Matteo Plebani

The notions of subject matter and aboutness have been objects of considerable attention among philosophers over the last few years. Current theories of subject matter take sentences to be the primary bearers of subject matter: “sentences have aboutness properties if anything has” (Yablo, Aboutness, Princeton University Press, 2014). However, some subsentential expressions can also be thought of as being about something. Moreover, it appears that the subject matters of sentences depend in a systematic way on the aboutness properties of their subsentential components. In this paper, we focus on the question of what predicates are about. We provide an account of predicative subject matter in which subject matters are assigned to predicates in a natural way, and which can be smoothly integrated with some existing accounts of sentential subject matter. We also argue that the notion of predicative subject matter is a worthy object of study, both within the current debate on subject matter and in its own right.

Recent work in the philosophy of language attempts to elucidate the elusive notion of aboutness. A natural question concerning such a project has to do with its motivation: why is the notion of aboutness important? Stephen Yablo offers an interesting answer: taking into consideration not only the conditions under which a sentence is true, but also what a sentence is about opens the door to a new style of criticism of certain philosophical analyses. We might criticize the analysis of a given notion not because it fails to assign the right truth conditions to a class of sentences, but because it characterizes those sentences as being about something they are not about. In this paper, I apply Yablo’s suggestion to a case study. I consider meta-fictionalism, the view that the content of a mathematical claim S is ‘according to standard mathematics, S’. I argue, following Woodward, that, on certain assumptions, meta-fictionalism assigns the right truth-conditions to typical assertoric utterances of mathematical statements. However, I also argue that meta-fictionalism assigns the wrong aboutness conditions to typical assertoric utterances of mathematical statements.

I will contrast two conceptions of the nature of mathematical objects: the conception of mathematical objects as preconceived objects, and heavy duty platonism. I will argue that friends of the indispensability argument are committed to some metaphysical theses and that one promising way to motivate such theses is to adopt heavy duty platonism. On the other hand, combining the indispensability argument with the conception of mathematical objects as preconceived objects yields an unstable position. The conclusion is that the metaphysical commitments of the indispensability argument should be carefully scrutinized.

This paper introduces a new framework, based on the notion of compatibility space, obtained by adding a primitive incompatibility relation to a state space in the sense of Fine. The key idea inspiring the framework is to modify Fine's truthmaker semantics by taking the notion of incompatibility as primitive, and use it to define other notions. We discuss some interesting features of the framework and explore its advantages over the standard framework of state spaces. We review some applications of the framework, including proofs of soundness and completeness theorems for a number of logics, one way to use compatibility states to mirror Kripke frames, and an exploration of a way to use the new framework to provide truthmaking clauses for modal formulas.

The notion of subject matter is a key concern of contemporary philosophy of language and logic. A central task for a theory of subject matter is to characterise the notion of sentential subject matter, that is, to assign to each sentence of a given language a subject matter that may count as its subject matter. In this paper, we elaborate upon David Lewis’ account of subject matter. Lewis’ proposal is simple and elegant but lacks a satisfactory characterisation of sentential subject matter. Drawing on linguistic literature on focus and on the question under discussion, we offer a neo-Lewisian account of subject matter, which retains all the virtues of Lewis’ but also includes an attractive characterisation of sentential subject matter.

Meinongians in general, and Routley in particular, subscribe to the principle of the independence of Sosein from Sein. In this paper, I put forward an interpretation of the independence principle that philosophers working outside the Meinongian tradition can accept. Drawing on recent work by Stephen Yablo and others on the notion of subject matter, I offer a new account of the notion of Sosein as a subject matter and argue that in some cases Sosein might be independent from Sein. The question whether numbers exist, for instance, is not part of the question of how numbers are, which is the topic mathematicians are interested in.

We contribute to the ongoing discussion on mathematical structuralism by focusing on a question that has so far been neglected: when is a structure part of another structure? This paper is a first step towards answering the question. We will show that a certain conception of structures, abstractionism about structures, yields a natural definition of the parthood relation between structures. This answer has many interesting consequences; however, it conflicts with some standard mereological principles. We argue that the tension between abstractionism about structure and classical mereology is an interesting result and conclude that the mereology of abstract structures is a subject that deserves further exploration. We also point out some connections between our discussion of the mereology of structures and recent work on non-well-founded mereologies.

Mathematical platonism is the view that abstract mathematical objects exist. Ontological pluralism is the view that there are many modes of existence. This paper examines the prospects for plural platonism, the view that results from combining mathematical platonism and ontological pluralism. I will argue that some forms of platonism are in harmony with ontological pluralism, while other forms of platonism are in tension with it. This shows that there are some interesting connections between the platonism–antiplatonism dispute and recent debates over ontological pluralism.

‘Grounding and the indispensability argument’ presents a number of ways in which nominalists can use the notion of grounding to rebut the indispensability argument for the existence of mathematical objects. I will begin by considering the strategy that puts grounding to the service of easy-road nominalists. I will give some support to this strategy by addressing a worry some may have about it. I will then consider a problem for the fast-lane strategy and a problem for easy-road nominalists willing to accept Liggins’ grounding strategy. Both are related to the problem of formulating nominalistic explanations at the right level of generality. I will then consider a problem that Liggins only hints at. This problem has to do with mathematics’ function of providing the sort of covering generalizations we need in scientific explanations

The platonism/nominalism debate in the philosophy of mathematics concerns the question whether numbers and other mathematical objects exist. Platonists believe the answer to be in the positive, nominalists in the negative. According to non-factualists, the question is ‘moot’, in the sense that it lacks a correct answer. Elaborating on ideas from Stephen Yablo, this article articulates a non-factualist position in the philosophy of mathematics and shows how the case for non-factualism entails that standard arguments for rival positions fail. In particular, showing how and why non-factualists reject nominalism illuminates the originality and interest of their position.

In the recent literature there has been some debate between advocates of deflationist and fictionalist positions in metaontology. The purpose of this paper is to advance the debate by reconsidering one objection presented by Amie Thomasson against fictionalist strategies in metaontology. The objection can be reconstructed in the following way. Fictionalists need to distinguish between the literal and the real content of sentences belonging to certain areas of discourse. In order to make that distinction, they need to assign different truth-conditions to the real and the literal content. But it is hard to see what more is required for the literal content to be true than for the real content to be true. So, fictionalism is an unsatisfactory position. Here I offer a novel reply to Thomasson’s challenge. I argue that the literal and the real content need not be distinguished in terms of their truth-conditions; rather, they can be distinguished in terms of their different subject-matters, leaving it open whether their truth-conditions coincide or not. I explain how replying to Thomasson’s objection is crucial for deepening our understanding of fictionalist strategies in metaontology.

Some people think that numbers and other mathematical entities exist. They believe in a platonic heaven of ideal mathematical objects, as some people like to put it. This may seem a very strange thing to believe in: after all, we cannot see numbers, nor touch them, nor smell them. So why should one believe that they exist? Because, as Putnam and Quine used to say, numbers are indispensable to science: it seems almost impossible to state our best scientific theories without mentioning numbers or other mathematical objects

A caricature can reveal an aspect of its subject that a more faithful representation would fail to render: by depicting a slow and clumsy person as a monkey one can point out such qualities of the depicted subject, and by depicting a person with quite big ears as a person with enormous ears one can point out that the depicted person has rather big ears. How can a form of representation that is by definition inaccurate be so representationally powerful? Figurative language raises a similar puzzle. Metaphors, taken at face value, are usually false: men are not wolves. The same goes for hyperbolic talk: Putnam did not change his position one billion times in his career. Still, figurative language is expressively powerful: by saying that human beings are wolves or that Putnam changed his position one billion times in his career one conveys, in a very vivid way, some true information about the world (something concerning the facts that human beings are cruel and that Putnam frequently changed opinion). Kendall Walton (1993) provides an elegant explanation of the expressive utility of figurative language by linking metaphor and prop oriented make-believe. We explore the hypothesis that the theory of prop oriented make-believe can also explain the representational efficacy of caricatures.

'Ontology and Metaontology: A Contemporary Guide' is a clear and accessible survey of ontology, focussing on the most recent trends in the discipline. Divided into parts, the first half characterizes metaontology: the discourse on the methodology of ontological inquiry, covering the main concepts, tools, and methods of the discipline, exploring the notions of being and existence, ontological commitment, paraphrase strategies, fictionalist strategies, and other metaontological questions. The second half considers a series of case studies, introducing and familiarizing the reader with concrete examples of the latest research in the field. The basic sub-fields of ontology are covered here via an accessible and captivating exposition: events, properties, universals, abstract objects, possible worlds, material beings, mereology, fictional objects. The guide's modular structure allows for a flexible approach to the subject, making it suitable for both undergraduates and postgraduates looking to better understand and apply the exciting developments and debates taking place in ontology today.

Is all that exists part of the natural world? If there are non-natural entities, what is their difference from natural things? Is the human-independent realm of nature the only paradigm for ontological respectability, as naturalism claims? Can existence be simply explained away by means of formal devices? Philosophers keep struggling with such questions. Still, the two basic notions involved, that of existence and that of nature, have not yet been fully explored. The four essays collected here address the issue from the points of view of the philosophy of mathematics, of analytic ontology, of early modern philosophy, and of contemporary phenomenology. The results will surprise the reader: difficult topics are unlocked, long-received views are called into question, and new perspectives are opened.

This paper investigates the question of how we manage to single out the natural number structure as the intended interpretation of our arithmetical language. Horsten submits that the reference of our arithmetical vocabulary is determined by our knowledge of some principles of arithmetic on the one hand, and by our computational abilities on the other. We argue against such a view and we submit an alternative answer. We single out the structure of natural numbers through our intuition of the absolute notion of finiteness.