a scientific theory. I then use this investigation to show that, when it comes to using the concept of shared structure, there is no need to agree with French that “without a formal framework for explicating this concept of ‘structure-similarity’ it remains vague, just as Giere’s concept of similarity between models does ...” (French, 2000, Synthese, 125, pp. 103–120, p. 114). Neither concept is vague; either can be made precise by appealing to the concept of a morphism, but it is the context (and not any set-theoretic type) that determines the appropriate kind of morphism. I make use of French’s (1999, From physics to philosophy (pp. 187–207). Cambridge: Cambridge University Press) own example from the development of quantum theory to show that, for both Weyl and Wigner’s programmes, it was the context of considering the ‘relevant symmetries’ that determined that the appropriate kind of morphism was the one that preserved the shared Lie-group structure of both the theoretical and phenomenological models. (shrink)

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

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.

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

In this paper I claim that Quinean naturalist accounts of science, that deny that there are any a priori statements in scientific frameworks, cannot account for the foundational role of certain classes of statements in scientific practice. In this I follow Michael Friedman who claims that certain a priori statements must be presupposed in order to formulate empirical hypotheses. I also show that Friedman's account, in spite of his claims to the contrary, is compatible with a type of non-Quinean naturalism (...) that I sketch. Finally I also show that Friedman's account needs amending because it cannot provide a rational account of theory change. I accomplish this by arguing for a structural realist view of theory change. I show how this view fits well with an account like Friedman's and helps it deal with the problem of theory change and in retaining its superiority over Quinean naturalism. (shrink)

In this paper I argue against Nancy Cartwright’s claim that we ought to abandon what she calls “fundamentalism” about the laws of nature and adopt instead her “dappled world” hypothesis. According to Cartwright we ought to abandon the notion that fundamental laws (even potentially) apply universally, instead we should consider the law-like statements of science to apply in highly qualified ways within narrow, non-overlapping and ontologically diverse domains, including the laws of fundamental physics. For Cartwright, “laws” are just locally applicable (...) refinements of a more open-ended concept of capacities. By providing a critique of the dappled world approach’s central notion of open ended capacities and substituting this concept with an account of properties drawn from recent writing on the subject of structural realism I show that a form of fundamentalism is viable. I proceed from this conclusion to show that this form of fundamentalism provides a superior reading of case studies, such as the effective field theory program (EFT) in quantum field theory, than the “dappled world” view. The case study of the EFT program demonstrates that ontological variability between theoretical domains can be accounted for without altogether abandoning fundamentalism or adopting Cartwright’s more implausible theses. (shrink)

In recent years Structural Realism has been revived as a compromise candidate to resolve the long-standing question of scientific realism. Recent debate over structural realism originates with Worrall's (1989) paper "Structural Realism: The best of Both Worlds". However, critics such as Psillos contend that structural realism incorporates an untenable distinction between structure and nature, and is therefore unworkable. In this paper I consider three versions of structural realism that purport to avoid such criticism. The first is Chakravartty's "semirealism" which proceeds (...) by trying to show that structural realism and entity realism entail one another. I demonstrate that this position will not work, but follow Chakravartty's contention that structural realism need not imply that scientific knowledge can only be of mathematical structure. I advance from this conclusion to sketch a version of structural realism that is consistent with recent deflationary approaches to the scientific realism question. Finally, I consider a third approach to structural realism Ladyman's "metaphysical structural realism" which tries to avoid the difficulties of earlier versions by taking structure to be ontologically primary. I show that the deflationary approach to structural realism undermines the rationale behind Ladyman's approach. (shrink)

In this paper I consider two accounts of scientific discovery, Robert Hudson’s and Peter Achinstein’s. I assess their relative success and I show that while both approaches are similar in promising ways, and address experimental discoveries well, they could address the concerns of the discovery sceptic more explicitly than they do. I also explore the implications of their inability to address purely theoretical discoveries, such as those often made in mathematical physics. I do so by showing that extending Hudson’s or (...) Achinstein’s account to such cases can sometimes provide a misleading analysis about who ought to be credited as a discoverer. In the final sections of the paper I work out some revisions to the Hudson/Achinstein account by drawing from a so-called structural realist view of theory change. Finally, I show how such a modified account of discovery can answer sceptical critics such as Musgrave or Woolgar without producing misleading analyses about who ought to receive credit as a discoverer in cases from the mathematical sciences. I illustrate the usefulness of this approach by providing an analysis of the case of the discovery of the Casimir effect. (shrink)

In the last decade, structural realism has been presented as the most promising strategy for developing a defensible realist view of science. Nevertheless, controversy still continues in relation to the exact meaning of the proposed structuralism. The stronger version of structural realism, the so-called ontic structural realism, has been argued for on the basis of some ideas related to quantum mechanics. In this paper, I will first outline these arguments, mainly developed by Steven French and James Ladyman, then challenge them, (...) putting a particular emphasis on a metaphysical principle (the Principle of the Identity of the Indiscernibles) which, even though it is crucial for the whole argument, hasn''t been, in my opinion, clearly stated and examined yet. My overall view will be that a weaker version of the form of realism we are considering is more plausible – namely, epistemic structural realism. (shrink)

In this paper I argue that singularist approaches to solving the Pessimistic Induction, such as Structural Realism, are unacceptable, but that when a pluralist account of methodological principles is adopted this anti-realist argument can be dissolved. The proposed view is a contextual methodological pluralism in the tradition of Normative Naturalism, and is justified by appeal to meta-methodological principles that are themselves justified via an externalist epistemology. Not only does this view provide an answer to the Pessimistic Induction, it can also (...) accommodate our strongest intuitions regarding the progress of science. (shrink)

John Worrall recently provided an account of epistemic structural realism, which explains the success of science by arguing for the correct mathematical structure of our theories. He accounts for the historical failures of science by pointing to bloated ontological interpretations of theoretical terms. In this paper I argue that Worrall’s account suffers from five serious problems. I also show that Pierre Cruse and David Papineau have developed a rival structural realism that solves all of the problems faced by Worrall. This (...) Ramsey-sentence realism is a significant advance in the debate, but still ultimately fails for its incomplete account of reference. (shrink)

In his paper ``What is Structural Realism?'' James Ladyman drew a distinction between epistemological structural realism and metaphysical (or ontic) structural realism. He also drew a suggestive analogy between the perennial debate between substantivalist and relationalist interpretations of spacetime on the one hand, and the debate about whether quantum mechanics treats identical particles as individuals or as `non-individuals' on the other. In both cases, Ladyman's suggestion is that an ontic structural realist interpretation of the physics might be just what is (...) needed to overcome the stalemate. The main thesis of this paper is that, whatever the interpretative difficulties of generally covariant spacetime physics are, they do not support or suggest structural realism. In particular, I hope to show that there is in fact no analogy that supports a similar interpretation of the metaphysics of spacetime points and of quantum particles. (shrink)

This paper takes issue with Ontic Structural Realism (OSR). It is structured around the three elements of the title. Section 2 highlights a substantive non-structural assumption that needs to be in place before we can talk about the structure. Then, by drawing on some relevant issues concerning mathematical structuralism, it claims that (a) structures need objects and (b) scientific structuralism should focus on in re structures. But then pure structuralism is undermined. Section 3 discusses whether the world has ‘excess structure’ (...) over the structure of appearances. The main point is: the claim that only structure can be known is false. Finally, section 4 argues directly against ORS that it lacks the resources to accommodate causation within the structuralist slogan that “all that there is, is structure”. (shrink)

This paper examines in detail two paths that lead to Structural Realism (SR), viz. a substantive philosophical position which asserts that only the structure of the world is knowable. The upward path is any attempt to begin with empiricist premises and reach a sustainable realist position. (It has been advocated by Russell, Weyl, and Maxwell among others.) The downward path is any attempt to start from realist premises and construct a weaker realist position. (It has been recently advocated by Worrall, (...) French, and Ladyman.) This paper unravels and criticizes the metaphysical presuppositions of both paths to SR. It questions its very possibility as a substantive-and viable-realist thesis. (shrink)