David Lewis

This paper brings two fresh perspectives on Lewis’s theory of time travel. First: many key aspects and theoretical desiderata of Lewis’s theory can be captured in a framework that does not commit to eternalism about time. Second: implementing aspects of Lewisian time travel in a non-eternalist framework provides theoretical resources for a better treatment of time travel to the future. While time travel to the past has been extensively analyzed, time travel to the future has been comparatively underexplored. I make (...) progress on this topic. Along the way, I discuss Lewis’s lesser-known time travel oeuvre, especially his volume of correspondence and lectures on the topic collected in Beebee and Fisher (2020) and Janssen-Lauret & MacBride (forthcoming). Lewis’s body of unpublished work on time travel yields fruitful insights into his broader thinking on the subject. (shrink)

David Lewis rejected consequentialism in ethics. However, two aspects of his meta-ethical views make it a challenge to see how consequentialism could be resisted. Lewis endorses a maximising conception of rationality, where to be rational is to maximise value of a certain sort; he appears to think it is possible to be both rational and moral; and yet he rejects conceptions of moral action as acting to maximise moral value. The second tension in Lewis's views arises from his meta-ethics. Lewis's (...) naturalisation of morality is in terms of a naturalised account of value, including moral value. Insofar as he offers a motivational story for moral judgements, it is one that goes via a motivational connection to value. Yet his anti-consequentialism seems to commit him to rejecting a story of moral action entirely in terms of pursuit of moral value. In both cases there are things to be said about how to weave these strands of Lewis's thought together. After setting out these two apparent tensions in Lewis's thought about ethics, the paper discusses what a Lewisian could best say about these puzzles. Lewisians do have a number of plausible options for dealing with the first challenge. While there are things a Lewisian could attempt to extend Lewis's moral naturalism in a way that could deal with the second challenge, it is harder to see how to do this in a satisfying way. Attention then turns to what Lewis said in his letters on these topics: on that basis, perhaps Lewis was close to being an agent-relative consequentialist after all. (shrink)

The problem of the many seems to problematize the platitude that we can think about particular things in the world. How is it that, given how very many cat-like candidates there are, we often manage to think and talk about a particular cat? I argue that this challenge stems from an under-examined assumption about the relationship between metaphysics and intentionality. I explore and develop a way of characterizing what it is to think and talk about the world, according to which (...) an abundant ontology poses no obstacle to our ability to think and talk about particular things. (shrink)

This paper offers an argument in favour of a Lewisian version of concretism that maintains both the principle of material inheritance and the materiality-modality link.

On the standard analysis, a counterfactual conditional such as “If P had been the case, then Q would have been the case” is true in the actual world if, in all nearest possible worlds in which its antecedent (P) is true, its consequent (Q) is also true. Despite its elegance, this analysis faces a difficulty if the laws of nature are deterministic. Then the antecedent could not have been true, given prior conditions. So, it is unclear what the relevant “nearest (...) possible worlds” are. David Lewis suggested that they are ones in which a local breach of the laws occurred: a “small miracle”. Others have suggested that they are ones in which the initial conditions were different (“backtracking”). I propose another response. It builds on the idea that the special sciences, where counterfactual reasoning is most common, operate at a higher level of description from fundamental physics, and that the world may behave indeterministically at higher levels even if it behaves deterministically at the fundamental physical one. The challenge from determinism can then be bypassed for many special-science counterfactuals. (shrink)

I explore the relationship between a prominent analysis of intrinsic properties, due to Langton and Lewis, and the phenomenon of quantum entanglement. As I argue, the analysis faces a puzzle. The full analysis classifies certain properties of entangled particles as intrinsic. But when combined with an extremely plausible assumption about duplication, the main part of the analysis classifies those properties as non-intrinsic instead. I conclude that much of Lewis’s metaphysics is in trouble: Lewis based many of his metaphysical views—his thesis (...) of Humean supervenience, for instance, and his account of recombination—on an analysis of intrinsicality which does not sit well with quantum phenomena. (shrink)

It has been argued recently that classical theism and Lewisian modal realism are incompatible theses. The most substantial argument to this effect takes the form of a trilemma. It argues that no sense can be made of God’s being a necessary being in the modal realistic picture, on pain of, among other things, modal collapse. The question of this essay is: Is that so? My goal here is to detail the reasons that have been offered in support of this contention (...) and then defend the coherence of theistic modal realism from the trilemma. I call my reply to the argument an “Anselmian-Thomistic” defense, since it appeals to resources from classical medieval philosophy, especially from Anselm and Aquinas. (shrink)

This paper takes issue with an influential interpretationist argument for physicalism about intentionality based on the possibility of radical interpretation. The interpretationist defends the physicalist thesis that the intentional truths supervene on the physical truths by arguing that it is possible for a radical interpreter, who knows all of the physical truths, to work out the intentional truths about what an arbitrary agent believes, desires, and means without recourse to any further empirical information. One of the most compelling arguments for (...) the possibility of radical interpretation, associated most closely with David Lewis and Donald Davidson, gives a central role to decision theoretic representation theorems, which demonstrate that if an agent’s preferences satisfy certain constraints, it is possible to deduce probability and utility functions that represent her beliefs and desires. We argue that an interpretationist who wants to rely on existing representation theorems in defence of the possibility of radical interpretation faces a trilemma, each horn of which is incompatible with the possibility of radical interpretation. (shrink)

The Indeterminacy of Translation and Radical Interpretation The indeterminacy of translation is the thesis that translation, meaning, and reference are all indeterminate: there are always alternative translations of a sentence and a term, and nothing objective in the world can decide which translation is the right one. This is a skeptical conclusion because what it … Continue reading The Indeterminacy of Translation and Radical Interpretation →.

Bernard Williams argues that philosophy is in some deep way akin to history. This article is a novel exploration and defense of the Williams thesis —though in a way anathema to Williams himself. The key idea is to apply a central moral from what is sometimes called the analytic philosophy of history of the 1960s to the philosophy of philosophy of today, namely, the separation of explanation and laws. I suggest that an account of causal explanation offered by David Lewis (...) may be modified to bring out the way in which this moral applies to philosophy, and so to defend the Williams thesis. I discuss in detail the consequences of the thesis for the issue of philosophical progress and note also several further implications: for the larger context of contemporary metaphilosophy, for the relation of philosophy to other subjects, and for explaining, or explaining away, the belief that success in philosophy requires a field-specific ability or brilliance. (shrink)

In this paper, I discuss a connection between quidditism and the Lewisian principle of recombination. I begin by reconstructing a typical characterisation of a Lewisian principle of recombination, followed by an explanation of quidditism. In the remainder, I argue that a proponent of a Lewisian principle of recombination cannot endorse quidditism without some important modifications of her view.

David Lewis’s arguments against magical ersatzism are notoriously puzzling. Untangling different strands in those arguments is useful for bringing out what he thought was wrong with not just one style of theory about possible worlds, but with much of the contemporary metaphysics of abstract objects. After setting out what I take Lewis’s arguments to be and how best to resist them, I consider the application of those arguments to general theories of properties and relations. The constraints Lewis motivates turn out (...) to yield an argument for concretism about possible individuals that is quite different from the better-known Lewisian arguments for that position. The discussion also touches on the puzzling question of whether things are the way they are because of the properties they have, or are the properties and relations the way they are because of the things that have them. (shrink)

A popular approach in philosophy, the so-called Canberra Plan, is critically scrutinized. Two aspects of this research program, the formal and the informal program, are distinguished. It is argued that the formal program runs up against certain serious technical problems. It is also argued that the informal program involves an unclear leap at its core. Consequently, it is argued that the whole program is much more problematic than its advocates recognize.

David Lewis objected to theories that posit necessary connections between distinct entities and to theories that involve a magical grasping of their primitives. In On the Plurality of Worlds, Lewis objected to nondescript ersatzism on these grounds. The literature contains several reconstructions of Lewis’ critique of nondescript ersatzism but none of these interpretations adequately address his main argument because they fail to see that Lewis’ critique is based on broader methodological considerations. I argue that a closer look at his methodology (...) reveals the broader objection he presented against nondescript ersatzism. This objection, I further argue, remains a challenge for the ersatzer who posits structure-less entities as possible worlds. (shrink)

Ramseyan humility is the thesis that we cannot know which properties realize the roles specified by the laws of completed physics. Lewis seems to offer a sceptical argument for this conclusion. Humean fundamental properties can be permuted as to their causal roles and distribution throughout spacetime, yielding alternative possible worlds with the same fundamental structure as actuality, but at which the totality of available evidence is the same. On the assumption that empirical knowledge requires evidence, we cannot know which of (...) these worlds is actual. However, Lewis also appeals to a range of familiar semantic principles when framing his argument, which leads some authors to suppose that he can also plausibly be interpreted as offering a purely semantic argument for humility in addition. In this paper I grant that these arguments are Lewisian, but argue that Lewis is also committed to a theory of mind that licenses a purely metaphysical argument for humility based on the idea that mental properties supervene on fundamental structure. Given that knowing which x is the F requires knowing that a is the F, the supposition that we could come to know which properties actually occupy the fundamental roles entails differences in mental properties between worlds with the same fundamental structure, violating supervenience. Humility follows right away, without any further epistemic or semantic principles. This argument is immune to almost every way of rebutting the sceptical and semantic arguments; conversely, almost every way of rebutting the metaphysical argument tells equally against the others. (shrink)

In the middle of last century metaphysics was widely criticized, ridiculed, and committed to the flames. During this period a handful of philosophers, against several anti-metaphysical trends, defended metaphysics and articulated novel metaphysical doctrines. Donald C. Williams was one of these philosophers. But while his contributions to metaphysics are well known his defence of metaphysics is not and yet it played a key part in the development and revival of metaphysics. In this paper I present his defence of metaphysics in (...) its historical context. I also show how his defence is relevant in response to recent attacks on metaphysics. (shrink)

Aaccording to D. K. lewis (1973), would-couterfactuals and might-counterfactuals are duals. from this, it follows that the negation of a would-counterfactual is equiv- alent to the corresponding “might-not”-counterfactual and that the negation of a might-counterfactual is equivalent to the corresponding “would-not”- counterfactual. there are cases, however, where we seem to be entitled to accept the would- counterfactual and we are also equally entitled to accept the corresponding might-not-counterfactual and cases where we seem to be entitled to accept the might-counterfactual without (...) being equally entitled to reject the corresponding would-not-counterfactual. In this paper, I will show that a distinction between two types of rejections for counterfactuals (p-rejection and s-rejection) and the recognition that might-not-counterfactuals may play the role of p-rejections (by an application to counterfactuals of the lewisian approach to conversational scores) could explain why the problematic cases should not be seen as cases where the duality of would- and might-counterfactuals fails. (shrink)

Divers presents a set of de re modal truths which, he claims, are inconvenient for Lewisean modal realism. We argue that there is no inconvenience for Lewis.

The revival of analytic metaphysics in the latter half of the twentieth century is typically understood as a consequence of the critiques of logical positivism, Quine’s naturalization of ontology, Kripke’s Naming and Necessity, clarifications of modal notions in logic, and the theoretical exploitation of possible worlds. However, this explanation overlooks the work of metaphysicians at the height of positivism and linguisticism that affected metaphysics of the late twentieth century. Donald C. Williams is one such philosopher. In this paper I explain (...) how Williams’s fundamental ontology and philosophy of time influenced in part the early formation of David Lewis’s metaphysics. Thus, Williams played an important role in the revival of analytic metaphysics. (shrink)

We offer a new argument for the claim that there can be non-degenerate objective chance (“true randomness”) in a deterministic world. Using a formal model of the relationship between different levels of description of a system, we show how objective chance at a higher level can coexist with its absence at a lower level. Unlike previous arguments for the level-specificity of chance, our argument shows, in a precise sense, that higher-level chance does not collapse into epistemic probability, despite higher-level properties (...) supervening on lower-level ones. We show that the distinction between objective chance and epistemic probability can be drawn, and operationalized, at every level of description. There is, therefore, not a single distinction between objective and epistemic probability, but a family of such distinctions. (shrink)

Lewis is famous as a contemporary philosophical system-builder. The most obvious way his philosophy exhibited a system was in its content: Lewis’s metaphysics, for example, provided answers to many metaphysical puzzles in an integrated way, and there are illuminating connections to be drawn between his general metaphysical views and, for example, his various views about the mind and its place in nature.

Fine is widely thought to have refuted the simple modal account of essence, which takes the essential properties of a thing to be those it cannot exist without exemplifying. Yet, a number of philosophers have suggested resuscitating the simple modal account by appealing to distinctions akin to the distinction Lewis draws between sparse and abundant properties, treating only those in the former class as candidates for essentiality. I argue that ‘sparse modalism’ succumbs to counterexamples similar to those originally posed by (...) Fine, and fails to capture paradigmatic instances of essence involving abundant properties and relations. (shrink)

This paper is a response to Lewis’ ‘Humean Supervenience Debugged’ . Lewis was in the business of defending Humean Supervenience, and the project seemed successful until the case of chance. Lewis thus originally named chance the ‘big bad bug’ for Humean Supervenience until the aforementioned paper in which he claims victory. Here I argue that he was unsuccessful and that Humean Supervenience remains bugged by chance. I will show how this bug remains due to a misdiagnosis of where the problem (...) lies with regard to undermining. First, I define Humean Supervenience and chance, and state the bug in its original form, then secondly I describe Lewis’ attempt to remove the bug. Thirdly, I explain why the bug persists, despite Lewis’ efforts, and show the real source of the undermining problem to be due to the circularity of Humean Supervenient style accounts of chance. Finally I describe the situation this leaves chance in, and show how the incompatibility of chance and Humean Supervenience is evidence for the nonexistence of chance. I conclude that it is the circularity of the formation of Humean Supervenient laws of chance which continue to bug Humean Supervenience, leaving it untenable and resulting in little chance for chance. (shrink)

Neste artigo, analisa-se como as histórias em quadrinhos sobre automo-bilismo, notadamente a do personagem Michel Vaillant, conseguem en- gendrar, em sua narrativa, mundos possíveis, que, mesmo com atributos ficcionais, se vinculam à referencialidade dos fatos ocorridos no esporte. Utilizando o arcabouço teórico de Umberto Eco e de David Lewis, o objetivo aqui é refletir acerca desse exercício de isomorfismo linguístico, bem como desvelar as estratégias altermundistas utilizadas.

O presente artigo deseja observar como a crônica esportiva de futebol (especialmente a produção textual de Nelson Rodrigues e José Lins do Rego) consegue engendrar, em sua narrativa, mundos possíveis que, mesmo com atributos ficcionais, se vinculam à referencialidade dos fatos ocorridos no esporte. Utilizando-se o arcabouço teórico de Umberto Eco e de David Lewis, o objetivo aqui é refletir acerca desse exercício de isomorfismo linguístico, bem como desvelar as estratégias altermundistas utilizadas.

Unlike any other monograph on legal liability, Michael S. Moore’s book CAUSATION AND RESPONSIBILITY contains a well-informed and in-depth discussion of the metaphysics of causation. Moore does not share the widespread view that legal scholars should not enter into metaphysical debates about causation. He shows respect for the subtleties of philosophical debates on causal relata, identity conditions for events, the ontological distinctions between events, states of affairs, facts and tropes, and the counterfactual analysis of event causation, and he considers all (...) these issues relevant to law. In this contribution, I defend an amended version of the COUNTERFACTUAL theory of event causation both against Moore’s criticism and against some traits of Lewis’s version of the theory. On a number of counts, I simply defend Lewis against Moore’s misdirected criticism. Moore’s unreasonable demand that all the commonplaces about causation have to FOLLOW from the counterfactual analysis rests on his mistaken claim that the counterfactual theory IDENTIFIES causation with counterfactual dependence. In other respects, I part company with Lewis in order to highlight some underrated strengths of the counterfactual approach. The common denominator of my revisions is that they make the counterfactual theory unambiguously singularist. The suggested revisions comprise: performing the counterfactual analysis with Davidsonian rather than with Lewisian events, taking seriously the ex post-character of singular causal statements, making explicit the indexical ceteris paribus clause that fixes the actual circumstances of the causing event, abandoning the alleged transitivity of causation, and, last but not least, doing everything in the correct order. The correct order is to start with bedrock intuitions about the nature of causality rather than with a general possible world semantics, and then to turn these intuitions into constraints for the class of counterfactuals that a counterfactual analysis of causation has to consider. (shrink)

Many writers have held that in his later work, David Lewis adopted a theory of predicate meaning such that the meaning of a predicate is the most natural property that is (mostly) consistent with the way the predicate is used. That orthodox interpretation is shared by both supporters and critics of Lewis's theory of meaning, but it has recently been strongly criticised by Wolfgang Schwarz. In this paper, I accept many of Schwarze's criticisms of the orthodox interpretation, and add some (...) more. But I also argue that the orthodox interpretation has a grain of truth in it, and seeing that helps us appreciate the strength of Lewis's late theory of meaning. (shrink)

David Lewis argues that centered worlds give us a way to capture de se, or self-locating, contents in philosophy of language and philosophy of mind. In recent years, centered worlds have also gained other uses in areas ranging widely from metaphysics to ethics. In this paper, I raise a problem for centered worlds and discuss the costs and benefits of different solutions. My investigation into the nature of centered worlds brings out potentially problematic implicit commitments of the theories that employ (...) them. In addition, my investigation shows that the conception of centered worlds widely attributed to David Lewis is not only problematic, but in fact not his. (shrink)

David Lewis presented Convention as an alternative to the conventionalism characteristic of early-twentieth-century analytic philosophy. Rudolf Carnap is well known for suggesting the arbitrariness of any particular linguistic convention for engaging in scientific inquiry. Analytic truths are self-consistent, and are not checked against empirical facts to ascertain their veracity. In keeping with the logical positivists before him, Lewis concludes that linguistic communication is conventional. However, despite his firm allegiance to conventions underlying not just languages but also social customs, he pioneered (...) the view that convening need not require any active agreement to participate. Lewis proposed that conventions arise from “an exchange of manifestations of a propensity to conform to a regularity” .In reasserting the conventional quality of languages and other practices resting on mutual expectations, Lewis comfortably works within the analytic tradition. Yet he also deviates from his predecessors because his conventionalist approach is comprehensively grounded in instrumentalism. Lewis adopts an extension of David Hume's desire-belief psychology articulated in rational choice theory. He develops his philosophy of convention relying on the highly formal mid-twentieth-century expected utility and game theories. This attempt to account for language and social customs wholly in terms of instrumental rationality has the implication of reducing normativity to preference satisfaction. Lewis’ approach continues in the trend of undermining normative political philosophy because institutions and practices arise spontaneously, without the deliberate involvement of agents. Perhaps Lewis’ Convention is best seen as a resurgent form of analytic philosophy, characterized by “a style of argument, hostility to [ambitious] metaphysics, focus on language, and the dominance of logic and formalization” that solves the dilemma of “combining the analytic inheritance…with normative concerns” by reducing normativity to individuals’ preference fulfillment consistent with the axioms of rational choice. (shrink)

The interpretation of Lewis‘s doctrine of natural properties is difficult and controversial, especially when it comes to the bearers of natural properties. According to the prevailing reading – the minimalist view – perfectly natural properties pertain to the micro-physical realm and are instantiated by entities without proper parts or point-like. This paper argues that there are reasons internal to a broadly Lewisian kind of metaphysics to think that the minimalist view is fundamentally flawed and that a liberal view, according to (...) which natural properties are instantiated at several or even at all levels of reality, should be preferred. Our argument proceeds by reviewing those core principles of Lewis‘s metaphysics that are most likely to constrain the size of the bearers of natural properties: the principle of Humean supervenience, the principle of recombination in modal realism, the hypothesis of gunk, and the thesis of composition as identity. (shrink)

In Lewis reconstructs set theory using mereology and plural quantification (MPQ). In his recontruction he assumes from the beginning that there is an infinite plurality of atoms, whose size is equivalent to that of the set theoretical universe. Since this assumption is far beyond the basic axioms of mereology, it might seem that MPQ do not play any role in order to guarantee the existence of a large infinity of objects. However, we intend to demonstrate that mereology and plural quantification (...) are, in some ways, particularly relevant to a certain conception of the infinite. More precisely, though the principles of mereology and plural quantification do not guarantee the existence of an infinite number of objects, nevertheless, once the existence of any infinite object is admitted, they are able to assure the existence of an uncountable infinity of objects. So, ifMPQ were parts of logic, the implausible consequence would follow that, given a countable infinity of individuals, logic would be able to guarantee an uncountable infinity of objects. (shrink)

On Hume’s account of motivation, beliefs and desires are very different kinds of propositional attitudes. Beliefs are cognitive attitudes, desires emotive ones. An agent’s belief in a proposition captures the weight he or she assigns to this proposition in his or her cognitive representation of the world. An agent’s desire for a proposition captures the degree to which he or she prefers its truth, motivating him or her to act accordingly. Although beliefs and desires are sometimes entangled, they play very (...) different roles in rational agency. In two classic papers (Lewis 1988, 1996), David Lewis discusses several challenges to this Humean picture, but ultimately rejects them. We think that his discussion of a central anti-Humean alternative – the desire-as-belief thesis – is in need of refinnement. On this thesis, the desire for proposition p is given by the belief that p is desirable. Lewis claims that ‘[e]xcept in trivial cases, [this thesis] collapses into contradiction’(Lewis 1996, p. 308). The problem, he argues, is that the thesis is inconsistent with the purportedly plausible requirement that one’s desire for a proposition should not change upon learning that the proposition is true; call this the invariance requirement. In this paper, we revisit Lewis’s argument. We show that, if one carefully distinguishes between non-evaluative and evaluative propositions, the desire-asbelief thesis can be rendered consistent with the invariance requirement. Lewis’s conclusion holds only under certain conditions: the desire-as-belief thesis conflicts with the invariance requirement if and only if there are certain correlations between non-evaluative and evaluative propositions. But when there are such correlations, we suggest, the invariance requirement loses its plausibility. Thus Lewis’s argument against the desire-as-belief thesis appears to be valid only in cases in which it is unsound. (shrink)

I have two aims in this paper. In §§2-4 I contend that Moore has two arguments (not one) for the view that that ‘good’ denotes a non-natural property not to be identified with the naturalistic properties of science and common sense (or, for that matter, the more exotic properties posited by metaphysicians and theologians). The first argument, the Barren Tautology Argument (or the BTA), is derived, via Sidgwick, from a long tradition of anti-naturalist polemic. But the second argument, the Open (...) Question Argument proper (or the OQA), seems to have been Moore’s own invention and was probably devised to deal with naturalistic theories, such as Russell’s, which are immune to the Barren Tautology Argument. The OQA is valid and not (as Frankena (1939) has alleged) question-begging. Moreover, if its premises were true, it would have disposed of the desire-to-desire theory. But as I explain in §5, from 1970 onwards, two key premises of the OQA were successively called into question, the one because philosophers came to believe in synthetic identities between properties and the other because it led to the Paradox of Analysis. By 1989 a philosopher like Lewis could put forward precisely the kind of theory that Moore professed to have refuted with a clean intellectual conscience. However, in §§6-8 I shall argue that all is not lost for the OQA. I first press an objection to the desire-to-desire theory derived from Kripke’s famous epistemic argument. On reflection this argument looks uncannily like the OQA. But the premise on which it relies is weaker than the one that betrayed Moore by leading to the Paradox of Analysis. This suggests three conclusions: 1) that the desire-to-desire theory is false; 2) that the OQA can be revived, albeit in a modified form; and 3) that the revived OQA poses a serious threat to what might be called semantic naturalism. (shrink)

In a survey of his views in the philosophy of mind, David Lewis criticizes much recent work in the field by attacking an imaginary opponent, Strawman. His case against Strawman focuses on four central theses which Lewis takes to be widely accepted among contemporary philosophers of mind. These theses concern (1) the language of thought hypothesis and its relation to folk psychology, (2) narrow content, (3) de se content, and (4) rationality. We respond to Lewis, arguing that he underestimates Strawman’s (...) theoretical resources in a variety of important ways. (shrink)

The death of David Lewis at the age of 60 has deprived philosophy of one of its most original and brilliant thinkers. Lewis was a systematic philosopher in a traditional sense, who created a system of thought (or metaphysical system) which attempts to reconcile the insights of modern science with pervasive elements of commonsense belief. Lewis was not a populariser and he had little to do with the more concrete and practical areas of philosophy. His work is forbiddingly abstract, and (...) deals with many of the deepest and most difficult of philosophy’s traditional concerns, including the nature of mind, causation, necessity and being. (shrink)

This paper begins with a puzzle regarding Lewis' theory of radical interpretation. On the one hand, Lewis convincingly argued that the facts about an agent's sensory evidence and choices will always underdetermine the facts about her beliefs and desires. On the other hand, we have several representation theorems—such as those of (Ramsey 1931) and (Savage 1954)—that are widely taken to show that if an agent's choices satisfy certain constraints, then those choices can suffice to determine her beliefs and desires. In (...) this paper, I will argue that Lewis' conclusion is correct: choices radically underdetermine beliefs and desires, and representation theorems provide us with no good reasons to think otherwise. Any tension with those theorems is merely apparent, and relates ultimately to the difference between how 'choices' are understood within Lewis' theory and the problematic way that they're represented in the context of the representation theorems. For the purposes of radical interpretation, representation theorems like Ramsey's and Savage's just aren't very relevant after all. (shrink)

In May 1999, David Lewis sent Timothy Williamson an intriguing letter about knowledge and vagueness. This paper has a brief discussion of Lewis on evidence, and a longer discussion of a distinctive theory of vagueness Lewis puts forward in this letter, one rather different from standard forms of supervaluationism. Lewis's theory enables him to provide distinctive responses to the challenges to supervaluationism famously offered in chapter 5 of Timothy Williamson's 1994 book Vagueness. However these responses bring out a number of (...) very surprising features of Lewis's own view. -/- The letter from Lewis itself is available on the blog of The Age of Metaphysical Revolution Project, University of Manchester. (shrink)