Alessandro Torza

Lewis proposed to test the validity of a modal thesis by checking whether its possible-world translation is a theorem of counterpart theory. However, that criterion fails to validate many standard modal laws, thus raising doubts about the logical adequacy of the Lewisian framework. The present paper considers systems of counterpart theory of increasing strength and shows how each can be motivated by exhibiting a suitable intended model. In particular, perfect counterpart theory validates all the desired modal laws and therefore provides a way out of the logical objection. Finally, a weakening of perfect counterpart theory is put forward as a response to some metaphysical objections.

Metaphysical indeterminacy (MI) is indeterminacy originating in the nonrepresentational world. I develop a theory of MI in terms of objective chance with a number of attractive features: it provides a reductive analysis of MI; it applies at both macroscopic and microscopic scales; it demystifies the target phenomenon by employing no special‐purpose metaphysical primitives; it does not prejudge the question whether the logic of a language capable of describing an indeterminate subject matter is classical, or whether its semantics is bivalent; it comes with built‐in epistemic criteria informed by a naturalistic methodology. The chancy account is compared to three salient alternatives: the Third‐Way View, which postulates the existence of indeterminate propositions; Metaphysical Supervaluationism, which takes indeterminacy to be a metaphysical primitive; and the Determinable‐Based Account, which reduces the target phenomenon to patterns of determinables and determinates. It is argued that the chancy account fares better overall when tested against two paradigmatic case studies: future indeterminacy, and quantum indeterminacy. Applications to further domains are also sketched, and a number of open problems outlined.

Timothy Williamson has defended two hypotheses concerning counterfactual conditionals: that necessity can be defined in counterfactual terms; and that we follow a heuristic to the effect that a counterfactual is assessed by assessing the consequent while counterfactually supposing the antecedent. The two hypotheses form the bedrock for a program aiming to reduce the epistemology of modality to the epistemology of counterfactual thinking. This paper argues that the pair of theses, if construed as Williamson intends it, has the unwanted consequence of trivializing our judgements about necessity and possibility, thus threatening the reductionist program. Trivialization can be avoided if we suitably weaken a background hypothesis concerning the way we assess pairs of mutually inconsistent statements. One important corollary of the proposed solution is that the suppositional heuristic need not yield incorrect judgements about counterpossibles, pace Williamson. Moreover, the proposal remains compatible with vacuism, the view that all counterpossibles are true.

Ted Sider has famously argued that existence, in the unrestricted sense of ontology, cannot be vague, as long as vagueness is modeled by means of precisifications. The first section of Chapter 9 exposes some controversial assumptions underlying Sider’s alleged _reductio_ of vague existence. The upshot of the discussion is that, although existence cannot be vague, it can be _super-vague_, i.e. higher-order vague, for all orders. The second section develops and defends a novel framework, dubbed _negative supervaluationary semantics_, which makes room for the possibility of super-vague existence.

Philosophers distinguish between having a property essentially and having it accidentally. The way the distinction has been drawn suggests that it is modal in character, and so that it can be captured in terms of necessity, or cognate notions. The present chapter takes the suggestion at face value by considering a number of modal characterizations of the essential/accidental distinction that have been articulated and discussed since the early 20th century, as well as some of the challenges that they face.

The way we represent the world in thought and language is shot through with indeterminacy: we speak of red apples and yellow apples without thereby committing to any sharp cutoff between the application of the predicate ‘red’ and of the predicate ‘yellow’. But can reality itself be indeterminate? In other words, can indeterminacy originate in the mind-independent world, and not only in our representations? If so, can the phenomenon also arise at the microscopic scale of fundamental physics? Section 1 of this Element provides a brief overview of the question of indeterminacy. Section 2 discusses the thesis that the world is comprised of indeterminate objects, whereas Section 3 focuses on the thesis that there are indeterminate states of affairs. Finally, Section 4 is devoted to the case study of indeterminacy in quantum physics.

I articulate a Global Best-System Account (GBSA) of laws of nature along broadly Mill–Ramsey–Lewis lines. The guiding idea is that the job of laws is to capture real patterns across time—where a pattern is real if it allows to compress information about matters of particular fact. The GBSA’s key ingredient is a definition of ‘best system’ in terms of a ranking method that meets a number of desiderata: it is rigorously defined; it outputs the ranking based on the candidate systems’ epistemic virtues; it is objective, in that the output does not depend on one’s choice of basic concepts; it avoids two trivialization results (by Lewis, and Arrow-Okasha); and it does not appeal to naturalness, or other metaphysical notions in that vicinity. Although the GBSA is independent of the controversial thesis of Humean Supervenience, it satisfies the weaker thesis that laws of nature supervene on the total physical state of the world. Moreover, the resulting notion of lawhood is hyperintensional, unlike the neighboring notion of nomological necessity. Finally, GBSA-laws do not track naturalness, contra the Lewisian orthodoxy.

Say that metaphysical indeterminacy occurs just when there is a fact such that neither it nor its negation obtains. The aim of this work is to shed light on the issue of whether orthodox quantum mechanics provides any evidence of metaphysical indeterminacy by discussing the logical, semantic, and broadly methodological presuppositions of the debate. I argue that the dispute amounts to a verbal disagreement between classical and quantum logicians, given Eli Hirsch’s account of substantivity; but that it need not be so if Ted Sider’s naturalness-based account of substantivity is adopted instead. Given the latter approach, can anything be said in order to tip the balance of the dispute either way? Some prima facie reasonable constraints on naturalness entail that the classicist is right, and the quantum world is therefore determinate. Nevertheless, there are reasons for weakening those constraints, to the effect that the dispute remains very much open. Finally, I discuss alternative accounts of metaphysical indeterminacy, and argue that they are unsuitable for framing the quantum indeterminacy debate.

The chapter introduces and defends structural pluralism: the view that there is a plurality of ways of carving nature at the joints. The first part of the chapter argues that structural pluralism is able to meet a challenge to Ted Sider’s monism about joint-carving. The second part spells out the metaontological consequences of adopting structural pluralism, and shows that the view is compatible with a moderate form of deflationism about ontological disagreement. The third and last part fleshes out a number of consequences of adopting structural pluralism, and suggests further applications of that view, including a reassessment of an influential argument against vague existence

An influential theory has it that metaphysical indeterminacy occurs just when reality can be made completely precise in multiple ways. That characterization is formulated by employing the modal apparatus of ersatz possible worlds. As quantum physics taught us, reality cannot be made completely precise. I meet the challenge by providing an alternative theory which preserves the use of ersatz worlds but rejects the precisificational view of metaphysical indeterminacy. The upshot of the proposed theory is that it is metaphysically indeterminate whether p just in case it is neither true nor false that p, and no terms in ‘p’ are semantically defective. In other words, metaphysical indeterminacy arises when the world cannot be adequately described by a complete set of sentences defined in a semantically nondefective language. Moreover, the present theory provides a reductive analysis of metaphysical indeterminacy, unlike its influential predecessor. Finally, I argue that any adequate logic of a language with an indeterminate subject matter is neither compositional nor bivalent.

The grounding relation is routinely characterized by means of logical postulates. The aim of this paper is twofold. First, I show that a subset of those postulates is incompatible with a minimal characterization of metaphysical modality. Then I consider a number of ways for reconciling ground with modality. The simplest and most elegant solution consists in adopting serious actualism, which is best captured within a first-order modal language with predicate abstraction governed by negative free logic. I also explore a number of alternative strategies by revising the ground-theoretic postulates, while keeping the modal ones fixed. As I argue, each of those strategies is either unviable, highly contentious, or insufficiently motivated.

The threat of ontological deflationism (the view that disagreement about what there is can be non‐substantive) is averted by appealing to realism about fundamental structure—or so tells us Ted Sider. In this paper, the notion of structural indeterminacy is introduced as a particular case of metaphysical indeterminacy; then it is argued that structural indeterminacy is not only compatible with a metaphysics of fundamental structure, but it can even safeguard it from a crucial objection; finally, it is shown that, if there are instances of structural indeterminacy, a hitherto unacknowledged variety of ontological deflationism will arise. Unless structure is shown to be determinate, ontological deflationism remains a live option. Furthermore, I will consider whether structural indeterminacy could be challenged by adopting a naturalistic epistemology of structure; the question is answered in the negative on the basis of a formal result concerning theory choice. Finally, I submit a new way of articulating the epistemology of structure, which hinges on the very possibility of structural indeterminacy.

Ted Sider has famously argued that existence, in the unrestricted sense of ontology, cannot be vague, as long as vagueness is modeled by means of precisifications. The first section of Chapter 9 exposes some controversial assumptions underlying Sider’s alleged reductio of vague existence. The upshot of the discussion is that, although existence cannot be vague, it can be super-vague, i.e. higher-order vague, for all orders. The second section develops and defends a novel framework, dubbed negative supervaluationary semantics, which makes room for the possibility of super-vague existence.

On one influential view, metaphysical fundamentality can be understood in terms of joint‐carving. Ted Sider has recently argued that (i) some first order quantifier is joint‐carving, and (ii) modal notions are not joint‐carving. After vindicating the theoretical indispensability of quantification against recent criticism, I will defend a logical result due to Arnold Koslow which implies that (i) and (ii) are incompatible. I will therefore consider an alternative understanding of Sider's metaphysics to the effect that (i) some first order quantifier is joint‐carving, and (iii) intensional notions are not joint‐carving. Another result due to Koslow entails that (i) and (iii) are also incompatible. I will argue that this second result is inconclusive. Nevertheless, (iii) is incompatible with another tenet of Sider's metaphysics, namely that (iv) ‘being joint‐carving’ is itself joint‐carving. In order to resolve the inconsistency, I will tentatively argue that condition (iv) should be renounced.

Eduardo García-Ramírez has offered a reductio of the counterfactual analysis of causation. The argument purportedly shows that, given a natural generalization of Lewis’ semantics for counterfactuals, statements expressing the existence of causal dependence across worlds are satisfiable. The aim of the present paper is twofold. In the first part, I show that the purported reductio is flawed, as it relies on an overly strong construal of the semantics for counterfactuals. In particular, it is assumed that we can assign a degree of similarity to any given pair of possible worlds. As it turns out, that assumption reduces to the thesis that the relations of comparative similarity featured in the standard semantics for counterfactuals define an interval scale of measurement on the set of all possible worlds. It will be argued that such a thesis is incompatible with a viable understanding of comparative similarity. The second part of the paper is devoted to a new proof of the possibility of trans-world causation. Nevertheless, the new proof does not amount to a reductio of Lewis’ account of causation per se, but rather of the conjunction of several substantive theses (the counterfactual analysis of causation, modal plenitude, the existence of mereological sums and the best theory account of natural laws).

Lewis proposed to test the validity of a modal thesis by checking whether its possible-world translation is a theorem of counterpart theory. However, that criterion fails to validate many standard modal laws, thus raising doubts about the logical adequacy of the Lewisian framework. The present paper considers systems of counterpart theory of increasing strength and shows how each can be motivated by exhibiting a suitable intended model. In particular, perfect counterpart theory validates all the desired modal laws and therefore provides a way out of the logical objection. Finally, a weakening of perfect counterpart theory is put forward as a response to some metaphysical objections

Anti-haecceitism is the thesis that things cannot differ from actuality in a purely non-qualitative fashion. Anti-haecceitism being a modal notion, we would expect it to be explicable in terms of possible worlds. Bradford Skow denied that, arguing that alternative conceptions of possible worlds prompt non-equivalent characterizations of anti-haecceitism. Therefore, the haecceitism debate should take place in the modal language, rather than in the language of possible worlds. The aim of this paper is to provide a metaphysically neutral possible-world characterization of anti-haecceitism, i.e. one compatible with alternative understandings of the nature of possible worlds.

This volume covers a wide range of topics that fall under the 'philosophy of quantifiers', a philosophy that spans across multiple areas such as logic, metaphysics, epistemology, and even the history of philosophy. It discusses the import of quantifier variance in the model theory of mathematics. It advances an argument for the uniqueness of quantifier meaning in terms of Evert Beth’s notion of implicit definition, and clarifies the oldest explicit formulation of quantifier variance: the one proposed by Rudolf Carnap. The volume further examines what it means that a quantifier can have multiple meanings, and addresses how existential vagueness can induce vagueness in our modal notions. Finally, the book explores the role played by quantifiers with respect to various kinds of semantic paradoxes, the logicality issue, ontological commitment, and the behavior of quantifiers in intensional contexts. ​

I introduce and defend the semantic notion of counterfactual identity, distinguishing it from the metaphysical notion of transworld identity. After showing that Lewis's counterpart theory misconstrues counterfactual identity facts, I outline and motivate a ‘Leibnizian counterpart theory’ where the notion of counterfactual identity is adequately modelled. Finally, I show that counterfactual identity can be characterized without relying on some implausible features of Lewis's theory of conditionals

Languages involving modalities and languages involving vagueness have each been thoroughly studied. On the other hand, virtually nothing has been said about the interaction of modality and vagueness. This paper aims to start filling that gap. Section 1 is a discussion of various possible sources of vague modality. Section 2 puts forward a model theory for a quantified language with operators for modality and vagueness. The model theory is followed by a discussion of the resulting logic. In Section 3, the framework will permit us to address a puzzle raised by Elizabeth Barnes and Robert Williams.

Classical modalism about essence is the view that essence can be analysed in modal terms. Despite Kit Fine's influential critique, no general refutation of classical modalism has yet been given. In the first part of the paper, I provide such a refutation by showing that the notion of essence cannot be analysed in terms of any sentential operator definable in the language of standard quantified modal logic. As a reaction to Fine's critique, some have defended sophisticated modalism, which attempts to analyse essence in an enriched modal language quantifying over both possible and impossible worlds. In the second part of the paper, I argue that sophisticated modalism falls prey to variations on Fine's counterexamples to classical modalism. I conclude that the most promising approaches to understanding the notion of essence consist in taking essence either as primitive or as analysable via a combination of modal and non-modal notions.