Matteo Morganti

Ontic structural realism (OSR) is the view that (i) in spite of the discontinuities that characterise the historical development of science, we can be realist about something, i.e., the concrete counterpart of certain theoretical structures that remain preserved across theory-change; and (ii) such structure is all there is in the actual world, at least at the fundamental level. It is thus a thesis about the fundamental—one whereby relations, not objects, are the basic building blocks of reality. However, there are in fact several dimensions to the structuralism-fundamentality link, and many alternative ways of cashing out the idea that reality is fundamentally structural. Arguably, these require a more systematic and detailed assessment than acknowledged in the literature so far. The chapter provides such an assessment based on considerations coming from both physics and analytic metaphysics, and concludes by pointing to a hitherto quite neglected theoretical option.

This paper explores alternatives to metaphysical foundationalism, the view that grounding relations determine vertical chains that terminate in something fundamental and ungrounded. Rather than offering an exhaustive taxonomy or wide-ranging claims about metaphysical structure per se, the goal is to offer an initial investigation of non-conventional models of the metaphysical architecture of reality. Examples are provided with a view to illustrating that, and how, physics may avail itself of both ‘infinitist’ and ‘coherentist’ models—the former dropping the idea of a fundamental level, the latter abandoning the view that the world must have a hierarchical structure.

In this paper, I critically assess the view that quantum mechanics, and quantum theory more generally, is best interpreted on the basis of an ontology of non-individual objects. I argue that—if one opts for non-individuality at all—one should go for a property- rather than object-based framework. To support this claim, I consider first the role that the Principle of the Identity of the Indiscernibles is supposed to play in this context. Then, I look at more specific facts concerning particle number in quantum field theory and the no-go results that obtain in relativistic quantum field theory. In all these cases, I argue, a theory of non-individual objects falls short of providing a satisfactory explanation, while an ontology of properties fares much better. The necessity follows to provide a precise interpretation of what has been referred to as the Received View of quantum mechanics, and to reassess an ongoing line of research based on the notion of non-individual object.

In recent work, Nina Emery has defended the view that, in the context of naturalistic metaphysics, one should maintain the same epistemic attitude towards science and metaphysics. That is, naturalists who are scientific realists ought to be realists about metaphysics as well; and naturalists who are antirealists about science should also be antirealists about metaphysics. We call this the ‘parity thesis’. This paper suggests that the parity thesis is widely, albeit often implicitly, accepted among naturalistically inclined philosophers, and essentially for reasons similar to Emery’s. Then, reasons are provided for resisting Emery’s specific inference from scientific realism to realism about metaphysics. The resulting picture is a more nuanced view of the relationship between science and metaphysics within the naturalistic setting than the one which is currently most popular.

Metaphysics is traditionally conceived as aiming at the truth — indeed, the most fundamental truths about the most general features of reality. Philosophical naturalists, urging that philosophical claims be grounded on science, have often assumed an eliminativist attitude towards metaphysics, consequently paying little attention to such a definition. In the more recent literature, however, naturalism has instead been taken to entail that the traditional conception of metaphysics can be accepted if and only if one is a scientific realist (and puts the right constraints on acceptable metaphysical claims). Here, we want to suggest that naturalists can, and perhaps should, pick a third option, based on a significant yet acceptable revision of the established understanding of metaphysics. More particularly, we will claim that a fictionalist approach to metaphysics is compatible with both the idea that the discipline inquires into the fundamental features of reality and naturalistic methodology; at the same time, it meshes well with both scientific realism and instrumentalism.

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.

This Element presents and critically examines the relationship between metaphysics and the sciences. Section 1 provides a brief introduction. Section 2 looks at the methodological issues that arise when metaphysics and science get into contact, which is a much-debated aspect of the larger dispute concerning philosophical 'naturalism' and 'anti-naturalism'. A taxonomy of possible views is offered. Section 3 looks more specifically at milder forms of naturalism about metaphysics, which attempt in various ways to make it 'continuous' with science while preserving some degree of autonomy for it. Section 4 adds some reflections on what might be regarded as the most pressing open problem when it comes to doing scientifically oriented metaphysics (but also when practising metaphysics or science in isolation): the problem concerning theory choice and the value of non-empirical factors in determining which explanation of certain phenomena should be preferred.

I discuss naturalism in the philosophy of science, with a special focus on the issue of scientific realism. After introducing the theme of naturalism in more general terms, I critically assess whether and how the debate over scientific realism lends itself to a naturalistic approach. I then carry out an analogous inquiry with respect to the relationship between metaphysics and science – a careful analysis of which appears to be particularly important from the point of view of the scientific realist. In both cases, I suggest that a naturalistic approach is both possible and potentially fruitful, provided that naturalism is given a “mild” or “liberal” characterization. In the course of the discussion, I offer an overview of existing positions and provide some considerations in favor of a metaphysically engaged scientific realism.

We put forward a new, ‘coherentist’ account of quantum entanglement, according to which entangled systems are characterized by symmetric relations of ontological dependence among the component particles. We compare this coherentist viewpoint with the two most popular alternatives currently on offer—structuralism and holism—and argue that it is essentially different from, and preferable to, both. In the course of this article, we point out how coherentism might be extended beyond the case of entanglement and further articulated.

This paper discusses the view according to which time is not an objective feature of reality, independent of the knowing subject. Rather than attempting to provide an exhaustive historical reconstruction of the debate concerning the (un)reality of time, we will proceed by looking at two paradigmatic and rather different arguments to the effect that time is an illusion: a well-known, purely philosophical argument due to McTaggart, and an argument (or, maybe better, a family of considerations) coming from contemporary research in physics, in particular quantum gravity. Interesting common aspects will be emphasized and, in closing, a few more general considerations will be made.

In this paper, we evaluate some proposals that have been put forward to clarify the ontological consequences of relational quantum mechanics. We first focus on priority monism and ontic structural realism and argue that these views are not suitable for providing an ontological interpretation of the theory. Then, we discuss an alternative interpretation that we regard as more promising, based on so-called ‘metaphysical coherentism’, which we also connect to the idea of an event-based, or ‘flash’, ontology.

In this paper, we evaluate some proposals that can be advanced to clarify the ontological consequences of Relational Quantum Mechanics. We first focus on priority monism and ontic structural realism and argue that these views are not suitable for providing an ontological interpretation of the theory. Then, we discuss an alternative interpretation that we regard as more promising, based on so-called ‘metaphysical coherentism’, which we also connect to the idea of an event-based, or ‘flash’, ontology.

In this paper, we focus on two related reductive theses in metaphysics—Humean Supervenience and Composition as Identity—and on their status in light of the indications coming from science, in particular quantum mechanics. While defenders of these reductive theses claim that they can be updated so as to resist the quantum evidence, we provide arguments against this contention. We claim that physics gives us reason for thinking that both Humean Supervenience and Composition as Identity are at least contingently false, as the very process of composition determines, at least in some cases, the nature of composed systems. The argument has essentially to do with the fact that denying the reductive theses in question allows one to provide better explanations for the quantum evidence.

This paper puts forward the hypothesis that the distinctive features of quantum statistics are exclusively determined by the nature of the properties it describes. In particular, all statistically relevant properties of identical quantum particles in many-particle systems are conjectured to be irreducible, ‘inherent’ properties only belonging to the whole system. This allows one to explain quantum statistics without endorsing the ‘Received View’ that particles are non-individuals, or postulating that quantum systems obey peculiar probability distributions, or assuming that there are primitive restrictions on the range of states accessible to such systems. With this, the need for an unambiguously metaphysical explanation of certain physical facts is acknowledged and satisfied.