This book is a defense of modal realism; the thesis that our world is but one of a plurality of worlds, and that the individuals that inhabit our world are only a few out of all the inhabitants of all the worlds. Lewis argues that the philosophical utility of modal realism is a good reason for believing that it is true.

There are several important arguments in metaethics that rely on explanatory considerations. Gilbert Harman has presented a challenge to the existence of moral facts that depends on the claim that the best explanation of our moral beliefs does not involve moral facts. The Reliability Challenge against moral realism depends on the claim that moral realism is incompatible with there being a satisfying explanation of our reliability about moral truths. The purpose of this chapter is to examine these and related arguments. (...) In particular, this chapter will discuss four kinds of arguments – Harman’s Challenge, evolutionary debunking arguments, irrelevant influence arguments, and the Reliability Challenge – understood as arguments against moral realism. The main goals of this chapter are (i) to articulate the strongest version of these arguments; (ii) to present and assess the central epistemological principles underlying these arguments; and (iii) to determine what a realist would have to do to adequately respond to these arguments. (shrink)

forthcoming in R. Cameron, B. Hale and A. Hoffmann (ed.s), The Logic, Epistemology and Metaphysics of Modality, Oxford University Press. Presents a concept-grounding account of modal knowledge.

Challenging, with several powerful arguments, some of our deepest beliefs about rationality, morality, and personal identity, Parfit claims that we have a false view about our own nature. It is often rational to act against our own best interersts, he argues, and most of us have moral views that are self-defeating. We often act wrongly, although we know there will be no one with serious grounds for complaint, and when we consider future generations it is very hard to avoid conclusions (...) that most of us will find very disturbing. (shrink)

David Hume's Enquiry concerning Human Understanding is the definitive statement of the greatest philosopher in the English language. His arguments in support of reasoning from experience, and against the "sophistry and illusion"of religiously inspired philosophical fantasies, caused controversy in the eighteenth century and are strikingly relevant today, when faith and science continue to clash. The Enquiry considers the origin and processes of human thought, reaching the stark conclusion that we can have no ultimate understanding of the physical world, or indeed (...) our own minds. In either sphere we must depend on instinctive learning from experience, recognizing our animal nature and the limits of reason. Hume's calm and open-minded skepticism thus aims to provide a new basis for science, liberating us from the "superstition" of false metaphysics and religion. His Enquiry remains one of the best introductions to the study of philosophy, and his edition places it in its historical and philosophical context. (shrink)

In "Mathematical Truth", Paul Benacerraf articulated an epistemological problem for mathematical realism. His formulation of the problem relied on a causal theory of knowledge which is now widely rejected. But it is generally agreed that Benacerraf was onto a genuine problem for mathematical realism nevertheless. Hartry Field describes it as the problem of explaining the reliability of our mathematical beliefs, realistically construed. In this paper, I argue that the Benacerraf Problem cannot be made out. There simply is no intelligible problem (...) that satisfies all of the constraints which have been placed on the Benacerraf Problem. The point generalizes to all arguments with the structure of the Benacerraf Problem aimed at realism about a domain meeting certain conditions. Such arguments include so-called "Evolutionary Debunking Arguments" aimed at moral realism. I conclude with some suggestions about the relationship between the Benacerraf Problem and the Gettier Problem. (shrink)

Suppose we grant that evolutionary forces have had a profound effect on the contours of our normative judgments and intuitions. Can we conclude anything from this about the correct metaethical theory? I argue that, for the most part, we cannot. Focusing my attention on Sharon Street’s justly famous argument that the evolutionary origins of our normative judgments and intuitions cause insuperable epistemological difficulties for a metaethical view she calls "normative realism," I argue that there are two largely independent lines of (...) argument in Street’s work which need to be teased apart. The first of these involves a genuine appeal to evolutionary considerations, but it can fairly easily be met by her opponents. The second line of argument is more troubling; it raises a significant problem, one of the most difficult in all of philosophy, namely how to justify our reliance on our most basic cognitive faculties without relying on those same faculties in a question-begging manner. However, evolutionary considerations add little to this old problem, and rejecting normative realism is not a way to solve it. (shrink)

This collection highlights the new trend away from rationalism and toward empiricism in the epistemology of modality. Accordingly, the book represents a wide range of positions on the empirical sources of modal knowledge. Readers will find an introduction that surveys the field and provides a brief overview of the work, which progresses from empirically-sensitive rationalist accounts to fully empiricist accounts of modal knowledge. Early chapters focus on challenges to rationalist theories, essence-based approaches to modal knowledge, and the prospects for naturalizing (...) modal epistemology. The middle chapters present positive accounts that reject rationalism, but which stop short of advocating exclusive appeal to empirical sources of modal knowledge. The final chapters mark a transition toward exclusive reliance on empirical sources of modal knowledge. They explore ways of making similarity-based, analogical, inductive, and abductive arguments for modal claims based on empirical information. Modal epistemology is coming into its own as a field, and this book has the potential to anchor a new research agenda. (shrink)

According to modal empiricism, our justification for believing possibility and necessity claims is a posteriori. That is, experience does not merely play an enabling role in modal justification; it isn’t simply that experience explains how, say, we acquire the relevant concepts. Rather, the view is that modal claims answer to the tribunal of experience in roughly the way that claims about quarks and quails answer to it. One serious objection to modal empiricism is the problem of empirical conservativeness: it doesn’t (...) seem that experience can distinguish between modal claims. And if experience can’t manage that, it’s hard to see how it can provide evidence for one claim over the other. So if modal empiricism is true, we ought to be modal skeptics. On the assumption that we shouldn’t be modal skeptics, we should reject modal empiricism. I have two aims here: first, to reply to this objection to modal empiricism; second, to sketch a modal epistemology that fits with the reply I offer. (shrink)

Die Allgemeine Erkenntnislehre gilt als das Hauptwerk von Moritz Schlick. Hierin entwickelt Schlick in Auseinandersetzung mit zeitgenössischen Positionen seine einflussreichen Gedanken zum Wesen der Erkenntnis, zum Verhältnis zwischen Psychologie und Logik, zum Leib-Seele-Problem und zum erkenntnistheoretischen Realismusstreit. Der Text wurde während der frühen Rostocker Jahre Schlicks, von 1911 bis 1916, verfasst. Die Allgemeine Erkenntnislehre ist ein Meilenstein der wissenschaftlichen Philosophie und grundlegend für die spätere Entwicklung des Wiener Kreises des Logischen Empirismus.

This collection highlights the new trend away from rationalism and toward empiricism in the epistemology of modality. Accordingly, the book represents a wide range of positions on the empirical sources of modal knowledge. Readers will find an introduction that surveys the field and provides a brief overview of the work, which progresses from empirically-sensitive rationalist accounts to fully empiricist accounts of modal knowledge. Early chapters focus on challenges to rationalist theories, essence-based approaches to modal knowledge, and the prospects for naturalizing (...) modal epistemology. The middle chapters present positive accounts that reject rationalism, but which stop short of advocating exclusive appeal to empirical sources of modal knowledge. The final chapters mark a transition toward exclusive reliance on empirical sources of modal knowledge. They explore ways of making similarity-based, analogical, inductive, and abductive arguments for modal claims based on empirical information. Modal epistemology is coming into its own as a field, and this book has the potential to anchor a new research agenda. (shrink)

Philosophical theories often hinge on claims about what is necessary or possible. But what are possibilities and necessities, and how could we come to know about them? This book aims to help demystify the methodology of philosophy, by treating such claims not as attempted descriptions of strange facts or distant 'possible worlds', but rather as ways of expressing rules or norms.

Alan Sidelle's Necessity, Essence, and Individuation is a sustained defense of empiricism—or, more generally, conventionalism—against recent attacks by realists. Sidelle focuses his attention on necessity a posteriori, a kind of necessity which contemporary realists have taken to support realism over empiricism. Turning the tables against the realists, Sidelle argues that if there are in fact truths necessary a posteriori, it is not realism, but rather empiricism which provides the best explanation for them.

Evolutionary debunking arguments move from a premise about the influence of evolutionary forces on our moral beliefs to a skeptical conclusion about those beliefs. My primary aim is to clarify this empirically grounded epistemological challenge. I begin by distinguishing among importantly different sorts of epistemological attacks. I then demonstrate that instances of each appear in the literature under the ‘evolutionary debunking’ title. Distinguishing them clears up some confusions and helps us better understand the structure and potential of evolutionary debunking arguments.

Many important metaphysical arguments validly deduce an actuality from a possibility. For example: Because it is possible for me to exist in the absence of anything material, I am not my body. I argue that there is no reason to suppose that our capacity for modal judgment is equal to the task of determining whether the "possibility" premise of any of these arguments is true. I connect this thesis with Stephen Yablo's recent work on the epistemology of modal statements.

Despite the otherwise-dominant trends towards physicalism and naturalism in philosophy, it has become increasingly common for metaphysicians to accept the existence either of modal facts and properties, or of Lewisian possible worlds. This paper raises the historical question: why did these heavyweight realist views come into prominence? The answer is that they have arisen in response to the demand to find truthmakers for our modal statements. But this demand presupposes that modal statements are descriptive claims in need of truthmakers. This (...) presupposition was, however, rejected by many earlier analytic philosophers, including the logical positivists, Wittgenstein, Ryle and Sellars, all of whom denied that modal statement were descriptive at all. Yet the non-descriptivist approach has largely fallen out of discussion and out of philosophical consciousness. In this paper I examine why non-descriptivist views first came into and then fell out of favor, and consider what the prospects are for reviving this more deflationary approach to modality. (shrink)

Modality presents notorious philosophical problems, including the epistemic problem of how we could come to know modal facts and metaphysical problems about how to place modal facts in the natural world. These problems arise from thinking of modal claims as attempts to describe modal features of this world that explain what makes them true. Here I propose a different view of modal discourse in which talk about what is “metaphysically necessary” does not aim to describe modal features of the world, (...) but, rather, provides a particularly useful way of expressing constitutive semantic and conceptual rules in the object language. The result is a “modal normativist” view that enables us to avoid the epistemic problems of modality and mitigate the metaphysical worries, while also leaving open the possibility of a unified account of the function of modal language. Finally, I address a serious challenge: we have the norms we do in order to track the modal facts of the world, so that the order of explanation must go in the opposite direction. I close by showing how the normativist may answer that challenge. (shrink)

Contemporary realist theories of value claim to be compatible with natural science. In this paper, I call this claim into question by arguing that Darwinian considerations pose a dilemma for these theories. The main thrust of my argument is this. Evolutionary forces have played a tremendous role in shaping the content of human evaluative attitudes. The challenge for realist theories of value is to explain the relation between these evolutionary influences on our evaluative attitudes, on the one hand, and the (...) independent evaluative truths that realism posits, on the other. Realism, I argue, can give no satisfactory account of this relation. On the one hand, the realist may claim that there is no relation between evolutionary influences on our evaluative attitudes and independent evaluative truths. But this claim leads to the implausible skeptical result that most of our evaluative judgements are off track due to the distorting pressure of Darwinian forces. The realist’s other option is to claim that there is a relation between evolutionary influences and independent evaluative truths, namely that natural selection favored ancestors who were able to grasp those truths. But this account, I argue, is unacceptable on scientific grounds. Either way, then, realist theories of value prove unable to accommodate the fact that Darwinian forces have deeply influenced the content of human values. After responding to three objections, the third of which leads me to argue against a realist understanding of the disvalue of pain, I conclude by sketching how antirealism is able to sidestep the dilemma I have presented. Antirealist theories of value are able to offer an alternative account of the relation between evolutionary forces and evaluative facts —
an account that allows us to reconcile our understanding of evaluative truth with our understanding of the many non-rational causes that have played a role in shaping our evaluative judgements. (shrink)

The two-dimensional modal logic of Davies and Humberstone [3] is an important aid to our understanding the relationship between actuality, necessity and a priori knowability. I show how a cut-free hypersequent calculus for 2D modal logic not only captures the logic precisely, but may be used to address issues in the epistemology and metaphysics of our modal concepts. I will explain how the use of our concepts motivates the inference rules of the sequent calculus, and then show that the completeness (...) of the calculus for Davies–Humberstone models explains why those concepts have the structure described by those models. The result is yet another application of the completeness theorem. (shrink)

Being Known is a response to a philosophical challenge which arises for every area of thought: to reconcile a plausible account of what is involved in the truth of statements in a given area with a credible account of how we can know those statements. Christopher Peacocke presents a framework for addressing the challenge, a framework which links both the theory of knowledge and the theory of truth with the theory of concept-possession.

Excerpts from Robert Nozick's "Invariances" Necessary truths are invariant across all possible worlds, contingent ones across only some.

In the last few decades of the twentieth century there was a revolution in metaphysics: the intensional revolution. Many metaphysicians rejected the doctrine, associated with Quine and Davidson, that extensional analyses and theoretical resources were the only acceptable ones. Metaphysicians embraced tools like modal and counterfactual analyses, claims of modal and counterfactual dependence, and entities such as possible worlds and intensionally individuated properties and relations. The twenty-first century is seeing a hypterintensional revolution. Theoretical tools in common use carve more finely (...) than by necessary equivalence: two pieces of language can apply to the same entities across all possible worlds but not be equivalent; thoughts can be necessarily equivalent in truth value but not synonymous. This paper argues that hyperintensional resources are valuable in metaphysics outside theories of representation, and discusses some promising areas of hyperintensional metaphysics. (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)

An original and elegant work of metaethics, this book brings a new clarity and rigor to the discussion of these tangled issues, and will significantly alter the ...

On the most popular account of material constitution, it is common for a material object to coincide precisely with one or more other material objects, ones that are composed of just the same matter but differ from it in sort. I argue that there is nothing that could ground the alleged difference in sort and that the account must be rejected.

According to modalism, modality is primitive. In this paper, we examine the implications of this view for modal epistemology, and articulate a modalist account of modal knowledge. First, we discuss a theoretical utility argument used by David Lewis in support of his claim that there is a plurality of concrete worlds. We reject this argument, and show how to dispense with possible worlds altogether. We proceed to account for modal knowledge in modalist terms.

Extending the project of analysis -- Elaborating abilities : the expressive role of logic -- Artificial intelligence and analytic pragmatism -- Modality and normativity : from Hume and Quine to Kant and Sellars -- Incompatibility, modal semantics, and intrinsic logic -- Intentionality as a pragmatically mediated semantic relation -- Afterword : philosophical analysis and analytic philosophy.

Robert Brandom's latest book, the product of his John Locke lectures in Oxford in 2006, is a return to the philosophy of language and is easily read as a continuation and development of the views defended in Making it Explicit. The text of the lectures is presented much as they were delivered, but it contains an ‘Afterword’ of more than 30 pages which responds to questions raised when he gave the lectures, and also when they were subsequently delivered in Prague (...) the following year. The published text also contains relatively technical appendices to two of the lectures.The individual lectures engage with some important and difficult issues, often ones that were explored in detail in the earlier book. However, these discussions are located within a broader meta-philosophical context, and it says something about the abstract and difficult character of these views that they provide the main subject matter of the Afterword. This framework affects how we should understand the relations between this book and Making It Explicit too. Although most of the detailed discussions happily belong within the general project of the earlier book, they are offered as illustrations of a framework that is independent of this project. Indeed, Brandom suggests that defenders of the semantic views of David Lewis, for example, could embrace his main message as well as those who favour Brandom's own form of pragmatism.Neo-pragmatist philosophers such as Brandom's teacher, Richard Rorty, often present themselves as rejecting the analytic tradition in philosophy. When Brandom describes the ‘pragmatist challenge’ to the ‘classical project of analysis’, he appeals to the criticisms found in the work of Wittgenstein and Sellars that are often appealed to by the critics of the analytic tradition. The message of the new book is that the views he has built on this …. (shrink)

A lot of people believe that distinct objects can occupy precisely the same place for the entire time during which they exist. Such people have to provide an answer to the 'grounding problem' – they have to explain how such things, alike in so many ways, nonetheless manage to fall under different sortals, or have different modal properties. I argue in detail that they cannot say that there is anything in virtue of which spatio-temporally coincident things have those properties. However, (...) I also argue that this may not be as bad as it looks, and that there is a way to make sense of the claim that such properties are primitive. (shrink)

Individual objects have potentials: paper has the potential to burn, an acorn has the potential to turn into a tree, some people have the potential to run a mile in less than four minutes. Barbara Vetter provides a systematic investigation into the metaphysics of such potentials, and an account of metaphysical modality based on them. -/- In contemporary philosophy, potentials have been recognized mostly in the form of so-called dispositions: solubility, fragility, and so on. Vetter takes dispositions as her starting (...) point, but argues for and develops a more comprehensive conception of potentiality. She shows how, with this more comprehensive conception, an account of metaphysical modality can be given that meets three crucial requirements: Extensional correctness: providing the right truth-values for statements of possibility and necessity; formal adequacy: providing the right logic for metaphysical modality; and semantic utility: providing a semantics that links ordinary modal language to the metaphysics of modality. -/- The resulting view of modality is a version of dispositionalism about modality: it takes modality to be a matter of the dispositions of individual objects. This approach has a long philosophical tradition going back to Aristotle, but has been largely neglected in contemporary philosophy. In recent years, it has become a live option again due to the rise of anti-Humean, powers-based metaphysics. The aim of Potentiality is to develop the dispositionalist view in a way that takes account of contemporary developments in metaphysics, logic, and semantics. (shrink)

Existence questions have been topics for heated debates in metaphysics, but this book argues that they can often be answered easily, by trivial inferences from uncontroversial premises. This 'easy' approach to ontology leads to realism about disputed entities, and to the view that metaphysical disputes about existence questions are misguided.