Naomi Thompson

This paper argues for an alternative to orthodox foundationalist accounts of metaphysical structure as characterized by grounding relations. There are good reasons to take grounding to be a non-symmetric (rather than an asymmetric) relation, and to take facts to be related in complex networks of ground. These networks are closely analogous to the networks of justified beliefs characteristic of coherentism about justification. This position is called _metaphysical interdependence_. The chapter argues that grounding is an explanatory relation (rather than merely a relation which backs explanations), and that there are good reasons to resist the contention that explanation is asymmetric, including cases seemingly best described as cases of holistic metaphysical explanation. Metaphysical interdependence is a promising account of the metaphysical structure of reality.

Some metaphysically interesting notions fall outside of the realm of the mind-independent, and as such will erroneously be considered unworthy of our attention by any view that thinks only of realist metaphysics as substantive (Taylor, 2023). In this article I propose two ways of conceiving of substantive metaphysics that includes some mind-dependent phenomena. The first is to understand substantivity in terms of carving at the joints, but to take where the ‘joints’ are to depend in part on our own interests, preferences, and conceptual schemes (the joints are ours, not nature’s). The second is to think of ‘reality’ as a system of explanatory dependence that includes some suitably embedded mind-dependent phenomena, and thus to deny (if we continue to characterize realism in terms of mind-independence) that we should be realists about all of ‘reality’.

Thomasson is a simple realist about the vast majority of entities: she thinks that they exist, and that their existence is to be accepted as a trivial consequence of the truth of various uncontroversial sentences (Thomasson, Ontology Made Easy. Oxford: Oxford University Press, 2015, p. 156). This position is to be taken in contrast to the explanatory realism familiar from dominant post-Quinean metaontology: the view that entities are posited to explain phenomena, and that (very roughly) we should believe in whatever we need in order for our best scientific theories to come out as true. Recent literature further suggests an approach I’ll call ‘fundamentality realism’: the idea that we should understand realism in connection with notions of fundamentality and metaphysical priority. I introduce these notions and the relations between them before describing an objection to Thomasson-style simple realism. I argue that this objection can be overcome by combining simple realism with elements of fundamentality realism, and that such a view can nevertheless be seen to fit with Thomasson's overall metaphysical worldview.

This paper develops an account of metaphysical explanation according to which metaphysical explanations are answers to what-makes-it-the-case-that questions. On this view, metaphysical explanations are not to be considered entirely objective, but are subject to epistemic constraints imposed by the context in which a relevant question is asked. The resultant account of metaphysical explanation is developed independently of any particular views about grounding. Toward the end of the paper an application of the view is proposed that takes metaphysical explanations conceived in this way to characterize reality's structure. According to this proposal, reality's structure is partly constituted by a projection of our explanatory practices onto reality.

Karen Bennett’s Making Things Up argues that talk of generation and construction, giving rise to, and getting one thing out of another are to be understood in terms of building. Building-talk is commonplace if not ubiquitous in philosophy, and so building is one of the most important philosophical notions. Making Things Up offers a refreshing perspective on the debate about structure and fundamentality. Whilst Bennett of course engages with the recent literature, she sets things up in her own terms, and with the big picture in mind. The result is a thorough and compelling account of how reality is constructed.

Grounding talk has become increasingly familiar in contemporary philosophical discussion. Most discussants of grounding think that grounding talk is useful, intelligible, and accurately describes metaphysical reality. Call themrealistsabout grounding. Some dissenters reject grounding talk on the grounds that it is unintelligible, or unmotivated. They would prefer to eliminate grounding talk from philosophy, so we can call themeliminitivistsabout grounding. This paper outlines a new position in the debate about grounding, defending the view that grounding talk is (or at least can be) intelligible and useful. Grounding talk does not, however, provide a literal and veridical description of mind-independent metaphysical reality. This (non-eliminative)irrealismabout grounding treads a path between realism and eliminativism.

This thesis explores attempts to characterise the structure of reality. Three notions stand out: Lewisian naturalness, Sider’s ‘structure’, and grounding, where the latter has become the most popular way to characterise the structure of reality in the contemporary literature. I argue that none of these notions, as they are currently understood, are suited for limning the metaphysical structure of reality. In the first part of the thesis I argue that, by the lights of the relevant theories, both naturalness and structure fall short of the theoretical role carved out for those posits. In the second part of the thesis I present two challenges to the ‘orthodox’ conception of grounding. The first contests the standard assumption that grounding is asymmetric, both by citing what I take to be best described as symmetric instances of grounding, and by developing and arguing for a new theory of metaphysical structure – ‘metaphysical interdependence’ – which takes grounding to be nonsymmetric. The second challenge concerns the relationship between grounding and explanation, and leads to a dilemma for the grounding theorist. My proposed resolution to the dilemma is to adopt an antirealist approach to grounding, which I further motivate and develop in the final chapter.

The perfectly natural properties and relations are special—they are all and only those that "carve nature at its joints." They act as reference magnets, form a minimal supervenience base, figure in fundamental physics and in the laws of nature, and never divide duplicates within or between worlds. If the perfectly natural properties are the (metaphysically) important ones, we should expect being a perfectly natural property to itself be one of the (perfectly) natural properties. This paper argues that being a perfectly natural property is not a very natural property, and examines the consequences.

Attempts to elucidate grounding are often made by connecting grounding to metaphysical explanation, but the notion of metaphysical explanation is itself opaque, and has received little attention in the literature. We can appeal to theories of explanation in the philosophy of science to give us a characterization of metaphysical explanation, but this reveals a tension between three theses: that grounding relations are objective and mind-independent; that there are pragmatic elements to metaphysical explanation; and that grounding and metaphysical explanation share a close connection. Holding fixed the mind-independence of grounding, I show that neither horn of the resultant dilemma can be blunted. Consequently, we should reject the assumption that grounding relations are mind-independent.

It is commonly assumed that grounding relations are asymmetric. Here I develop and argue for a theory of metaphysical structure that takes grounding to be nonsymmetric rather than asymmetric. Even without infinite descending chains of dependence, it might be that every entity is grounded in some other entity. Having first addressed an immediate objection to the position under discussion, I introduce two examples of symmetric grounding. I give three arguments for the view that grounding is nonsymmetric (I call this view ‘metaphysical interdependence’). These arguments are: (i) that metaphysical interdependence is the only theory able to reconcile competing intuitions about grounding; (ii) that it is the only theory consistent with both ‘gunk’ and ‘junk’; and (iii) that offers a satisfactory solution to the problem concerning whether or not grounding is itself grounded.

In this dissertation I suggest an answer to the famous question ‘why is there something rather than nothing?’ I argue that there is something because there could not have been nothing. The focus of my discussion is the empty possible world of metaphysical nihilism, and the first chapter is a rejection of the only prominent argument for that position; the subtraction argument. In the second part of my discussion I construct a positive argument against metaphysical nihilism, I assume, as is common in the literature, that inconceivability provides evidence of impossibility. I establish the inconceivability of nothingness taking propositional imagining to be the core of conceivability, claiming that we have no experience of nothingness in the relevant sense and are unable to imagine it. Finally, I suggest that a distinction should be made between everyday use of the term ‘nothing’, and the sense under discussion here. The inconceivability of nothingness applies only in the latter case. Given that nothingness is inconceivable, we have prima facie reason to suppose that the empty world is impossible. I conclude that given the failure of the subtraction argument and in light of my argument against metaphysical nihilism, that position should be rejected.