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)

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.

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)

Social Change in a Material Worldoffers a new, practice theoretical account of social change and its explanation. Extending the author's earlier account of social life, and drawing on general ideas about events, processes, and change, the book conceptualizes social changes as configurations of significant differences in bundles of practices and material arrangements. Illustrated with examples from the history of bourbon distillation and the formation and evolution of digitally-mediated associations in contemporary life, the book argues that chains of activity combine with (...) material events and processes to cause social changes. The book thereby stresses the significance of the material dimension of society for the constitution, determination, and explanation of social phenomena, as well as the types of space needed to understand them. The book also challenges the explanatory significance of such key phenomena as power, dependence, relations, mechanisms, and individual behavior. As such, it will appeal to sociologists, geographers, organization studies scholars, and others interested in social life and social change. As such, it will appeal to sociologists, geographers, organization studies scholars, and others interested in social life and social change. (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.

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)

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)

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)

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)

"A magisterial accomplishment that will be the standard in this field for years to come."--John D. Caputo, Villanova University "Outstanding, entirely original, absolutely groundbreaking.... It is quite simply the best account to date--and the best we can expect for decades in the future--of the philosophical development of Heidegger's early thought."--Thomas Sheehan, Loyola University "A magisterial accomplishment that will be the standard in this field for years to come."--John D. Caputo, Villanova University.

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)

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 book is about the teaching profession and what it takes to become a successful teacher.

Calls to hold artificial intelligence to account are intensifying. Activists and researchers alike warn of an “accountability gap” or even a “crisis of accountability” in AI. Meanwhile, several prominent scholars maintain that accountability holds the key to governing AI. But usage of the term varies widely in discussions of AI ethics and governance. This chapter begins by disambiguating some different senses and dimensions of accountability, distinguishing it from neighboring concepts, and identifying sources of confusion. It proceeds to explore the idea (...) that AI operates within an accountability gap arising from technical features of AI as well as the social context in which it is deployed. The chapter also evaluates various proposals for closing this gap. I conclude that the role of accountability in AI ethics and governance is vital but also more limited than some suggest. Accountability’s primary job description is to verify compliance with substantive normative principles—once those principles are settled. Theories of accountability cannot ultimately tell us what substantive standards to account for, especially when norms are contested or still emerging. Nonetheless, formal mechanisms of accountability provide a way of diagnosing and discouraging egregious wrongdoing even in the absence of normative agreement. Providing accounts can also be an important first step toward the development of more comprehensive regulatory standards for AI. (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)

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)

I expand modal normativism, a theory of metaphysical modality, to give a normativist account of metaphysical explanation. According to modal normativism, basic modal claims do not have a descriptive function, but instead have the normative function of enabling language users to express semantic rules that govern the use of ordinary non-modal vocabulary. However, a worry for modal normativism is that it doesn’t keep up with all of the important and interesting metaphysics we can do by giving and evaluating metaphysical explanations. (...) So, I advance modal normativism by arguing that metaphysical explanations also have a normative rather than descriptive function. In particular, non-causal explanatory claims have formal and semantic properties that make them expressively stricter than basic modal claims and so are better suited to express fine-grained aspects of semantic rules. A major payoff of my normativist account of metaphysical explanations is that it yields a plausible story about how we come to evaluate and know metaphysical explanations—we do this primarily by conceptual analysis. I also respond to a number of objections, including the objection that the epistemic payoffs of my view are not worth the metaphysical costs. (shrink)

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)

The kinds of real or natural kinds that support explanation and prediction in the social sciences are difficult to identify and track because they change through time, intersect with one another, and they do not always exhibit their properties when one encounters them. As a result, conceptual practices directed at these kinds will often refer in ways that are partial, equivocal, or redundant. To improve this epistemic situation, it is important to employ open-ended classificatory concepts, to understand when different research (...) programs are tracking the same real kind, and to maintain an ongoing commitment to interact causally with real kinds to focus reference on those kinds. A tempting view of these non-idealized epistemic conditions should be avoided: that they signal an ontological structure of the social world so plentiful that it would permit ameliorated classificatory schemes to achieve their normative aims regardless of whether they defer to real-kind classificatory schemes. To ground these discussions, the essay appeals to an overlooked convergence in the systematic naturalistic frameworks of Richard Boyd and Ruth Millikan. (shrink)

Many scholars of organizations see social enterprise as a promising approach to advancing social justice but neglect to scrutinize the normative foundations and limitations of this optimism. This article draws on Rawlsian political philosophy to investigate whether and how social enterprises can support social justice. We propose that this perspective assigns organizations a duty to foster institutional capacity, a concept we define and elaborate. We investigate how this duty might apply specifically to social enterprises, given their characteristic features. We theorize (...) six different mechanisms through which social enterprises might successfully discharge this duty. These results affirm the value of conversation between organizational studies and political philosophy and shed new light on debates regarding social enterprise, institutional theory, and several other topics. (shrink)

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)

This essay explores consonant aspects of the relationship between phenomenology and practice theory. It makes three basic claims. The first is really just an observation, namely, that phenomenology makes incisive contributions to the account of action found in practice theory. The second claim is that practice theory updates an important conception of sociality developed in post Heideggerian phenomenology. And the third claim is that phenomenologies and practice theories can combine to form wider accounts of human life that encompass such phenomena (...) as experience, consciousness, emotions, and the body that phenomenology has well analyzed and practice theory has somewhat ignored. (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)

Stephanie Morain and Emily Largent’s (2023) target article “Think Pragmatically: Investigators’ Obligations to Patient-Subjects When Research is Embedded in Care” identified a number of important c...

I argue that we can accept modal normativism—a view that the function of modal claims is to express semantic rules—while also accepting possible worlds semantics. I argue that by keeping the metaphysical insights of normativism at the level of metasemantics—i.e., at the level of accounts of what metaphysically explains facts about the meaning of modal claims—it is open to the normativist to wholeheartedly accept possible worlds semantics.

Hunting for sport or pleasure is ethical because (1) it does not violate any animal’s moral rights, (2) it has as its primary object the exercise of human skills, which is a sufficient good to compensate for the evil that results from it, namely, the death of the animal, and (3) it contributes to the ecological system by directly participating in the balancing process of life and death upon which the ecosystem thrives, thus indirectly benefiting the human community. As such, (...) hunting is not only a natural good, but also a moral good. (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)

In domains like stock brokerage, clinical psychiatry, and long‐term political forecasting, experts generally fail to outperform novices. Empirical researchers agree on why this is: experts must receive direct or environmental learning feedback during training to develop reliable expertise, and these domains are deficient in this type of feedback. A growing number of philosophers resource this consensus view to argue that, given the absence of direct or environmental philosophical feedback, we should not give the philosophical intuitions or theories of expert philosophers (...) greater credence than those of novice philosophers. This article has three objectives. The first is to explore several overlooked issues concerning the strategy of generalizing from empirical studies of non‐philosophical expertise to the epistemic status of philosophical expertise. The second is to explain why empirical research into a causal relationship between direct learning feedback and enhanced expert performance does not provide good grounds for abandoning a default optimism about the epistemic superiority of expert philosophical theories. The third is to sketch a positive characterization of learning feedback that addresses developmental concerns made salient by the empirical literature on expert performance for specifically theory‐driven or “armchair” domains like philosophy. (shrink)

There is broad agreement among social researchers and social ontologists that the project of dividing humans into social kinds should be guided by at least two methodological commitments. First, a commitment to what best serves moral and political interests, and second, a commitment to describing accurately the causal structures of social reality. However, researchers have not sufficiently analyzed how these two commitments interact and constrain one another. In the absence of that analysis, several confusions have set in, threatening to undermine (...) shared goals for the responsible modeling of social kinds of humans. This essay first explains the source and substance of these confusions. Then, by distinguishing different value-laden investigative questions into the classification of social kinds of humans, it sets out specific relations of dependence and constraint between empirically-driven investigations and value-driven investigations into social kinds of humans. The result is a more detailed and fruitful framework for thinking about the classification of social kinds that respects both normative interests and mind-independent causal regularities. (shrink)

In this paper, a response to Ed Levy's discussion of medical quantification, I reflect on the ambitions of my book Trust in Numbers. I explore the idealized method of randomized clinical trials, revealed in his case study, as a social technology, one endowed with a persuasive scientific rationale but shaped also by political and social demands. The scholarly study of quantification requires not a choice between blind admiration and sweeping rejection, but a nuanced understanding. This should take into account not (...) only the cognitive aspects of science, but also its role in relation to institutions and customs, examined with some specificity. While history is narrowed and distorted when it is written to support a position on some present issue, historical and social studies of science should at least provide tools of criticism. For this, the historian of science must look beyond narrow communities of specialists, and seek a wider perspective on science as an administrative tool and a bearer of cultural and political values. (shrink)

In some domains experts perform better than novices, and in other domains experts do not generally perform better than novices. According to empirical studies of expert performance, this is because the former but not the latter domains make available to training practitioners a direct form of learning feedback. Several philosophers resource this empirical literature to cast doubt on the quality of philosophical expertise. They claim that philosophy is like the dubious domains in that it does not make available the good, (...) direct kind of learning feedback, and thus there are empirical grounds for doubting the epistemic quality of philosophical expertise. I examine the empirical studies that are purportedly bad news for professional philosophers. On the basis of that examination, I provide three reasons why the empirical study of non-philosophical expertise does not undermine the status of philosophical expertise. First, the non-philosophical task-types from which the critics generalize are unrepresentative of relevant philosophical task-types. Second, empirical critiques of non-philosophical experts are often made relative to the performance of linear models—a comparison that is inapt in a philosophical context. Third, the critics fail to discuss findings from the empirical study of non-philosophical expertise that have more favorable implications for the epistemic status of philosophical expertise. In addition to discussing implications for philosophical expertise, this article makes progress in the philosophical analysis of the science of expertise and expert development. (shrink)

is an important principle, worthy of serious scrutiny. Its truth or falsity bears on the question of whether moral rightness, obligatoriness, etc., are a matter of factors “internal” to an agent, or whether “external” factors are relevant to determining the moral normative status of acts. Moreover, Access enjoys considerable intuitive support. If I destroy Greensboro in professor Sorensen’s example by pushing the wrong button, I seem to have a good excuse to give to anyone who would accuse me of wrongdoing: (...) “I had no way of knowing that this action would be wrong!” But if I have a good excuse, then pushing the button doesn’t seem wrong; and if that action isn’t wrong, then I had no obligation to refrain from pushing that button. A principle distinct from, but analogous to, Access also deserves our attention. (shrink)

Thus, says Hare, a judgment that someone is happy is an appraisal, not a statement of fact. I do not wish to deny that there are some uses of 'happy', ascribed to a person or to a life, for which this is the case; but I would like to maintain that there are other uses of 'happy', philosophically important ones, in which a judgment that a third person is happy is not an appraisal, but is rather a report about him (...) which may be true or false; and in which a first person judgment that one is happy, while it involves an appraisal, is still a report which may be true or false. (shrink)

In this paper I address some of the problems that the historical development of science poses for a realist and discuss whether a realist construal of scientific activity is conducive to historiographical practice. First, I discuss, by means of historical examples, Ian Hacking's defense of entity realism. Second, I try to show, drawing on Kuhn's recent work on incommensurability, that the realism problem is relevant to historiography and that a realist position entails a particular historiographical strategy, which faces problems. Finally, (...) I suggest that for historiographical purposes an agnostic attitude with respect to scientifictheories and unobservable entities is the most appropriate. (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 ...

In an article in Scientific American (March 1994, pp. 68–74) entitled “The Quantum Physics of Time Travel”, Oxford physicist David Deutsch and Oxford philosopher Michael Lockwood give a defense of the physical possibility of time travel based on the “Many Worlds” interpretation of quantum mechanics. This positive view of theirs is not my concern, however—I want to quarrel with their argument that time travel cannot be accommodated in any other way.1 The best way to spell out the traditional “grandfather paradox” (...) that appears to threaten the possibility of time travel involves the notion of ability, or personal possibility, or free will. An example of David Lewis’s: Tim travels back in time with the intent to kill his grandfather.2 Let us fix the case as one in which Tim in fact will not kill Grandfather; still, it seems that he can kill Grandfather because he is a good shot, has a gun, and is alone with Grandfather at close range. As Lewis says, Tim “has what it takes” to kill Grandfather. However, it is also compelling that Tim cannot kill Grandfather, because if Grandfather had been killed in his youth, Tim would not have existed to kill him. It is important to realize that the paradox essentially involves the notion of ability. No inconsistency results from supposing that Tim does not kill Grandfather. As for the case in which Tim does kill Grandfather, there are various possibilities. We could tell a consistent time travel story in which Tim kills Grandfather, but Grandfather is miraculously resurrected. Or one in which Tim kills Grandfather, but in which Grandfather has already had a child. Or one in which Tim kills Grandfather permanently, before Grandfather has any children, but in which Tim’s grandfather is someone other than Grandfather. As for the story in which Tim both kills Grandfather permanently in such a way that Grandfather has no children, and also is descended from Grandfather, this is an inconsistent time travel story; but of course the existence of some.... (shrink)