Epistemic modals have peculiar logical features that are challenging to account for in a broadly classical framework. For instance, while a sentence of the form $$p\wedge \Diamond \lnot p$$ (‘p, but it might be that not p’) appears to be a contradiction, $$\Diamond \lnot p$$ does not entail $$\lnot p$$, which would follow in classical logic. Likewise, the classical laws of distributivity and disjunctive syllogism fail for epistemic modals. Existing attempts to account for these facts generally either under- or over-correct. (...) Some theories predict that $$ p\wedge \Diamond \lnot p$$, a so-called epistemic contradiction, is a contradiction only in an etiolated sense, under a notion of entailment that does not always allow us to replace $$p\wedge \Diamond \lnot p$$ with a contradiction; these theories underpredict the infelicity of embedded epistemic contradictions. Other theories savage classical logic, eliminating not just rules that intuitively fail, like distributivity and disjunctive syllogism, but also rules like non-contradiction, excluded middle, De Morgan’s laws, and disjunction introduction, which intuitively remain valid for epistemic modals. In this paper, we aim for a middle ground, developing a semantics and logic for epistemic modals that makes epistemic contradictions genuine contradictions and that invalidates distributivity and disjunctive syllogism but that otherwise preserves classical laws that intuitively remain valid. We start with an algebraic semantics, based on ortholattices instead of Boolean algebras, and then propose a possibility semantics, based on partial possibilities related by compatibility. Both semantics yield the same consequence relation, which we axiomatize. We then show how to lift an arbitrary possible worlds model for a non-modal language to a possibility model for a language with epistemic modals. The goal throughout is to retain what is desirable about classical logic while accounting for the non-classicality of epistemic vocabulary. (shrink)

There is an extensive literature in social choice theory studying the consequences of weakening the assumptions of Arrow's Impossibility Theorem. Much of this literature suggests that there is no escape from Arrow-style impossibility theorems unless one drastically violates the Independence of Irrelevant Alternatives (IIA). In this paper, we present a more positive outlook. We propose a model of comparing candidates in elections, which we call the Advantage-Standard (AS) model. The requirement that a collective choice rule (CCR) be rationalizable by the (...) AS model is in the spirit of but weaker than IIA; yet it is stronger than what is known in the literature as weak IIA (two profiles alike on x, y cannot have opposite strict social preferences on x and y). In addition to motivating violations of IIA, the AS model makes intelligible violations of another Arrovian assumption: the negative transitivity of the strict social preference relation P. While previous literature shows that only weakening IIA to weak IIA or only weakening negative transitivity of P to acyclicity still leads to impossibility theorems, we show that jointly weakening IIA to AS rationalizability and weakening negative transitivity of P leads to no such impossibility theorems. Indeed, we show that several appealing CCRs are AS rationalizable, including even transitive CCRs. (shrink)

A leader in the modern commentary on ethics and philosophy, Mary Warnock casts a critical eye over her life and times.

This selection consists of extracts from writings of women concerned solely with the pursuit of abstract ideas, historically contextualized. The texts, for the most part, reflect issues widely debated in their contemporary societies. Extracts from lesser-known writers are also included, providing a diversity of arguments spanning four centuries and including some notable contemporary philosophers.

Whether to do business with rights violating regimes is one of many dilemmas faced by socially responsible corporations. In this article the difficult case of Myanmar is considered. Ruled for decades by a closed and sometimes brutal military elite, the country has long been subject to informal and formal sanctions. However, as sanctions have failed to trigger political reform, it is necessary to review the policy options. The focus here is on the contribution socially responsible corporations might make to change. (...) The article sketches contextual features of the case, examines the recent history and present pattern of business links with Myanmar, and assesses whether current approaches can stimulate reform. Concluding that they cannot, it considers fresh possibilities for corporate engagement. The argument is that socially responsible corporations, committed to improving individual life chances through engagement with developing societies, should undertake collaborative and principled direct investment in Myanmar. The underlying strategy and problems of codification and implementation are all analyzed. To close, the article contends that, by doing business with Myanmar’s rights violating regime, multinational corporations can extend the frontiers of global corporate social responsibility. (shrink)

Whether to do business with rights violating regimes is one of many dilemmas faced by socially responsible corporations. In this article the difficult case of Myanmar is considered. Ruled for decades by a closed and sometimes brutal military elite, the country has long been subject to informal and formal sanctions. However, as sanctions have failed to trigger political reform, it is necessary to review the policy options. The focus here is on the contribution socially responsible corporations might make to change. (...) The article sketches contextual features of the case, examines the recent history and present pattern of business links with Myanmar, and assesses whether current approaches can stimulate reform. Concluding that they cannot, it considers fresh possibilities for corporate engagement. The argument is that socially responsible corporations, committed to improving individual life chances through engagement with developing societies, should undertake collaborative and principled direct investment in Myanmar. The underlying strategy and problems of codification and implementation are all analyzed. To close, the article contends that, by doing business with Myanmar's rights violating regime, multinational corporations can extend the frontiers of global corporate social responsibility. (shrink)

How is hope to be found amid the ethical and political dilemmas of modern life? Writer and philosopher Mary Zournazi brought her questions to some of the most thoughtful intellectuals at work today. She discusses "joyful revolt" with Julia Kristeva, the idea of "the rest of the world" with Gayatri Spivak, the "art of living" with Michel Serres, the "carnival of the senses" with Michael Taussig, the relation of hope to passion and to politics with Chantal Mouffe and Ernesto (...) Laclau. A dozen stimulating minds weigh in with their visions of a better social and political order. The result is a collaboration - of writing, of thinking, and of politics - that demonstrates more clearly than any single-authored project could how ideas encountering one another can produce the vision needed for social change. (shrink)

All religion and much philosophy has been concerned with the contrast between the ephemeral and the eternal. Human beings have always sought ways to overcome time, and to prove that death is not the end. This book consists then in an exploration of certain closely related ideas: personal identity, time, history and our commitment to the future, and the role of imagination in life.

In this article, we tell a story about incompleteness in modal logic. The story weaves together an article of van Benthem, “Syntactic aspects of modal incompleteness theorems,” and a longstanding open question: whether every normal modal logic can be characterized by a class of completely additive modal algebras, or as we call them, ${\cal V}$-baos. Using a first-order reformulation of the property of complete additivity, we prove that the modal logic that starred in van Benthem’s article resolves the open question (...) in the negative. In addition, for the case of bimodal logic, we show that there is a naturally occurring logic that is incomplete with respect to ${\cal V}$-baos, namely the provability logic $GLB$. We also show that even logics that are unsound with respect to such algebras do not have to be more complex than the classical propositional calculus. On the other hand, we observe that it is undecidable whether a syntactically defined logic is ${\cal V}$-complete. After these results, we generalize the Blok Dichotomy to degrees of ${\cal V}$-incompleteness. In the end, we return to van Benthem’s theme of syntactic aspects of modal incompleteness. (shrink)

Fundamental principles : the nature of the dispute -- Types of euthanasia -- Psychiatric assisted suicide -- Neonates -- Incompetent adults -- Human life is sacred -- The slippery slope -- Medical views -- Four methods of easing death and their effect on doctors -- Looking further ahead.

In two of the earliest papers on extending modal logic with propositional quantifiers, R. A. Bull and K. Fine studied a modal logic S5Π extending S5 with axioms and rules for propositional quantification. Surprisingly, there seems to have been no proof in the literature of the completeness of S5Π with respect to its most natural algebraic semantics, with propositional quantifiers interpreted by meets and joins over all elements in a complete Boolean algebra. In this note, we give such a proof. (...) This result raises the question: For which normal modal logics. (shrink)

En este libro, la autora desarrolla su concepción del juicio reflexionante inspirada en Emmanuel Kant y en Hannah Arendt para concentrarse en cómo cierto tipo de narraciones modelan nuestras nociones de lo que consideramos moral. Lara nos ofrece distintas concepciones sobre el mal en su formulación histórica mediante los ejemplos de las tragedias griegas, las diferentes concepciones sobre el mal en la obra de Shakespeare, el uso literario de la metáfora en la obra de Joseph Conrad y en narraciones fílmicas (...) que describen la crueldad humana. Lara sugiere que el aprendizaje moral es un proceso en el que intervienen las instituciones sociales, la voluntad de los individuos y de las sociedades para comprometerse a un debate abierto y con ello modelar los juicios colectivos sobre el pasado. Lara enfatiza que el juicio reflexionante se da entre un evento, una narración de dicho evento y la recepción pública de dicha narrativa. En este libro se aportan importantes métodos para la comprensión del fenómeno moral del mal, porque introducen nuevas verdades desvelatorias acerca de eventos particulares que no pueden ser simplemente captados por medio de categorías conceptuales. Lara utiliza como fuentes a Jürgen Habermas, Walter Benjamin, Primo Levi, Giorgio Agamben y Ariel Dorfman para probar la conclusión de este tipo de narraciones: la acción (de crueldad) ata de manera definitiva al perpetrador con su víctima. (shrink)

Nature and Mortality is a challenging look at some of the major public issues of our time through the eyes of one of our most influential and probing liberal humanists. It is a frank account on where we stand today on such controversial matters as human embryology, genetic engineering, euthanasia and abortion. Warnock's views may seem like a red rag to a bull to some, but her contribution to the debate is always stimulating. Enlivened by autobiographical anecdote and some delicious (...) side-swipes, Nature and Mortality is Mary Warnock at her most perceptive, wise and entertaining. (shrink)

The works of Mary Wollstonecraft (1759-1797) ranged from the early _Thoughts on the Education of Daughters_ to _The Female Reader_, a selection of texts for girls, and included two novels. But her reputation is founded on _A Vindication of the Rights of Woman_ of 1792. This treatise is the first great document of feminism—and is now accepted as a core text in western tradition. It is not widely known that the germ of Wollstonecraft’s great work came out of an (...) earlier and much shorter vindication—A Vindication of the Rights of Men (1790), written in the context of the issues raised by the French Revolution. This edition, which follows the model of other Broadview Editions in including a range of materials that help the reader to see the work in the context of its era out of which it emerged, is arranged chronologically, opening with Wollstonecraft’s “other vindication.” It also includes a wide range of other documents in appendices, as well as a comprehensive and authoritative introduction, chronology, and full index. (shrink)

This chapter first distinguishes between originality and creativity. True originality is rare, whether in art, science, or LEGO, because to be truly original means to have done something that no one has ever done before, and that no one could have anticipated. Most LEGO creations will not meet that condition, for with the exception of serious hobbyists who undertake massive builds, most players who make original creations are making creations that are commonplace. Painting or remolding or placing stickers on the (...) bricks counts against the spirit of LEGO creation. The chapter then discusses The LEGO Movie embodies the paradox that presents three conflicting models of creative LEGO play, illustrated by the Master Builders, Finn's father, and Emmet. The movie's creators were deliberately playing around with conflicting popular conceptions of creativity: creativity as madness, creativity as thinking outside the box, and creativity as vision. (shrink)

In two of the earliest papers on extending modal logic with propositional quantifiers, R. A. Bull and K. Fine studied a modal logic S5Π extending S5 with axioms and rules for propositional quantification. Surprisingly, there seems to have been no proof in the literature of the completeness of S5Π with respect to its most natural algebraic semantics, with propositional quantifiers interpreted by meets and joins over all elements in a complete Boolean algebra. In this note, we give such a proof. (...) This result raises the question: For which normal modal logics L can one axiomatize the quantified propositional modal logic determined by the complete modal algebras for L? (shrink)

Western philosophical orthodoxy places many aspects of other people's lives outside the scope of our knowledge. Demonstrating an alternative to this view, however, this book argues that Jean-Paul Sartre's application of his unique psychoanalytic method to Gustave Flaubert is the culmination of his project to show that it is possible to know everything there is to know about another person. It examines how Sartre aims to revolutionize our way of thinking about others by presenting his existential psychoanalysis as the means (...) to knowledge of both ourselves and others. By so doing, it highlights how his determination to solve the longstanding philosophical conundrum about other minds drives him not only to incorporate insights from Descartes, Hegel, Husserl, Freud, Marx, and Beauvoir into his philosophy, but also to supplement and enhance his philosophy through the development and application of a new form of psychoanalysis. -/- Sartre's Existential Psychoanalysis integrates, for the first time, Sartre's psychoanalysis into his overarching philosophical project. By offering a critical interrogation of the role his psychoanalytical studies played in the development of his existentialism, Mary Edwards uncovers the overlooked philosophical significance of his existential psychoanalysis and brings it into a new and productive dialogue with current research in the fields of philosophy, psychology, and psychotherapy. (shrink)

The unity of aesthetic and teleological judgment, the third and earlier Critiques, is based on Kant′s discovery of a “heuristic method” for applying judgments regarding sense phenomena to abstract thought, a “second attention” which enables an “idea of the whole”. Synthetic judgment, basis for cognition and human action, depends on efficacy of non-empirical insights: the transcendental standpoint, “regulative” ideas, consciousness of “ought” and the reality of freedom, universality of natural mechanism, the principle of “fortuitous” purposiveness. The activity of reflective judgment (...) in the encounter with the beautiful, sublime, living, and two paradigmatic types of explanation, inspired by Spinoza′s distinction of extensio and cogitatio, permit Kant to bridge the gap between freedom and necessity, theoretical knowledge and morality. (shrink)

Brouwer's views on the foundations of mathematics have inspired the study of intuitionistic logic, including the study of the intuitionistic propositional calculus and its extensions. The theory of these systems has become an independent branch of logic with connections to lattice theory, topology, modal logic and other areas. This paper aims to present a modern account of semantics for intuitionistic propositional systems. The guiding idea is that of a hierarchy of semantics, organized by increasing generality: from the least general Kripke (...) semantics on through Beth semantics, topological semantics, Dragalin semantics, and finally to the most general algebraic semantics. While the Kripke, topological, and algebraic semantics have been extensively studied, the Beth and Dragalin semantics have received less attention. We bring Beth and Dragalin semantics to the fore, relating them to the concept of a nucleus from pointfree topology, which provides a unifying perspective on the semantic hierarchy. (shrink)

The standard topological representation of a Boolean algebra via the clopen sets of a Stone space requires a nonconstructive choice principle, equivalent to the Boolean Prime Ideal Theorem. In this article, we describe a choice-free topological representation of Boolean algebras. This representation uses a subclass of the spectral spaces that Stone used in his representation of distributive lattices via compact open sets. It also takes advantage of Tarski’s observation that the regular open sets of any topological space form a Boolean (...) algebra. We prove without choice principles that any Boolean algebra arises from a special spectral space X via the compact regular open sets of X; these sets may also be described as those that are both compact open in X and regular open in the upset topology of the specialization order of X, allowing one to apply to an arbitrary Boolean algebra simple reasoning about regular opens of a separative poset. Our representation is therefore a mix of Stone and Tarski, with the two connected by Vietoris: the relevant spectral spaces also arise as the hyperspace of nonempty closed sets of a Stone space endowed with the upper Vietoris topology. This connection makes clear the relation between our point-set topological approach to choice-free Stone duality, which may be called the hyperspace approach, and a point-free approach to choice-free Stone duality using Stone locales. Unlike Stone’s representation of Boolean algebras via Stone spaces, our choice-free topological representation of Boolean algebras does not show that every Boolean algebra can be represented as a field of sets; but like Stone’s representation, it provides the benefit of a topological perspective on Boolean algebras, only now without choice. In addition to representation, we establish a choice-free dual equivalence between the category of Boolean algebras with Boolean homomorphisms and a subcategory of the category of spectral spaces with spectral maps. We show how this duality can be used to prove some basic facts about Boolean algebras. (shrink)

The article contributes to debates about core executive capacity by analyzing the British and Japanese cases. First it examines the historical development, contemporary structures and current operations of the two cases. Then it compares their performance in five key areas: overseeing government policy in the domestic sphere; overseeing government policy in the external sphere; managing executive relations with the legislature; overseeing public finances; and managing public relations. It finds that the performance of the two systems is variable both internally across (...) distinct areas of business and, to a lesser extent, comparatively across similar areas. Overall, however, the British core executive is shown to have considerably greater capacity for coordinating and managing policy flows through the system than the Japanese. Governing from the centre is more feasible in Britain than in Japan. (shrink)

This paper studies connections between two alternatives to the standard probability calculus for representing and reasoning about uncertainty: imprecise probability andcomparative probability. The goal is to identify complete logics for reasoning about uncertainty in a comparative probabilistic language whose semantics is given in terms of imprecise probability. Comparative probability operators are interpreted as quantifying over a set of probability measures. Modal and dynamic operators are added for reasoning about epistemic possibility and updating sets of probability measures.

Reasoning about what other people know is an important cognitive ability, known as epistemic reasoning, which has fascinated psychologists, economists, and logicians. In this paper, we propose a computational model of humans’ epistemic reasoning, including higher-order epistemic reasoning—reasoning about what one person knows about another person’s knowledge—that we test in an experiment using a deductive card game called “Aces and Eights”. Our starting point is the model of perfect higher-order epistemic reasoners given by the framework of dynamic epistemic logic. We (...) modify this idealized model with bounds on the level of feasible epistemic reasoning and stochastic update of a player’s space of possibilities in response to new information. These modifications are crucial for explaining the variation in human performance across different participants and different games in the experiment. Our results demonstrate how research on epistemic logic and cognitive models can inform each other. (shrink)

In "A Problem in Possible-World Semantics," David Kaplan presented a consistent and intelligible modal principle that cannot be validated by any possible world frame (in the terminology of modal logic, any neighborhood frame). However, Kaplan's problem is tempered by the fact that his principle is stated in a language with propositional quantification, so possible world semantics for the basic modal language without propositional quantifiers is not directly affected, and the fact that on careful inspection his principle does not target the (...) world part of possible world semantics—the atomicity of the algebra of propositions—but rather the idea of propositional quantification over a complete Boolean algebra of propositions. By contrast, in this paper we present a simple and intelligible modal principle, without propositional quantifiers, that cannot be validated by any possible world frame precisely because of their assumption of atomicity (i.e., the principle also cannot be validated by any atomic Boolean algebra expansion). It follows from a theorem of David Lewis that our logic is as simple as possible in terms of modal nesting depth (two). We prove the consistency of the logic using a generalization of possible world semantics known as possibility semantics. We also prove the completeness of the logic (and two other relevant logics) with respect to possibility semantics. Finally, we observe that the logic we identify naturally arises in the study of Peano Arithmetic. (shrink)

We prove that the generalized cancellation axiom for incomplete comparative probability relations introduced by Rios Insua and Alon and Lehrer is stronger than the standard cancellation axiom for complete comparative probability relations introduced by Scott, relative to their other axioms for comparative probability in both the finite and infinite cases. This result has been suggested but not proved in the previous literature.

Epistemic closure has been a central issue in epistemology over the last forty years. According to versions of the relevant alternatives and subjunctivist theories of knowledge, epistemic closure can fail: an agent who knows some propositions can fail to know a logical consequence of those propositions, even if the agent explicitly believes the consequence (having “competently deduced” it from the known propositions). In this sense, the claim that epistemic closure can fail must be distinguished from the fact that agents do (...) not always believe, let alone know, the consequences of what they know—a fact that raises the “problem of logical omniscience” that has been central in epistemic logic. This paper, part I of II, is a study of epistemic closure from the perspective of epistemic logic. First, I introduce models for epistemic logic, based on Lewis’s models for counterfactuals, that correspond closely to the pictures of the relevant alternatives and subjunctivist theories of knowledge in epistemology. Second, I give an exact characterization of the closure properties of knowledge according to these theories, as formalized. Finally, I consider the relation between closure and higher-order knowledge. The philosophical repercussions of these results and results from part II, which prompt a reassessment of the issue of closure in epistemology, are discussed further in companion papers. As a contribution to modal logic, this paper demonstrates an alternative approach to proving modal completeness theorems, without the standard canonical model construction. By “modal decomposition” I obtain completeness and other results for two non-normal modal logics with respect to new semantics. One of these logics, dubbed the logic of ranked relevant alternatives, appears not to have been previously identified in the modal logic literature. More broadly, the paper presents epistemology as a rich area for logical study. (shrink)

In traditional semantics for classical logic and its extensions, such as modal logic, propositions are interpreted as subsets of a set, as in discrete duality, or as clopen sets of a Stone space, as in topological duality. A point in such a set can be viewed as a "possible world," with the key property of a world being primeness—a world makes a disjunction true only if it makes one of the disjuncts true—which classically implies totality—for each proposition, a world either (...) makes the proposition true or makes its negation true. This chapter surveys a more general approach to logical semantics, known as possibility semantics, which replaces possible worlds with possibly partial "possibilities." In classical possibility semantics, propositions are interpreted as regular open sets of a poset, as in set-theoretic forcing, or as compact regular open sets of an upper Vietoris space, as in the recent theory of "choice-free Stone duality." The elements of these sets, viewed as possibilities, may be partial in the sense of making a disjunction true without settling which disjunct is true. We explain how possibilities may be used in semantics for classical logic and modal logics and generalized to semantics for intuitionistic logics. The goals are to overcome or deepen incompleteness results for traditional semantics, to avoid the nonconstructivity of traditional semantics, and to provide richer structures for the interpretation of new languages. (shrink)

This article identifies a prevalent strand of feminist writing on beauty and aesthetic surgery and explores some of the contradictions and inconsistencies inscribed within it. In particular, we concentrate on three central feminist claims: that living in a misogynist culture produces aesthetic surgery as an issue predominantly concerning women; that pain - both physical and psychic - is a central conceptual frame through which aesthetic surgery should be viewed; and that aesthetic surgery is inherently a normalizing technology. Engaging with these (...) ‘myths’, we explore the tensions uncovered through a historical analysis of the practices of aesthetic surgery as well as the challenges to feminist claims offered by post-feminism. In particular we seek to destabilize the connection in feminist writing between beauty and passivity. We argue that through aesthetic references to denigrated black and working-class bodies, young women may mobilize aesthetic surgeries to reinscribe active sexuality on the feminine body. (shrink)

Known as the “Mother of Tibetan Buddhism” and the “Mother of Knowledge,” Yeshe Tsogyal built upon indigenous Bön philosophy and Mahāyāna Buddhism to bring about a Buddhism that is identifiably Tibetan. I report on her life, her works and teaching. Then summarize her significance as a philosopher of Tibetan Buddhist metaphysics, epistemology and ethics. Lastly, I append portions of several writings attributed to her.

A well-known open problem in epistemic logic is to give a syntactic characterization of the successful formulas. Semantically, a formula is successful if and only if for any pointed model where it is true, it remains true after deleting all points where the formula was false. The classic example of a formula that is not successful in this sense is the “Moore sentence” p ∧ ¬BOXp, read as “p is true but you do not know p.” Not only is the (...) Moore sentence unsuccessful, it is self-refuting, for it never remains true as described. We show that in logics of knowledge and belief for a single agent (extended by S5), Moorean phenomena are the source of all self-refutation; moreover, in logics for an introspective agent (extending KD45), Moorean phenomena are the source of all unsuccessfulness as well. This is a distinctive feature of such logics, for with a non-introspective agent or multiple agents, non-Moorean unsuccessful formulas appear. We also consider how successful and self-refuting formulas relate to the Cartesian and learnable formulas, which have been discussed in connection with Fitch’s “paradox of knowability.” We show that the Cartesian formulas are exactly the formulas that are not eventually self-refuting and that not all learnable formulas are successful. In an appendix, we give syntactic characterizations of the successful and the self-refuting formulas. (shrink)

Recently, concerns have been raised about the phenomenon of 'overdiagnosis', the diagnosis of a condition that is not causing harm, and will not come to cause harm. Along with practical, ethical, and scientific questions, overdiagnosis raises questions about our concept of disease. In this paper, we analyse overdiagnosis as an epistemic problem and show how it challenges many existing accounts of disease. In particular, it raises questions about conceptual links drawn between disease and dysfunction, harm, and risk. We argue that (...) "disease" should be considered a vague concept with a nonclassical structure. On this view, overdiagnosed cases are 'borderline' cases of disease, falling in the zone between cases that are clearly disease, and cases that are clearly not disease. We then develop a précising definition of disease designed to provide practical help in preventing and limiting overdiagnosis. We argue that for this purpose, we can define disease as dysfunction that has a significant risk of causing severe harm to the patient. (shrink)

This chapter argues that epistemologists should replace a “standard alternatives” picture of knowledge, assumed by many fallibilist theories of knowledge, with a new “multipath” picture of knowledge. The chapter first identifies a problem for the standard picture: fallibilists working with this picture cannot maintain even the most uncontroversial epistemic closure principles without making extreme assumptions about the ability of humans to know empirical truths without empirical investigation. The chapter then shows how the multipath picture, motivated by independent arguments, saves fallibilism (...) from this problem. The multipath picture is based on taking seriously the idea that there can be multiple paths to knowing some propositions about the world. An overlooked consequence of fallibilism is that these multiple paths to knowledge may involve ruling out different sets of alternatives, which should be represented in a fallibilist picture of knowledge. The chapter concludes by considering inductive knowledge and strong epistemic closure from this multipath perspective. (shrink)

Epistemic modals have peculiar logical features that are challenging to account for in a broadly classical framework. For instance, while a sentence of the form ‘p, but it might be that not p’ appears to be a contradiction, 'might not p' does not entail 'not p', which would follow in classical logic. Likewise, the classical laws of distributivity and disjunctive syllogism fail for epistemic modals. Existing attempts to account for these facts generally either under- or over-correct. Some theories predict that (...) 'p and might not p', a so-called epistemic contradiction, is a contradiction only in an etiolated sense, under a notion of entailment that does not allow substitution of logical equivalents; these theories underpredict the infelicity of embedded epistemic contradictions. Other theories savage classical logic, eliminating not just rules that intuitively fail, like distributivity and disjunctive syllogism, but also rules like non-contradiction, excluded middle, De Morgan’s laws, and disjunction introduction, which intuitively remain valid for epistemic modals. In this paper, we aim for a middle ground, developing a semantics and logic for epistemic modals that makes epistemic contradictions genuine contradictions and that invalidates distributivity and disjunctive syllogism but that otherwise preserves classical laws that intuitively remain valid. We start with an algebraic semantics, based on ortholattices instead of Boolean algebras, and then propose a more concrete possibility semantics, based on partial possibilities related by compatibility. Both semantics yield the same consequence relation, which we axiomatize. Then we show how to extend our semantics to explain parallel phenomena involving probabilities and conditionals. The goal throughout is to retain what is desirable about classical logic while accounting for the non-classicality of epistemic vocabulary. (shrink)

This chapter provides a brief introduction to propositional epistemic logic and its applications to epistemology. No previous exposure to epistemic logic is assumed. Epistemic-logical topics discussed include the language and semantics of basic epistemic logic, multi-agent epistemic logic, combined epistemic-doxastic logic, and a glimpse of dynamic epistemic logic. Epistemological topics discussed include Moore-paradoxical phenomena, the surprise exam paradox, logical omniscience and epistemic closure, formalized theories of knowledge, debates about higher-order knowledge, and issues of knowability raised by Fitch’s paradox. The references (...) and recommended readings provide gateways for further exploration. (shrink)

Neil Levy argues that while addicts who believe they are not addicts are self-deceived, addicts who believe they are addicts are just as self-deceived. Such persons accept a false belief that their addictive behaviour involves a loss of control. This paper examines two implications of Levy's discussion: that accurate self-knowledge may be particularly difficult for addicts; and that an addict's self-deceived belief that they cannot control themselves may aid their attempts at self-control. I argue that the self-deceived beliefs of addicts (...) in denial and of self-described addicts differ in kind. Unlike the self-deception of an addict in denial, that of the self-described addict allows them to acknowledge their behaviour. As such, it may aid an addict to develop more self-control. A paradoxical implication is that this self-deception may allow an addict more self-knowledge. (shrink)

We introduce new algebraic and topological semantics for inquisitive logic. The algebraic semantics is based on special Heyting algebras, which we call inquisitive algebras, with propositional valuations ranging over only the ¬¬-fixpoints of the algebra. We show how inquisitive algebras arise from Boolean algebras: for a given Boolean algebra B, we define its inquisitive extension H(B) and prove that H(B) is the unique inquisitive algebra having B as its algebra of ¬¬-fixpoints. We also show that inquisitive algebras determine Medvedev’s logic (...) of finite problems. In addition to the algebraic characterization of H(B), we give a topological characterization of H(B) in terms of the recently introduced choice-free duality for Boolean algebras using so-called upper Vietoris spaces (UV-spaces). In particular, while a Boolean algebra B is realized as the Boolean algebra of compact regular open elements of a UV-space dual to B, we show that H(B) is realized as the algebra of compact open elements of this space. This connection yields a new topological semantics for inquisitive logic. (shrink)

In this paper, we explore semantics for comparative epistemic modals that avoid the entailment problems shown to result from Kratzer’s (1991) semantics by Yalcin (2006, 2009, 2010). In contrast to the alternative semantics presented by Yalcin and Lassiter (2010, 2011), based on finitely additive probability measures, we introduce semantics based on qualitatively additive measures, as well as semantics based on purely qualitative orderings, including orderings on propositions derived from orderings on worlds in the tradition of Kratzer (1991). All of these (...) semantics avoid the entailment problems that result from Kratzer’s semantics. Our discussion focuses on methodological issues concerning the choice between different semantics. (shrink)

Mary Anne Warren investigates a theoretical question that is at the centre of practical and professional ethics: what are the criteria for having moral status? That is: what does it take to be an entity towards which people have moral considerations? Warren argues that no single property will do as a sole criterion, and puts forward seven basic principles which establish moral status. She then applies these principles to three controversial moral issues: voluntary euthanasia, abortion, and the status of (...) non-human animals. (shrink)

Epistemic modal predicate logic raises conceptual problems not faced in the case of alethic modal predicate logic : Frege’s “Hesperus-Phosphorus” problem—how to make sense of ascribing to agents ignorance of necessarily true identity statements—and the related “Hintikka-Kripke” problem—how to set up a logical system combining epistemic and alethic modalities, as well as others problems, such as Quine’s “Double Vision” problem and problems of self-knowledge. In this paper, we lay out a philosophical approach to epistemic predicate logic, implemented formally in Melvin (...) Fitting’s First-Order Intensional Logic, that we argue solves these and other conceptual problems. Topics covered include: Quine on the “collapse” of modal distinctions; the rigidity of names; belief reports and unarticulated constituents; epistemic roles; counterfactual attitudes; representational vs. interpretational semantics; ignorance of co-reference vs. ignorance of identity; two-dimensional epistemic models; quantification into epistemic contexts; and an approach to multi-agent epistemic logic based on centered worlds and hybrid logic. (shrink)