Metascience (2011) 20:417–442 DOI 10.1007/s11016-010-9465-5

BOOK SYMPOSIUM

Scientific representation: A long journey from pragmatics to pragmatics Bas C. van Fraassen: Scientific representation: Paradoxes of perspective. Oxford: Clarendon Press, 2008, xiv+408pp, £35.00 HB

James Ladyman • Ota´vio Bueno • Mauricio Sua´rez • Bas C. van Fraassen

Published online: 17 November 2010 Springer +Business Media B.V. 2010

James Ladyman

Once again, van Fraassen has given us an incredibly rich, learned and profound book that will be studied and argued about for decades to come. The book is about scientific representation, but from the perspective of Bas van Fraassen’s this means ‘‘representation of the empirical phenomena’’ (1). He is keen to distance himself from the empiricist tradition that would interpret the latter notion in terms of mental representation, and instead focuses his attention on mathematical and material representations, and one main form of representation in which he is interested is the representational aspect of measurement. Following and extending the line of argument that we find in the work of Poincare´ and Weyl among others, van Fraassen argues for the ‘‘essential indexical’’ (3) in science. This is a radical view that is at odds with the idea of objective inquiry that enables us to transcend our situation and describe the world independently of human beings, which is how many philosophers, especially scientific realists, see science. van Fraassen’s

J. Ladyman (&) Department of , University of Bristol, 9 Woodland Rd, Bristol BS8 1TB, UK e-mail: [email protected]

O. Bueno (&) Department of Philosophy, University of Miami, Coral Gables, FL 33124, USA e-mail: [email protected]

M. Sua´rez (&) Department of Logic and , Complutense University of Madrid, 28040 Madrid, Spain e-mail: msuarez@filos.ucm.es

B. C. van Fraassen (&) Philosophy Department, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA e-mail: [email protected] 123 418 (2011) 20:417–442 empiricist and antimetaphysical philosophy permeates his treatment of scientific representation and he repeatedly highlights those aspects of how we draw, describe and measure the phenomena that have to do with our relationship to both the latter and the representations themselves. He argues for subjectivity’s place in our understanding of science and denies that science can ever achieve a fully objective representation of the world. In the light of these observations, it is questionable whether the project of describing how scientific representation works can really be largely orthogonal to the realism/antirealism dispute as van Fraassen claims (3). Van Fraassen did a great deal to reinvigorate the scientific realism debate after the post-positivist repudiation of previously popular forms of instrumentalism. In a much-anthologised chapter of The Scientific Image, he defended the idea that the aim of science is ‘‘to save the phenomena’’. The latter were understood to be the same as the appearances, but there is an important in his thought expressed by the distinction he now draws between the phenomena and the appearances, where the former are observable entities and the latter are the contents of observation or measurement outcomes (8). So, for example, the measurement of temperature (Chapter 5) is to be understood in terms of the distinction between the phenomena associated with heat and the appearances that are saved by scientific theories mapping to representations of the appearances in the form of experimen- tally determined values of temperature. As van Fraassen explains, the construction of appropriate appearances—thermometry—is a rich science in its own right. Here, he cites approvingly the work of Cartwright, Giere and others who have argued that scientific representation must be understood not only at the level of high theory but also in the local domains in which high theory is de-idealised and experimental phenomena are modelled in detail. The distinction between phenomena and appearances is the distinction between what is immediately manifest in experience, and the special kinds of experience that are constructed by scientific experimentation and then codified in the form of ‘‘measurement outcomes’’. Clearly, the appearances will be highly theory laden, as in the case of temperature previously mentioned, and in all the appearances of fundamental physics. Van Fraassen stresses that when a theory is said to ‘‘save the phenomena’’, what this usually means is ‘‘saving the appearances’’. The latter can naturally be understood in terms of structural relationships between representations because the appearances are usually in mathematical form. Consider the case of the planetary orbits and their theoretical representation in Copernicus’ model of the solar system (Chapter 12). Here, the phenomena are the orbits of the planets and the appearances are the perspectival measurements of the positions of particular heavenly bodies in the night sky. Hence, retrograde motion belongs merely to the appearances and is not a genuine phenomenon. Note however that while the phenomena are supposed to be observable, they are only manifest to us in the form of one or other set of appearances (the positions of points of light in the night sky on Earth seen with the naked eye or through a telescope, as opposed to the positions of lights in the night sky seen from the Moon). So are the phenomena inferred and theoretical (though perhaps not usually as much as the appearances)? Van Fraassen would, I think, say not because he insists that the phenomena are observable entities, events and processes. He denies that we can 123 Metascience (2011) 20:417–442 419 reduce the observation of a galloping horse to a series of mental representations with some characteristic content and structure, and then claim that the horse is inferred as the best explanation. Now of course nobody would deny that in our actual cognition the representation of a continuing entity that moves through space is not a matter of inference. It is in philosophical vein when we ask about the source of our knowledge of the horse and what limits there are to that knowledge that indirect or representative realism is tied to the choices we face among competing explanations of the world we see around us. Returning to the case of the night sky, the appearances were once interpreted in very different terms by people who had no inkling of the distinction between planets and stars. The interpretation of the appearances is up for grabs and is only stabilised as the result of sophisticated inference to orbits based on lots of data. What in principle is different between the case of the orbits and the measurements of them, and cells and how they look through a microscope or particle collisions and the tracks they cause in cloud chambers? Measurement outcomes in general ‘‘show not how the phenomena are but how they look’’. However, if how they are must be inferred from how they look, then ultimately that they are must also be so inferred. This may not go for charging horses, but it surely does for the Moon and public objects like gases such as methane, which we can smell, electromagnetic fields, which we can see in the form of sparks and lightning, and so on. Tracks in particle chambers and images in microscopes are public objects, but van Fraassen classifies them as akin to mirages or rainbows, namely as public images. Phenomenologically, he is correct but the objection I have in mind is that the public objects he takes to be part of the realm of the phenomena are as much inferred as theoretical objects. I think we have good reason to believe that the inferences in the case of everyday objects are ones that we are evolutionarily predisposed to make as we are stimulated by the senses in the course of our development. Furthermore, if someone spends the daily life in a physics laboratory, it is unclear what should we count as the everyday things around him or her. Of course, van Fraassen has in the past set great store in the distinction between the unobservable and the merely unobserved, in the sense that horses galloping too far away to see are nonetheless in the realm of the phenomena. His view in the present work is much the same for the phenomena include all the observable entities—events, objects, processes—that there are, have been, or will be, whether observed or measured or not (307, his emphasis). I have argued that the modal status of the observable is a problem for van Fraassen’s empiricism, but whether or not that is correct, it is worth considering also whether his account of scientific representation has aporia related to modality. Van Fraassen argues that represen- tation must be understood contextually and pragmatically in terms of the use or function it has for someone (23). It seems then that he rules out the naturalisation of representation in evolutionary theory and biology more generally. On this view, RNA and DNA do not represent anything unless used by a genetic engineer to do so, and the state of the visual cortex per se does not represent the environment. This is mysterious, for we are told nothing about how human subjects manage to introduce representation out of nowhere. It is also implausible to make representation and subjectivity all-or-nothing and to confine them to human beings. I see no reason to 123 420 Metascience (2011) 20:417–442 deny that animals’ senses represent their environments to them. Representation may concern ‘‘aboutness’’ but if the processing in the visual cortex is not about anything, then why suppose that my words are? In van Fraassen’s view, intentionality seems to be an all-or-nothing matter of which scientific understanding is impossible. However, the coupling of brain states to behaviour can be investigated scientifically and I see no reason to deny that science can tell us about how we represent the world. More importantly, though it seems that while the modality of natural necessity is rejected as un-empiricist metaphysics, the modality of natural teleology in the form of subjective agency is a vital metaphysical commitment for van Fraassen’s view. When it comes to measurement, van Fraassen says that ‘‘a measurement is at the same time a physical interaction and a meaningful information gathering process’’ (91). However, it is questionable whether we can properly understand measurement without incurring modal commitments again, for to believe that a device is measuring a system it must be interacting with the system, where interaction seems to be causal or modal notion; relatedly, it must be the case that had the system had a different state with respect to the relevant physical property, the measurement device would have been in a correspondingly different state too. Van Fraassen claims that representation can be of something non-existent, and hence that to call something a representation ‘‘will not imply anything about the reality of what it depicts’’ (35). This is important for his antirealist view of representations of the unobservable in science, for it means that representations of the unobservable need not depict anything real. He emphasises that representations such as maps are useless without knowledge of one’s location relative to them and argues that measurement functions as the source of this knowledge. The perspectival of spatial measurement is a special case of the general necessity for something indexical to relate theoretical models to empirical situations that van Fraassen approvingly quotes Hermann Weyl calling the ‘‘ineliminable residue of the annihilation of the ego’’ (87). Van Fraassen’s fundamentally Kantian thesis is that scientific representation cannot transcend subjectivity and provide us with a ‘‘view from above’’. The relationship between theories and the world is mediated by agents that must be situated with respect to the representation and use it as one for it to be a representation at all. For all the sophistication and persuasiveness of van Fraassen’s elaboration of the Kantian arguments concerning the need for the subjects to locate themselves indexically in order to use a map, there seems to be a fundamental objection to the conclusion which he draws from them about the impossibility of objective representation. If I am presented with a map of a region I may for example know that the region is mountainous, or hilly, or flat without knowing where I am in relation to the map. If the contour lines on the map correlate very well with the topography of the region represented, and if the map is just the way it is because that is how the region is, then what grounds do we have for denying that the map represents the region even if the person holding the map has no idea where it is? Van Fraassen would presumably reply that isomorphism between the map and some part of reality is not sufficient for it to be a representation and that for the latter to be the case it is a necessary condition that it be taken by someone to be a 123 Metascience (2011) 20:417–442 421 representation. While I believe this may be true, it does not seem to change the fact that there is a representation there to be had in the way that there is not if someone was looking at a blank page. Again, this can be put in modal terms; some physical objects are in virtue of their properties disposed or able to be used as representations even if actually being a representation requires an agent to use them thus. At this point, we run into another one of those arguments that is intended to reduce the idea of a representation per se to absurdity and which van Fraassen discusses at length in Part III. Surely, there is some mapping from any blank sheet of paper to the topography of any region according to which the former can be regarded as structurally similar to the latter? Realists resist this suggestion with the insistence that some mappings are more natural than others. In the end, van Fraassen’s way with Putnam’s paradox, the Newman problem for structuralism and I suspect with the argument that a rock computes every finite state automaton is to accept that representation and computation are to be individuated in the light of our pragmatic relationships towards certain systems. However, the problems surveyed seem to presuppose extensionalism and perhaps intensionalism about the relevant relational structure might be combined with some form of realist alternative to van Fraassen’s pragmatism. Structuralism is an attempt to find objectivity in scientific representation by drawing attention to the product of our abstractions from the content of our concepts about force, mass, extension and so on. The mathematical structures that we now use to express physical concepts like momentum, energy, frequency and so on are far removed from direct connection with the source of those ideas in the experience we have of mechanics and oscillatory phenomena in the manifest image. The idea of understanding representation in terms of isomorphism or structure-preserving maps of some kind is prima facie plausible, given the apparent complexity and richness of the examples of such connections we see in the we have. Mathematics is often said to be the science of structures. Science, as van Fraassen emphasises, centrally involves mathematical representation. We may say at least that it involves logic, since the theoretical part of science has always been associated with the domain of deduction: relationships of entailment among propositions that are expressed by a language that is enriched with general terms and predicates which introduce taxonomic and systematising discipline to our cognition and enable us to cleanly state ceteris paribus laws and universal generalisations. These linguistic resources are extended by stages to become the highly mathematical representations that we now have that describe the behaviour of familiar things in the manifest image, but also of course, of the whole Earth and the rest of the universe. However, much debates about the scientific method lay unresolved, we know clearly enough that something like hypothetico-deductivism is the basic model of much of science, especially theoretical physics. There is an extraordinary connection between the mathematical structure of Hilbert space and concrete phenomena that can be represented by statistical methods as appearances to be embedded in empirical substructures of theories. Clearly, on the purely theoretical side, deductive logic and mathematics (which may include probability theory) exert the only absolute constraints. On the other hand, the connection between our representations and reality is governed by the vagaries of induction and abduction. 123 422 Metascience (2011) 20:417–442

Van Fraassen follows Duhem in his belief that the scientific method is not decidable, in the sense that there is no set of rules that we can use to determine what theory-choice is the correct one on any given occasion. However, Duhem thought that this underdetermination is always temporary, and fully expects that the real decision is made with hindsight as the domain in which the underdetermined theories apply is expanded so as to result in new experimental results about which the theories differ. Van Fraassen would, I think, applaud this insistence on the search for more empirical data, for that is what drives science. However, he differs from Duhem in that he rejects the idea that there is some element of natural classification to the relationship of our theories with the world, upon which ontologically different theories are none the less converging. This returns us to the problem of understanding the accord between the logical/mathematical modality of representations, and our considerable success in using them to accurately represent and predict the fine structure of the phenomena. The view that van Fraassen denies has it that there is in the world some causal or nomological structure that is represented by logical and mathematical relationships in our theoretical thought. He (306) approvingly quotes Hertz as follows: …the necessary consequences of the pictures in thought are always the pictures of the necessary consequences in nature of the things pictured…The pictures which we here speak of are our conceptions of things. With the things themselves they are in conformity in one important respect, namely in satisfying the above requirement. For our purpose it is not necessary that they should be in conformity with the things in any other respect whatever. However, there is a way of reading Hertz here according to which he is giving voice to a form of realism, for the ‘‘above requirement’’ could be taken to require that the modality in the model represent the modality in the world rather than being so much superfluous structure over and above what is needed to entail the actual extensional regularities in the phenomena. At the end of the book, van Fraassen discusses what he calls the ‘‘Appearance from Reality criterion’’ according to which science is incomplete until it explains the appearances, where this is understood to require that the latter be not merely predicted but described in terms of the modal constraints or causes that govern them. Van Fraassen argues that much contemporary philosophy of mind has rejected the Appearance from Reality criterion in so far as it is accepted that supervenience without reduction is the relationship between mental states and brain states. He then argues that the Copenhagen interpretation of quantum mechanics also shows us how the criterion is no longer important for science despite its origins in the Scientific Revolution. He here argues that the measurement problem is not a problem for the empiricist. This is interesting because much recent discussion in the philosophy of quantum mechanics has concerned precisely whether the Everett interpretation can be adequate given its alleged failure to make clear how the branching structure of quasi-classical worlds can give rise to the appearance of a definite unique world, where it is often supposed that by contrast, Bohm’s theory does solve the appearance from reality problem by positing particles. Van Fraassen will have no truck with either of these approaches of course, but it is not clear that philosophers 123 Metascience (2011) 20:417–442 423 of physics at least have abandoned the criterion in line with Copenhagen orthodoxy. Whether this speaks well or ill of them depends on the empirical question as to whether the measurement problem and the attempts to solve it contribute to the future development of physics.

Ota´vio Bueno

Scientific Representation is an impressive, rich and sophisticated work. It offers an empiricist treatment of representation in science, exploring along the way some lessons that can be gained from representation in art, and integrating the resulting approach with a conception of the role that mathematical representations and structural considerations play in scientific practice. I will focus on two key features of van Fraassen’s argument: the connections between scientific representation and microscopy, and the status of mathematical models in an empiricist stance.

Scientific representation and microscopy

The central feature of constructive empiricism is the characterisation of the aim of science as the construction of empirically adequate theories, that is, theories that correctly describe the observable. According to van Fraassen, the observable is, ultimately, what can be observed with the naked eye. The focus on the observable has been an ongoing source of concern about constructive empiricism, since the proposal was first advanced. Critics have complained, in particular, about what is epistemically special about observation, and how to reconcile the emphasis on the observable (narrowly understood in the constructive empiricist way) with the fundamental role played in contemporary science by a variety of scientific instruments, such as different kinds of microscopes, which aim to allow scientists to visualise what is in fact unobservable to our unaided eyes. In Scientific Representation, van Fraassen provides a very provocative response to this problem (93–113). He suggests that rather than thinking about microscopes as windows to the invisible world (as realists about microscopy insist they are), we can think of them as engines of creation, that is, as instruments that produce phenomena that then need to be explained. Furthermore, the images generated by microscopes, although copy-qualified (that is, they can be thought of as being a copy of some object), are ultimately public hallucinations. The images are public in the sense that several people can share them simultaneously and the images can be photographed. However, they are hallucinations given that there is no object—there is no thing—that the images are images of. In this respect, microscopes’ images are similar to rainbows. The latter are also public images (rainbows, after all, can be easily photographed) even though there is no thing—there is no object—they are about. The same person sees a rainbow in different locations as he or she moves around, and closely located people see a rainbow in different places. Are they seeing the same rainbow? The specification of identity conditions for rainbows is no trivial matter. In fact, it is not even clear whether there are such conditions. But if there is no thing that a rainbow stands for, seeing a rainbow is a form a hallucination—although a public one. 123 424 Metascience (2011) 20:417–442

By thinking of microscopes’ images in these terms, van Fraassen can easily motivate his agnostic attitude toward the unobservable. Maybe unobservable objects exist; maybe they do not. The empiricist need not settle the issue. But a difficulty also emerges. It is unclear how to reconcile this agnostic attitude toward the unobservable with the role played by microscopes in contemporary science. Microscopes’ images are often taken as evidence for the existence of certain unobservable entities. Suppose that, on an image generated by a transmission electron microscope, particulate components of the membranes of cells are seen (Palade 1955). Such particulate components are neither artefacts of the microscope nor of the method of preparation of the sample, given that such components are invariably present despite changes in the preparation method and triangulation with other instruments (such as a centrifuge that indicates different decantation times in the items of the sample). In this situation, it seems almost perverse to insist that the images produced by the instruments are not evidence for the existence of ribosomes, but are only public hallucinations that produce phenomena that need to be explained. What additional explanation is needed in this case but to point out that the ribosomes that are present in the sample, given the interaction with the electron microscope, produced the resulting image? It is unclear how a response much different from that can make sense of the role played by such instruments as sources of visual evidence in scientific practice. Of course, the constructive empiricist could deny that microscopes produce visual evidence for the existence of those unobservable entities that presumably are studied with such instruments. But this is not the move that van Fraassen favours. After all, he advances an agnostic view about the unobservable rather than a sceptical one. As he notes (109): To keep neutrality in this respect [i.e. to think of microscopes’ images as public hallucinations, thus remaining agnostic about them] does not prevent us from gathering empirically attestable information by means of the microscope, or to base e.g. medical advice on what the microscope shows us. We should recognize that a false contrast is made if we oppose ‘merely’ producing images to producing something informative about the objects with which the instruments are placed in interaction. The contrast here may indeed be a false one. But the point still remains. Microscopes’ images do have content: they describe the unobservable objects, processes and events these images are about as being in a certain way. How exactly can an agnostic view about the content of microscope’s images—that avoids the commitment to the existence of the relevant unobservable objects—be reconciled with the idea that such images produce something informative about these objects? Part of the difficulty here is that van Fraassen takes ‘‘information’’ to be an endorsing term (157). He insists that, despite the communication engineer’s neutral usage of ‘‘information’’, which to some extent has begun to modify the common usage of this term, it would still be puzzling or provocative to hear ‘We get information from observation, measurement, fictions, lies, and popular astrology.’ If we insist

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that measurement is information gathering, we mean in part that fictionalizing or speculating or guessing is not measurement (157). If ‘‘information’’ is, thus, an endorsing term, it is unclear how microscopes can produce something informative about the objects with which they interact, while we remain agnostic about the very existence of these objects. Prima facie, the informativeness of microscopes (understood in an endorsing sense) about the relevant objects seems to undermine the possibility of maintaining an agnostic stance toward the latter. Given that microscopes are intended to yield visually salient information about unobservable objects, that information would be significantly misleading if such objects turn out not to exist. But this is a possibility that the agnostic needs to leave always open. Perhaps, the constructive empiricist has a response here. In the case of scientific theories, the constructive empiricist correctly insists that such theories need not be taken to be true, as long as they are empirically adequate (i.e., roughly, provided that they are true about the observable world). This moves draw a line between, on the one hand, commitment to every aspect of a given scientific theory (if such a theory is true, this includes both the observable and the unobservable aspects of the world) and, on the other hand, commitment to only part of it (if the theory is empirically adequate only, commitment is restricted to the observable). And maybe the constructive empiricist could invoke something like this distinction—between truth and empirical adequacy—to motivate an agnostic view about microscopes’ images, while still acknowledging that the latter can be informative. But how exactly can such a distinction be drawn here? What would it mean to state that a microscope’s image is empirically adequate? As opposed to a scientific theory, which in order to be tested does include a part that refers to observable objects, no part of a typical microscope’s image—say, the micrograph of a cell produced by an electron microscope—is about something observable in van Fraassen’s sense. It is simply unclear how the line between truth and empirical adequacy could be properly drawn in this context. We also face a related concern. There seems to be a tension between the characterisation of microscopes’ images as being both copy-qualified and public hallucinations. On the one hand, if these images are copy-qualified, presumably there is some object such images are copies of (even if we may be mistaken about which object exactly is involved). On the other hand, if microscopes’ images are public hallucinations, there is simply no object these images are about, no object that produces such images and which is represented by the latter as being in a certain way. In fact, it’s the absence of such object that turns the image into a hallucination. As a result, the alleged hallucinatory nature of microscopes’ images is now in tension with their copy-qualified status. For in virtue of being copy-qualified, such images have a representational content—there is something the images are about, and they represent the relevant objects in a certain manner. But this is precisely the feature that public hallucinations lack. What is needed here is a well-motivated account that specifies the conditions under which one is entitled to take the representational content of images seriously— when the relevant microscopes yield images that genuinely represent objects and

123 426 Metascience (2011) 20:417–442 relations at the unobservable level—and when this is not the case. In this way, a suitable account of the status of microscopes’ images can be advanced, and the grounds that support an agnostic view, when the latter is justified, can be offered. I think the key condition for the reliability of microscopes is that they are counterfactually dependent on the specimen under study. In particular, two conditions need to be satisfied: (C1) Had the specimen under study been different (within the sensitivity range of the microscope), the resulting image would be correspondingly different. (C2) Had the specimen under study been the same (within the sensitivity range of the microscope), the resulting image would be the same. In this way, it is possible to track the relevant features of the specimen using the microscope. If conditions (C1) and (C2) are satisfied—and if we know that they are satisfied—the resulting images do provide us with significant information about the specimen. In this case, the images offer us evidence that the relevant features of the sample do obtain. However, if these conditions are not satisfied, clearly the microscope fails to provide adequate evidence. In this case, we are not dealing with a reliable instrument. Finally, if we just do not know whether the conditions are satisfied or not, an agnostic stance is then clearly well motivated.

Scientific representation and mathematical models

An additional source of concern about constructive empiricism emerges from the status of mathematics within an empiricist framework. Given that mathematical objects are unobservable, and since the constructive empiricist restricts his or her commitments to observable objects, processes and events, it is difficult to reconcile the role of mathematics in science with constructive empiricism. What is needed is an account of mathematics that squares the lack of commitment to mathematical objects with the undeniable role that mathematics plays in empirical science. Van Fraassen (1985) is, of course, aware of the issue. And he insists that there ought to be some feature of mathematical practice that motivates the lack of commitment to mathematical objects despite the need for quantifying over such objects as part of scientific, and philosophical, practice. Interestingly, van Fraassen is sceptical that any form of nominalism ultimately works. I think part of the difficulty concerns the fact that nominalist views tend to provide reconstructions of mathematical discourse and thus are unable to take the latter literally. And a distinctive feature of constructive empiricism, in striking contrast with earlier forms of empiricism—in particular, logical —is the fact that it takes scientific discourse in a literal way. If according to a given scientific theory, quarks exist, the constructive empiricist will not rewrite that theory so that no commitment to quarks is forthcoming. The empiricist will simply take such a theory to be empirically adequate rather than true. It is then perfectly understandable why the constructive empiricist is not moved by standard forms of nominalism that end up doing to mathematical theories precisely what the empiricist tries to avoid with scientific theories: to rewrite them.

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However, an account then needs to be offered of how exactly mathematical theories can be used in science—while being taken literally—without the resulting commitment to mathematical entities ever emerging. In Scientific Representation, van Fraassen attempts to dissolve the problem, at least in a particular context. It is not clear to me, however, that the proposed solution works. After examining van Fraassen’s solution, I will suggest another that seems to satisfy the demands he correctly imposed on the problem. The concept of empirical adequacy, as van Fraassen characterises it, involves reference to unobservable entities, such as models and isomorphic mappings. Even if the concept of isomorphism can be expressed in a way that does not involve commitment to abstract entities (e.g. it can be formulated with the resources of a second-order language), the statement that a given scientific theory is empirically adequate involves reference to models—namely, the empirical substructures of a given scientific theory—which are abstract. But perhaps this commitment can be avoided. As van Fraassen points out (243), ‘‘Snow is white’’ is true only in virtue of snow being white, not in virtue of the existence of a universal, whiteness, to which snow bears some relation. And he continues: The same point applies to isomorphism. Let’s take a particular case of a concrete physical, observable object: this table top is metrically isomorphic to a Euclidean square. That is true, but simply because this table top is square— c’est tout! It is true because the top’s sides are of equal length and the angles between them are right angles. It could be paraphrased as ‘‘the table top instantiates the Euclidean square Form’’, but the cash value of the assertion carries no metaphysical commitment: it is just that the table top is square (249). The point is quite right in the particular case of concrete objects. But it is not clear how exactly it can be extended when we are asserting that a given scientific theory is empirically adequate. For in this case, as opposed to the case of a concrete object, the isomorphism in question connects two abstract structures: an empirical substructure (a structure from a given theory that describes the relevant observable objects, processes, and events) and the surface model (the mathematical structure that represents the data that have been obtained empirically). Here, we cannot say that the cash value of the assertion carries no metaphysical commitment, since we are asserting that two abstract objects have the same structure (that is, there is a one- to-one mapping between the empirical substructure and the surface models that preserves the relations in each of them). Is there a way out? One possibility is to insist that there is no need to interpret the quantifiers in an ontologically loaded way. We can, of course, quantify over objects in whose existence we have no reason to believe, such as average moms who have 2.4 children. Commitment to the existence of something is only indicated by a suitable existence predicate, whose sufficient (but not necessary) conditions include having a form of access to objects that is robust, can be refined, and that allows us to track the relevant objects in space and time. (Interestingly, these conditions are all satisfied by the output of scientific instruments that meet the two counterfactual conditions 123 428 Metascience (2011) 20:417–442 mentioned earlier.) In this way, the constructive empiricist is in a position to take mathematical discourse literally, quantify over mathematical objects in the formulation of scientific theories, but refrain from being committed to such objects (for details, see Bueno 2005, 2009). Thus, it is possible to make sense of the indispensable role mathematical models and various morphisms (such as isomorphism or partial isomorphism) play in scientific representation—so insightfully described by van Fraassen—without overstepping the boundaries of constructive empiricism. In the end, scientific representation and empiricism can live in quiet harmony.

Mauricio Sua´rez

Scientific Representation is the latest stage in Van Fraassen’s sustained and profound defence of empiricism against scientific realism over the years. The book’s key message may be summarised as follows: ‘‘constructive empiricism’’—the antirealist view first defended in the celebrated The Scientific Image (1980)—needs to be modified in some substantial ways to make room for an appropriate notion of representation. The modification yields ‘‘empiricist structuralism’’ or, as I shall call it, ‘‘structural empiricism’’. The shift is meant to preserve the central epistemic commitments of the old view while bringing in some new advantages. Van Fraassen provides reasons for the change and offers arguments for the new position. But like any shift this is a gamble. If the reasons for change are convincing but the arguments for the alternative are not, we end up in no man’s land. Or in someone else’s land. I think, we end up in the land of pragmatism. A good way to express the reasons for change is by reference to an old paper of mine discussed critically in what appear to be two key passages of the book (25–26 and 247–250). Since I do not think my views are described or identified correctly, perhaps some extensive discussion and self-quotation will be forgiven in the first part of the review. The second part critically reviews the arguments for structural empiricism. In the third and final part, a more positive assessment is provided, which hopefully will make it clear that I think Scientific Representation is nonetheless a very good book. Its main merit is to point towards a thoroughly pragmatist conception of science.

Moving away from constructive empiricism

There is a standard line on constructive empiricism that we all have been taught and go on to teach our students. It takes as central a commitment to the aim of science, encapsulated in the famous slogan: Science aims to give us theories which are empirically adequate, and acceptance of a theory involves as belief only that it is empirically adequate. The definition of empirical adequacy then enables us to extract out of the slogan the nuanced and rich position that is constructive empiricism. As is well known, Van Fraassen takes the empirical adequacy of a theory to crucially turn on a distinction between observable and unobservable 123 Metascience (2011) 20:417–442 429 domains of the world. The theory is true if it literally describes the world accurately; and it is empirically adequate if it describes the observable part of the world accurately. Hence, a false theory may be empirically adequate; and the commit- ments of realism and constructive empiricism come apart. Of course, we must remind ourselves all along that the language of ‘‘truth’’, ‘‘description’’ and ‘‘says’’ is, taken literally, fundamentally inappropriate. It is a fac¸on de parler, inherited from a syntactic, or language-based, view of theories. On the appropriate semantic conception, a theory is rather a set of mathematical structures: ‘‘To present a theory is to specify a family of structures, its models; and secondly, to specify certain parts of those models (the empirical substructures) as candidates for the direct representation of observable phenomena.’’ (Van Fraassen 1980, 64). We may then say that the theory is true if it is isomorphic to the world, and empirically adequate if some of its substructures are isomorphic to the observable part of the world. Truth and empirical adequacy are then structural surrogates of the linguistic ‘‘truth’’ and ‘‘empirical adequacy’’. So, what is the problem then? It turns out that this conception of a theory’s truth and empirical adequacy is in tension with a proper account of scientific representation. The not-so-often-quoted sentence right after the passage above reads as follows: ‘‘The structures which can be described in experimental and measure- ment reports we call appearances; the theory is empirically adequate if it has some model such that all appearances are isomorphic to empirical substructures of that model’’. This sentence leaves little doubt that the empirical adequacy of a theory is to be understood as the isomorphism of the phenomenological and the empirical substructures of the theory (Sua´rez 2005). In conjunction with the previous quote, it seems to render the view that scientific representation is isomorphism; and that constructive empiricism stipulates that the acceptance of a theory implies the belief that the theory structurally embeds, i.e. represents, the observable phenomena. It is not surprising then to find Van Fraassen’s commentators and critics over the years assuming that his version of the semantic conception requires an isomorphism conception of scientific representation. Among the commentators, I include my own (Sua´rez 1999b), which might have unfortunately started the trend. At least it led Steven French (French 2003) to respond by arguing for isomorphism as a necessary and sufficient condition on representation in general. Scientific Representation makes it clear however that this is not Van Fraassen’s considered view. Rather he agrees that representation is not definable by means of any necessary or sufficient conditions: it is not the sort of notion that stands in need of any theory. Instead representation is linked to use; the hauptsatz is: ‘‘there is no representation except in the sense that some things are used, made, or taken, to represent some things as thus or so’’ (23). But the recognition of the fundamental role of use in scientific representation poses problems for constructive empiricism—which I flagged over a decade ago. Unfortunately, Van Fraassen seems to have misunderstood what I wrote then (although he clearly recognises the tension). He writes: ‘‘In a comment on similar ‘‘intentional’’ views of what constitutes representation, Mauricio Sua´rez suggests that it will hamstring the idea that theories represent’’ (26). And he then quotes the following sentence: ‘‘on the intentional conception of representation a theory cannot 123 430 Metascience (2011) 20:417–442

‘represent’ a phenomenon that hasn’t yet been observed’’ (Sua´rez 1999b, 81). But the extract has been taken out of context. Far from criticising ‘‘intended use’’, my paper set out explicitly to critique what I took it to be the received understanding of Van Fraassen’s conception of representation as isomorphism—and I argued against it precisely by showing it to ignore intended use! My own view is of course that representation is essentially linked to representational use, and I have always accepted the hauptsatz above. (Even though the hauptsatz is really very thin and provides little by way of understanding the relevant practices). This is precisely the sense in which theories do not always represent—their representational uses are not built in. The claim van Fraassen ascribes to me in no way follows from this. An ‘intended use’ conception does not hamstring the idea that theories represent at all. It rather shows that theories sometimes represent, and sometimes do not, and whether they do or not depends on nothing other than use. In particular, it does not depend on isomorphism. (In criticising isomorphism, partial isomorphism, etc., I took myself to be working in the tradition of Goodman. It is a cruel irony of life that van Fraassen (349, n. 1) appears to ascribe the application of Goodman’s exemplification to the assessment of the accuracy of scientific representation to—of all people—Steven French!) The misunderstanding might have its source in a conflation of ‘‘intentionality’’ and ‘‘intended use’’ conceptions of representation. From the start, I set out to defend an intended-use conception: Velazquez’s portrait of Innocent X and Picasso’s Guernica are explicitly advanced to illustrate that use is the key to establish representational contents or targets in general. As a reaction to a draft of my paper, van Fraassen sent me a draft of the paper that eventually appeared as his (van Fraassen 2000), which continues his (van Fraassen 1994) development of an intentional conception. Since this view is also at least prima facie incompatible with the reduction to isomorphism, the difference between ‘‘intended use’’ and ‘‘intentional’’ in general did not matter to my purpose then—which was to criticise and reject the reduction to isomorphism. So in the rejoinder I wrote in response, ‘‘intended use’’ and ‘‘intentional’’ were run together. Later on, I did make clear that the differences do matter for the appropriate conception of representation (Sua´rez 2003). Chapter 2 of Scientific Representation is to my knowledge van Fraassen’s first attempt to disentangle these two different views. Despite of some residual hesitations on pp. 26–29, he also seems to be ultimately inclined towards an intended-use conception. I realise this is indulging in some self-referential score-keeping, so let us quickly take stock before we move on. I once made the following claim: ‘‘there is tension between an intentional notion of representation and van Fraassen’s constructive empiricism’’ (Sua´rez 1999b, 81). With the appropriate caveat to read ‘‘intentional’’ as ‘‘intended use’’, I continue to endorse it. It actually nicely summarises the main reasons that have moved van Fraassen towards ‘‘structural empiricism’’.

The arguments for ‘structural empiricism’

The most original material in Scientific Representation is contained in part II, which reveals great attention to the practices of measurement and instrumentation. Many 123 Metascience (2011) 20:417–442 431 years ago, the Stanford school urged philosophers to turn towards an experimental philosophy of science. Some of us embraced the call, while others resisted. The resistance often presented van Fraassen as a leading theory-monger and employed him as a banner for the entire movement. This no longer seems credible: Scientific Representation is a turning point for admirably taking stock of the literature on instrumentation and experimentation of the last two decades. The autonomy of the experimental sciences is fundamentally taken to heart, which is a wonderful development for at least two reasons. First, it is refreshing to find a senior and distinguished figure in the field taking honest stock of a distinct and even contrary tradition. Second, constructive empiricism suffered from lack of detail in the experimental side of the theory– dichotomy that it promoted; and this was undermining it in the contemporary context of new experimentalism. The most outstanding outcome of this encounter with experimentalism is a new distinction between the observable phenomena and the appearances, which comes to the fore in Part IV of the book. The introduction of a 3-layer model (theory- phenomena-appearances) is motivated by both the autonomy of experiment and the use-based conception of representation. The observable phenomena underlies (and presumably causes) the appearances (Van Fraassen of course refrains from using any causal language). These are the outcomes of measurement procedures, recorded in various data models, and routinely employed to represent the phenomena. But the representation at this level cannot be isomorphism—since while the data models are mathematical structures, the phenomena are real entities and processes in the physical world. Rather, the appearances represent the phenomena in the prescribed use-based sense of representation—in the given context and for the purposes required. No proof of isomorphism or similarity are needed: it just makes no sense for users of the data model to deny that the model represents the phenomenon— since the claim is built into their very use (250–261). The theory is then empirically adequate if it embeds the appearances—and this no longer carries the implication that a substructure of the theory must be shown to be isomorphic to the phenomena. ‘‘Saving the phenomena’’ has turned into ‘‘embedding the appearances that represent the phenomena’’. The adoption of the 3-layer model – and consequent rejection of the theory-phenomena dichotomy—turns constructive empiricism into structural empiricism. The rest of the book is a defence of structural empiricism against (a) objections to structuralism in general (part III) and (b) the requirement that the phenomena ought to productively explain the appearances (part IV). While I have some sympathy with the rebuttal of (b), the arguments in part III don’t strike me as successful. Van Fraassen points out similarities between Newman’s argument against Russell’s structuralism, and Putnam’s model-theoretic argument against metaphysical real- ism. Roughly, both Newman and Putnam show that the statement of isomorphism between theory and world picks out nothing but the cardinality of the domains. Van Fraassen’s resolution to the problem resembles Goodman’s solution of the ‘‘new riddle’’ of induction in that it appeals to entrenched facts of our linguistic practice— in particular the inevitable use of indexicals within a familiar language in setting up the right coordination or correspondences between theory and world. Goodman’s ‘‘entrenchment’’ move has been considered ad hoc or circular as a justification of 123 432 Metascience (2011) 20:417–442 induction. Similarly, critics of structuralism might be inclined to point out that van Fraassen’s move is ad hoc or circular as a justification of structuralism. It cannot ground structuralism as the correct account of our theoretical knowledge of the world—whether in its realist or empiricist variety. One way to defend Goodman’s argument is to point to the impossibility of any ultimate justification of induction. Instead ‘‘entrenchment’’ must be understood as vindication of the use of induction in practice. But this is of course a surreptitious rejection of pure induction—for it assumes that all inductive reasoning presupposes some basic non-inductive practical knowledge of the rules that inform inquiry. Similarly, van Fraassen’s ‘‘solution’’ of Newman’s objection and Putnam’s argument may be seen to surreptitiously abandon structuralism in either the empiricist or realist varieties. Once again, the key lies instead in the features of the underlying practice of representation users. But such features, however indispens- able in the production and acquisition of knowledge, are not structural but social.

Towards pragmatism

There is increasing consensus in the literature that representation may not be naturalised, reduced or defined, as either a property of the objects that stand in the representational relation or a property of the intentionality of the agents that employ it. Instead, representation is grounded upon the representational uses of particular communities, and no further reduction seems available or required. This is all very welcome (it is music to the ears of an inferentialist like me!), but it might at first seem to contradict the semantic conception of scientific theories. Van Fraassen argues successfully that this is not the case (Appendix to Chapter 1: 309–311), and his argument can be strengthened further. The semantic conception is a view about the objects that are scientific theories. By itself it says nothing about the nature of representation, which is instead best thought of as an activity. The object—the theory—is at best the product of the activity: representation. But to characterise the activity by means of its product would commit a category mistake, and fallacies would ensue. More precisely, it would entail the fallacy that every feature of an activity must have a correlate in its product, or vice versa. And this is fallacious for any activity we know, whether or not productive in the required sense. Some activities simply lack the products to carry out the process–product correlation (e.g. riding a bicycle, playing tennis). And those that are productive in the required sense invariably violate the process–product correlation requirement (e.g. pottery, painting, cooking). The view that the semantic conception of theories entails a particular view of representation commits the same category mistake. Notice that the argument above turns on accepting a broadly intended-use conception that grounds representation in the social world. On this view, representation is an activity carried out by a community engaged in a collective social practice—and the underlying norms of the practice determine representa- tional sources and targets. An intentionality conception, by contrast, takes it that sources and targets are determined by some intentional state of some particular agent or agents, regardless of community, practice, and indeed any intended or unintended uses. On such view, which has its origins in the writings of Brentano and 123 Metascience (2011) 20:417–442 433 infuses the phenomenological tradition, representation is necessarily the property of individuals: representation is ‘in the head’. The turn from ‘‘intentionality’’ to ‘‘intended use’’ views is thus the first step towards a thoroughly pragmatist and social conception of scientific representation and knowledge that leaves conven- tional empiricism, structuralism and realism all behind. Scientific Representation is useful book that reorients the debate in the right direction, but much work still remains to be done.1

Author’s response: Bas C. van Fraassen

Bueno, Ladyman, and Sua´rez come with a quiver full of challenges to my account of scientific representation, but offer at the same time good and welcome positive suggestions—I am grateful for both. Selection of the points for response was not easy; Ladyman’s remarks concerning modality and Bueno’s on mathematics are among the important parts left aside for now. Upon reflection, the shift in focus on representation from the semantic level to the pragmatic, which Sua´rez highlights, provides a unifying theme for central points made by each, so I will begin by responding to Sua´rez.

Sua´rez on the pragmatic turn

To set the record straight, I want to acknowledge a great debt to Mauricio Sua´rez’ writings of recent years. Sua´rez played a central role in fostering the, as he rightly describes it, increasing consensus in the literature that representation may not be naturalised, reduced or defined, as either a property of the objects that stand in the representational relation, or a property of the intentionality of the agents that employ it. Instead, as he argues, representation is grounded upon the represen- tational uses of particular communities, and no further reduction seems available or required. Perhaps I had felt a little hurt when his words had seemed to set in train the charge that the semantic approach to science (at least as I had presented it) involved the view that representation is isomorphic copy-making. Undoubtedly, too, there was textual evidence to lend plausibility to that charge, and I am ready to express my contrition. But the upshot of all this is that we are in solid agreement, as far as I can see, on how the activity and product of representation are to be conceived. In a footnote to his 2004 article, Sua´rez graciously pointed out how the pragmatic side of Giere’s and my concepts of representation had sometimes been misunder- stood. For my part, I regret that some of my remarks (2008: 25–26) show that I had not properly assimilated Sua´rez’s valuable distinction between an intensional and an

1 This review was written while visiting Harvard University in 2009 and I want to thank the Philosophy Department, and Hilary Putnam in particular, for sponsorship during my visit. Financial support is acknowledged from the Spanish Ministry of Science and Innovation, project HUM2008-06418-C03-01, and stay abroad PR2008-0079. 123 434 Metascience (2011) 20:417–442 intended-use concept of representation. But enough about our feelings! What I will do is follow Sua´rez’s example a little, and outline just how my thoughts about this subject evolved—from, I think, initial insight via temporary oblivion to insight recovered. If I describe a politician as a poltroon, I represent him a laughable. This use of ‘‘represent’’ is, to my mind, entirely in order: description is, as much as depiction, a form of representation. Although empiricists in the twentieth century went overboard when they concentrated on linguistic representation, with their syntax (vocabulary and grammar)-oriented view of theories, it is still true that much that was pertinent to representation came along in discussion of language. So let us begin with a little detour via the subject of language. There the counterpart of simple-minded ‘‘resemblance’’ views of representation were ‘‘correspondence’’ views of truth.2 In The Scientific Image, whenever the notion of truth came up, I wrote in terms that would be characteristic of someone who held a correspondence view. Mea culpa! I made then no effort to put some distance between myself and that sort of blatantly realist jargon (cf. pages 3, 7, 8, and 197). All the more disturbing, because I was after all a student of Wilfrid Sellars, and therefore well acquainted with the issues as seen through decidedly more sophisticated eyes. At the risk of special pleading, I submit that I set aside those issues, at that point, for the sake of keeping the debate over scientific realism undistracted. This may not seem entirely implausible if read in the context of what I had been writing before 1980. Truth, like reference, is a technical term in semantics. Semantics is the study of language in relation to the world, of expressions in relation to what they are about, of sentences in relation to the facts. But what is the status of semantics? We cannot take exception to the claim of semantics to have its own technical concepts. But this does not rule out the continued demand for an interpretation of these concepts: in that case, however, answers which go outside semantics proper must be acceptable. Such a demand for interpretation can only be construed as a request that we show the concepts in question to have a significant role. There is in fact an obvious field which may provide such a grounding for semantic concepts, namely, pragmatics. And I propose accordingly that we construe the demand for an interpretation of semantic concepts as answerable by the exhibition of a clear pragmatic counterpart (van Fraassen 1967, 166–167). The use of the semantic concept signals a certain level of abstraction, which involves disregarding the vagaries of contextual factors, idiosyncratic usage, changes in usage with time, and so on. But had the concept of denotation no clear pragmatic counterpart, its use would have no clear relevance to the study of language at all (ibid.)

2 My discussion here will repeat some of what I (2006b, 152–158) wrote in response to Rosenhagen. 123 Metascience (2011) 20:417–442 435

In a follow-up on modal language I added: The use of a concept in formal semantics is at once warranted and of philosophical interest if and only if the concept has a clear pragmatic counterpart. And we call the second concept a pragmatic counterpart of the first if the first is arrived at from the second by abstraction from relations to user and to context of use (van Fraassen 1969, closing paragraph). My guiding example was ‘‘the semantic statement ‘The term W denotes the object O’ has as pragmatic counterpart ‘The person X uses the term W to refer to the object O (at time t)’.’’ For truth the similar point would then be that the semantic statement ‘‘Sentence S is true’’ has as pragmatic counterpart ‘‘The person X makes a true assertion by use of sentence S (at time t)’’. But what is it to make a true assertion? Here Sellars (whose views on language are cited as source in both articles) insisted on our providing ‘‘cash value’’ for such generalities in essentially Tarskian terms: if the sentence S is a sentence in our language, we must ‘disquote’ it to spell this out. For example: X makes a true assertion by use of ‘‘Snow is white’’ if and only if snow is white. This format will only work well if the context of X’s use is the same as the context of use of this long sentence itself. (Try placing ‘‘I am happy’’ in the place of ‘‘Snow is white’’, to see what could go wrong!) However that may be spelled out in detail, these reflections lead then quickly to what I now call ‘‘pragmatic tautologies’’ and ‘‘pragmatic incoherence’’, hinging on the role of indexicality (though the indexicality may not be overt; consider ‘‘There are no sentences’’). This subject too I had explored earlier on (van Fraassen 1977). The Scientific Image did not enter upon the status of semantics, or the implications for the concepts of truth and reference. But it does introduce pragmatics as the appropriate level of study wherever it touches relevantly on the issues in philosophy of science (e.g. Chapter 4, Sect. 4; Chapter 5, Sect. 4; and especially Chapter 6, Sect. 5) and includes references to those three previous papers, as well as to the then on-going pioneering work by Richmond Thomason, Robert Stalnaker, and David Kaplan. Sua´rez puts it rather too strongly when he writes that the language of ‘‘truth’’, ‘‘description’’, and ‘‘says’’ is fundamentally inappropriate, only a fac¸on de parler, inherited from a syntactic, or language-based, view of theories. Even after we shift to the ‘‘semantic’’ view of theories (in retrospect, not the most fortunate choice of name for the approach that was replacing the then so-called ‘‘received view’’), there are important issues in philosophy of science that must be relegated to study of the language(s) of science. But Sua´rez is entirely right to mark the important historical shift as from a focus on truth to a focus on representation: to present a theory is to present a family of models, as candidates for representation of the phenomena. So, as for ‘‘truth’’, so for ‘‘representation’’! We can use ‘‘represent’’ as a technical term in a properly extended semantics (where ‘‘empirically adequate’’ can finally be properly explicated) but that term too has meaning and significance only if there is a clear pragmatic counterpart. It is this required pragmatic counterpart that has been presented, with variations in emphasis but fundamental harmony, in a series of 123 436 Metascience (2011) 20:417–442 articles by Sua´rez (1999a, 2003, 2004, 2005, 2010) and myself (1997, 2000, 2004, 2006a), among others.

Ladyman: epistemic qualms encounter pragmatics

The first part of Ladyman’s article presents his epistemic qualms evoked by my placing the essential indexical at the centre of scientific representation of the phenomena, and the related emphasis on the appearance/phenomena distinction. He is right to say that I am following and extending a line of argument pressed by Poincare´ and Weyl, and perhaps right to call that a radical view. But why would that view be ‘‘at odds with the idea of objective inquiry that enables us to transcend our situation and describe the world independently of human beings’’? Scientists as well as the rest of us can and do produce descriptions in ‘‘eternal sentences’’, maps with no ‘‘you are here’’ pointers, and models in which no viewer or observer is depicted. That is the form of theoretical physics, at the very least. The qualification I insist on is that the main use of these artefacts requires locating ourselves in them or with respect to them. That point, about the conditions of use, is what brings in our own perspective. Later on in his article Ladyman relates this worry, about a loss of objectivity, to the larger issue of the concept of representation as to be ‘‘understood contextually and pragmatically in terms of the use or function’’. He asks the provocative question ‘‘Representation may concern ‘aboutness’ but if the processing in the visual cortex is not about anything then why suppose that my words are?’’ My short answer would of course be that we do not use the processing in the visual cortex to represent something—indeed, brain processes are not something available for our use at all. Ladyman may be right to suspect this sort of answer of implying that philosophical ‘‘naturalising’’ programmes are barking up the wrong tree. But why would this answer imply anything contrary to Ladyman’s, and surely everyone’s, conviction ‘‘that science can tell us about how we represent the world’’? It can certainly tell us something! Everything we do or undergo can be a proper subject of scientific investigation, at many levels, including our use of artefacts. I do see scant hope for the idea that representation can be naturalised, in the sense that Ladyman appears to mean that. With respect to his provocative question concerning ‘aboutness’, we should remember the well-known argument (generally called Frege’s, but properly developed by Goedel and discussed many times since) that leads from some simple premises to the conclusion that all truths are about the same thing.3 Those premises are just that logically equivalent sentences are about exactly the same thing(s), and that co-referential singular terms can be substituted one for another in a sentence without affecting what the sentence is about.Do processes in the visual cortex make what the medievals called not only real but also intentional and even Scotus’ formal distinctions? Despite heroic efforts in non- standard forms of semantics, Frege’s argument provides us with a prime example of the limits when understanding remains on a purely semantic level. Problems about ‘‘about’’, i.e. intentionality, urge us to look for a proper counterpart in pragmatics, in

3 For an exploration of this issue in a critique of constructive empiricism see Sober (1985). 123 Metascience (2011) 20:417–442 437 the study of use, intentional use, when it comes to understanding any form of representation. But let us return to an epistemological issue in the first part of Ladyman’s article. This concerns the distinction between the phenomena (the observable entities) and the appearances (the contents of observation or measurement outcomes). Ladyman characterises this distinction fairly and correctly. But then he raises the question: since the phenomena ‘‘are only manifest to us in the form of one or other set of appearances’’, ‘‘are the phenomena inferred and theoretical’’? The argument he gives for a positive answer is quite short: Measurement outcomes in general ‘show not how the phenomena are but how they look’. However, if how they are must be inferred from how they look then ultimately that they are must also be so inferred. (my italics) I think we could perhaps construe this in a quite innocuous sense. For example, if the measurement outcome was that, as sighted from one airplane, the jet fighter’s speed was 900 mph, that outcome implies that there was a jet fighter that was sighted. Often, no special inference is needed: relating the appearance implies the reality of the phenomenon. But Ladyman does not mean the conclusion to be innocuous: Phenomenologically, he is correct but the objection I have in mind is that the public objects he takes to be part of the realm of the phenomena are as much inferred as theoretical objects. I think we have good reason to believe that the inferences in the case of everyday objects are ones that we are evolutionarily predisposed to make as we are stimulated by the senses in the course of our development. His examples show that by ‘‘theoretical objects’’ he means theoretically postulated unobservable objects. So it appears that Ladyman wants to argue that the examples of what I count as phenomena, such as planets and their motions, trees and flowering, are after all not observable. And the argument, if I understand it, is that since all we have to go on are appearances, our beliefs that there are e.g. planets and trees, their motions and flowerings, are the conclusions of inferences, based on whatever it is we have by way of having appearances. Again, a simple distinction might disarm the point. Very often, we do have to infer the reality of putative phenomena from the appearances in measurement outcomes. But that does not mean that they are not observable entities. If I see black droppings and infer the presence of a mouse, the mouse’s reality is inferred, but the mouse is not unobservable. Again, though, it is clear that Ladyman is after bigger game. The conclusion of the quoted argument itself is a rudimentary theory of human functioning, postulating unconscious processes of inference, inference from something minimal to something more contentful. But why is that appropriate here? Appearances are contents of measurement outcomes, and measurements are made by instruments which are human-sized manipulable entities. One could not take something to be a measurement outcome without taking it to the outcome of a procedure carried out with such instruments. These instruments are, however, just the sort of thing that Ladyman here classifies as inferred and theoretical. Where does the inferring end? 123 438 Metascience (2011) 20:417–442

Are a scientist’s microscope and oscilloscope unobservable entities, and does s/he have something quite different at hand from which to infer their reality? There are two difficulties with a view that this is so. When the molecular biologist, for example, presents us ostensibly with new data, those supposed data are really data only if s/he was really using a microscope. Suppose we take that to be an inference on the scientist’s part, and ask for an assessment of what support there was for that inference. It is to be doubted that an answer will be forthcoming, yet hard to insist that there was a gap in the scientist’s chain of evidence because of that. Worse: if an assessment is needed across the board for the reality of the putative macroscopic objects handled in the laboratory, it would have to be by someone who could tell in which cases they were real and when they were not. But on the above view it seems that there could be no judge in a better position to assess that than the handlers themselves, who are said to have to infer their reality. Perhaps I have reconstructed this argument uncharitably. To try and get to the heart of the matter, that may be dividing us, I would like to make one further point. It is about the familiar ‘‘seeing something’’ versus ‘‘seeing that something is thus or so’’ distinction. Seeing that something is thus or so: that is typically perspectival, in that the content of the observational report is tacitly ‘‘from here’’. Correct. But that point does not contradict the other contention that, on such an occasion, one is seeing the object, event, or process in question. On the contrary, that one is doing so is logically implied by a direct report of the seeing that.4

Sua´rez and Ladyman on structuralism

Sua´rez and Ladyman have very different, well-known, views concerning structur- alism in the philosophy of science. So they have quite different reactions to the sorts of arguments, like the Newman problem, that threaten the very possibility of a structuralist view of science. But they are equally critical of my dissolution of those threats. It seems to me that Sua´rez left out of focus precisely the crucial difference between what I proposed as an empiricist structuralist view of science and any form of structural realism. Ladyman, on the other hand, proposes ways in which structural realism might escape those same problems; they are, though, ways that would not go at all with empiricist structuralism. The crucial difference between the two structuralisms is this. Structuralism, in the sense of what Ladyman dubbed ‘‘ontic structural realism’’, is a view of what the world is like, and only derivatively, a view of how science is to be understood. Empiricist structuralism, on the other hand, is a view of science, with no implications for what the world is like. So examples and arguments that may look like posing a single problem for both—e.g. the Newman argument—actually pose very different problems for each. For the structural realist, the problem is just this. A purely structural description appears to be trivially satisfiable, no matter what its subject is like, provided only

4 This goes for simple, direct reports of observation or measurement outcomes. Not for some more complex sorts of report: that I saw that James was not in the room does not imply that I saw James. 123 Metascience (2011) 20:417–442 439 the size is right. For all structures that can be instantiated in a collection of a certain size can be ‘‘read into’’ any collection of that same size. The standard sort of realist response to this point—Newman’s point—is to limit what counts as proper instantiation, with reference to certain features of the subject, such as properties that single out some demarcations as ‘‘natural’’. The immediate objection to that response is that it gives up on structuralism, for the demarcation of those properties is not by structural features. This is probably a bullet the structural realists have to bite. The suggestions Ladyman offers, such as ‘‘intensionalism about the relevant relational structure’’ or ‘‘that there is in the world some causal or nomological structure that is represented by logical and mathematical relationships in our theoretical thought’’ may just push the problem one step back. If the relevant relational structure is distinguished from other such structures in that it is natural rather than gerrymandered, is the distinction made by a purely structural feature of that relational structure? If the relevant relational structure is e.g. causal, is that causal character a purely structural feature of that relational structure? My guess is that the ontic structural realist must in the end renounce the ambitions of ‘‘pure’’ structuralism, and be satisfied with something just a bit more realistic and a bit less pure, than a purely structuralist ontology. Perhaps, it could be seen as a metaphysical discovery, that absolutely pure structuralism is impossible?5 When the similar-sounding problem is faced by empiricist structuralism, the situation is entirely different. In fact, all that is required is to spell out that view more fully. Begin with a crude statement of the empiricist structuralist view of science: what scientific theories give us for representing the phenomena are models; models are mathematical structures; mathematical structures are not distin- guishable beyond isomorphism; therefore scientific representation of phe- nomena does not go beyond representation of their structure. At once, with this formulation—correct as far as it goes—we face Carnap’s question for his own account: ‘‘this seems to be a paradoxical assertion…in empirical science, one ought to know whether one speaks of persons or villages’’, even if the structures are the same. But in what sense is it true that models are mathematical structures? Only in the same sense that paintings are bits of canvas or wood with paint on them! To call the item ‘‘model’’ or ‘‘painting’’ conveys more, and this more is to be spelled out—as for representation in general—in terms that are not structural. To say that the painting is a portrait of Lisa del Giocondo is to assert a good deal more than that the picture resembles her. If it resembles several young women, the painter could still have told his friend Vespucci ‘‘I am painting a portrait of la Gioconda’’ and that would settle whose portrait it is. There is more to this matter, including the

5 In an earlier symposium with Ladyman (van Fraassen 2007) I acknowledged the coherence Ladyman’s view, while suggesting a qualification that seemed to me not to count as a defeat. But I think that it was not in the spirit of ontic structural realism. 123 440 Metascience (2011) 20:417–442

‘‘Wittgensteinian’’ move that exposes certain confusions as akin to Moore’s paradox—but all of it requires shifting the discussion to pragmatics. As Sua´rez rightly remarks, ‘‘Once again the key lies instead in the features of the underlying practice of representation users. But such features, however indispens- able in the production and acquisition of knowledge, are not structural but social’’. This is not a critique of empiricist structuralism, but a spelling out of the involved concept of representation—the ambitions of ‘‘pure’’ structuralism are foreign to it from the outset.

Bueno: role of the instrument in scientific practice

While Scientific Representation means to address issues that are of common concern to empiricist and scientific realist alike, Bueno is right to emphasise that the positions developed on those issues are consonant with and elaborate on constructive empiricism. So it is in order to ask how it stands now with problems that were originally raised for The Scientific Image. In doing so, Bueno adopts an effective rhetorical strategy: presenting the evidence as it is seen through scientific realist eyes. Ian Hacking introduced the microscope in his provocative (1981), as challenge to the contention that the aim of science is to provide empirically adequate accounts of the phenomena, with no regard as to truth about the unobservable. Bueno continues this challenge in two ways. First he characterises the relevant scientific practice: he refers to ‘‘the role played by microscopes in contemporary science’’ and says that microscopes’ images ‘‘are often taken as evidence for the existence of certain unobservable entities’’. That remark involves the familiar contention that the working scientist is a Scientific Gnostic. I contend, to the contrary, that if the sociological evidence is presented in neutral fashion, it illuminates only the phenomenology of immersion in the theory within which the scientist works. Secondly, more importantly, Bueno criticises my account of the instruments as engines of creation—of new phenomena, to be accounted for by science—rather than windows into the ‘‘invisible world’’. In my account microscopes’ images are indeed classified as public hallucinations. Bueno takes this to imply that they are classified as only ‘‘copy-qualified’’ but not copies of anything. That is not implied at all: copy-qualified public hallucinations include for instance shadows and reflec- tions in the water, which are indeed copies of the objects that cast the shadows or are reflected in the water (see diagram on p. 104). The classification is neutral here; the question of reality is bracketed. The scientific theory according to which the microscopes’ images are copies of ribosomes or whatever may indeed be true, and not just empirically adequate. It is not irrational to believe that it is true, but according to constructive empiricism, that is a supererogatory belief for the scientist. However, in what is for me his most important argument, Bueno then points to a tension between the informativeness of such measurement outcomes and their classification:

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Microscopes’ images do have content: they describe the unobservable objects, processes and events these images are about as being in a certain way. How exactly can an agnostic view about the content of microscope’s images—that avoids the commitment to the existence of the relevant unobservable objects— be reconciled with the idea that such images produce something informative about these objects? Content indeed: the appearances of objects are the contents of outcomes of measurements performed on those objects. But on what objects are those measurements by means of microscopes made? On observable objects. Leeuwen- hoek inspected samples of pond water, others inspect specially prepared slides with samples of tissue. The microscope images are how these observable objects appear in those measurement set-ups. And these appearances are informative about those observable objects, not in and by themselves, but relative to the (presumed) empirically adequate theories that accommodate them. There does not seem to be any difficulty relating to the conditions that Bueno requires to be satisfied for the reliability of microscopes: (C1) Had the specimen under study been different (within the sensitivity range of the microscope), the resulting image would be correspondingly different. (C2) Had the specimen under study been the same (within the sensitivity range of the microscope), the resulting image would be the same. Agreed! In fact, these are conditions closely related to what I call ‘‘empirical grounding’’, which I take to be, in effect, Hermann Weyl’s empirical requirement of ‘‘concordance’’, and Schlick’s and Reichenbach’s of ‘‘unique coordination’’ (see further van Fraassen 2009). What then of Bueno’s reasoning: If conditions (C1) and (C2) are satisfied—and if we know that they are satisfied—the resulting images do provide us with significant information about the specimen. In this case, the images offer us evidence that the relevant features of the sample do obtain. The first sentence is true, but the second does not follow logically from the first. At least, it does not follow if by ‘‘relevant features … do obtain’’ Bueno means (as it seems he does) unobservable features of which the microscope’s images are faithful copies. In the discussion of the microscope and other such instruments too, we need to focus on scientific practice on the level of pragmatics. The scientist is naturally immersed in a certain theoretical context, which determines the logical relationships in the language in use there. The philosophical onlooker must have a way to describe this practice, a way that is not theoretically charged like the scientist’s description of his target, even if governed by contextual presuppositions of its own. That is, such philosophical discourse must not have among its presuppositions some that beg the question with respect to the issues at stake in the philosophical debate about that practice. Trying to speak simultaneously in the roles of scientist-at-work and philosophical-onlooker threatens incoherence. 123 442 Metascience (2011) 20:417–442

Coda

Responding to such valuable critical discussions as Bueno, Ladyman and Sua´rez offered here was itself a journey of discovery. What seemed so natural while writing is suddenly seen to have unsuspected depths of unmade distinction and unrealised nuance, on which there is no way the author can pretend to have been clear already. I am truly grateful.

References

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