Michel Ghins

This book addresses central issues in the philosophy and metaphysics of science, namely the nature of scientific theories, their partial truth, and the necessity of scientific laws within a moderate realist and empiricist perspective. Accordingly, good arguments in favour of the existence of unobservable entities postulated by our best theories, such as electrons, must be inductively grounded on perceptual experience and not their explanatory power as most defenders of scientific realism claim. Similarly, belief in the reality of dispositions such as causal powers which ground the natural necessity of scientific laws must be based on experience. Hence, this book offers a synthetic presentation of an original metaphysics of science, namely a metaphysics of properties, both categorical and dispositional, while at the same time opposing strong versions of necessitarism according to which laws are true in all possible worlds. The main theses and arguments are clearly presentedin a non-technical way. Thus, on top of being of interest to the specialists of the topics discussed, it is also useful as a textbook in courses for third year and more advanced university students.

Explanationist strategies for defending epistemological scientific realism (ESR) make heavy use of a particular version of inference to the best explanation known as the no-miracle argument. I consider ESR to be a genuinely philosophical—non-naturalistic—thesis which contends that there are strong arguments to believe in some non-observational claims made by scientific theories that are partially observationally correct. In this paper, I examine the grounds of the strength of these arguments from what I call a contemplative perspective which focuses on the end products, i.e. theories, of the scientific activity as opposed to the pragmatist view which considers science to be primarily an activity. I briefly rehearse the main difficulties of the no-miracle argument and of inference to the best explanation in general. I argue that a convincing defence of ESR should be based on the empirically ascertained reality of causal connections between theoretical entities which possess properties that are in principle observable (OP properties) and the results of measurements or observations. The knowledge of those causal connections may well deliver an—even the best—explanation of the appearances. But belief in the existence of some unobservable entities is mainly justified by their empirically attested causal role, not on their possible explanatory function.

In this chapter I first present the objectifying attitude, which is characteristic of science, in contrast with the holistic attitude, which is specific to art, friendship and religion. Then, I define models as structures of properties organised by relations, such as nomological formulas like PV=KT. I explain how models can represent scientific objects, namely systems of properties, by endorsing a structural view of representation. According to the model-theoretic view of theories, these are classes of models, whereas for the syntactic view, theories are sets of propositions. I advocate what I call a “synthetic view” according to which theories are constituted of both propositions and models. Models perform a dual role: they can represent objects and also make true some propositions, among which scientific laws. Since scientific theories are supposed to explain phenomena, I contend that the explanatory power of a theory relies on mechanistic models which make causal laws true. A causal law is defined in a syntactic way as a universal proposition which contains a time derivative (or something equivalent to it), which refers to the effect whereas the other terms refer to the cause. Finally, I briefly discuss the issue of determinism.

In the present chapter, I propose a way of defending epistemological scientific realism that differs from the usual explanationist strategies. Instead of developing a top-down explanatory argumentation which consists in evaluating the merits of several explanations of phenomena and then claim that the loveliest explanation is likely to be true, I offer a bottom-up inductivist strategy which starts from observations to go back to the causes that produce them, which can then be claimed to have been detected. I contend that this bottom-up approach is not vulnerable to the objections raised against inference to the best explanation (IBE). To illustrate this point I argue that the celebrated arguments for the existence of Neptune by Le Verrier and the reality of atoms by Perrin are convincing precisely because they implement such a bottom-up strategy. In addition, I attempt to show that this defence of scientific realism makes it possible to respond to the classical underdetermination objection according to which theories are undetermined by the available data. I also criticize the famous antirealist argument developed by Larry Laudan and known as the historical pessimistic meta-induction. I also show that the stability of reference of terms which denote detected entities can be preserved in spite of important theory changes. To do this, I adopt a causal descriptivist conception of reference based the works of Saul Kripke, David Lewis and Robert Nola and I apply it to the case of the electron.

This chapter is devoted to a presentation and critique of the categorical conceptions of laws. For categorical monists, only categorical properties exist; powers and all other dispositional properties can be reduced to categorical properties, namely, their categorical bases. Before clarifying the all-important distinction between categorical and dispositional properties, we must be clear on what a property is. I argue in favour of construing properties as universals. After that, I briefly address the issue of the distinction between categorical and dispositional properties. I then proceed to discuss the regularity account of laws, which has been initiated by David Hume and developed by Mill, Ramsey and Lewis, and I elaborate on the reasons why the various versions of regularism are unsatisfactory. In the last part of this chapter, I examine how Armstrong, Dretske and Tooley strive to overcome the difficulties encountered by the regularists by introducing a contingent relation of necessitation between properties, while remaining faithful to categoricalism and Humean contingency. I conclude that categorical accounts of laws, whether in their regularist or necessitarian versions, face insuperable difficulties.

I start this chapter with a presentation and critique of Brian Ellis’ new essentialism, which consists in a dualist metaphysics of laws based on both categorical properties and powers. Like Ellis, I defend a dualist metaphysics of nature. However, unlike him, I attempt to dispense with essences and natural kinds and advocate an enlarged view of categorical properties. These include not only spatial and structural properties but all observable properties. Besides, I submit that categorical properties are not quiddities and that their identity across possible worlds doesnot reduce to a mysterious primitiveness. I also develop an empirical argumentation in favour of the reality of irreducible causal powers which ground the necessity of laws and their associated counterfactual conditionals. Since the instantiation of powers is relative to some possible worlds, the necessity of laws of nature is contingent. Such conditioned de re necessity of laws is distinct from the de dicto necessity of analytic propositions.

This chapter begins by discussing what Bas van Fraassen called “the loss of reality objection”. Since models are constructed by our action of extracting properties from the phenomena, do we lose contact with reality in this process? While van Fraassen proposes a pragmatic dissolution of this problem, I advocate for a solution grounded on the truth of propositions, which ensure the connection of some models with external reality. Then, I argue in favour of a correspondence view – not theory – of truth according to which true propositions are satisfied by external truthmakers. I proceed by showing that the philosophical issue of epistemological scientific realism does not hinge on the reasons to believe in the reality of entities which are not directly observable – which is the business of science – but on the normative evaluation of these reasons. I define epistemological scientific realism thus: we have better reasons to believe in the existence of some detected entities (sets of properties) and in the truth of some propositions about them rather than adopting an agnostic suspension of judgement. Detected properties are properties that are observable in principle, but which can only be observed with the aid of instruments.Most scientific realists resort to abductive strategies to defend their position. According to the no miracle argument the success of science would be inexplicable, i.e. would be a miracle, if our best theories were not at least partially true about entities such as electrons, genes, etc. I argue that abductive explanationist strategies are unconvincing. As an alternative, I propose an inductivist strategy to defend a moderate version of scientific realism.

The present paper critically examines the main claims of the new mechanist account of explanation defended by Glennan and Machamer, among others. The two major difficulties of the new mechanism, namely the circularity objection and the bottoming out problem are discussed and addressed. To solve the bottoming out problem, this paper proposes a modification and enlargement of the mechanist account of explanation advocated by Salmon and Dowe. Such extension can then successfully apply to the explanations provided for the global behaviour of complex systems, not only in physics but also in other disciplines such as biology and the social sciences. The proposed enlarged version of Salmon’s and Dowe’s account provides a monistic account of explanation based on causal generalizations or laws which need not be construed as necessary to fulfil their explanatory role. Such change-relating generalizations or laws are characterized by the presence of a term that refers to the variation in time of some property, which is identified to the effect whereas the other terms refer to the causes. Thus, by enlarging the Salmon and Dowe notion of mechanism, I advocate a nomological theory of causation instead of the mechanistic theory of causation proposed by Glennan et alii.

This dissertation attempts to provide an answer to the following question: what must be the properties and the structure of physical space-time so that the inertial effects be satisfactorily explained? ;To answer that question in a precise manner, five meanings--logical, ontological, mathematical, empirical, physical--of the terms "absolute" and "relative" are distinguished according as they refer either to space-time or to motions. ;In the first part of the dissertation, this conceptual framework is applied to Newton's Principia, the Leibniz-Clarke controversy, Clarke's vindication by Euler and classical mechanics as set forth in contemporary textbooks of physics. ;In the second part, the classical electromagnetic theory and the special theory of relativity are examined in the light of these five distinct meanings. ;Finally, in the third part, the conceptual framework is applied to the general theory of relativity as it is found in the writings of Einstein, Weyl and Weinberg. A study of Mach's ideas and some cosmological considerations are included. ;This detailed analysis allows us to establish the following four points: So far, physics has not succeeded in completely eliminating absolute space-time; it is shown in a precise way in what sense and to what extent this elimination has not yet taken place. We can speak of a progress in the history of scientific theories from Newton to Einstein in the sense that absolute space-time, cause of the inertial effects, becomes more and more empirical, nonetheless without reaching Mach's ideal. Metascientific concerns, such as the demand to connect real effects with real causes, have played a significant role in the evolution of physics. The epistemological status of the space-time concept must be approached via the problematic of the origin of inertial forces, rather than via the problematic of empirically founding geometrical properties on the observable behaviour of rods and clocks. Writings by physicists--including Einstein--show that their main concern is to provide a satisfactory account of inertial forces; besides, the behaviour of metrical devices is not the same for all reference systems

More than a quarter of century has elapsed since Hilary Putnam first proposed his famous ‘no-miracle’ argument in ‘What is mathematical truth?’ (1975). The argument, also known as the ‘Ultimate argument’ (van Fraassen 1980) is still widely discussed and is considered by many, just as Putnam believed, to be the major argument in favour of scientific realism (Leplin 1997, Psillos 1999). In this paper, I will review various forms of the argument and show them to be unconvincing from a naturalist’s point of view. My main point is that scientific realism conceived as a scientific explanation of the success of science is indefensible, not because other – ‘better’ - explanations are available or because the no-miracle argument is logically flawed or because examples of false empirically successful theories can be produced, but because scientific realism is a philosophical position and cannot possibly count as a scientific explanation of any fact. Essentially, I want to question the scientific explanatory force of truth and, at the same time, argue against a form of naturalism which construes scientific realism as a scientific hypothesis.

Great scholars in philosophy possess a keen analytical mind, excel in logical reasoning, and exhibit meticulous attention to detail. They rigorously define terms, avoiding ambiguities and errors. Originality and the willingness to challenge conventions are their hallmarks. They make significant contributions across various philosophical fields. They transparently address the exact aim of their research, and what it is not. Finally, they anticipate the impact of their theories on the current literature, and how such an impact should blossom across the future generations. In this respect, great philosophers address open problems and propose big questions for the foreseeable research efforts of those who will follow. Mario Alai embodies the qualities of a great scholar in philosophy, and the various essays in this volume are an evidence to that. It is challenging to condense a lifetime of research in one book. However, the Editors of the present volume’s aim was to face this challenge, to make a collection dedicated to Mario Alai’s work not only possible but, as metaphysicians would say, actual. The book attempts to bring together the reflections of three different generations of scholars - i.e., mentors, colleagues, and students - on Alai’s thought. Viewed from this perspective, the extensive and valuable contributions that follow, crafted in honor of Mario Alai and his scholarly endeavors, come as no surprise. All the chapters focus on a theme that was very dear to the philosophical curiosity of Mario Alai. Moreover, in engaging with these different topics, the plethora of contributions gives us a sense of the work by Alai. To make sense of the different contributions as a unified enterprise, this volume is organized into three sections, which seek to gather writings that revolve around Mario’s most substantial contributions, while elucidating their contemporary significance in the global discourse. Moreover, it endeavors to offer precious insights into the origins and development of these contributions, as observed through Mario’s writings and responses. This represents a sort of closure of the theoretical circle, clearly showing how the work by Mario Alai has been appreciated through different generations, originating from his relation to his mentors, on the one hand, while also shedding new light on his students’ research interests, on the other. Editing such a wealth of material was, again, no small feat. Still, the taxonomy we have chosen for this book will assist readers in navigating the profound depths of Alai’s philosophical research. Consequently, the book is structured into the following three parts: 1. Realism in History of Philosophy, History of Science, and Metaphysics. 2. Scientific Realism. 3. Realism in Philosophy of Language, Epistemology, and Experimental Philosophy. Each contribution actively participates in a substantial conversation with Alai’s body of work, as a deep theoretical dialogue between the author and Mario. Consequently, it appeared fitting to let Alai conclude this conversation, with direct responses to these philosophy-provoking pieces in his honor. We shall refrain from further commentary on the works within this book and allow them to express their significance independently to appreciate the river of ideas flowing through Mario’s work1. Beyond their philosophical substance, they are a vivid testament to Alai’s enduring dedication and ongoing contributions, in different moments of his research life.

L’opposition d’Ernst Mach à l’existence de l’espace absolu et à celle des atomes fait partie des lieux communs de l’histoire de la philosophie des sciences. Mais cette opposition est souvent exagérée et, de plus, mal comprise. La plupart du temps, son attitude anti-réaliste en ce qui concerne l’espace absolu, les atomes et les entités théoriques en général est interprétée comme une conséquence immédiate de sa position empiriste, parfois qualifiée de « sensationnaliste »ii. Cette idée reçue (défendue entre autres par John Blackmore [1972]) sur les thèses de Mach en matière d’épistémologie - et j’entends par ce terme d’épistémologie une conception philosophique de la connaissance en général (Erkenntnislehre) et pas seulement de la connaissance scientifique - comporte une grande part de vérité. Mais une part de vérité seulement. En réalité, les objections soulevées par Mach contre une interprétation réaliste des théories scientifiques – et qui sont moins radicales qu’on ne le pense habituellement – reposent également sur des considérations méthodologiques qui relèvent davantage de la philosophie des sciences (Wissenschaftlehre). On verra d’ailleurs que la pensée de Mach montre une grande cohérence, et même une continuité, entre sa philosophie de la connaissance d’une part, et sa philosophie de la connaissance ordinaire et des sciences d’autre part. Je présenterai d’abord les traits saillants des positions de Mach en ce qui concerne la connaissance humaine en général; ensuite, j’examinerai ses objections à l’encontre de l’espace absolu et, de façon plus détaillée, celles soulevées contre les atomes. Je me pencherai enfin sur les relations entre ces objections et sa prise de position empiriste. Cette analyse nous permettra de mieux comprendre la nature exacte de l’antiréalisme de Mach. Je tenterai de montrer que Mach peut être qualifié – même si cela peut paraître surprenant - de « réaliste scientifique » dans la mesure où certaines entités théoriques possèdent le même statut d’existence, prise en un sens faible, que les objets ordinaires.

In this paper I argue in favour of a moderate and selective version of scientific realism with respect to the existence of some physical theoretical objects and the truth of some statements about them. The analysis of common sense or ordinary experience reveals that existence and truth assertions concerning familiar objects are warranted if they satisfy what we call the criteria of presence and invariance. Ordinary objects exemplify a form or a structure determined by constant and changing features with respect to the variation of the conditions of observation and a content given in sensory presence. It is claimed that some theoretical physical objects that possess a structure or a form determined by invariant and variable characteristics relatively to a specified group of transformations and a content provided by observations on which the measurement of those characteristics is grounded can also be justifiably asserted to exist. We further show that this defence of scientific realism in physics doesn't fall prey to the objections that have been raised against the usual vindication of scientific realism based on the no-miracle argument. Some standard objections to scientific realism, such as the underdetermination of theories by observations and the pessimistic meta-induction, are examined and shown to be unconvincing

After a brief presentation of what I take to be the representational démarche in science, I stress the fundamental role of true judgements in model construction. The success and correctness of a representation rests on the truth of judgements which attribute properties to real targeted entities, called “ontic judgements”. I then present what van Fraassen calls “the Loss of Reality objection”. After criticizing his dissolution of the objection, I offer an alternative way of answering the Loss of Reality objection by showing that the contact of our models with reality is grounded on the truth of ontic judgements. I conclude by examining.

A scientific mathematical law is causal if and only if it is a process law that contains a time derivative. This is the intrinsic criterion for causal laws we propose. A process is a space-time line along which some properties are conserved or vary. A process law contains a time variable, but only process laws that contain a time derivative are causal laws. An effect is identified with what corresponds to a time derivative of some property or magnitude in a process law, whereas the other terms correspond to the cause(s). According to our criterion, causes are simultaneous with their effects and causality has no temporal direction. Several examples from natural and social disciplines support the applicability of our criterion to all scientific laws. Various objections to our proposal are presented and refuted. The merits our intrinsic theory of causality vis-à-vis the Salmon–Dowe conserved quantity theory are discussed.

After a presentation of some relevant aspects of Chakravartty's semi-realism (A Metaphysics for scientific realism. Knowing the unobservable. Cambridge University Press, Cambridge, 2007), this paper addresses two difficulties that appear to be inherent to important components of his proposed metaphysics for scientific realism. First, if particulars and laws are concrete structures, namely actual groupings of causal properties as the semirealist contends, the relation between particulars and laws becomes also a relation between particulars with some annoying consequences. This worry—and some others—are resolved if laws are taken to be statements and particulars are construed not only as groupings of properties, but things that contain a non-conceptual ingredient which can be given in perceptual awareness. Second, on the semirealist's view of particulars it becomes difficult to defend an epistemological version of scientific realism according to which we have good reasons to believe that the same things are referred to despite the fact that successive theories may attribute different properties to them

This article argues that Thomas Kuhn's views on the existence of the world have undergone significant change in the course of his philosophical career. In Structure, Kuhn appears to be committed to the existence of the ordinary empirical world as well as the existence of an independent metaphysical world, but realism about the empirical world is abandoned in his later writings. Whereas in Structure the only relative worlds are the scientific worlds inhabited by the practitioners of various paradigms, the later Kuhn puts the non-scientific worlds of particular groups or cultures on the same footing as the paradigm-related scientific worlds. The article shows that, on what Ian Hacking called the "new-world problem", the later Kuhn has moved to a more radical antirealist position. It is also argued that the earlier and later solutions to the "new-world problem" face insuperable difficulties, which render Kuhn's account of scientific change implausible.