James Ladyman, University of Bristol, UK

Natural Necessity is just the Stuff for Ontic Structural Realism

Many empiricists and naturalists champion the reduction of natural necessity to logical or semantic necessity, or complete nihilism about natural necessity. On the other hand, realism about modality is associated with rationalism, and the current idea of sui generis ‘metaphysical modality’ is similarly often accompanied by an a priori methodology. There are forms of structuralism in general, and structural realism in particular, that are not naturalistic. This paper argues that naturalism requires the kind of ontic structural realism in which the commitment to natural necessity is what differentiates it from structural empiricism, and makes for a realist position.

Amanda Bryant, Trent University, Canada

Naturalized Modal Metaphysics: How Science Speaks to Possibility and Necessity

Modal metaphysics might seem recalcitrant to naturalization, since science is primarily concerned with the actual and since, prima facie, actuality does not acquaint us with possibility or necessity. Standard rationalist approaches to metaphysical modality rely on modal intuition and hence are neither naturalistically kosher nor epistemically satisfactory. While developing forms of modal empiricism better their rationalist rivals epistemically, they don’t satisfy the naturalist, because they don’t build in any explicit role for science. I argue that science can bear on and guide modal metaphysics more robustly. This paper will spell out my conception of scientifically responsible modal metaphysics, according to which the metaphysician takes current science as an evidence-base for the justification of modal claims and a model of good modal reasoning. A naturalized modal metaphysics does not rely on dubious metaphysical intuitions, allows for greater resolution of disagreement, accounts for modal error, and provides modal metaphysics with much needed epistemic discipline and control.

Iulian Toader, University of Salzburg, Austria/University of Bucharest, Romania

Structuralism, Formal Semantics, and the Ghost of Modality

Quantum logical calculus does not determine its semantics uniquely, as it admits of non-isomorphic algebraic models. This lack of categoricity has consequences for the view that the analysis of quantum logic provides the paradigm for the semantic analysis of quantum mechanics. Nevertheless, to the best of my knowledge, these consequences have not been discussed so far. The paper will attempt to remedy this situation, by focusing on the relation between the model-theoretical properties of quantum logic and those of quantum mechanics. This discussion is particularly relevant for structuralist views of science and modality.

Claudio Calosi, University of Geneva, Switzerland

Indeterminacy and Modality in a Quantum World

The paper addresses whether quantum mechanics provides examples of genuine metaphysical indeterminacy (it is argued it does), and whether such an alleged indeterminacy can be accounted for in purely modal terms (it is argued it cannot, in that the modal account cannot respect the algebraic structure of quantum observables). Finally, it puts forward a novel account of quantum indeterminacy that crucially draws on determinable and determinate properties. According to such an account there is quantum indeterminacy iff a quantum system instantiates a quantum determinable but not a unique determinate of that determinable.

Alastair Wilson, University of Birmingham, UK

Four Grades of Naturalistic Involvement

How, if at all, should metaphysics be guided by the results of our best science? How, if at all, should science be guided by the results of our best metaphysics? Over the past 20 years, philosophers have answered these questions in a range of highly divergent ways, from the science-first empiricism of James Ladyman and Don Ross to the metaphysics-first rationalism of George Bealer and E.J. Lowe. In this talk I’ll propose an account of what it is for metaphysics to be naturalistic, and show how the account enables us to distinguish four degrees of increasing naturalisticness in our theorizing about specific metaphysical topics. I’ll illustrate with applications to the metaphysics of modality and – time permitting – of time.



Michael Esfeld, University of Lausanne, Switzerland

Super-Humeanism: Ontic Structural Realism, Modality and Natural Relations

The talk argues for Super-Humeanism: this is the stance that admits exactly one type of relations that individuate basic physical objects. The relations are distances and the objects are point particles. This stance implements the idea of (moderate) ontic structural realism according to which there are objects, but all there is to them are the relations in which they stand. Everything in the physical world is fixed by the distance relations and their change. I elaborate on the view of modality that follows from this ontology and spell out why it is superior to a view that includes a primitive modality in the basic relations.

Johanna Wolff, Kings College London, UK

Dimensional Invariance as a Constraint on Laws of Nature

Laws of physics are (typically) dimensionally invariant. Is dimensional invariance a deep constraint on laws of nature, or are laws merely conventionally dimensionally invariant? In this talk I argue that dimensional invariance is indeed deep, and show why this speaks in favour of structuralism about quantities.

Dan Marshall, Lingnan University, Hong Kong

Metaphysical Structuralism

Metaphysical structuralists deny that the fundamental properties and relations include properties such as being unit positively charged and relations such as being 1 meter from. Instead, metaphysical structuralists hold there are no fundamental properties and that the only fundamental relation is the relation of instantiation. In this paper, I argue that, despite being extremely ideologically parsimonious, metaphysical structuralism should be rejected.

Vera Matarese, Institute of Philosophy (Czech Academy of Sciences), Czechia

Super Humeanism: A Naturalized Metaphysical Theory?

Are our best metaphysical theories sufficiently naturalistic? This question occupies a special role in debates in the metaphysics of science, especially after Ladyman and Ross’ defense of naturalized metaphysics (Ladyman and Ross 2007). My talk will ask whether Super-Humeanism (SH) is a naturalized metaphysical theory. While its proponents claim so (Esfeld and Deckert 2018), Wilson (2018) argues that it is an a prioristic and insufficiently naturalistic theory. It is surely difficult to settle the debate if we appeal to general methodological principles. For this reason, I will examine specific cases which show how Super-Humeanism is implemented in physical theories. One of them will touch a central notion of Super-Humeanism, which is the impenetrability of particles; in particular, I will discuss whether the commitment to impenetrable particles can be justified ‘naturalistically’, without presupposing some kind of natural necessity.