Thomas Hofweber

Many significant problems in metaphysics are tied to ontological questions, but ontology and its relation to larger questions in metaphysics give rise to a series of puzzles that suggest that we don't fully understand what ontology is supposed to do, nor what ambitions metaphysics can have for finding out about what the world is like. Thomas Hofweber aims to solve these puzzles about ontology and consequently to make progress on four metaphysical debates tied to ontology: the philosophy of arithmetic, the metaphysics of ordinary objects, the problem of universals, and the question of whether the fact-like aspect of reality is independent of us. Crucial parts of the proposed solution involve considerations about quantification and its relationship to ontology, the place of reference in natural languages, the relationship between syntactic form and focus, whether there could be any ineffable facts, and others.

Everyone working on metaphysical questions about properties or propositions knows the reaction that many non-philosophers, even nonmetaphysicians, have to such questions. Even though they agree that Fido is a dog and thus has the property (or feature or characteristic) of being a dog, it seems weird, suspicious, or confused to them to now ask what that thing, the property of being a dog, is. The same reservations do not carry over to asking what this thing, Fido, is. There is a substantial and legitimate project to find out more about Fido, but is there a similar substantial and legitimate project to find out more about the property of being a dog? Metaphysicians know that there is a straightforward way to motivate such a project, and much of the contemporary debate in the metaphysics of properties is in the ballpark of carrying it out. If we agree that Fido has the property of being a dog, then there is something that is a property and that Fido has. Thus we can ask about what this thing is that he has. How does it relate to Fido? Is it concrete or abstract? Is it fully present in each object that has it? And so on and so forth. Maybe the nonphilosophers are merely not used to asking such questions about unusual entities such as properties, but they are equally legitimate for them as they are for any other thing. However, even metaphysicians sometimes have the nagging feeling that something has gone wrong in the metaphysics of properties, and that a substantial metaphysical investigation into their..

In “Tense and Reality”, Kit Fine () proposed a novel way to think about realism about tense in the metaphysics of time. In particular, he explored two non-standard forms of realism about tense, arguing that they are to be preferred over standard forms of realism. In the process of defending his own preferred view, fragmentalism, he proposed a fragmentalist interpretation of the special theory of relativity, which will be our focus in this paper. After presenting Fine's position, we will raise a problem for his fragmentalist interpretation of STR. We will argue that Fine's view is in tension with the proper explanation of why various facts obtain. We will then consider whether similar considerations also speak against fragmentalism in domains other than STR, notably fragmentalism about tense.

Cardinality arguments against regular probability measures aim to show that no matter which ordered field ℍ we select as the measures for probability, we can find some event space F of sufficiently large cardinality such that there can be no regular probability measure from F into ℍ. In particular, taking ℍ to be hyperreal numbers won't help to guarantee that probability measures can always be regular. I argue that such cardinality arguments fail, since they rely on the wrong conception of the role of numbers as measures of probability. With the proper conception of their role we can see that for any event space F, of any cardinality, there are regular hyperreal-valued probability measures.

Hilbert’s program in the philosophy of mathematics comes in two parts. One part is a technical part. To carry out this part of the program one has to prove a certain technical result. The other part of the program is a philosophical part. It is concerned with philosophical questions that are the real aim of the program. To carry out this part one, basically, has to show why the technical part answers the philosophical questions one wanted to have answered. Hilbert probably thought that he had completed the philosophical part of his program, maybe up to a few details. What was left to do was the technical part. To carry it out one, roughly, had to give a precise axiomatization of mathematics and show that it is consistent on purely finitistic grounds. This would come down to giving a relative consistency proof of mathematics in finitist mathematics, or to give a proof-theoretic reduction of mathematics on to finitist mathematics (we will look at these notions in more detail soon). It is widely believed that Gödel’s theorems showed that the technical part of Hilbert’s program could not be carried out. Gödel’s theorems show that the consistency of arithmetic can not even be proven in arithmetic, not to speak of by finitistic means alone. So, the technical part of Hilbert’s program is hopeless, and since Hilbert’s program essentially relied on both the technical and the philosophical part, Hilbert’s program as a whole is hopeless. Justified as this attitude is, it is a bit unfortunate. It is unfortunate because it takes away too much attention from the philosophical part of Hilbert’s program. And this is unfortunate for two reasons.

I argue that the semantic thesis of direct reference and the meta- physical thesis of the supervenience of the non-physical on the physical cannot both be true. The argument first develops a necessary condition for supervenience, a so-called conditional locality requirement, which is then shown to be incompatible with some physical object having object dependent properties, which in turn is required for the thesis of direct reference to be true. We apply this argument to formulate a new argument against the claim that a thisness is analyzable in purely general terms, one that does not rely on complete symmetry nor the falsity of the identity of indiscernibles. I outline a strategy at the end how the conclusion could be avoided, at a price.

Idealism in its strong form is the view that our human minds in particular, not just minds in general, are metaphysically central to reality, somehow. This chapter presents an argument for this strong form of idealism. The argument will come largely from the philosophy of language, which might sound dubious. However, it will be shown that such an argument can establish a substantial metaphysical conclusion nonetheless. One key move is to distinguish two versions of idealism tied to two ways of conceiving of reality: the totality of facts vs. the totality of things. Ontological idealism is false: we are not central for reality understood as the totality of things. However, conceptual idealism, a version of idealism concerning the totality of facts, is true. The argument given in this chapter aims to show why and how that can be.

Although there is a prima facie strong case for a close connection between the meaning and inferential role of certain expressions, this connection seems seriously threatened by the semantic and logical paradoxes which rely on these inferential roles. Some philosophers have drawn radical conclusions from the paradoxes for the theory of meaning in general, and for which sentences in our language are true. I criticize these overreactions, and instead propose to distinguish two conceptions of inferential role. This distinction is closely tied to two conceptions of deductive logic, and it is the key, I argue, for understanding first the connection between meaning and inferential role, and second what the paradoxes show more generally.

forthcoming in Meanings and other Things: essays on Stephen Schiffer Gary Ostertag (ed.) MIT Press 2007. Schiffer substantially changed his view about propositions and that-clauses somewhere between his two most recent books: Remnants of Meaning and The Things We Mean. I look at what problems his earlier view had, and what reason Schiffer gives for giving it up in favor of his more recent view. I argue that Schiffer’s reasons are not very good reasons, and that instead the problems for Remnants can be solved, contrary to the ones Things faces. I outline how a view in the spirit of the one Schiffer held in Remnants can be formulated and defended against the problems that his version faces. In the end we should go back to a view like the one he held in Remnants.

An under-explored intermediate position between traditional materialism and traditional idealism is the view that although the spatiotemporal world is purely material, minds nonetheless have a metaphysically special place in it. One way this can be is via a special role that subjects have in the metaphysics of material objects. Some metaphysical aspect of material objects might require the existence of subjects. This would support that minds must exist if material objects exist and thus that a mindless material world is impossible. This view, labeled the subjectivity thesis by Anton Friedrich Koch, was defended by him with an intriguing, purely metaphysical argument connected to the individuation of material objects in space and time. The present paper hopes to make progress on assessing the viability of such a position. It starts by critically examining Koch's argument for the subjectivity thesis, as well as similar arguments that give minds a central place in the metaphysics of material objects via considerations about identity and difference. It then compares these ideas to similar ones in the philosophy of time, and concludes with an outlook on whether such a position is viable and what needs to be done to fill the gaps unearthed along the way

In his groundbreaking Grundlagen, Frege (1884) pointed out that number words like ‘four’ occur in ordinary language in two quite different ways and that this gives rise to a philosophical puzzle. On the one hand ‘four’ occurs as an adjective, which is to say that it occurs grammatically in sentences in a position that is commonly occupied by adjectives. Frege’s example was (1) Jupiter has four moons, where the occurrence of ‘four’ seems to be just like that of ‘green’ in (2) Jupiter has green moons. On the other hand, ‘four’ occurs as a singular term, which is to say that it occurs in a position that is commonly occupied by paradigmatic cases of singular terms, like proper names: (3) The number of moons of Jupiter is four. Here ‘four’ seems to be just like ‘Wagner’ in (4) The composer of Tannhäuser is Wagner, and both of these statements seem to be identity statements, ones with which we claim that what two singular terms stand for is identical. But that number words can occur both as singular terms and as adjectives is puzzling. Usually adjectives cannot occur in a position occupied by a singular term, and the other way round, without resulting in ungrammaticality and nonsense. To give just one example, it would be ungrammatical to replace ‘four’ with ‘the number of moons of Jupiter’ in (1): (5) *Jupiter has the number of moons of Jupiter moons. This ungrammaticality results even though ‘four’ and ‘the number of moons of Jupiter’ are both apparently singular terms standing for the same object in (3). So, how can it be that number words can occur both as singular terms and as adjectives, while other adjectives cannot occur as singular terms, and other singular terms cannot occur as adjectives?

It is natural to think that questions in the metaphysics of chance are independent of the mathematical representation of chance in probability theory. After all, chance is a feature of events that comes in degrees and the mathematical representation of chance concerns these degrees but leaves the nature of chance open. The mathematical representation of chance could thus, un-controversially, be taken to be what it is commonly taken to be: a probability measure satisfying Kolmogorov’s axioms. The metaphysical questions about chance seem to be left open by all this. I argue that this is a mistake. The employment of real numbers as measures of chance in standard probability theory brings with it commitments in the metaphysics of (objective) chance that are not only substantial but also mistaken. To measure chance properly we need to employ extensions of the real numbers that contain infinitesimals: positive numbers that are infinitely small. But simply using infinitesimals alone is not enough, as a number of arguments show. Instead we need to put three ideas together: infinitesimals, the non-locality of chance and flexibility in measurement. Only those three together give us a coherent picture of chance and its mathematical representation.

Philosophers and theorists have long been puzzled by humans' ability to talk about things that do not exist, or to talk about things that they think exist but, in fact, do not. _Empty Names, Fiction, and the Puzzles of Non-Existence_ is a collection of 13 new works concerning the semantic and metaphysical issues arising from empty names, non-existence, and the nature of fiction. The contributors include some of the most important researchers working in these fields. Some of the papers develop and defend new positions on these matters, while others offer important new perspectives and criticisms of the existing approaches. The volume contains a comprehensive introductory essay by the editors, which provides a survey of the philosophical issues concerning empty names, the various responses to these issues, and the literature on the subject to date

Every fifteen years or so Stephen Schiffer writes a state of the art book on the philosophy of language, with special emphasis on belief ascriptions, meaning, and propositions. The latest is his terrific new book The Things we Mean. It is again full of ideas, insights, arguments, expositions, and theories. For us, however, who believe that that-clauses are first and foremost clauses, not referring expressions, and that they thus do not refer to propositions or anything else, The Things we Mean brings home the news that our champion, the author of Remnants of Meaning, has, alas, crossed over to the dark side. Although Schiffer’s earlier book defended one of the best versions of the no-reference theory, and brought up many of the issues that need to be addressed to defend such a theory, he now has recanted and switched sides. His new theory holds that propositions do exist after all, and that-clauses do refer to them. However, some of the motivation for the no-reference theory is incorporated into his new theory. In Remnants of Meaning one of the main reasons for rejecting the reference of that-clauses was the apparent impossibility to compositionally assign that-clauses their referents, and thus to give a compositional semantics for natural language. In The Things we Mean Schiffer still finds fault with any way to compositionally determine what things propositions are. But now the conclusion is not that they are not things, but that they are things that are not reducible to certain other things: they are sui generis entities. But they are not just any kind of sui generis entities, they are pleonastic entities. The use of the term ”pleonastic” might be slightly confusing, though, since propositions according to the new theory are neither pleonastic in the sense of redundant, nor pleonastic in the sense of the pleonastic it, which suggests a no-reference theory. Rather they are pleonastic in a certain technical sense. Simply put, pleonastic entities are the ones that i) can be introduced by 1 something-from-nothing transformations, and ii) the statement that there are such entities doesn’t imply anything about other entities that wasn’t implied before..

Ontology is the philosophical discipline that tries to find out what there is: what entities make up reality, what is the stuff the world is made from? Thus, ontology is part of metaphysics, and in fact it seems to be about half of all of metaphysics. It tries to establish what (kinds of) things there are, the other half tries to find out what the (general) properties of these things are and what (general) relations they have to each other. Settling questions in ontology would bring with it major progress in metaphysics. And it would bring with it major progress in a variety of areas in philosophy outside of metaphysics as well. Many philosophical debates outside of metaphysics are quite directly influenced by how things turn out in ontology. Whether or not there are certain entities will give rise to quite different answers in various philosophical debates. I would like to very briefly describe three debates where ontological questions play a central role. These debates are either directly from metaphysics or from other areas of philosophy and they will be of central importance throughout this paper.

One puzzling feature of talk about properties, propositions and natural numbers is that statements that are explicitly about them can be introduced apparently without change of truth conditions from statements that don't mention them at all. Thus it seems that the existence of numbers, properties and propositions can be established`from nothing'. This metaphysical puzzle is tied to a series of syntactic and semantic puzzles about the relationship between ordinary, metaphysically innocent statements and their metaphysically loaded counterparts, statements that explicitly mention numbers, properties and propositions, but nonetheless appear to be equivalent to the former. I argue that the standard solutions to the metaphysical puzzles make a mistaken assumption about the semantics of the loaded counterparts. Instead I propose a solution to the syntactic and semantic puzzles, and argue that this solution also gives us a new solution to the metaphysical puzzle. I argue that instead of containing more semantically singular terms that aim to refer to extra entities, the loaded counterparts are focus constructions. Their syntactic structure is in the service of presenting information with a focus, but not to refer to new entities. This will allow us to spell out Frege's metaphor of content carving.