The knower paradox states that the statement ‘We know that this statement is false’ leads to inconsistency. This article presents a fresh look at this paradox and some well-known solutions from the literature. Paul Égré discusses three possible solutions that modal provability logic provides for the paradox by surveying and comparing three different provability interpretations of modality, originally described by Skyrms, Anderson, and Solovay. In this article, some background is explained to clarify Égré’s solutions, all three of which hinge on (...) intricacies of provability logic and its arithmetical interpretations. To check whether Égré’s solutions are satisfactory, we use the criteria for solutions to paradoxes defined by Susan Haack and we propose some refinements of them. This article aims to describe to what extent the knower paradox can be solved using provability logic and to what extent the solutions proposed in the literature satisfy Haack’s criteria. Finally, the article offers some reflections on the relation between knowledge, proof, and provability, as inspired by the knower paradox and its solutions. (shrink)

Ce numéro thématique de la revue Philosophiques est consacré aux Conférences Hugues Leblanc qui ont eu lieu du 1er au 3 avril 2010 au Département de philosophie de l'Université du Québec à Montréal. À cette occasion, le conférencier invité était Kevin Mulligan, titulaire de la chaire de philosophie analytique au Département de philosophie de l'Université de Genève, qui a prononcé trois conférences sous le titre " Wittgenstein vs ses prédécesseurs austro-allemands ", publiées dans ce numéro. Mulligan y développe un de (...) ses thèmes historiques de prédilection, à savoir la dette de Wittgenstein, dans ses travaux sur l'esprit et le langage, à l'endroit de ses prédécesseurs austro-allemands. Comme le veut la formule des conférences Hugues Leblanc, nous avons réuni quelques collègues afin de discuter de quelques-uns des aspects des travaux du conférencier invité et nous avons ajouté, pour compléter ce numéro de Philosophiques, quelques articles originaux portant également sur d'autres aspects des travaux de Mulligan. On peut regrouper l'ensemble de ces contributions sous quatre des grands thèmes exploités par Mulligan en philosophie : le domaine de l'ontologie (incluant les relations, les tropes, les états de choses et les vérifacteurs), le domaine de la philosophie de l'esprit, celui des émotions et des valeurs, et enfin le thème historique de la philosophie austro-allemande, de Bolzano à Wittgenstein en passant par M. Scheler et la phénoménologie de Munich. Faute de pouvoir rendre compte dans cette préface de l'ensemble de ces riches contributions à ce numéro de Philosophiques, je me contenterai de renvoyer le lecteur aux résumés, préparés par les auteurs de ces contributions, qui précèdent chacun des articles. (shrink)

Belief revision from the point of view of doxastic logic. Logic Journal of the IGPL, 3(4), 535–553. Segerberg, K. (1995). Conditional action. In G. Crocco, L. Fariñas, & A. Herzig (Eds.), Conditionals: From philosophy to computer science, Studies ...

The aim of this dissertation is to provide support for the following claim: if Hanks’ theory of propositions as act-types is correct, then there exists a plausible extension of this theory that solves the Frege-Geach problem for normative propositions. I assume that Hanks’ theory is correct, and in this framework develop an account of semantic expressivism that addresses three versions of the Frege-Geach problem: the embedding, inference and negation problems. First, I examine in detail one existing attempt to support the (...) claim, due to Hom and Schwartz. I argue that their extension is not plausible for two reasons: it does not satisfy a key expressivist constraint, and it encounters a problem with interrogatives. Then I argue that even if their extension were plausible, it would not solve the embedding problem for conditionals, for two reasons: it does not place suitable constraints on applications of force-indicators, and it encounters a problem with mixed descriptive-normative conditionals. Second, I give a new extension of Hanks’ theory for atomic normative sentences, and argue that it is plausible. Then I extend it further by defining force-indicators that are generalizations of assertion and of normative endorsement (and of denial and anti-endorsement) and by defining logical relations that apply uniformly to as- sertive and normative propositions. I argue that this extension provides a neutral logical framework within which the embedding, inference and negation problems for normative propositions can be more effectively addressed. (shrink)

The thesis defended, the “guise of the ought”, is that the formal objects of desires are norms (oughts to be or oughts to do) rather than values (as the “guise of the good” thesis has it). It is impossible, in virtue of the nature of desire, to desire something without it being presented as something that ought to be or that one ought to do. This view is defended by pointing to a key distinction between values and norms: positive and (...) negative norms (obligation and interdiction) are interdefinable through negation; positive and negative values aren’t. This contrast between the norms and values, it is argued, is mirrored, within the psychological realm, by the contrast between the desires and emotions. Positive and negative desires are interdefinable through negation, but positive and negative emotions aren’t. The overall, Meinongian picture suggested is that norms are to desires what values are to emotions. (shrink)

There has been a recent surge of work on deontic modality within philosophy of language. This work has put the deontic logic tradition in contact with natural language semantics, resulting in significant increase in sophistication on both ends. This chapter surveys the main motivations, achievements, and prospects of this work.

The principle of alternate possibilities says that you are morally praiseworthy or blameworthy for something you do only if you could have done otherwise. Frankfurt examples are putative counterexamples to PAP. These examples feature a failsafe mechanism that ensures that some agent cannot refrain from doing what she does without intervening in how she conducts herself, thereby supposedly sustaining the upshot that she is responsible for her behavior despite not being able to do otherwise. I introduce a Frankfurt example in (...) which the agent who could not have done otherwise is God. Paying attention to the freedom requirements of moral obligation, the example is commissioned, first, to assess whether various statesof affairs that are unavoidable for God can be obligatory for God and for whichGod can be praiseworthy. The example is, next, used to unearth problems with conventional Frankfurt examples that feature human agents. I argue that conceptual connections between responsibility and obligation cast suspicion on these examples. Pertinent lessons that the divine Frankfurt example helps to reveal motivate the view that divine foreknowledge and determinism, assuming that both preclude freedom to do otherwise, may well imperil obligation and responsibility. (shrink)

This chapter presents a new semantics for inductive empirical knowledge. The epistemic agent is represented concretely as a learner who processes new inputs through time and who forms new beliefs from those inputs by means of a concrete, computable learning program. The agent’s belief state is represented hyper-intensionally as a set of time-indexed sentences. Knowledge is interpreted as avoidance of error in the limit and as having converged to true belief from the present time onward. Familiar topics are re-examined within (...) the semantics, such as inductive skepticism, the logic of discovery, Duhem’s problem, the articulation of theories by auxiliary hypotheses, the role of serendipity in scientific knowledge, Fitch’s paradox, deductive closure of knowability, whether one can know inductively that one knows inductively, whether one can know inductively that one does not know inductively, and whether expert instruction can spread common inductive knowledge—as opposed to mere, true belief—through a community of gullible pupils. (shrink)

Normative reasons are of constant importance to us as agents trying to navigate through life. For this reason it is natural and vital to ask philosophical questions about reasons and the normative realm. This thesis explores various issues concerning reasons and normativity. The thesis consists of five free-standingpapers and an extended introduction. The aim of the extended introduction is not merely to situate the papers within a wider philosophical context but also to provide an overview of some of the central (...) research questions concerning reasons and normativity. The introduction is divided into five chapters. Chapter 1 introduces and outlines the dissertation. Chapter 2 concerns the issue of what a reason is and what different types of reasons there are, such as pro tanto reasons and overall reasons. Chapter 3 discusses the frequently employed weighing metaphor, i.e. that reasons have a certain weight and can be weighed against the weight of other reasons. Chapter 4 covers how reasons relate to other normative notions such as ought, value, and obligation. For example, it discusses whether it is the case that for something to be valuable just is for there to be reasons to favor it. Chapter 5 concludes the introduction by briefly exploring how it all relates.The thesis can be said to be embedded in a recent research trend within philosophy of normativity that has a distinguished focus on reasons.The five papers deal with various issues concerning reasons and normativity. Paper I argues for a novel and theoretically parsimonious way to understand background conditions for values and reasons. Paper II explores an interpretation of the distinction between subjectivism and objectivism about reasons and value so as to accommodate that the distinction does not commit either party to certain first order claims about what reasons there are or what makes objects valuable. Paper III discusses the dictum ‘ought implies can’and how to properly interpret the ‘can’. Paper IV defends principles according to which what we ought and have reasons to do transmit from ends to the necessary means of that action. Paper V analyzes how the Fitting Attitudes analysis of value should best understand degrees of value. (shrink)

I propose a unified solution to two puzzles: Ross's puzzle and free choice permission. I begin with a pair of cases from the decision theory literature illustrating the phenomenon of act dependence, where what an agent ought to do depends on what she does. The notion of permissibility distilled from these cases forms the basis for my analysis of 'may' and 'ought'. This framework is then combined with a generalization of the classical semantics for disjunction — equivalent to Boolean disjunction (...) on the diagonal, but with a different two-dimensional character — that explains the puzzling facts in terms of semantic consequence. (shrink)

This paper argues for extreme rational permissivism—the view that agents with identical evidence can rationally believe contradictory hypotheses—and a mild version of steadfastness. Agents can rationally come to different conclusions on the basis of the same evidence because their way of weighing the theoretic virtues may differ substantially. Nevertheless, in the face of disagreement, agents face considerable pressure to reduce their confidence. Indeed, I argue that agents often ought to reduce their confidence in the higher-order propositions that they know or (...) rationally believe disputed content. I argue, however, that when the subject matter is difficult, there is more flexibility for agents to simultaneously believe that p while withholding belief about whether such belief is rational or known. This allows for modest steadfastness on hard questions in, e.g., philosophy and religion. (shrink)

Conditional logics were originally developed for the purpose of modeling intuitively correct modes of reasoning involving conditional—especially counterfactual—expressions in natural language. While the debate over the logic of conditionals is as old as propositional logic, it was the development of worlds semantics for modal logic in the past century that catalyzed the rapid maturation of the field. Moreover, like modal logic, conditional logic has subsequently found a wide array of uses, from the traditional (e.g. counterfactuals) to the exotic (e.g. conditional (...) obligation). Despite the close connections between conditional and modal logic, both the technical development and philosophical exploitation of the latter has outstripped that of the former, with the result that noticeable lacunae exist in the literature on conditional logic. My dissertation addresses a number of these underdeveloped frontiers, producing new technical insights and philosophical applications. -/- I contribute to the solution of a problem posed by Priest of finding sound and complete labeled tableaux for systems of conditional logic from Lewis' V-family. To develop these tableaux, I draw on previous work on labeled tableaux for modal and conditional logic; errors and shortcomings in recent work on this problem are identified and corrected. While modal logic has by now been thoroughly studied in non-classical contexts, e.g. intuitionistic and relevant logic, the literature on conditional logic is still overwhelmingly classical. Another contribution of my dissertation is a thorough analysis of intuitionistic conditional logic, in which I utilize both algebraic and worlds semantics, and investigate how several novel embedding results might shed light on the philosophical interpretation of both intuitionistic logic and conditional logic extensions thereof. -/- My dissertation examines deontic and connexive conditional logic as well as the underappreciated history of connexive notions in the analysis of conditional obligation. The possibility of interpreting deontic modal logics in such systems (via embedding results) serves as an important theoretical guide. A philosophically motivated proscription on impossible obligations is shown to correspond to, and justify, certain (weak) connexive theses. Finally, I contribute to the intensifying debate over counterpossibles, counterfactuals with impossible antecedents, and take—in contrast to Lewis and Williamson—a non-vacuous line. Thus, in my view, a counterpossible like "If there had been a counterexample to the law of the excluded middle, Brouwer would not have been vindicated" is false, not (vacuously) true, although it has an impossible antecedent. I exploit impossible (non-normal) worlds—originally developed to model non-normal modal logics—to provide non-vacuous semantics for counterpossibles. I buttress the case for non-vacuous semantics by making recourse to both novel technical results and theoretical considerations. (shrink)

This paper proposes a semantics for free choice permission that explains both the non-classical behavior of modals and disjunction in sentences used to grant permission, and their classical behavior under negation. It also explains why permissions can expire when new information comes in and why free choice arises even when modals scope under disjunction. On the proposed approach, deontic modals update preference orderings, and connectives operate on these updates rather than propositions. The success of this approach stems from its capacity (...) to capture the difference between expressing the preferences that give rise to permissions and conveying propositions about those preferences. (shrink)

A dynamic semantics for iffy oughts offers an attractive alternative to the folklore that Chisholm's paradox enforces an unhappy choice between the intuitive inference rules of factual and deontic detachment. The first part of the story told here shows how a dynamic theory about ifs and oughts gives rise to a nonmonotonic perspective on deontic discourse and reasoning that elegantly removes the air of paradox from Chisholm's puzzle without sacrificing any of the two detachment principles. The second part of the (...) story showcases two bonus applications of the framework suggested here: it offers a response to Forrester's gentle murder paradox and avoids Kolodny and MacFarlane's miners paradox about deontic reasoning under epistemic uncertainty. A comparison between the dynamic semantic proposal made in this paper and a more conservative approach combining a static semantics with a dynamic pragmatics is provided. (shrink)

There is a growing consensus, long maintained by Derek Parfit, that there is an important distinction between what we have reason to do on the one hand, and what it is rational for us to do on the other. Philosophers are now realising that there is a conceptual distinction between rationality and normativity. Given this distinction, it thus becomes a substantive question whether rationality is genuinely normative; that is, whether there is any reason to do what rationality requires. While some (...) philosophers have argued that we sometimes have reason to do what rationality requires, it is notoriously difficult to show that there are always universal and categorical reasons to do what rationality requires. But if it is not the case that there are always universal and categorical reasons to do what rationality requires, then rationality is not genuinely normative.This dissertation offers a vindication of the normativity of rationality. I maintain that there is a robust relation between rational requirements and normative reasons. In arguing for this claim, I develop what I call the reasons-sensitive view of rationality, according to which rational requirements are normative verdicts: they are second-order claims about what there is conclusive reason of rationality to do. This view explains why there are always universal and categorical reasons to be rational. So while we may not always have most reason to do what it is rational for us to do, there is always some reason—reasons of rationality—to do what it is rational for us to do. I then show how this reasons-sensitive view addresses and responds to what I diagnose to be the major sources of skepticism about the normativity of rationality. (shrink)

Vít Gvoždiak published a reconciliatory analysis of Searle’s social ontology with semiotics in Gvoždiak (2012). Without prior knowledge of his paper, an analysis of the same subject appeared in Msimang (2014). Even though Searle’s social ontology is a common point of reference in the formulation of semiotics in these papers, it also serves as a point of departure in their understanding of semiotics and its development. The semiotic theory expressed in Gvoždiak (2012) is an inherently linguistic (speech act centred) theory, (...) whereas the semiotic theory presented in Msimang (2014) tends more towards a general theory of communicative systems in which social ontology, which follows from speech act theory, is an interesting part. It is my purpose in this note to contrast the two positions of semiotic theory as they appear in the aforementioned papers in reference to their appropriation of Searle’s social ontology. (shrink)

The mantra that "the best way to predict the future is to invent it" (attributed to the computer scientist Alan Kay) exemplifies some of the expectations from the technical and innovative sides of biomedical research at present. However, for technical advancements to make real impacts both on patient health and genuine scientific understanding, quite a number of lingering challenges facing the entire spectrum from protein biology all the way to randomized controlled trials should start to be overcome. The proposal in (...) this chapter is that philosophy is essential in this process. By reviewing select examples from the history of science and philosophy, disciplines which were indistinguishable until the mid-nineteenth century, I argue that progress toward the many impasses in biomedicine can be achieved by emphasizing theoretical work (in the true sense of the word 'theory') as a vital foundation for experimental biology. Furthermore, a philosophical biology program that could provide a framework for theoretical investigations is outlined. (shrink)