Theorem. There is a non-empty Π10 class of reals, each of which computes a real of minimal degree. Corollary. WKL “there is a minimal Turing degree”. This answers a question of H. Friedman and S. Simpson.

Persistence through time is like extension through space. A road has spatial parts in the subregions of the region of space it occupies; likewise, an object that exists in time has temporal parts in the various subregions of the total region of time it occupies. This view — known variously as four dimensionalism, the doctrine of temporal parts, and the theory that objects “perdure” — is opposed to “three dimensionalism”, the doctrine that things “endure”, or are “wholly present”.1 I will (...) attempt to resolve this dispute in favor of four dimensionalism by means of a novel argument based on considerations of vagueness. But before argument in this area can be productive, I believe we must become much clearer than is customary about exactly what the dispute is, for the usual ways of formulating the dispute are flawed, especially where three dimensionalism is concerned. (shrink)

Mereological nihilism says that there do not exist (in the fundamental sense) any objects with proper parts. A reason to accept it is that we can thereby eliminate 'part' from fundamental ideology. Many purported reasons to reject it - based on common sense, perception, and the possibility of gunk, for example - are weak. A more powerful reason is that composite objects seem needed for spacetime physics; but sets suffice instead.

In , Peter van Inwagen asked a good question. (Asking the right question is often the hardest part.) He asked: what do you have to do to some objects to get them to compose something---to bring into existence some further thing made up of those objects? Glue them together or what?1 Some said that you don’t have to do anything.2 No matter what you do to the objects, they’ll always compose something further, no matter how they are arranged. Thus we (...) learned of the fusion of the coins in our pockets and the Eiffel tower. (shrink)

Traditional debate on the metaphysics of gender has been a contrast of essentialist and social-constructionist positions. The standard reaction to this opposition is that neither position alone has the theoretical resources required to satisfy an equitable politics. This has caused a number of theorists to suggest ways in which gender is unified on the basis of social rather than biological characteristics but is “real” or “objective” nonetheless – a position I term social objectivism. This essay begins by making explicit the (...) motivations for, and central assumptions of, social objectivism. I then propose that gender is better understood as a real kind with a historical essence, analogous to the biologist’s claim that species are historical entities. I argue that this proposal achieves a better solution to the problems that motivate social objectivism. Moreover, the account is consistent with a post-positivist understanding of the classificatory practices employed within the natural and social sciences. (shrink)

This anthology introduces advanced undergraduates and beginning graduate students to today's debates in metaphysics. The book consists of essays by contemporary metaphysicians, and all but one appear here for the first time. For each of nine topics, there are two essays, one "pro-" and one "con-".

Some philosophers believe that everyday objects are 4-dimensional spacetime worms, that a person (for example) persists through time by having temporal parts, or stages, at each moment of her existence. None of these stages is identical to the person herself; rather, she is the aggregate of all her temporal parts.1 Others accept “three dimensionalism”, rejecting stages in favor of the notion that persons “endure”, or are “wholly present” throughout their lives.2 I aim to defend an apparently radical third view: not (...) only do I accept person stages; I claim that we are stages.3 Likewise for other objects of our everyday ontology: statues are statue-stages, coins are coin-stages, etc. At one level, I accept the ontology of the worm view. I believe in spacetime worms, since I believe in temporal parts and aggregates of things I believe in. I.. (shrink)

A property, F, is maximal iff, roughly, large parts of an F are not themselves Fs.' Maximality makes trouble for a recent analysis of intrinsicality by Rae Langton and David Lewis.

The existence and importance of supervenience principles for identity across times and worlds have been noted, but insufficient attention has been paid to their precise nature. Such attention is repaid with philosophical dividends. The issues in the formulation of the supervenience principles are two. The first involves the relevant variety of supervenience: that variety is global, but there are in fact two versions of global supervenience that must be distinguished. The second involves the subject matter: the names “identity over time” (...) and “identity across worlds” are misnomers, for in neither case is identity at issue. The philosophical dividends then follow. Nathan Salmon’s argument that identity over time needs no “grounds” in matters of qualitative fact can be answered, as can an argument offered by many, that coincident objects would require objectionably ungrounded differences in identities across times and worlds. (shrink)

One often hears a complaint about “bare particulars”. This complaint has bugged me for years. I know it bugs others too, but no one seems to have vented in print, so that is what I propose to do. (I hope also to say a few constructive things along the way.) The complaint is aimed at the substratum theory, which says that particulars are, in a certain sense, separate from their universals. If universals and particulars are separate, connected to each other (...) only by a relation of instantiation, then, it is said, the nature of these particulars becomes mysterious. In themselves, they do not have any properties at all. They are nothing but a pincushion into which universals may be poked. They are Locke’s “I know not what” (1689, II, xxiii, §2); they are Plato’s receptacles (Timaeus 48c–53c); they are “bare particulars”.1 Against substratum theory there is the bundle theory, according to which particulars are just bundles of universals. The substratum and bundle theories agree on much. They agree that both universals and particulars exist. And they agree that a particular in some sense has universals. (I use phrases like ‘particular P has universal U ’ and ‘particular P ’s universals’ neutrally as between the substratum and bundle theories.) But the bundle theory says that a particular is exhaustively composed of (i.e., is a mereological fusion of) its universals. The substratum theory, on the other hand, denies this. Take a particular, and mereologically subtract away its universals. Is anything left? According to the bundle theory, no. But according to the substratum theory, something is indeed left. Call this remaining something a thin particular. The thin particular does not contain the universals as parts; it instantiates them. (shrink)

We often speak of an object being composed of various other objects. We say that the deck is composed of the cards, that a road is the sum total of its sections, that a house is composed of its walls, ceilings, floors, doors, etc. Suppose we have some material objects. Here is a philosophical question: what conditions must obtain for those objects to compose something? In his recent book Material Beings, Peter van Inwagen addresses this question, which he calls the (...) ‘special composition question’; his answer is:1 (1) For any material objects X , the X s compose something iff the activity of the X s constitutes a life, or there is only one of the Xs. Additionally, he accepts a simpler thesis that follows from (1):2 (2) Every material object is either a mereological atom or a living thing, where a mereological atom is an object lacking proper parts. (2) may seem radical. If it is true then there are no tables, chairs, planets, protons, galaxies, gas stations, etc. But van Inwagen does not hold it lightly— there are serious difficulties with alternate views. Moreover, he claims that.. (shrink)

Logic for Philosophy is an introduction to logic for students of contemporary philosophy. It is suitable both for advanced undergraduates and for beginning graduate students in philosophy. It covers (i) basic approaches to logic, including proof theory and especially model theory, (ii) extensions of standard logic that are important in philosophy, and (iii) some elementary philosophy of logic. It emphasizes breadth rather than depth. For example, it discusses modal logic and counterfactuals, but does not prove the central metalogical results for (...) predicate logic (completeness, undecidability, etc.) Its goal is to introduce students to the logic they need to know in order to read contemporary philosophical work. It is very user-friendly for students without an extensive background in mathematics. In short, this book gives you the understanding of logic that you need to do philosophy. (shrink)

A property, F, is maximal i?, roughly, large parts of an F are not themselves Fs. Maximal properties are typically extrinsic, for their instantiation by x depends on what larger things x is part of. This makes trouble for a recent argument against microphysical superve- nience by Trenton Merricks. The argument assumes that conscious- ness is an intrinsic property, whereas consciousness is in fact maximal and extrinsic.

Presentism is the doctrine that only the present is real. Since ordinary talk and thought are full of quantification over non-present objects, presentists are in a familiar predicament: in their unreflective moments they apparently commit themselves to far more than their ontological scruples allow. A familiar response is to begin a project of paraphrase. Truths appearing to quantify over problematic entities are shown, on analysis, to not involve quantification over those entities after all. But I think that we might be (...) better off abandoning paraphrase altogether. I suggest a project of discovering “underlying truths” rather than paraphrases. I will explore this strategy as applied to defending presentism, but my hope is that lovers of desert landscapes everywhere will herein find words of comfort. (shrink)

While many are impressed with the utility of possible worlds in linguistics and philosophy, few can accept the modal realism of David Lewis, who regards possible worlds as sui generis entities of a kind with the concrete world we inhabit.1 Not all uses of possible worlds require exotic ontology. Consider, for instance, the use of Kripke models to establish formal results in modal logic. These models contain sets often regarded for heuristic reasons as sets of “possible worlds”. But the “worlds” (...) in these sets can be anything at all; they can be numbers, or people, or sh. The set of worlds, together with the accessibility relation and the rest of the model, is used as a purely formal structure.2 One can even go beyond establishing results about formal systems and apply Kripke models to English, as Charles Chihara has recently argued.3 Chihara shows, for instance, how to use Kripke models (plus primitive modal notions) to give an account of validity for English modal sentences. In other cases worlds are not really needed at all. It is often vivid to give a counterexample thus: “There is a possible world in which P. Since your theory implies that in all worlds, not-P, your theory is wrong.” But the counterexample could just as easily be given using modal operators: “Possibly, P. Since your theory implies that it is necessary that not-P, your theory is wrong.”. (shrink)

In July 2020, more than 1000 companies that advertise on social media platforms withdrew their business, citing failures of the platforms (especially Facebook) to address the proliferation of harmful content. The #StopHateForProfit movement invites reflection on an understudied topic: the ethics of boycotting by corporations. Under what conditions is corporate boycotting permissible, required, supererogatory, or forbidden? Although value-driven consumerism has generated significant recent discussion in applied ethics, that discussion has focused almost exclusively on the consumption choices of individuals. As this (...) article underscores, value-driven consumerism by business corporations complicates these issues and invites further examination. We propose principles for the ethics of boycotting by corporations, indicate how these principles relate to different CSR paradigms, and show how these insights can help assess recent instances of corporate boycotting. (shrink)

There is growing support for the view that social categories like men and women refer to “objective types” (Haslanger 2000, 2006, 2012; Alcoff 2005). An objective type is a similarity class for which the axis of similarity is an objective rather than nominal or fictional property. Such types are independently real and causally relevant, yet their unity does not derive from an essential property. Given this tandem of features, it is not surprising why empirically-minded researchers interested in fighting oppression and (...) marginalization have found this ontological category so attractive: objective types have the ontological credentials to secure the reality (and thus political representation) of social categories, and yet they do not impose exclusionary essences that also naturalize and legitimize social inequalities. This essay argues that, from the perspective of these political goals of fighting oppression and marginalization, the category of objective types is in fact a Trojan horse; it looks like a gift, but it ends up creating trouble. I argue that objective type classifications often lack empirical adequacy, and as a result they lack political adequacy. I also provide, and in reference to the normative goals described above, several arguments for preferring a social ontology of natural kinds with historical essences. (shrink)

An intrinsic property, as David Lewis puts it, is a property "which things have in virtue of the way they themselves are", as opposed to an extrinsic property, which things have "in virtue of their relations or lack of relations to other things".1 Having long hair is an intrinsic property; having a long-haired brother is not. Intuitive as this notion is (and valuable in doing philosophy, I might add), it seems to resist analysis. Analysis, that is, to “quasi-logical” notions such (...) as necessity, spatiotemporal location: using stronger tools, Lewis has given an analysis of intrinsicality that I take to be roughly correct. Lewis initially described intrinsic properties in his 1983 paper "Extrinsic Properties" as follows. (shrink)

Quantifier variantists accept multiple alternative ontological languages in which quantifiers obey the usual inference rules despite having different meanings. But collapse arguments seem to show that these quantifiers would be provably equivalent to one another. Cian Dorr has pushed this discussion forward by formulating the collapse argument in terms of an algebra of meanings that are common amongst the languages. I attempt to show that quantifier variantists can respond. But an important distinction between types of quantifier variance emerges, between those (...) in which quantifier meanings draw on a single objective backbone of “portions of reality,” and those (such as the type that is arguably associated with neo-Fregeanism) in which they do not. (shrink)

Ideas for integrating AI into politics are now emerging and advancing at accelerating pace. This chapter highlights a few different varieties and show how they reflect different assumptions about the value of democracy. We cannot make informed decisions about which, if any, proposals to pursue without further reflection on what makes democracy valuable and how current conditions fail to fully realize it. Recent advances in political philosophy provide some guidance but leave important questions open. If AI advances to a state (...) where it can secure superior political outcomes, leading perspectives in political philosophy suggest that democracy may become obsolete. If we find this suggestion troubling, we need to put the case for democracy on stronger foundations. (shrink)

Using four principles common to several theories about possible worlds, It is argued that the necessary existence of a divine being that is essentially omnipotent, Omniscient, And morally perfect is impossible. The central argument employs the premise that there are possible worlds that any divine being ought not to actualize (because of their evil contents). This premise is then defended on the grounds that the same sort of justification that we give for other modal statements that we accept can be (...) given for modal statements which entail the premise. It is concluded that we must reject the guiding principle that gives rise to the traditional theistic concept, Viz., That if a property p of an individual is an excellence of it and hence its having p is good, Then its having p necessarily or essentially is better. (shrink)

According to four dimensionalism, the material world is divided into momentary stages. In a four-dimensional world, which objects are the ordinary things, the things we normally name and quantify over? Aggregates of stages, according to most four-dimensionalists, but according to stage theorists (or exdurantists), ordinary objects are instead to be identified with the stages themselves. (A temporal counterpart theoretic account of de re temporal predication is then given.) This paper argues that a stage theorist is best positioned to accept David (...) Lewis's argument from temporary intrinsics for four-dimensionalism, since stage theorists are the only four-dimensionalists who attribute monadic temporary intrinsic properties to ordinary things. (shrink)

Counterpossibles are counterfactuals that involve some metaphysical impossibility. Modal normativism is a non-descriptivist account of metaphysical necessity and possibility according to which modal claims, e.g. ‘necessarily, all bachelors are unmarried’, do not function as descriptive claims about the modal nature of reality but function as normative illustrations of constitutive rules and permissions that govern the use of ordinary non-modal vocabulary, e.g. ‘bachelor’. In this paper, I assume modal normativism and develop a novel account of counterpossibles and claims about metaphysical similarity (...) between possible and impossible worlds. I argue that considerations of metaphysical similarity between various impossible worlds and the actual world only require us to tacitly consider how the actual constitutive rules that govern the use of our terms change in order to accommodate the description of some hypothetical impossible scenario. I then argue for my account by raising worries for alternative epistemic and realist accounts of counterpossibles and showing how my account avoids those worries. (shrink)

This paper considers the evolution of the problem of scientific rationality from Kant through Carnap to Kuhn. I argue for a relativized and historicized version of the original Kantian conception of scientific a priori principles and examine the way in which these principles change and develop across revolutionary paradigm shifts. The distinctively philosophical enterprise of reflecting upon and contextualizing such principles is then seen to play a key role in making possible rational intersubjective communication between otherwise incommensurable paradigms.

In no possible world does a time traveler succeed in killing herearlier self before she ever enters a time machine. So if many,many time travelers went back in time trying to kill theirunprotected former selves, the time travelers would fail inmany strange, coincidental ways, slipping on bananapeels, killing the wrong victim, and so on. Such cases producedoubts about time travel. How could ``coincidences'' beguaranteed to happen? And wouldn't the certainty of coincidentalfailure imply that time travelers are not free to killtheir (...) earlier selves? But if so, what would inhibit theirfreedom? Despite initial appearances, these and other doubtsmay be answered: the possibility of time travel survives yetanother challenge. (shrink)

Intergenerational transfers are a core feature of the practice of private philanthropy. A substantial portion of the resources committed to charitable causes comes from transfers (either during life or at death) that continue to pay out after death. Indeed, much of the power of the charitable foundation lies in its ability to extend the life of an enterprise beyond the mortal existence of its initiating agents. Despite their prevalence, whether and in what way the instruments of intergenerational philanthropy can be (...) justified is controversial. Many have argued that these instruments unfairly privilege the interests of the dead at the expense of the living and unborn. More recently, others have argued that intergenerational charitable transfers comport with the demands of distributive justice and are therefore legitimate. This paper contends that both of these perspectives fail to see the problem for what it is. Intergenerational charitable transfers may indeed promote justice in certain respects, but they do so at the cost of imposing the judgments of the dead onto the living. Respecting the wishes of the past conflicts with an interest in “generational sovereignty.” The paper concludes that properly accounting for this interest in generational sovereignty doesn’t require the abolition of intergenerational philanthropy. But it does tell in favor of a different regulatory orientation than most legal systems currently adopt. (shrink)

A certain conception of Hell is inconsistent with God's traditional attributes. My argument is novel in focusing on considerations involving vagueness. God is in charge of the selection procedure, so the selection procedure must be just; any just procedure will have borderline cases; but according to the traditional conception, the afterlife is binary and has no borderline cases.

This dissertation explores the concepts of naturalness, intrinsicality, and duplication. An intrinsic property is had by an object purely in virtue of the way that object is considered in itself. Duplicate objects are exactly similar, considered as they are in themselves. The perfectly natural properties are the most fundamental properties of the world, upon which the nature of the world depends. In this dissertation I develop a theory of intrinsicality, naturalness, and duplication and explore their philosophical applications. Chapter 1 introduces (...) the notions, gives a preliminary survey of some proposed conceptual connections between the notions, and sketches some of their proposed applications. Chapter 2 gives my background assumptions and introduces notational conventions. In chapter 3 I present a theory of naturalness. Although I take ‘natural’ as a primitive, I clarify this notion by distinguishing and explicating various conceptions of naturalness. In chapter 4 I give a theory of various notions related to naturalness, especially intrinsicality and duplication. I show that ‘intrinsic’ and ‘duplicate’ are interde nable, and then give analyses of these and other notions in terms of naturalness. If, as I think likely, naturalness cannot be analyzed, then what is the proper response? David Lewis suggests: accept naturalness as a primitive. I am sympathetic to this proposal, but not to the form Lewis gives it: chapter 5 contains an argument against Lewis’s theory of naturalness. In chapter 6 I reject the idea that naturalness is analyzable in terms of immanent universals. I focus on the work of D. M. Armstrong. I also criticize Armstrong’s arguments against transcendent universals. (shrink)

One of the most eminent Heidegger scholars of our time, Theodore Kisiel has found worldwide critical acclaim, his particular strength being to set Heidegger's ...

Exotic ontologies are all the rage. Distant from common sense and often science as well, views like mereological essentialism, nihilism, and fourdimensionalism appeal to our desire to avoid arbitrariness, anthropocentrism, and metaphysical conundrums.1 Such views are defensible only if they are materially adequate, only if they can “reconstruct” the world of common sense and science. (No disrespect to the heroic metaphysicians of antiquity, but this world is not just an illusion.) In the world of common sense and science, bicycles survive (...) changes in their parts, billiard balls strike one another, and nothing travels faster than light. The mereological essentialist denies the rst, but offers this replacement: “there exist successions of numerically distinct, but appropriately related, bicycles with different parts” (Chisholm, , chapter ). The nihilist denies the second, but offers this replacement: “there exist X s and Y s such that the X s are arranged billiard-ball-wise, the Y s are also arranged billiard-ball-wise, and the X s strike the Y s”.2 The four-dimensionalist denies the third, but offers this replacement: “no sequences of matter-stages that are related by genidentity travel faster than light”.3 There is room for disagreement over what exactly “reconstruction” amounts to, but at a minimum: when a metaphysical theory reconstructs ordinary sentences φ1. . . as replacement sentences ψ1. . . , ordinary and scienti c evidence must not refute the view that, strictly speaking, it is ψ1. . . rather than φ1. . . that are true. The metaphysician needs reconstruction in order to face the tribunal of experience. An intriguing newcomer to the contemporary scene is the ancient doctrine of monism, the claim that “reality is one”.4 I will argue that, contrary to.. (shrink)

Not until the twentieth century did science come to be regarded as fundamentally technical in nature. A technical field, after all, meant not just a difficult one, but one relying on concepts and vocabulary that matter only to specialists. The alternative, to identify science with an ideal of public reason, attained its peak of influence in the late nineteenth century. While the scale and applicability of science advanced enormously after 1900, scientists have more and more preferred the detached objectivity of (...) service to bureaucratic experts over the cultivation of an engaged public. This reshaping of science, which has been both celebrated and condemned, provided a stimulus to the incipient field of history of science, and it remains a key historical problem. (shrink)

Some say that presentism precludes time travel into the past since it implies that the past does not exist, but this is a bad argument. Presentism says that only currently existing entities exist, and that the only properties and relations those entities instantiate are those that they currently instantiate. This does in a sense imply that the past does not exist. But if that precluded time travel into the past, it would also preclude the one-second-per-second “time travel” into the future (...) that is ordinary persistence, for presentism accords the future the same ontological status as the past. Instead of quantifying over past and future objects and events, presentists speak a tensed language, regimented with primitive sentential tense operators. For a presentist, a persisting person is one who did exist, and who will exist. Regimented, these claims become: it was the case that she exists, and it will be the case that she exists. The presentist may then apply the same strategy to time travel proper. Suppose Katy travels back to the time of the dinosaurs. The presentist can say that it was the case two hundred million years ago that Katy exists. This claim, which consists of a present-tense statement “Katy exists” embedded within the past tense operator it was the case two hundred million years ago that, is exactly the sort of statement about time that a presentist is free to accept. This has all been made clear by Simon Keller and Michael Nelson ( ). In addition to rebutting the bad argument against the consistency of presentism and time travel, Keller and Nelson argue positively in favor of consistency by showing how to translate David Lewis’s ( ) account of time travel into the presentist’s tensed language. The appearance of con ict between presentism and time travel, they argue, is due only to the fact that most defenders of time travel (for example Lewis) have tended to phrase their defenses in nonpresentist terms. As much as I applaud their rebuttal of the bad argument, I wish to sound a note of caution.. (shrink)

Peter Forrest and D.M. Armstrong have given an argument against a theory of naturalness proposed by David Lewis based on the fact that ordered pairs can be constructed from sets in any of a number of different ways. 1. I think the argument is good, but requires a more thorough defense. Moreover, the argument has important consequences that have not been noticed. I introduce a version of Lewis’s proposal in section one, and then in section two I present and defend (...) my version of the argument. After addressing a worry about my argument in section three, in section four I argue that a similar “argument from arbitrariness” jeopardizes Lewis’s solution to the Kripke/Wittgenstein puzzle of the content of thought. (shrink)

Recent discussions of consequentialism have drawn our attention to the so-called “self-other” asymmetry. Various cases presented by Michael Slote and Michael Stocker are alleged to demonstrate a fundamental asymmetry between our obligations to others and ourselves.1 Moreover, these cases are taken to constitute a difficulty for consequentialism, and for the various versions of utilitarianism in particular. I agree that there is a fundamental asymmetry between our obligations to ourselves and to others, and that this fact is inconsistent with the letter (...) of traditional utilitarianisms. However, I do not think this represents a deep shortcoming of the spirit behind utilitarianism. In this paper I will argue that the self-other asymmetry can be accommodated in a broadly utilitarian framework. First, in section one, I characterize moral “asymmetry” in general. Then, in section two, I argue that the cases presented by Slote and Stocker do indeed represent a genuine self-other asymmetry. In part, this involves criticism of an attempt to accommodate the asymmetry within a preferentist framework. Finally, I will present my own solution to the problem of self and other. (shrink)

The logical positivists adopted Poincare's doctrine of the conventionality of geometry and made it a key part of their philosophical interpretation of relativity theory. I argue, however, that the positivists deeply misunderstood Poincare's doctrine. For Poincare's own conception was based on the group-theoretical picture of geometry expressed in the Helmholtz-Lie solution of the space problem, and also on a hierarchical picture of the sciences according to which geometry must be presupposed be any properly physical theory. But both of this pictures (...) are entirely incompatible with the radically new conception of space and geometry articulated in the general theory of relativity. The logical positivists's attempt to combine Poincare's conventionalism with Einstein's new theory was therefore, in the end, simply incoherent. Underlying this problem, moreover, was a fundamental philosophical difference between Poincare's and the positivists concerning the status of synthetic a priori truths. (shrink)

First published, here, in English. Reproduced (also in English) in Adorno's Gesammelte Schriften, 20.I.