Thomas Hofweber

In Ontology Made Easy and elsewhere Amie Thomasson has made a proposal about the significance of easy arguments for metaphysics. Easy arguments are apparently trivial inferences from premises that seem philosophically innocent to conclusions that seem to be philosophically substantial. In this paper my focus will be on well-know easy arguments for the existence of numbers, properties, and composite objects. I critically investigate Thomasson’s proposal about how to understand easy arguments and what significance they have. In particular, I will focus on the philosophy of language in the background of these arguments, and raise various problems for Thomasson’s account. I will also discuss her critical take on the proposals that others have made about these arguments, in particular her criticism in Ontology Made Easy of my own proposal.

It seems to be impossible to draw metaphysical conclusions about the world merely from our concepts or our language alone. After all, our concepts alone only concern how we aim to represent the world, not how the world in fact is. In this paper I argue that this is mistaken. We can sometimes draw substantial metaphysical conclusions simply from thinking about how we represent the world. But by themselves such conclusions can be flawed if the concepts from which they are drawn are themselves flawed. I propose that we can overcome these limitations by focusing on a special class of concepts: inescapable concepts. Combining arguments about what the world is like from considerations about our concepts alone, together with an argument that the relevant concepts are inescapable, leads to a novel method for metaphysics, which is broadly neo-Kantian.

In their recent article ‘Resolving Frege’s other Puzzle’ Eric Snyder, Richard Samuels, and Stewart Shapiro defend a semantic type-shifting solution to Frege’s other Puzzle and criticize my own cognitive type-shifting solution. In this article I respond to their criticism and in turn point to several problems with their preferred solution. In particular, I argue that they conflate semantic function and semantic value, and that their proposal is neither based on general semantic type-shifting principles nor adequate to the data.

Although higher-order metaphysics seems prima facie to be a promising new approach to metaphysics, it is nonetheless based on a mistake. This mistake is tied to a misuse of formal languages in metaphysics in general, not just to the use of higher-order rather than lower-order languages. I hope to highlight the mistake by discussing a popular recent example of higher- order metaphysics: the argument that reality is not structured using reasoning inspired by the Russell-Myhill paradox. A key issue will be the relationship between higher-order quantification in formal languages and quantification in English, in particular the questions whether such quantifiers are already to be found in English, and whether they could simply be added to English if not in order to gain expressive strength. I will conclude that little of metaphysical significance follows from this Russell-Myhill inspired argument against structure. The reason why the results of higher-order logic show little of metaphysical significance generalizes to other uses of higher-order logic in metaphysical theorizing, and with it supports that higher-order metaphysics is a flawed research program. I end with some reflections on what positive role formal tools like higher-order logic can have in metaphysics, and what the fundamental mistake is on which higher-order metaphysics is based.

Do human beings have a special and distinguished place in reality? In Idealism and the Harmony of Thought and Reality Thomas Hofweber contends that they do. We are special since there is an intimate connection between our human minds and reality itself. This book defends a form of idealism which holds that our human minds constrain, but do not construct, reality as the totality of facts. Reality as the totality of facts is thus not independent of our minds, and our minds play a metaphysically special role in all of reality. But reality as the totality of things is taken to be completely independent of us. Hofweber's proposed form of conceptual idealism is formulated via the notion of a harmony between our minds and reality. This harmony is defended through considerations in the philosophy of language. How can one possibly defend a metaphysical thesis like idealism from considerations about our own representation? A key step in the book's argument is to consider a special class of concepts--inescapable concepts--which we cannot rationally replace with different ones. This leads to a new approach for making progress in metaphysics--immanent metaphysics--which is broadly neo-Kantian in spirit.

Although higher-order metaphysics seems prima facie to be a promising new approach to metaphysics, it is nonetheless based on a mistake. This mistake is tied to a misuse of formal languages in metaphysics in general, not just to the use of higher-order rather than lower-order languages. I hope to highlight the mistake by discussing a popular recent example of higher- order metaphysics: the argument that reality is not structured using reasoning inspired by the Russell-Myhill paradox. A key issue will be the relationship between higher-order quantification in formal languages and quantification in English, in particular the questions whether such quantifiers are already to be found in English, and whether they could simply be added to English if not in order to gain expressive strength. I will conclude that little of metaphysical significance follows from this Russell-Myhill inspired argument against structure. The reason why the results of higher-order logic show little of metaphysical significance generalizes to other uses of higher-order logic in metaphysical theorizing, and with it supports that higher-order metaphysics is a flawed research program. I end with some reflections on what positive role formal tools like higher-order logic can have in metaphysics, and what the fundamental mistake is on which higher-order metaphysics is based.

Can it ever be rational to revise one's own logic by one's own lights? In this paper I argue that logic is never rationally revisable, even if one's own logic gives rise to paradoxes and allows one to derive any conclusion whatsoever. Instead of revising logic, we need to revise a certain widely held position in the philosophy of logic, one tied to the standard conception of validity and to the alleged monotonicity of deductive reasoning. I develop the alternative conception of validity and of deductive reasoning, which explains why we are generally entitled to the conclusions of deductive reasoning, even though we rationally do not accept them in certain circumstances tied to paradoxes.

Nominalists, who believe that everything there is is concrete and nothing is abstract, seem to have a problem with mathematics. Mathematics says that there are lots of prime numbers, and prime numbers don’t seem to be concrete. What should a nominalist do with mathematics? In the last few decades several programs in the philosophy of mathematics have been formulated which are, more or less explicitly, accounts of what a nominalist can say about mathematics. These programs, and the criticism of them, make up a substantial part of the literature in the philosophy of mathematics during this time. Usually such a program involves two parts. One is purely philosophical. It deals with the motivation for nominalism, and argues why certain technical results would show that nominalists have an account of mathematics. The other part is to provide the technical results needed in the program.

Although idealism was widely defended in the history of philosophy, it is nowadays almost universally considered a non-starter. This holds in particular for a strong form of idealism, which asserts that not just minds or the mental in general, but our human minds in particular are metaphysically central to reality. Such a view seems to be excessively anthropocentric and contrary to what we by now know about our place in the universe. Nonetheless, there is reason to think that such a strong form of idealism is indeed correct. In this paper, I will present an argument for idealism of this kind through considerations about a harmony between our thought and reality. The central argument in favour of idealism will come from a possibly unexpected source: we can see that a strong form of idealism is true simply from considerations about our language alone. I shall argue that thinking about how we represent reality allows us to conclude that idealism is true, and thus that reality must be a certain way. But no argument of this kind seems to allow for a metaphysical conclusion like idealism, since considerations about our language alone only show how we represent reality, not how reality is. And thus idealism can’t possibly follow, since it concerns how reality is, not just how we represent it to be. A good part of the second half of the paper is devoted to showing how such an argument is possible after all, and that it really does establish idealism.

The terms `endurance' and `perdurance' are commonly thought to denote distinct ways for an object to persist, but it is surprisingly hard to say what these are. The common approach, defining them in terms of temporal parts, is mistaken, because it does not lead to two coherent philosophical alternatives: endurance so understood becomes conceptually incoherent, while perdurance becomes not just true but a conceptual truth. Instead, we propose a different way to articulate the distinction, in terms of identity rather than temporal parts: an object endures if its identity is determined at every moment at which it exists. We make precise what it means for the identity of an object to be determined at a moment. We also discuss what role the endurance / perdurance distinction, so understood, should play in the debates about time, material objects and personal identity

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.

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.