Timothy Williamson gives an original and provocative treatment of deep metaphysical questions about existence, contingency, and change, using the latest resources of quantified modal logic. Contrary to the widespread assumption that logic and metaphysics are disjoint, he argues that modal logic provides a structural core for metaphysics.

Vagueness provides the first comprehensive examination of a topic of increasing importance in metaphysics and the philosophy of logic and language. Timothy Williamson traces the history of this philosophical problem from discussions of the heap paradox in classical Greece to modern formal approaches such as fuzzy logic. He illustrates the problems with views which have taken the position that standard logic and formal semantics do not apply to vague language, and defends the controversial realistic view that vagueness is (...) a kind of ignorance--that there really is a grain of sand whose removal turns a heap into a non-heap, but we cannot know which one it is. (shrink)

In this paper we discuss how Causal Decision Theory should be modified to handle a class of problematic cases involving deterministic laws. Causal Decision Theory, as it stands, is problematically biased against your endorsing deterministic propositions (for example it tells you to deny Newtonian physics, regardless of how confident you are of its truth). Our response is that this is not a problem for Causal Decision Theory per se, but arises because of the standard method for assessing the truth of (...) certain counterfactuals. The truth of deterministic laws is `modally fragile' on the standard semantics for counterfactuals: if determinism is true and you were to do otherwise, the laws would be different. We provide two ways of avoiding this problem: 1) supplement the standard semantics for counterfactuals with impossible worlds, or 2) introduce rigid designators into the description of problematic decision situations. We argue that both of these approaches are well-motivated and can be readily incorporated into Lewisian Causal Decision Theory. (shrink)

The paper clarifies and defends the orthodox view that counterfactual conditionals with impossible antecedents are vacuously true against recent criticisms. It argues that apparent counterexamples to orthodoxy result from uncritical reliance on a fallible heuristic used in the processing of conditionals. A comparison is developed between such counterpossibles and vacuously true universal generalizations.

Understandably absorbed in technical details, discussion of the semantic paradoxes risks losing sight of broad methodological principles. This chapter sketches a general approach to the comparison of rival logics, and applies it to argue that revision of classical propositional logic has much higher costs than its proponents typically recognize.

When I take off my glasses, the world looks blurred. When I put them back on, it looks sharpedged. I do not think that the world really was blurred; I know that what changed was my relation to the distant physical objects ahead, not those objects themselves. I am more inclined to believe that the world really is and was sharp-edged. Is that belief any more reasonable than the belief that the world really is and was blurred? I see more (...) accurately with my glasses on than off, so visual appearances when they are on have some cognitive priority over visual appearances when they are off. If I must choose which kind of visual appearance to take at face value, I will choose the sharp-edged look. But what should I think when I see a mist, which looks very blurred however well I am seeing? Indeed, why choose to take any of the looks at face value? Why not regard all the choices as illegitimate projections of ways of seeing the world onto the world itself? (shrink)

The second volume in the _Blackwell Brown Lectures in Philosophy_, this volume offers an original and provocative take on the nature and methodology of philosophy. Based on public lectures at Brown University, given by the pre-eminent philosopher, Timothy Williamson Rejects the ideology of the 'linguistic turn', the most distinctive trend of 20th century philosophy Explains the method of philosophy as a development from non-philosophical ways of thinking Suggests new ways of understanding what contemporary and past philosophers are doing.

Imagine a philosophy conference in Presocratic Greece. The hot question is: what are things made of? Followers of Thales say that everything is made of water, followers of Anaximenes that everything is made of air, and followers of Heraclitus that everything is made of fire. Nobody is quite clear what these claims mean, and some question whether the founders of the respective schools ever made them. But amongst the groupies there is a buzz about all the recent exciting progress. The (...) mockers and doubters make plenty of noise too. They point out that no resolution of the dispute between the schools is in sight. They diagnose Thales, Anaximenes and Heraclitus as suffering from a tendency to overgeneralize. We can intelligibly ask what bread is made of, or what houses are made of, but to ask what things in general are made of is senseless, some suggest, because the question is posed without any conception of how to verify an answer; language has gone on holiday. Paleo-pragmatists invite everyone to relax, forget their futile pseudo-inquiries and do something useful instead. (shrink)

The philosophical relevance of experimental psychology is hard to dispute. Much more controversial is the so‐called negative program's critique of armchair philosophical methodology, in particular the reliance on ‘intuitions’ about thought experiments. This chapter responds to that critique. It argues that, since the negative program has been forced to extend the category of intuition to ordinary judgments about real‐life cases, the critique is in immediate danger of generating into global scepticism, because all human judgments turn out to depend on intuitions. (...) Recently, some proponents of the negative program have tried to demarcate the target of their critique more narrowly. However, their attempts are still far too indiscriminate, and over‐generate scepticism. Nevertheless, once experimental philosophy has refined its own methodology, it may contribute to the refinement of the methodology of mainstream philosophy, by filtering out the effects of cognitive bias, although it offers no prospect of doing without judgments on real or imaginary cases. (shrink)

This chapter aims to attempt no more than to make some informal and unsystematic remarks on the transformation of analytic philosophy. It deals with a few sketchy remarks on the historiography of recent analytic philosophy. Writing in 1981, David Lewis described “a reasonable goal for a philosopher” as bringing one’s opinions into stable equilibrium. A natural comparison is between Lewis’s Quinean or at least post‐Quinean methodology and the methodology of Peter Strawson, Quine’s leading opponent from the tradition of ordinary language (...) philosophy. Analytic epistemology provides a good case study of the philosophical application of Gricean pragmatics outside the philosophy of language. On Michael Dummett picture of the history of philosophy, Descartes had made epistemology first philosophy, the engine for the rest of philosophy, and then Frege had replaced epistemology by the philosophy of language as first philosophy. The chapter suggests that philosophy sometimes already uses an abductive methodology and ought to use it more in the future. (shrink)

Two opposing tendencies in the philosophy of language go by the names of ‘referentialism’ and ‘inferentialism’ respectively. In the crudest version of the contrast, the referentialist account of meaning gives centre stage to the referential semantics for a language, which is then used to explain the inference rules for the language, perhaps as those which preserve truth on that semantics (since a referential semantics for a language determines the truth-conditions of its sentences). By contrast, the inferentialist account of meaning gives (...) centre stage to the inference rules for the language, which are then used to explain its referential semantics, perhaps as the semantics on which the rules preserve truth. On pain of circularity, we cannot combine both directions of explanation. (shrink)

Knowledge and its Limits presents a systematic new conception of knowledge as a kind of mental stage sensitive to the knower's environment. It makes a major contribution to the debate between externalist and internalist philosophies of mind, and breaks radically with the epistemological tradition of analyzing knowledge in terms of true belief. The theory casts new light on such philosophical problems as scepticism, evidence, probability and assertion, realism and anti-realism, and the limits of what can be known. The arguments are (...) illustrated by rigorous models based on epistemic logic and probability theory. The result is a new way of doing epistemology and a notable contribution to the philosophy of mind. (shrink)

Metaphysical modalities are definable from counterfactual conditionals, and the epistemology of the former is a special case of the epistemology of the latter. In particular, the role of conceivability and inconceivability in assessing claims of possibility and impossibility can be explained as a special case of the pervasive role of the imagination in assessing counterfactual conditionals, an account of which is sketched. Thus scepticism about metaphysical modality entails a more far-reaching scepticism about counterfactuals. The account is used to question the (...) significance of the distinction between a priori and a posteriori knowledge. (shrink)

A case in point is Frank Jackson’s talk of “conceptual possibility” and “conceptual necessity.” He writes as if the issue between us is the relative methodological priority for philosophy of conceptual modalities and metaphysical modalities. In addition to the uncritical reliance on conceptual modality, another fallacy is surfacing. Paul Boghossian developed an epistemology of logic based on understanding‐assent links corresponding to fundamental rules of logic. His paradigm was modus ponens: a necessary condition for understanding “if” was supposed to be willingness (...) to assent to inferences by modus ponens involving “if.” Boghossian objects that Simon’s tolerance of assent to gappy statements undermines the presumption that he is assenting to them as true. In Nenad Miscevic paper, such competencies are postulated for the linguistic, spatial‐geometric, mathematical, metaphysical, epistemological, and moral domains. Thus Miscevic auxiliary modularity‐independent characterization offers little help in demarcating a useful category of intuition. (shrink)

Moore’s sympathies are anti‐realist. As an example of an antirealist account of truth, he gives what he calls “the Wittgensteinian View” of truth for mathematical discourse. In attempting to show how to “sidestep certainly apparently decisive objections” to the Wittgensteinian View, Moore acquiesces in the charge that it makes the consistency of a mathematical theory a matter of stipulation: we adopt a rule “that guarantees the consistency of Peano Arithmetic.” Moore’s main concern is the defensibility of anti‐realist view of philosophical (...) discourse. In “Williamson’s Philosophy of Philosophy”, Paul Horwich defends the idea that the proper business of philosophy is clarification rather than systematic theory‐building. In political philosophy, it would be hard to mount a credible defense of some system of government without considering what effects it causally explains. In terms of Diego Marconi’s clear version of Wittgenstein’s account, it is straightforward to explain why it is no longer a live option for so many philosophers. (shrink)

This chapter argues that the ordinary cognitive capacity to handle counterfactual conditionals carries with it the cognitive capacity to handle metaphysical modality. It aims to illustrate with examples our cognitive use of counterfactual conditionals, and sketches an epistemology for such conditionals. The chapter explains how they subsume metaphysical modality, and assesses the consequences for the distinction between a priori and a posteriori knowledge. It discusses the relation between metaphysical possibility and the restricted kinds of possibility that seem more relevant to (...) ordinary life. Philosophers’ ascriptions of metaphysical modality are far more deeply rooted in our ordinary cognitive practices than most skeptics about it realize. Many philosophers are more confident in their judgments about more or less realistic thought experiments in epistemology and moral philosophy than about more radically strange ones in metaphysics. Philosophical controversy will naturally make the unclear cases salient. (shrink)

This chapter explores some general aspects of the tension between one’s role as a believer and one’s role as an appraiser of oneself as a believer in philosophy. The proposal is to replace true belief by knowledge in a principle of charity constitutive of content. Knowledge maximization need not make the ascription of knowledge come too cheap. By contrast, Davidson’s principle of charity gives good marks to an interpretation for having Stone Age people assent to many truths of quantum mechanics, (...) if it happens to fit the compositional structure of their language. Perhaps the underlying worries about knowledge maximization can be captured in a more abstract form. A subtler attempt to extract knowledge from Davidson’s principle of charity exploits beliefs that one knows. Knowledge maximization implies that our ancestors had some primitive knowledge as soon as they had some primitive beliefs; it is not as though archaeology suggests otherwise. (shrink)

_Identity and Discrimination_, originally published in 1990 and the first book by respected philosopher Timothy Williamson, is now reissued and updated with the inclusion of significant new material. Williamson here proposes an original and rigorous theory linking identity, a relation central to metaphysics, and indiscriminability, a relation central to epistemology.__ Updated and reissued edition of Williamson’s first publication, with the inclusion of significant new material Argues for an original cognitive account of the relation between identity and (...) discrimination that has been influential in the philosophy of perception Pioneers the use of epistemic logic to solve puzzles about indiscriminability Develops the application of techniques from mathematical logic to understand issues about identity over time and across possible worlds. (shrink)

This paper explains and defends the idea that metaphysical necessity is the strongest kind of objective necessity. Plausible closure conditions on the family of objective modalities are shown to entail that the logic of metaphysical necessity is S5. Evidence is provided that some objective modalities are studied in the natural sciences. In particular, the modal assumptions implicit in physical applications of dynamical systems theory are made explicit by using such systems to define models of a modal temporal logic. Those assumptions (...) arguably include some necessitist principles. -/- Too often, philosophers have discussed ‘metaphysical’ modality — possibility, contingency, necessity — in isolation. Yet metaphysical modality is just a special case of a broad range of modalities, which we may call ‘objective’ by contrast with epistemic and doxastic modalities, and indeed deontic and teleological ones (compare the distinction between objective probabilities and epistemic or subjective probabilities). Thus metaphysical possibility, physical possibility and immediate practical possibility are all types of objective possibility. We should study the metaphysics and epistemology of metaphysical modality as part of a broader study of the metaphysics and epistemology of the objective modalities, on pain of radical misunderstanding. Since objective modalities are in general open to, and receive, natural scientific investigation, we should not treat the metaphysics and epistemology of metaphysical modality in isolation from the metaphysics and epistemology of the natural sciences. -/- In what follows, Section 1 gives a preliminary sketch of metaphysical modality and its place in the general category of objective modality. Section 2 reviews some familiar forms of scepticism about metaphysical modality in that light. Later sections explore a few of the many ways in which natural science deals with questions of objective modality, including questions of quantified modal logic. (shrink)

Lemmon and Scott introduced the notion of a modal system's providing the rule of disjunction. No consistent normal extension of KB provides this rule. An alternative rule is defined, which KDB, KTB, and other systems are shown to provide, while K and other systems provide the Lemmon-Scott rule but not the alternative rule. If S provides the alternative rule then either —A is a theorem of S or A is whenever A -> ΠA is a theorem; the converse fails. It (...) is suggested that systems with this property are appropriate for handling sorites paradoxes, where D is read as 'clearly*. The S4 axiom fails in such systems. (shrink)

This paper aims to identify the constitutive rule of assertion, conceived by analogy with the rules of a game. That assertion has such rules is by no means obvious; perhaps it is more like a natural phenomenon than it seems. One way to find out is by supposing that it has such rules, in order to see where the hypothesis leads and what it explains. That will be done here. The hypothesis is not perfectly clear, of course, but we have (...) at least a crude conception of constitutive rules, which we may refine as we elaborate the hypothesis. Although no attempt will be made here to define ‘rule’, some remarks on constitutive rules will focus the discussion. (shrink)

Rational agents face choices, even when taking seriously the possibility of determinism. Rational agents also follow the advice of Causal Decision Theory (CDT). Although many take these claims to be well-motivated, there is growing pressure to reject one of them, as CDT seems to go badly wrong in some deterministic cases. We argue that deterministic cases do not undermine a counterfactual model of rational deliberation, which is characteristic of CDT. Rather, they force us to distinguish between counterfactuals that are relevant (...) and ones that are irrelevant for the purposes of deliberation. We incorporate this distinction into decision theory to develop ‘Selective Causal Decision Theory’, which delivers the correct recommendations in deterministic cases while respecting the key motivations behind CDT. (shrink)

Epistemic logics for subjects of bounded rationality are in effect nonnormal modal logics. Admissible rules are of interest in such logics. However, the usual methods for establishing admissibility employ Kripke models and are therefore inappropriate for nonnormal logics. This paper extends syntactic methods for a variety of rules and nonnormal logics. In doing so it answers a question asked by Chellas and Segerberg.

On reading the last sentence, did you interpret me as saying falsely that everything — everything in the entire universe — was packed into my carry-on baggage? Probably not. In ordinary language, ‘everything’ and other quantifiers (‘something’, ‘nothing’, ‘every dog’, ...) often carry a tacit restriction to a domain of contextually relevant objects, such as the things that I need to take with me on my journey. Thus a sentence of the form ‘Everything Fs’ is true as uttered in a (...) context C if and only if everything that is relevant in C satisfies the predicate ‘F’; ‘everything’ ranges just over the contextually relevant things. Such generality is restricted in a context-relative way. (shrink)

A concept of informational equivalence between relations is explicated to generalize some suggestions by Geach. It is shown that two relations are informationally equivalent if and only if each can be defined in terms of the other without the use of quantifiers. It is shown that there is a general method for listing the ./-place relations informationally equivalent to an arbitrary given /-place relation if and only if i (...) the invariants of the group of invertible quantifier-free definitions, for / =j. Quantifier-free definition is contrasted with general first-order definition by means of an example of two first-order interdefinable relations which are not interdefined by any pair of mutually inverse first-order definitions. (shrink)

The book records a series of philosophical exchanges between its authors, amounting to a debate extended over more than fifteen years. Its subject matter is the nature and scope of reason. A central case at issue is basic logical knowledge, and the justification for basic deductive inferences, but the arguments range far more widely, at stake the distinctions between analytic and synthetic, and between a priori and a posteriori. The discussion naturally involves problems about the conditions for linguistic understanding and (...) competence, and what it might be to grasp a concept or to have an intuition. Since reason is central to philosophical method, there are associated implications for how philosophy itself works, or should work. In particular, the discussion raises fundamental concerns about how to approach epistemology. -/- . (shrink)

The theorems of the simplest and strongest sensible quantified modal logic include the Barcan Formula and its converse. Both formulas face strong intuitive objections. This paper develops a theory of possibilia to meet those objections.

Assertions are praised as true, informative, relevant, sincere, warranted, well-phrased, or polite. They are criticized as false, uninformative, irrelevant, insincere, unwarranted, ill-phrased, or rude. Sometimes they deserve such praise or criticism. If any respect in which performances of an act can deserve praise or criticism is a norm for that act, then the speech act of assertion has many norms. So has almost any act; jumps can deserve praise as long or brave, criticism as short or cowardly. But it is (...) natural to suppose that some norms are more intimately connected to the nature of asserting than any norm is to the nature of jumping. One might suppose, for example, that someone who knowingly asserts a falsehood has thereby broken a rule of assertion, much as if he had broken a rule of a game; he has cheated. On this view, the speech act, like a game and unlike the act of jumping, is constituted by rules. Thus, not all norms for assertion are on a par. Norms such as relevance, good phrasing, and politeness are just applications of more general cognitive or social norms to the specific act of assertion. Perhaps the norm of informativeness results from a more complex interaction between a general norm of cooperativeness and the nature of assertion as a source of information. But on this view, not all norms for assertion derive from more general norms; otherwise nothing would differentiate it from other speech acts. (shrink)

The paper challenges the inferentialist account of concept possession that Paul Boghossian takes as a premise in his account of the transmission of justification by deductive reasoning in his paper 'Blind Reasoning'. Unorthodox speakers who reject the inferences in an alleged possession condition can still have the concept by understanding a word for it. In that sense, the inferences are not analytic. Inferentialist accounts of logical constants, theoretical terms (using the Ramsey-Carnap-Lewis method) and pejorative expressions such as 'Boche' are examined (...) and rejected. It is suggested that epistemological questions cannot be reduced to questions in the theory of thought and meaning. (shrink)