Introduction

Abstract

Obviously, science matters to philosophy. But is philosophy also constrained by science? Naturalism is roughly the view that answers positively. However, even among proponents of naturalism, how science constrains philosophy has always been (and still is) a subject of debate. There are two basic dimensions in which the debate takes place, which give rise to two different kinds of naturalism: ontological and methodological. The former concerns what there is, while the latter deals with the methods whereby we acquire knowledge and beliefs. Ontological Naturalism is loosely the view that all of what there is belongs to the natural world, where the natural world is the world described by the natural sciences. By maintaining, in turn, that the ultimate structure of the world is what the natural sciences say it to be, it is to some extent close to Physicalism, according to which what most fundamentally exist are the entities and properties posited by basic physics. On the other hand, methodological naturalism is often thought of as making an epistemological claim akin to scientism—the claim that the best (perhaps the unique) approach to acquiring knowledge is that of natural sciences. Accordingly, it holds that the very same methods used to arrive at scientific theories are the only legitimate ones to be employed by philosophy.Each of these horns of naturalism implies important consequences for our understanding of the relationship between science and many areas of philosophy, including metaphysics. From the methodological point of view, naturalism might be said to entail the denial that our conception of reality needs to include whatever is exclusively accessible to metaphysical theorizing (or to “first philosophy”), understood as a distinct mode of inquiry that lacks ties to the results and practices of the sciences. Indeed, methodological naturalism is usually assumed to reject the project of a priori theorizing, and it is perhaps hard to see how the traditional metaphysics, as well as current analytical metaphysics, might be in the business of developing and assessing synthetic theories of the world supported by a posteriori evidence. From the ontological point of view, naturalism sees science as already giving us a full account of everything, including our place within that picture. Despite this, the debate around the nature of metaphysics remains very much alive (and complex), spreading its influence all across philosophy and our view of the world. The upshot is that much of metaphysical work is nowadays motivated by the naturalist desire to accommodate what the natural sciences have taught us about the world. This special issue stems exactly from the ongoing debate between naturalist and non-naturalist metaphysicians and aims to assess the prospects of naturalized projects in metaphysics and their relationships to traditional metaphysics.Are science and metaphysics separable enterprises? Should allowable metaphysical theories be constrained by and continuous with natural sciences? Does successful scientific research presuppose metaphysics? These are some of the questions addressed in the contributions comprising this special issue. In response, most of them undertake theoretical commitments of a general naturalist stamp, others challenge their philosophical cogency, while still others discuss and contrast the various versions of naturalism that are currently at the center of many metaphysical debates—which often involve some mixture of the two above-mentioned ones, in different proportions. As a result, this special issue hopes to represent the state of the art drawn from different perspectives, helping somehow to clarify extent and ongoing work in metaphysics with respect to the challenges posed by naturalist thinking and eventually to pave the way for future developments and discussions.The issue opens with Don Ross's paper “A flexible, sloppy blob? Ontology, AI, and the role of metaphysics.” In it, Ross defends a naturalized metaphysics that, in contrast with traditional metaphysical projects, is driven directly by fundamental physics. Therefore, since fundamental physics is taken to be the authoritative source of knowledge on the general structure of the universe, metaphysics should neither be separated from nor transcend it. In particular, he rejects more recent works on building metaphysical foundations for applied ontology—e.g., metaphysics for the foundations of AI—as somehow apt to vindicate the value of analytic metaphysics for the edifice of human knowledge. At the same time, however, he points out how his naturalist (methodological) naturalist approach neither incorporates nor implies a physicalistic reduction.Ferdinando Ceravolo and Steven French, in their contribution “What is a Naturalized Principle of Composition?” also support the project of a methodologically naturalized metaphysics. They focus on Van Inwagen's General Composition Question (GCQ). Specifically, they address the issue concerning whether GCQ could be underpinned by principles that are found to be naturalistically acceptable—that is, constrained and informed by advanced physical knowledge. Arguing positively, they outline two candidates for naturalistically accredited principles of composition and explore the various costs of choosing between them.Along the same lines, in his essay “Naturalism and the Question of Ontology,” Javier Cumpa argues for a naturalistic approach in metaontology based on the project of Wilfrid Sellars. He proposes a naturalistic criterion of relational substantivity for ontological questions, which is held to be naturalistic insofar as it relies on the epistemic value and the degree of understanding of the world in line with science that those questions provide us. Cumpa's view is certainly methodologically naturalist, however, although ontologically he does not seem to be committed to metaphysical notions such as ontological categories, he endorses what he calls an “Impure Eliminativism about Categories.”A more straightforward version of eliminativism is advocated by Otávio Bueno in his chapter “Dispensing with Facts, Substances, and Structures.” He contends that, even though ontological categories (i.e., structures, substances, and facts) play a central role in metaphysical theorizing, we do not need to be committed to their existence. Unlike metaphysical realists – who see true thought or assertion as adequately shaped in terms of the correct representation of completely thought and/or language independent bits of reality – he accounts for metaphysical discourse by offering a naturalist account of the linguistic practice that govern it, but without the ontological commitments that realism recommends. Nevertheless, by dropping realism he does not aim to drop metaphysics as an important form of understanding the world. In order to qualify metaphysical judgements as meaningful, he explores and invokes a distinctive deflationary strategy. The result is a view that takes metaphysical discourse literally but without ontologically inflationary maneuvers.The same deflationary strategy is pursued by Anjan Chakravartty in his piece “Last Chance Saloons for Natural Kind Realism.” But rather than on ontological categories in general, he focuses on natural kinds, arguing against realist views that contend for their mind-independent existence. Nevertheless, he shows how a deflationary approach to kinds, while rejecting kind realism, can be integrated with broader realist doctrines such as scientific realism. That is, we need not be committed to either the existence of these posits or with the metaphysically inflationary interpretations that support them in order to invoke these items in scientific theorizing and to vindicate as objective or mind-independent the truth or falsity of scientific as well as everyday claims about natural kinds.In contrast to the previous standpoints, in her article “Metaphysics as Essentially Imaginative and Aiming at Understanding,” Michaela M. McSweeney defends a non-naturalist view of metaphysics. She explores the idea that metaphysics is essentially imaginative and (at least in part) “up to us.” But treating metaphysics as essentially imaginative makes metaphysics methodologically different from scientific inquiry and more akin to art. Nevertheless, she maintains, it can still be deemed epistemologically valuable to the extent that imagination can lead to understanding. On her view, the central goal of the metaphysical project thus turns out to be understanding rather than truth.The closing paper of the issue investigates precisely the relationship between methodological naturalism and ontological naturalism. In “Methodological naturalism undercuts ontological naturalism,” Peter Forrest argues that the combination of ontological with methodological naturalism is untenable. According to his view, one way to defend ontological naturalism is to retain a version of nominalism: specifically, what he calls Redundancy Nominalism (a kind of deflationary nominalism). On the other hand, methodological naturalism requires adopting Categorial Realism. This means being a realist about universals in at least a minimal way. As a result, the fundamental description that methodological naturalism requires proves be contrary to ontological naturalism, whose precondition, in turn, is not available to methodological naturalists. This leads him to criticize ontological naturalism as a belief but, at the same time, to vindicate it as a speculation.