Should we choose one unique scientific theory? (MultiScienceS International Conference)

Pablo Acuña (speaker)
Philosophy Institute, Pontifical Catholic University of Chile
Commentator: Michel Bitbol

Quantum underdetermination and quantum pluralism
A central issue in the philosophy of physics is given by the different interpretations of quantum mechanics. Now, this way of speaking suggests that there is a single theory—quantum mechanics—that can be interpreted in different ways. However, as I will argue in this talk, a careful analysis of what it really means to interpret quantum mechanics shows that the situation corresponds to a rivalry between several predictively equivalent quantum theories. When we identify the un-interpreted common formal-conceptual core that all of the interpretations start out from, we see that such a core is not a full-fledged physical theory, insofar as it is not able to offer a determinate picture of what the quantum world is like.

In other words, although the un-interpreted quantum core is indeed a successful predictive recipe, it is only a template for a physical theory. Interpretations of quantum mechanics introduce extra conceptual-theoretical elements, and/or amendments in the theoretical template with the aim of obtaining a certain description of the quantum world. Now, since there are alternative and incompatible ways to interpret the formalism, several rival but predictively equivalent theories result. On the basis of this diagnosis, we have then a concrete instance of the problem of predictive equivalence and underdetermination of theory choice; which gives us the opportunity to use the conceptual tools in general philosophy of science about this problem to address the case of quantum mechanics. As I will argue in this talk, since the normal development of science (if some conditions are met) can lead to an evidentially based choice among predictively equivalent theories—thus breaking the underdetermination—a plural theoretical development of quantum theories becomes a potentially fruitful scenario.

That is, I will maintain that the problem of predictive equivalence and underdetermination in quantum mechanics illustrates the scientific value of pluralism: a pluralist development of theories can lead to a solution of the problem, and to new and better science.
 

Theodore Arabatzis (commentator)
Department of History and Philosophy of Science, National and Kapodistrian University of Athens, Greece
Comment on the talks of Hasok Chang, Gregory Radick, and Léna Soler
 

Manuel Bächtold (speaker)
LIRDEF, University of Montpellier, France
Commentator: Sjoerd Zwart

The multiple interpretations of quantum mechanics: a case of theory underdetermination?
Can the existence of multiple interpretations of quantum mechanics be admitted as a case of underdetermination of the theory by experiment? Since the publication of Cushing's book (1994), this connection between multiple interpretations of quantum mechanics and the notion of theory underdetermination seems to be widely accepted. However, if one focuses on the terms of the question as stated above, the latter may appear absurd and a negative answer seems self-evident: when one considers "multiple interpretations of quantum mechanics," one is talking about a single theory (i.e., quantum mechanics), which is therefore well determined. In this talk, I will first attempt to clarify the terms of this question by examining the possible definitions of theory and interpretation. I will argue that the case of quantum mechanics offers only a "weak" example of theory underdetermination. I will then discuss the implications of the pluralism of ontological and epistemic interpretations of quantum mechanics respectively. I will support the thesis that epistemic interpretations point to elements of knowledge that are, to some extent, exempt from interpretive pluralism.
 

Yemima Ben-Menahem (speaker)
Department of Philosophy, The Hebrew University of Jerusalem
Commentator: Sjoerd Zwart

Lessons from Empirical Equivalence and Non-Reductionism
Contradictory statements (and theories that contain them) cannot all be true. This is a truth of logic and as such it is incontestable. Thus, if two theories that cover the same domain are contradictory, at least one of them is false. There are however cases in which the logical relations between alternative theories is not straightforward. When this happens, the question of whether they are contradictory or could live together in logical and epistemic peace requires serious consideration. In this paper I consider two cases in which questions regarding conflict or peaceful co-existence come up. The first is the case of empirically equivalent (but logically distinct) theories. In this context, I refer to the current situation in the foundations of quantum mechanics, where different 'interpretations' —the Copenhagen interpretation, many worlds, Bohm's theory, QBism and so on—compete. I will also mention Quine's atypical wavering on the subject of under-determination and empirical equivalence. The second context I would like to discuss in relation to the question of a uniquely correct theory arises is the debate on reductionism. Reductionists seek to reduce all scientific theories to a single fundamental theory.  I will argue against reductionism, responding to worries that have been voiced, such as the danger of downward causation.  If I am right that reductionism is untenable, we can expect different theories to be applicable to different kinds of facts or different levels of reality. The ensuing answer to the conference's question would thus be negative. 
 

Michel Bitbol (commentator)
Directeur de recherche au CNRS, Archives Husserl, École normale supérieure Ulm, Paris, France.
Comment on the talks of Pablo Acuna, Marie Gueguen, and Oliver Passon
 

Hasok Chang (speaker and commentator)
Department of History and Philosophy of Science, University of Cambridge, United Kingdom
Commentator of Hasok Chang’s talk: Theodore Arabatzis
Comment of Hasok Chang on the talk of Steve Fuller

Why realism should be pluralist
It is often assumed that scientific realism implies monism, requiring that scientists make a choice of the one best theory (or paradigm or research program) among competing alternatives. In previous publications I have argued that pluralism is a productive epistemic attitude even for scientific realists seeking to find the one final truth about nature. In this paper I emphasize a more fundamental re-orientation of realism itself, to argue for a stronger affinity between realism and pluralism. Realism as I see it is has, at its core, an activist ideal of inquiry: a commitment to seek more and better knowledge about realities, continually improving our epistemic practices to that end. Such “activist realism” calls for a Feyerabendian proliferation of systems of practice, each of which can find a set of real entities and learn truths about them. This outlook is based on a pragmatist notion of reality, compatible with Quinean ‘ontological relativity’: what we mean when we call something ‘real’ is that we can engage in operationally coherent activities by means of them. Such ontological pluralism provides a comfortable basis for epistemic pluralism. Different systems of practice may come with mutually incommensurable ontologies, and there is no reason to choose one system and ontology to the exclusion of others. On the contrary, activist realism dictates that all systems that deliver truths about real entities should be kept and developed, and that more and more systems should be created as part of scientific progress. This forward-looking proliferation of systems should also be accompanied by an attitude of respect for past science, which I have previously called “conservationist pluralism”: systems of practice inherited from past science should be maintained for what they continue to do well, even after we make new systems in the same domain that are in some ways clearly superior to the older ones.
 

Steve Fuller (speaker)
Auguste Comte Chair in Social Epistemology, Department of Sociology, University of Warwick, United Kingdom
Commentator: Hasok Chang

Thinking with and beyond Mill: Towards a Scientific Pluralism in a Truly Open-Minded World
John Stuart Mill tried to operationalize democratic rule by something other than the sort of majoritarianism favored by his mentor Jeremy Bentham. It has resulted in many clever attempts by Mill’s admirers to mitigate the potentially deleterious effects of majoritarian rule by structuring the voting process so that the presumptively ignorant do not prevail. His spirit lives on in more recent proposals associated with ‘affirmative action’ and ‘epistemic justice’, which aim to provide greater voice for groups who might otherwise be ignored or misrepresented, even though their perspectives are crucial for achieving a sense of ‘truth’ relevant to all. These recent proposals have been much easier than Mill’s original one because the ‘minorities’ involved are much more numerous – and in the case of women, the ‘silent majority’, so to speak. This point bears on the prospects of scientific pluralism because Mill, like Popper after him, thought about science and politics as optimally operating according to similar principles.

To say that science and/or politics is a ‘collective learning experience’ leaves ambiguous whether each constituent of the collective or only the collective as a whole is supposed to learn from the experience. After all, the latter may involve, a la Bentham, the elimination of some of the individuals who didn’t ‘get it right’ the first time. In contrast, for Mill, ‘learning’ is a living not a legacy concept: The people who commit an ‘error’ (however defined) should learn from it. In short, Mill was imagining and promoting a much more fluid political space than, say, today’s ‘epistemic justice’ advocates do. Far from being narrowly self-interested, Mill’s individual is more like the proverbial ‘floating voter’, relatively indeterminate – in that sense, ‘metaphysically free’. This may be due to Mill’s ‘inductivist’ orientation, which does not presume a deep historical sense of a ‘system’ (a la ‘systemic racism’) whereby the past exerts a pull that prevents people from being heard properly even under nominally free conditions. Jon Elster has referred to this deep historical sense of causation as ‘hysteresis’, the physics term for temporal action at a distance.

There are important lessons here for how we think about ‘scientific pluralism’, which tends to be understood in a relatively limited way. It is mainly about troubleshooting the dominant scientific paradigms, not about providing alternative paradigms that draw on alternative readings of the history of science. A way to go forward is to reverse engineer an insight of Thomas Kuhn’s. He observed that all scientific revolutions are accompanied by a radical (‘Orwellian’) revision of the history of science taught to new paradigm’s new recruits. This involves an alteration of science’s genealogy. Figures who were previously peripheral become central players – and vice versa -- and some are written out of the line of descent altogether and others are written in. However, Kuhn thought that such historical revisionism happened as a consequence of a scientific revolution, not as an instigator of it. However, the postmodern – and now post-truth – condition should alert scientific pluralists to the prospect that a well-crafted revisionist history could well propel a revolution in science. This is because people are now more open to the idea that the dominant narrative in any sphere of life – including science – might be ‘false’ in the sense of systematically foreclosing other possibilities that might be pursued. It follows that scientific pluralists should try to recover the past’s lost futures for today’s world by practicing a strategically focused counterfactual historiography.
 

Marie Gueguen (speaker)
Marie Curie Fellow, Institut de Physique de Rennes 1, France
Commentator: Michel Bitbol

No view from nowhere: surplus structure, naturalism and theoretical internalism
Although logical empiricism is now mostly decried, their naturalist claim that a theory's content can be read off from its structure, with no philosophical considerations needed, still supports many strategies to escape cases of underdetermination. The appeal to theoretical equivalence to dismiss the need to choose between allegedly distinct theories for instance, or the use of theoretical virtues to justify the choice of one theory over its rival both assume that there is a neutral standpoint from which the structure of the theories can be analyzed, the physically relevant separated from the superfluous, and a comparison made between their theoretical content and virtues. In my presentation, I argue that the methodological principle underlying these strategies, according to which theories with no superfluous structure should be preferred, is unpractical, for what constitutes relevant structure is determined by epistemic considerations about the aim of scientific theories. As a consequence, I defend a pluralist thesis according to which choosing one unique scientific theory by appealing to these tools might be done at the cost of neglecting precisely what is interesting in the other, i.e., what cannot be modelled in the rival framework and could lead to fruitful and testable consequences when bringing this theory to maturity.
 

Cyrille Imbert (commentator)
Archives Henri Poincaré-PReST, CNRS, Université de Lorraine
Comment on the talk of Joseph D. Martin
 

Katherina Kinzel (speaker)
Assistant Professor in the History of Modern Philosophy, Department of Philosophy and Religious Studies, Utrecht University, Netherland
Commentator: Baptiste Mélès

From Perspectivism to Systematic Unity: Kant’s Ideas of Reason and the Debate on Scientific Pluralism
A central motivation for scientific pluralism is perspectivism, the idea that all human knowledge, including scientific knowledge, is necessarily perspectival – it is knowledge from and conditioned by a vantage point.

The notion of a perspective is metaphorical and vague. But there is some prima facie plausibility to the idea that the perspectival character of all knowledge implies a form of scientific pluralism that undermines the prospects, as well as the normative appeal, of unified science.

In this paper, I present a reading of Kant’s critical project as a form of perspectivism. This is a version of perspectivism, however, that motivates not scientific pluralism but the systematic unification of knowledge. In particular, Kant argues from the limitation of the human perspective towards the necessity of employing – within this perspective – regulative ideas that allow us to approximate the systematic unity of empirical cognitions. What is more, according to Kant, pursuing unification in this way also rationally requires us to assume the systematic unity of nature.

Having reconstructed Kant’s argument from perspectivism to unification, and to the systematic unity of nature, I explore how much room this account leaves for arguments in favor of scientific pluralism. I show that Kant’s regulative account of unification is more permissive of pluralism in science than might be expected. It stresses the processual and contingent character of empirical investigation, and it includes a pluralist heuristic. I conclude with observations on how Kant’s throughgoing concern with the limits of knowledge, and the way in which his argument centers the processual character of science, avoid some of the pitfalls of contemporary debates on pluralism in science.
 

Joseph D. Martin (speaker)
Durham University, Department of History, Durham, United Kingdom
Commentator: Cyrille Imbert

Institutional Entrenchment and the Trouble with “Science”
When we think about the uniqueness of scientific theories, we need to think about the characteristics of “science” as a category. I will argue that “science” is no longer useful. That is not to say that we shouldn’t value the intellectual outputs of the people commonly regarded as scientists—of course we should, in the right circumstances (what those circumstances are is a subject for subsequent discussion). Rather, the category of “science” itself is no longer up to the challenges of the age. Science became a powerful category, and like all powerful categories it has grown larger and more diffuse as a growing range of undertakings has sought to borrow its prestige and gain access to the resources it commands. This talk examines the institutional processes through which a peculiar notion of science has become entrenched and expounds on the consequences of that entrenchment for the monist stance modern science has adopted.
 

Baptiste Mélès (commentator)
CNRS, Archives Henri-Poincaré—PReST (UMR 7117), Université de Lorraine — Université de Strasbourg
Comment on the talk of Katherina Kinzel
 

Oliver Passon (speaker)
School of Mathematics and Natural Science, University of Wuppertal, Germany
Commentator: Michel Bitbol

Should we choose between the different interpretations of quantum mechanics?
This conference is devoted to the questions whether one should choose “one unique scientific theory”, on which underlying assumptions the common monistic position is based and if a more pluralistic standpoint would be more beneficial. In order to ask these questions the Duhem-Quine thesis has to be taken for granted. However, cases of genuine underdetermination are relatively rare. The textbook example within physics is the debate over the interpretation of quantum mechanics. And indeed, a specific oddity of quantum mechanics lies in the fact that this theory is at the same time (i) extremely successful and (ii) controversially debated with a number of competing interpretations. How, one might ask, can a successful theory be misunderstood? Apparently, the requirements for a manageable (say “operationally understood”) theory are different from the requirements and demands of a “philosophical understanding”. In any event, the overarching question of this conference translates into the problem whether one should choose one specific interpretation of quantum mechanics.

I will argue in this contribution that one should not choose between the different interpretations. However, this is no plea for a pluralistic outlook per se. Rather I will argue that it is reasonable to adopt the standpoint of an “operational understanding” and that the host of competing interpretations of quantum mechanics (say, Copenhagen, many-worlds or the de Broglie-Bohm theory) should be dismissed altogether. At the same time this is not to say that these different interpretations are without value. The mere existence of these alternatives and their specific properties provide an important hint to the nature and essence of quantum physics. A particularly striking example is provided by Bell’s theorem. Famously, it was the non-locality of the de Broglie-Bohm theory which inspired John Bell to investigate the question whether non-locality is a generic feature of micro-physics. Importantly, this conclusion holds (essentially) independent of any interpretation. A similar case can be made for decoherence theory. The development of this concept is strongly pushed by adherents of the many-wolrds interpretation although their results apply independent of any interpretation.

How does all this relate to the overarching question of this conference? Obviously I am not advancing a pluralistic view on the theory-choice issue although the value of alternative interpretations will be acknowledged. My argument even suggests that also quantum mechanics is no impressive example for the Duhem-Quine thesis which is the underlying assumption of the theory-choice debate in the first place.  
 

Gregory Radick (speaker)
School of Philosophy, Religion and History of Science, University of Leeds, United Kingdom
Commentator: Theodore Arabatzis

Why Plausibility Matters for Alternative-Science Counterfactuals
I want to share, and reflect on, my own recent experience of how judgments about the plausibility of counterfactual scenarios in the history of science form in practice, and relatedly to offer some reasons for thinking that plausibility matters for a counterfactualist historiography of science worth having. In particular, I shall stress the value of cultivating connections to the actual scientific past for making counterfactual speculation productively constrained while making historical — including archival — research productively unconstrained.
 

Jamie Shaw (speaker and commentator)
SSHRC Postdoctoral Fellow, Institute for History and Philosophy of Science and Technology, University of Toronto, Toronto, Ontario, Canada
Commentator of Jamie Shaw’s talk: Sjoerd Zwart
Comment of Jamie Shaw on the talk of Marij van Strien

Science Funding Policy without Theory Choice
The purpose of this paper is to defend a mechanism for allocating funds that does not rely on a substantive answer to issues concerning theory choice. ‘Theory choice’, at least when conceived within science funding policy, concerns the ability to give reasoned preferences for choosing one research portfolio over its alternatives. Rather, I propose that we should endorse funding science by lottery where we do not give reasons for our choices. While this proposal has already gained a great amount of traction in theory and practice, with the help of a philosophical framework inspired by the works of Paul Feyerabend and the pragmatists, I argue for a particular version of funding by lottery and attempt to delineate its scope of application. By accomplishing this, I hope to show when and how we should fund science without making any rational choices.
 

Léna Soler (speaker)
Université de Lorraine, Archives Henri Poincaré-PReST, Nancy, France
Commentator: Theodore Arabatzis

How the monist regime of our science loads the dice in philosophical debates about science
The aim of this talk is to reveal the surreptitious work accomplished, in our world, by a network of pivotal, mutually reinforcing commitments, globally characterizable as monist, inevitabilist, and realist, that are crucially involved in standard ways of practicing and apprehending science, and that “load the dice” in many philosophical debates about science.

My starting point will be (what I call) the “monist regime of our science” taken as a fact about how science is standardly conceived and practiced. I shall clarify the meaning of the monist regime and address the issue of its inevitability. Since the monism of our science could be relaxed, it is, at least in this sense, not inevitable. A first sketch of what would be a more pluralist scientific regime is then provided.

Next, I consider some paradigmatic arguments involved both in the traditional debate about empirically equivalent theories and the underdetermination of theory choice, and in the less traditional, more recent debate about the contingency or inevitability of taken-as-established scientific “results” (e.g., theories, experimental outcomes, etc.). I show that if the monist regime of our science and its ramifications are taken into account, the corresponding arguments look significantly different: their meaning, their epistemological status, and their scope, are simultaneously shifted. As a consequence, their force is at least weakened – when they do not completely collapse or appear downright illegitimate.

When thinking about what could plausibly happen if the monist regime of our science were relaxed, we realize that several features of our science, commonly treated, in philosophical debates about science, as “inexorable data” and as “empirical evidence”, are induced by the monist norm – i.e., by a human norm that is not itself inevitable and that could in principle be modified. These features would plausibly disappear, and would then no more appear as “empirical facts” about “science”, if some more pluralist scientific regimes were instituted.
 

Marij van Strien (speaker)
Bergische Universität Wuppertal, Germany
Commentator: Jamie Shaw

Quantum mechanics as a battle ground for monism and pluralism in philosophy of science
The question of whether scientists should stay within a certain framework or paradigm or should actively pursue alternatives was a topic of debate in philosophy of science in the 1950s, 1960s and 1970s, among such philosophers of science as Feyerabend, Kuhn, Popper and N. R. Hanson. All four of these philosophers of science had a deep and sustained interest in quantum physics, and parallel to their disagreements on the issue of monism or pluralism in their general philosophies of science, they held different views on the current situation in quantum physics. In this period, there was a broad community of physicists who thought that the foundational issues in quantum mechanics had largely been solved and that a consensus had been reached (known as the Copenhagen interpretation), and a small group of dissidents who thought that there was something not right in quantum physics and who pursued alternative approaches. I argue that this situation formed an important context to the formation of ideas on monism and pluralism in philosophy of science in this period. Popper and Feyerabend both defended the dissidents: Popper himself developed an alternative interpretation of quantum physics, and Feyerabend, partly through his interactions with the dissident quantum physicist David Bohm, developed a thorough-going pluralism, according to which scientists (and in particular quantum physicists) should always try to develop alternatives to currently accepted theories and there is no need for a unique theory. Their views were attacked by Hanson, who argued that developing an alternative interpretation of quantum mechanics would entail developing an altogether new theoretical framework, and that there was no need for this as long as the current theory worked well in practice. Also Kuhn thought that there was no need for quantum physicists to actively pursue alternative approaches, and no reason for philosophy of science to intervene in quantum physics. The latter point was later accepted by Feyerabend, which led him to Against Method; but he remained committed to pluralism in a broader sense.

The situation in quantum mechanics is often thought to be atypical: there is a wide range of different ‘interpretations’ of quantum mechanics (which can in fact partly be regarded as interpretations of the same theory, and partly as different theories) which are all empirically equivalent, thus presenting a particularly strong case of underdetermination. My talk will explore how the fact that exactly this case was central to debates about pluralism within philosophy of science can lead to a better understanding of this history.
 

Sjoerd S.D. Zwart (commentator)
Assistant professor in the philosophy of technology, Department of Values Technology and Innovation, Faculty of Technology, Policy and Management Delft, University of technology, The Netherlands
Comments on the talks of Manuel Bächtold, Yemima Ben-Menahem, and Jamie Shaw