The paper compares the suitability of two different epistemologies of counterfactuals—(EC) and (W)—to elucidate modalknowledge. I argue that, while both of them explain the data on our knowledge of counterfactuals, only (W)—Williamson’s epistemology—is compatible with all counterpossibles being true. This is something on which Williamson’s counterfactual-based account of modalknowledge relies. A first problem is, therefore, that, in the absence of further, disambiguating data, Williamson’s choice of (W) is objectionably biased. A second, deeper problem (...) is that (W) cannot satisfactorily elucidate modalknowledge. Third, from a naturalistic perspective, the nature of this second problem favours (EC) against (W). (shrink)
The paper presents a dilemma for both epistemic and non-epistemic versions of conceivability-based accounts of modalknowledge. On the one horn, non-epistemic accounts do not elucidate the essentialist knowledge they would be committed to. On the other, epistemic accounts do not elucidate everyday life de re modalknowledge. In neither case, therefore, do conceivability accounts elucidate de re modalknowledge.
The notion of conceivability has traditionally been regarded as crucial to an account of modalknowledge. Despite its importance to modal epistemology, there is no received explication of conceivability. One purpose of this paper is to argue that the notion is not fruitfully explicated in terms of the imagination. The most natural way of presenting a notion of conceivability qua imaginability is open to cogent criticism. In order to avoid such criticism, an advocate of the modal (...) insightfulness of the imagination must broaden the idea of what it is to be imaginable. I argue that this required broadening renders the imagination idle (in this context). Consequently, I distinguish two different accounts of the evidential basis of modalknowledge and present a more general argument that concludes that the very notion of conceivability should be eschewed in modal epistemology. (shrink)
How do we know what's (metaphysically) possible and impossible? Arguments from Kripke and Putnam suggest that possibility is not merely a matter of (coherent) conceivability/imaginability. For example, we can coherently imagine that Hesperus and Phosphorus are distinct objects even though they are not possibly distinct. Despite this apparent problem, we suggest, nevertheless, that imagination plays an important role in an adequate modal epistemology. When we discover what is possible or what is impossible, we generally exploit important connections between what (...) is possible and what we can coherently imagine. We can often come to knowledge of metaphysical modality a priori. (shrink)
In this paper I will offer a novel understanding of a priori knowledge. My claim is that the sharp distinction that is usually made between a priori and a posteriori knowledge is groundless. It will be argued that a plausible understanding of a priori and a posteriori knowledge has to acknowledge that they are in a constant bootstrapping relationship. It is also crucial that we distinguish between a priori propositions that hold in the actual world and merely (...) possible, non-actual a priori propositions, as we will see when considering cases like Euclidean geometry. Furthermore, contrary to what Kripke seems to suggest, a priori knowledge is intimately connected with metaphysical modality, indeed, grounded in it. The task of a priori reasoning, according to this account, is to delimit the space of metaphysically possible worlds in order for us to be able to determine what is actual. (shrink)
There is currently intense interest in the question of the source of our presumed knowledge of truths concerning what is, or is not, metaphysically possible or necessary. Some philosophers locate this source in our capacities to conceive or imagine various actual or non-actual states of affairs, but this approach is open to certain familiar and seemingly powerful objections. A different and ostensibly more promising approach has been developed by Timothy Williamson, according to which our capacity for modal (...) class='Hi'>knowledge is just an extension, or by-product, of our general capacity to acquire knowledge of true counterfactual conditionals — a capacity that we deploy ubiquitously in everyday life. Williamson’s account crucially involves a thesis to the effect that modal truths can be explained in terms of counterfactual truths. In this paper, I query Williamson’s account on a number of points, including this thesis. My positive proposal, which owes a debt to the work of Kit Fine on modality and essence, appeals instead to our capacity to grasp essences, understood in a neo-Aristotelian fashion, according to which essences are expressed by ‘real definitions’. (shrink)
Modal intuitions are the primary source of modalknowledge but also of modal error. According to the theory of modal error in this paper, modal intuitions retain their evidential force in spite of their fallibility, and erroneous modal intuitions are in principle identifiable and eliminable by subjecting our intuitions to a priori dialectic. After an inventory of standard sources of modal error, two further sources are examined in detail. The first source - (...) namely, the failure to distinguish between metaphysical possibility and various kinds of epistemic possibility - turns out to be comparatively easy to untangle and poses little threat to intuition-driven philosophical investigation. The second source is the local (i.e., temporary) misunderstanding of one's concepts (as opposed to outright Burgean misunderstanding). This pathology may be understood on analogy with a patient who is given a clean bill of health at his annual check-up, despite his having a cold at the time of the check-up: although the patient's health is locally (temporarily) disrupted, his overall health is sufficiently good to enable him to overcome the cold without external intervention. Even when our understanding of certain pivotal concepts has lapsed locally, our larger body of intuitions is sufficiently reliable to allow us, without intervention, to ferret out the modal errors resulting from this lapse of understanding by means of dialectic and/or a process of a priori reflection. This source of modal error, and our capacity to overcome it, has wide-ranging implications for philosophical method - including, in particular, its promise for disarming skepticism about the classical method of intuition-driven investigation itself. Indeed, it is shown that skeptical accounts of modal error (e.g., the accounts given by Hill, Levin, and several others) are ultimately self-defeating. (shrink)
The epistemology of modality is gradually coming to play a central role in general discussions about modality. This paper is a contribution in this direction, in particular I draw a comparison between Lewis’s Modal realism and Timothy Williamson’s recent account of modality in terms of counterfactual thinking. In order to have criteria of evaluation, I also formulate four requirements which are supposed to be met by any theory of modality to be epistemologically adequate.
I survey a number of views about how we can obtain knowledge of modal propositions, propositions about necessity and possibility. One major approach is that whether a proposition or state of affairs is conceivable tells us something about whether it is possible. I examine two quite different positions that fall under this rubric, those of Yablo and Chalmers. One problem for this approach is the existence of necessary a posteriori truths and I deal with some of the ways (...) in which these authors respond to the problem, including the use of two-dimensional modal semantics. Conventionalism about modality offers a complementary approach to modal epistemology, prompting us to identify our knowledge of modal truths with our mastery of linguistic or conceptual conventions. Finally, I discuss an approach to modal epistemology deriving from David Lewis's work that seeks to identify structural features of the modal space over which necessity and possibility are defined. (shrink)
Jason Stanley has argued recently that Epistemic Contextualism (EC) and Subject-Sensitive Invariantism (SSI) are explanatorily on a par with regard to certain data arising from modal and temporal embeddings of ‘knowledge’-ascriptions. This paper argues against Stanley that EC has a clear advantage over SSI in the discussed field and introduces a new type of linguistic datum strongly suggesting the falsity of SSI.
The paper provides an explanation of our knowledge of metaphysical modality, or modalknowledge, from our ability to evaluate counterfactual conditionals. The latter ability lends itself to an evolutionary explanation since it enables us to learn from mistakes. Different logical principles linking counterfactuals to metaphysical modality can be employed to extend this explanation to the epistemology of modality. While the epistemological use of some of these principles is either philosophically implausible or empirically inadequate, the equivalence of ‘Necessarily (...) p’ with ‘For all q, if q were the case, p would be the case’ is a suitable starting-point for an explanation of modalknowledge. (shrink)
Abstract Timothy Williamson has recently proposed to undermine modal skepticism by appealing to the reducibility of modal to counterfactual logic ( Reducibility ). Central to Williamson’s strategy is the claim that use of the same non-deductive mode of inference ( counterfactual development , or CD ) whereby we typically arrive at knowledge of counterfactuals suffices for arriving at knowledge of metaphysical necessity via Reducibility. Granting Reducibility, I ask whether the use of CD plays any essential role (...) in a Reducibility-based reply to two kinds of modal skepticism. I argue that its use is entirely dispensable, and that Reducibility makes available replies to modal skeptics which show certain propositions to be metaphysically necessary by deductive arguments from premises the modal skeptic accepts can be known. Content Type Journal Article Pages 1-19 DOI 10.1007/s11098-011-9784-4 Authors Juhani Yli-Vakkuri, Wolfson College, Oxford University, Oxford, OX2 6UD UK Journal Philosophical Studies Online ISSN 1573-0883 Print ISSN 0031-8116. (shrink)
Can we have a posteriori knowledge of modal facts? And if so, is that knowledge fundamentally a posteriori, or does a priori intuition provide the modal component of what is known? Though the latter view seems more straightforward, there are also reasons for taking the first option seriously.
Two approaches for defining common knowledge coexist in the literature: the infinite iteration definition and the circular or fixed point one. In particular, an original modelization of the fixed point definition was proposed by Barwise (1989) in the context of a non-well-founded set theory and the infinite iteration approach has been technically analyzed within multi-modal epistemic logic using neighbourhood semantics by Lismont (1993). This paper exhibits a relation between these two ways of modelling common knowledge which (...) seem at first quite different. (shrink)
The article argues against attempts to combine ontological realism about modality with the rejection of modal rationalism and it suggests that modal realism requires (at least a weak form of) modal rationalism. /// El artículo da argumentos en contra de que se intente combinar el realismo ontológico sobre la modalidad con el rechazo del racionalismo modal y sugiere que el realismo modal exige (por lo menos una forma débil de) racionalismo modal.
We study the problem of embedding Halpern and Moses's modal logic of minimal knowledge states into two families of modal formalism for nonmonotonic reasoning, McDermott and Doyle's nonmonotonic modal logics and ground nonmonotonic modal logics. First, we prove that Halpern and Moses's logic can be embedded into all ground logics; moreover, the translation employed allows for establishing a lower bound (3p) for the problem of skeptical reasoning in all ground logics. Then, we show a translation (...) of Halpern and Moses's logic into a significant subset of McDermott and Doyle's formalisms. Such a translation both indicates the ability of Halpern and Moses's logic of expressing minimal knowledge states in a more compact way than McDermott and Doyle's logics, and allows for a comparison of the epistemological properties of such nonmonotonic modal formalisms. (shrink)
In recent work Timothy Williamson argues that the epistemology of metaphysical modality is a special case of the epistemology of counterfactuals. I argue that Williamson has not provided an adequate argument for this controversial claim, and that it is not obvious how what he says should be supplemented in order to derive such an argument. But I suggest that an important moral of his discussion survives this point. The moral is that experience could play an epistemic role which is more (...) epistemically significant than a mere 'enabling' role but not equivalent to an evidential role. (shrink)
This article is a discussion of Hume's maxim Nothing we imagine is absolutely impossible. First I explain this maxim and distinguish it from the principle Whatever cannot be imagined (conceived), is impossible. Next I argue that Thomas Reid's criticism of the maxim fails and that the arguments by Tamar Szábo Gendler and John Hawthorne for the claim that "it is uncontroversial that there are cases where we are misled" by the maxim are unconvincing. Finally I state the limited but real (...) value of the maxim: it does help us, in certain cases, reliably to make up our minds. Along the way I show that Reid, his criticism of the maxim notwithstanding, actually employs it, and I furthermore argue that the principle What is inconceivable, is impossible is spurious. (shrink)
By the lights of a central logical positivist thesis in modal epistemology, for every necessary truth that we know, we know it a priori and for every contingent truth that we know, we know it a posteriori. Kripke attacks on both flanks, arguing that we know necessary a posteriori truths and that we probably know contingent a priori truths. In a reflection of Kripke’s confidence in his own arguments, the first of these Kripkean claims is far more widely accepted (...) than the second. Contrary to received opinion, the paper argues, the considerations Kripke adduces concerning truths purported to be necessary a posteriori do not disprove the logical positivist thesis that necessary truth and a priori truth are co-extensive. (shrink)
In attempting to build intelligent litigation support tools, we have moved beyond first generation, production rule legal expert systems. Our work integrates rule based and case based reasoning with intelligent information retrieval.When using the case based reasoning methodology, or in our case the specialisation of case based retrieval, we need to be aware of how to retrieve relevant experience. Our research, in the legal domain, specifies an approach to the retrieval problem which relies heavily on an extended object oriented/rule based (...) system architecture that is supplemented with causal background information. We use a distributed agent architecture to help support the reasoning process of lawyers. (shrink)
Many important metaphysical arguments validly deduce an actuality from a possibility. For example: Because it is possible for me to exist in the absence of anything material, I am not my body. I argue that there is no reason to suppose that our capacity for modal judgment is equal to the task of determining whether the "possibility" premise of any of these arguments is true. I connect this thesis with Stephen Yablo's recent work on the epistemology of modal (...) statements. (shrink)
Kripke claims that there are necessary a posteriori truths and contingent a priori truths. These claims challenge the traditional Kantian view that (K) All knowledge of necessary truths is a priori and all a priori knowledge is of necessary truths. Kripke’s claims continue to be resisted, which indicates that the Kantian view remains attractive. My goal is to identify the most plausible principles linking the epistemic and the modal. My strategy for identifying the principles is to investigate (...) two related questions. Are there compelling general supporting arguments for (K)? Are there decisive counterexamples to (K)? My investigation uncovers two intuitively plausible principles that are not open to decisive counterexamples but which enjoy no compelling independent support. (shrink)
This book gathers together thirteen of Peter van Inwagen's essays on metaphysics, several of which have acquired the status of modern classics in their field. They range widely across such topics as Quine's philosophy of quantification, the ontology of fiction, the part-whole relation, the theory of 'temporal parts', and human knowledge of modal truths. In addition, van Inwagen considers the question as to whether the psychological continuity theory of personal identity is compatible with materialism, and defends the thesis (...) that possible states of affairs are abstract objects, in opposition to David Lewis's 'extreme modal realism'. A specially-written introduction completes the collection, which will be an invaluable resource for anyone interested in metaphysics. (shrink)
This paper introduces a multi-modal polymorphic type theory to model epistemic processes characterized by trust, defined as a second-order relation affecting the communication process between sources and a receiver. In this language, a set of senders is expressed by a modal prioritized context, whereas the receiver is formulated in terms of a contextually derived modal judgement. Introduction and elimination rules for modalities are based on the polymorphism of terms in the language. This leads to a multi-modal (...) non-homogeneous version of a type theory, in which we show the embedding of the modal operators into standard group knowledge operators. (shrink)
In this paper I look at Fred Dretske’s account of information and knowledge as developed in Knowledge and The Flow of Information. In particular, I translate Dretske’s probabilistic definition of information to a modal logical framework and subsequently use this to explicate the conception of information and its flow which is central to his account, including the notions of channel conditions and relevant alternatives. Some key products of this task are an analysis of the issue of information (...) closure and an investigation into some of the logical properties of Dretske’s account of information flow. (shrink)
Naturalists who conceive of knowledge as a natural kind are led to treat ‘knowledge’ as a natural kind term. ‘Knowledge,’ then, must behave semantically in the ways that seem to support a direct reference theory for other natural kind terms. A direct reference theory for ‘knowledge,’ however, appears to leave open too many possibilities about the identity of knowledge. Intuitively, states of belief count as knowledge only if they meet epistemic criteria, not merely if (...) they bear a causal/historical relation to the term. I will develop this objection and show that it is grounded in modal considerations central to Kripke’s work on reference. I will also argue that a more plausible externalist semantics for natural kind terms disarms the objection. (shrink)
In this paper, the author defends Peter van Inwagen’s modal skepticism. Van Inwagen accepts that we have much basic, everyday modalknowledge, but denies that we have the capacity to justify philosophically interesting modal claims that are far removed from this basic knowledge. The author also defends the argument by means of which van Inwagen supports his modal skepticism, offering a rebuttal to an objection along the lines of that proposed by Geirrson. Van Inwagen (...) argues that Stephen Yablo’s recent and influential account of the relationship between conceivability and possibility supports his skeptical claims. The author’s defence involves a creative interpretation and development of Yablo’s account, which results in a recursive account of modal epistemology, what the author calls the “safe explanation” theory of modal epistemology. (shrink)
forthcoming in R. Cameron, B. Hale and A. Hoffmann (ed.s), The Logic, Epistemology and Metaphysics of Modality, Oxford University Press. Presents a concept-grounding account of modalknowledge.
I formulate and defend two sceptical theses on specific parts of our modalknowledge (unqualified and absolute modalities). My main point is that unqualified modal sentences are defective in that they fail to belong unambiguously to specific modal kinds and thus cannot be evaluated; hence, we must be sceptical of beliefs involving them.
In this article, I discuss Hawthorne's contextualist solution to Benacerraf's dilemma. He wants to find a satisfactory epistemology to go with realist ontology, namely with causally inaccessible mathematical and modal entities. I claim that he is unsuccessful. The contextualist theories of knowledge attributions were primarily developed as a response to the skeptical argument based on the deductive closure principle. Hawthorne uses the same strategy in his attempt to solve the epistemologist puzzle facing the proponents of mathematical and (...) class='Hi'>modal realism, but this problem is of a different nature than the skeptical one. The contextualist theory of knowledge attributions cannot help us with the question about the nature of mathematical and modal reality and how they can be known. I further argue that Hawthorne's account does not say anything about a priori status of mathematical and modalknowledge. Later, Hawthorne adds to his account an implausible claim that in some contexts a gettierized belief counts as knowledge. (shrink)
The past twenty-five years have seen a major renewal of interest in the topic of a priori knowledge. In the sixteen essays collected here, which span this entire period, philosopher Albert Casullo documents the complex set of issues motivating the renewed interest, identifies the central epistemological questions, and provides the leading ideas of a unified response to them. Throughout the essays, Casullo offers a systematic treatment of the concept of a priori knowledge, the existence of a priori (...) class='Hi'>knowledge, and the relationship between a priori knowledge and the related concepts of necessary truth and analytic truth. The essays fall into three categories: six published prior to his A Priori Justification (OUP, 2003), four published after the book, and four previously unpublished papers. The first six essays provide the background and introduction to a number of the major themes of the book: the articulation and defense of the minimal conception of a priori justification, an exposition of the limitations of the traditional arguments both for and against a priori knowledge, and the relevance of empirical investigation to providing supporting evidence for the claim that there are nonexperiential sources of justification. -/- The remaining four published essays explore diverse themes that were introduced in Casullo's previous book but not developed in detail: epistemic overdetermination, the relationship between a priori knowledge and necessary truth, testimony and a priori knowledge, and the bearing of socio-historical accounts of knowledge on the a priori. The four previously unpublished essays address issues that have either emerged or taken on more prominence in the literature on the a priori since the publication of Casullo's previous book: the evidential status of intuitions, the nature of modalknowledge, and challenges to the cogency or the significance of the a priori-a posteriori distinction. (shrink)
I describe /mindset semantics/, a semantical framework built around a conception of entailment as preservation of /support/ (implicit acceptance undergirded by competence) together with a /classical modal/ semantics for declarative sentences---with the central application of showing how a language could integrate discourse that is expressive with discourse that is informative (namely, of solving the 'Frege-Geach problem'). (The approach owes much to the work of Veltman and Yalcin, and, less proximally, of Stalnaker.) I provide a range of philosophical, technical, and (...) pedagogical arguments for mindset semantics. And I apply mindset semantics to as wide a range of phenomena as I have been able to think of (some more familiar, others less familiar): epistemic modals, avowals of belief, avowals of what it's like, /ascriptions/ of all these, 'looks'-sentences, avowals of presumption, avowals of subjective credence and statements of objective chance, indicative and subjunctive conditionals, conditional probability, deontic modals, questions, avowals of wonderment, metaphysical modals, metaphysical indeterminacy, avowals and ascriptions of knowledge, 'ought'-claims, and avowals of various practical positions (intending, trying, needing). (shrink)
What is our epistemic access to metaphysical modality? Timothy Williamson suggests that the epistemology of counterfactuals will provide the answer. This paper challenges Williamson's account and argues that certain elements of the epistemology of counterfactuals that he discusses, namely so called background knowledge and constitutive facts, are already saturated with modal content which his account fails to explain. Williamson's account will first be outlined and the role of background knowledge and constitutive facts analysed. Their key role is (...) to restrict our imagination to rule out irrelevant counterfactual suppositions. However, background knowledge turns out to be problematic in cases where we are dealing with metaphysically possible counterfactual suppositions that violate the actual laws of physics. As we will see, unless Williamson assumes that background knowledge corresponds with the actual, true laws of physics and that these laws are metaphysically necessary, it will be difficult to address this problem. Furthermore, Williamson's account fails to accommodate the distinction between conceivable yet metaphysically impossible scenarios, and conceivable and metaphysically possible scenarios. This is because background knowledge and constitutive facts are based strictly on our knowledge of the actual world. Williamson does attempt to address this concern with regard to metaphysical necessities – as they hold across all possible worlds – but we will see that even in this case the explanation is questionable. These problems, it will be suggested, cannot be addressed in a counterfactual account of the epistemology of modality. The paper finishes with an analysis of Williamson's possible rejoinders and some discussion about the prospects of an alternative account of modal epistemology. (shrink)
Proof Theory of Modal Logic is devoted to a thorough study of proof systems for modal logics, that is, logics of necessity, possibility, knowledge, belief, time, computations etc. It contains many new technical results and presentations of novel proof procedures. The volume is of immense importance for the interdisciplinary fields of logic, knowledge representation, and automated deduction.
For a novice this book is a mathematically-oriented introduction to modal logic, the discipline within mathematical logic studying mathematical models of reasoning which involve various kinds of modal operators. It starts with very fundamental concepts and gradually proceeds to the front line of current research, introducing in full details the modern semantic and algebraic apparatus and covering practically all classical results in the field. It contains both numerous exercises and open problems, and presupposes only minimal knowledge in (...) mathematics. A specialist can use the book as a source of references. Results and methods of many directions in propositional modal logic, from completeness and duality to algorithmic problems, are collected and systematically presented in one volume. (shrink)
Modal logics, originally conceived in philosophy, have recently found many applications in computer science, artificial intelligence, the foundations of mathematics, linguistics and other disciplines. Celebrated for their good computational behaviour, modal logics are used as effective formalisms for talking about time, space, knowledge, beliefs, actions, obligations, provability, etc. However, the nice computational properties can drastically change if we combine some of these formalisms into a many-dimensional system, say, to reason about knowledge bases developing in time or (...) moving objects. To study the computational behaviour of many-dimensional modal logics is the main aim of this book. On the one hand, it is concerned with providing a solid mathematical foundation for this discipline, while on the other hand, it shows that many seemingly different applied many-dimensional systems (e.g., multi-agent systems, description logics with epistemic, temporal and dynamic operators, spatio-temporal logics, etc.) fit in perfectly with this theoretical framework, and so their computational behaviour can be analyzed using the developed machinery. We start with concrete examples of applied one- and many-dimensional modal logics such as temporal, epistemic, dynamic, description, spatial logics, and various combinations of these. Then we develop a mathematical theory for handling a spectrum of 'abstract' combinations of modal logics - fusions and products of modal logics, fragments of first-order modal and temporal logics - focusing on three major problems: decidability, axiomatizability, and computational complexity. Besides the standard methods of modal logic, the technical toolkit includes the method of quasimodels, mosaics, tilings, reductions to monadic second-order logic, algebraic logic techniques. Finally, we apply the developed machinery and obtained results to three case studies from the field of knowledge representation and reasoning: temporal epistemic logics for reasoning about multi-agent systems, modalized description logics for dynamic ontologies, and spatio-temporal logics. The genre of the book can be defined as a research monograph. It brings the reader to the front line of current research in the field by showing both recent achievements and directions of future investigations (in particular, multiple open problems). On the other hand, well-known results from modal and first-order logic are formulated without proofs and supplied with references to accessible sources. The intended audience of this book is logicians as well as those researchers who use logic in computer science and artificial intelligence. More specific application areas are, e.g., knowledge representation and reasoning, in particular, terminological, temporal and spatial reasoning, or reasoning about agents. And we also believe that researchers from certain other disciplines, say, temporal and spatial databases or geographical information systems, will benefit from this book as well. Key Features: Integrated approach to modern modal and temporal logics and their applications in artificial intelligence and computer science Written by internationally leading researchers in the field of pure and applied logic Combines mathematical theory of modal logic and applications in artificial intelligence and computer science Numerous open problems for further research Well illustrated with pictures and tables. (shrink)
In this paper we examine Lewis's attempts to provide an epistemology of modality and we argue that he fails to provide an account that properly weds his metaphysics with an epistemology that explains the knowledge of modality that both he and his critics grant. We argue that neither the appeals to acceptable paraphrases of ordinary modal discourse nor parallels with Platonistic theories of mathematics suffice. We conclude that no proper epistemology for modal realism has been provided and (...) that one is needed. (shrink)
This book treats modal logic as a theory, with several subtheories, such as completeness theory, correspondence theory, duality theory and transfer theory and is intended as a course in modal logic for students who have had prior contact with modal logic and who wish to study it more deeply. It presupposes training in mathematical or logic. Very little specific knowledge is presupposed, most results which are needed are proved in this book.
Aristotle connects modality and time in ways strange and perplexing to modern readers. In this book the author proposes a new solution to this exegetical problem. Although primarily expository, this work explores topics of central concern for current investigations into causality, time, and change.
This paper contains replies to comments on the author's paper "A Priori Knowledge and the Scope of Philosophy." Several points in the argument of that paper are given further clarification: the notion of our standard justificatory procedure, the notion of a basic source of evidence, and the doctrine of modal reliabilism. The reliability of intuition is then defended against Lycan's skepticism and a response is given to Lycan's claim that the scope of a priori knowledge does not (...) include philosophically central topics such as the nature of consciousness. Next a counterfactual account of intuitions proposed by Sosa is criticized. Finally, in response to certain questions raised by Sosa, the explanation of the evidential status of intuition offered in the original paper receives further elaboration. (shrink)
Kant famously argued that, from experience, we can only learn how something actually is, but not that it must be so. In this paper, I defend an improved version of Kant's argument for the existence of a priori knowledge, the Modal Argument , against recent objections by Casullo and Kitcher. For the sake of the argument, I concede Casullo's claim that we may know certain counterfactuals in an empirical way and thereby gain epistemic access to some nearby, nomologically (...) possible worlds. But I maintain that our beliefs about metaphysical necessities still cannot be justified empirically. Furthermore, I reject Casullo's deflationary thesis about the significance of such justification. Kitcher's most troublesome objection is that we can gain any modal justification whatsoever through testimony , i.e. in an experiential way. This can be countered by distinguishing between productive sources of justification, like perception, and merely reproductive sources, like testimony. Thus, some productive a priori source will always be needed somewhere. 1. (shrink)
This paper motivates two bases for ascribing propositional semantic knowledge (or something knowledgelike): first, because it’s necessary to rationalize linguistic action; and, second, because it’s part of an empirical theory that would explain various aspects of linguistic behavior. The semantic knowledge ascribed on these two bases seems to differ in content, epistemic status, and cognitive role. This raises the question: how are they related, if at all? The bulk of the paper addresses this question. It distinguishes a variety (...) of answers and their varying philosophical and empirical commitments. (shrink)
Several justification logics have been created, starting with the logic LP, [1]. These can be thought of as explicit versions of modal logics, or of logics of knowledge or belief, in which the unanalyzed necessity (knowledge, belief) operator has been replaced with a family of explicit justification terms. We begin by sketching the basics of justification logics and their relations with modal logics. Then we move to new material. Modal logics come in various strengths. For (...) their corresponding justification logics, differing strength is reflected in different vocabularies. What we show here is that for justification logics corresponding to modal logics extending T, various familiar extensions are actually conservative with respect to each other. Our method of proof is very simple, and general enough to handle several justification logics not directly corresponding to distinct modal logics. Our methods do not, however, allow us to prove comparable results for justification logics corresponding to modal logics that do not extend T. That is, we are able to handle explicit logics of knowledge, but not explicit logics of belief. This remains open. (shrink)
In a series of influential articles, George Bealer argues for the autonomy of philosophical knowledge on the basis that philosophically known truths must be necessary truths. The main point of his argument is that the truths investigated by the sciences are contingent truths to be discovered a posteriori by observation, while the truths of philosophy are necessary truths to be discovered a priori by intuition. The project of assimilating philosophy to the sciences is supposed to be rendered illegitimate by (...) the more or less sharp distinction in these characteristic methods and its modal basis. In this article Bealer's particular way of drawing the distinction between philosophy and science is challenged in a novel manner, and thereby philosophical naturalism is further defended. (shrink)
Current epistemological orthodoxy has it that knowledge is incompatible with luck. More precisely: Knowledge is incompatible with epistemic luck (of a certain, interesting kind). This is often treated as a truism which is not even in need of argumentative support. In this paper, I argue that there is lucky knowledge. In the first part, I use an intuitive and not very developed notion of luck to show that there are cases of knowledge which are “lucky” in (...) that sense. In the second part, I look at philosophical conceptions of luck (modal and probabilistic ones) and come to the conclusion that knowledge can be lucky in those senses, too. I also turns out that a probabilistic notion of luck can help us see in what ways a particular piece of knowledge or belief can be lucky or not lucky. (shrink)
Standard Kripke models are inadequate to model situations of inexact knowledge with introspection, since positive and negative introspection force the relation of epistemic indiscernibility to be transitive and euclidean. Correlatively, Williamson’s margin for error semantics for inexact knowledge invalidates axioms 4 and 5. We present a new semantics for modal logic which is shown to be complete for K45, without constraining the accessibility relation to be transitive or euclidean. The semantics corresponds to a system of modular (...) class='Hi'>knowledge, in which iterated modalities and simple modalities are not on a par. We show how the semantics helps to solve Williamson’s luminosity paradox, and argue that it corresponds to an integrated model of perceptual and introspective knowledge that is psychologically more plausible than the one defended by Williamson. We formulate a generalized version of the semantics, called token semantics, in which modalities are iteration-sensitive up to degree n and insensitive beyond n. The multi-agent version of the semantics yields a resource-sensitive logic with implications for the representation of common knowledge in situations of bounded rationality. (shrink)
This paper has three parts. First, a discussion of our use of intuitions as evidence (reasons) in logic, mathematics, philosophy (hereafter, “the a priori disciplines”). Second, an explanation of why intuitions are evidence. The explanation is provided by modal reliabilism—the doctrine that there is a certain kind of qualified modal tie between intuitions and the truth. Third, an explanation of why there should be such a tie between intuitions and the truth. This tie is a consequence of what, (...) by definition, it is to possess the concepts involved in our intuitions. These three parts form the basis of a unified account of a priori evidence and, in turn, a priori knowledge. (shrink)
The situation calculus is one of the most established formalisms for reasoning about action and change. In this paper we will review the basics of Reiter’s version of the situation calculus, show how knowledge and time have been addressed in this framework, and point to some of the weaknesses of the situation calculus with respect to time. We then present a modal version of the situation calculus where these problems can be overcome with relative ease and without sacrificing (...) the advantages of the original. (shrink)
A theory of evidential probability is developed from two assumptions:(1) the evidential probability of a proposition is its probability conditional on the total evidence;(2) one's total evidence is one's total knowledge. Evidential probability is distinguished from both subjective and objective probability. Loss as well as gain of evidence is permitted. Evidential probability is embedded within epistemic logic by means of possible worlds semantics for modal logic; this allows a natural theory of higher-order probability to be developed. In particular, (...) it is emphasized that it is sometimes uncertain which propositions are part of one's total evidence; some surprising implications of this fact are drawn out. (shrink)
The starting point of this work is the gap between two distinct traditions in information engineering: knowledge representation and data-driven modelling. The first tradition emphasizes logic as a tool for representing beliefs held by an agent. The second tradition claims that the main source of knowledge is made of observed data, and generally does not use logic as a modelling tool. However, the emergence of fuzzy logic has blurred the boundaries between these two traditions by putting forward fuzzy (...) rules as a Janus-faced tool that may represent knowledge, as well as approximate non-linear functions representing data. This paper lays bare logical foundations of data-driven reasoning whereby a set of formulas is understood as a set of observed facts rather than a set of beliefs. Several representation frameworks are considered from this point of view: classical logic, possibility theory, belief functions, epistemic logic, fuzzy rule-based systems. Mamdani's fuzzy rules are recovered as belonging to the data-driven view. In possibility theory a third set-function, different from possibility and necessity plays a key role in the data-driven view, and corresponds to a particular modality in epistemic logic. A bi-modal logic system is presented which handles both beliefs and observations, and for which a completeness theorem is given. Lastly, our results may shed new light in deontic logic and allow for a distinction between explicit and implicit permission that standard deontic modal logics do not often emphasize. (shrink)
This paper examines the relationship between the classical theistic conception of God and modal realism. I suggest that realism about possible worlds has unwelcome consequences for that conception. First, that modal realism entails the necessity of divine existence eludes explanation in a way congenial to a commitment to both modal realism and classical theism. Second, divine knowledge is dependent on worlds independent of the creative role and action of God, thereby suggesting a limitation on the nature (...) of divine knowledge and on the nature of God's creative role. Third, modal realism indicates the existence of real, albeit non-actual, worlds of appalling evil threatening the classical conception of divine omnipotence and benevolence. (Published Online July 10 2006). (shrink)
A common criticism of Locke’s ideational definition of knowledge is that it contradicts his accounts of knowledge’s reality and sensitive knowledge. Here it is argued that the ideational definiton of knowledge is compatible with knowledge of idea-independent reality. The key is Locke’s notion of the signification. Nominal agreements obtain if and only if the ideas’ descriptive contents are the ground for truth; real agreements obtain only if their total denotation are the grounds for truth. The (...) signification of the ideas determine whether they denote real or fantastical objects. Three types of ideas, simple quality-ideas, modal ideas, and relational ideas, necessarily signify real objects. The fourth type, the ideas of substances, are real only if those particular combinations of qualitites have been perceived to co-exist. Locke’s ideas are intrinsically either real or fantastical and thus, it is argued, his models of truth and knowledge’s reality are far from typical correspondence theories. (shrink)
This paper does two things. First, it defends, against a potential threat to it, the claim that a capacity for essentialist knowledge should not be placed among the core capacities for counterfactual knowledge. Second, it assesses a consequence of that claim—or better: of the discussion by means of which I defend it—in relation to Kment's and Williamson's views on the relation between modality and counterfactuals.
John Perry’s Knowledge, Possibility, and Consciousness is based on the Jean Nicod Lectures, which he gave in Paris in 1999. The main goal of this book is to defend what he calls ‘antecedent physicalism’ from various common objections to physicalism. The book is organised as follows. In Chapter 1 Perry reviews a number of antiphysicalist arguments, which have been intensively discussed in the last few years among philosophers of mind. In Chapters 2 and 3 he formulates antecedent physicalism. Unlike (...) eliminativism, antecedent physicalism grants the subjective character of phenomenal experiences. It then tries to construct the best possible account of them on the assumption that they are physical (p. 27). However, according to Perry, it is a mistake to think that the antecedent physicalist is ‘a complete dogmatist for whom physicalism is a religious principle’. The antecedent physicalist is rather one ‘who is committed to physicalism in the sense that she or he sees some compelling reasons for it and will not give it up without seeing some clear reason to do so’ (p. 27). In the rest of the book Perry attempts to show how his antecedent physicalism can block existing antiphysicalist arguments. In PSYCHE: http://psyche.cs.monash.edu.au/ Chapter 4 he discusses the zombie argument, according to which physicalism is false because the existence of a zombie—someone physically identical to a human being but lacking conscious experience altogether—is a logical possibility. In Chapters 5, 6 and 7 Perry discusses the knowledge argument, according to which physicalism is false because there could be a scientist—call her Mary—who knows all the physical facts but does not know what it is like to see colour. In Chapter 8 Perry discusses the modal argument, according to which physicalism, the identity theory in particular, is false because psychophysical identity statements such as ‘pain=c-fibre stimulation’ cannot be true, even if we regard them as necessary and a posteriori.. (shrink)
Modal logic has been applied in many different areas, as reasoning about time, knowledge and belief, necessity and possibility, to mention only some examples. In the present paper, an attempt is made to use modal logic to account for the semantics of theoretical sentences in scientific language. Theoretical sentences have been studied extensively since the work of Ramsey and Carnap. The present attempt at a modal analysis is motivated by there being several intended interpretations of the (...) theoretical terms once these terms are introduced through the axioms of a theory. (shrink)
I analyze some classical solutions of the skeptical argument and some of their week points (especially the contextualist solution). First I have proposed some possible improvement of the contextualist solution (the introduction of the explicit-implicit belief and knowledge distinction beside the differences in the relevance of some counter-factual alternatives). However, this solution does not block too fast jumps of the everyday context (where empirical knowledge is possible) into skeptical context (where empirical knowledge is impossible). Then I analyze (...) some formal analogies between some modal arguments on the contingency of empirical facts (and the world as whole) and the skeptical arguments against empirical knowledge. I try to show that the skeptical conclusion “Empirical knowledge does not exist” is logically coherent with the thesis that they are empirical facts and that we have true belief on them. In order to do that without contradictions I have to accept a non-classical definition of knowledge: S knows that p:= S is not justified to allow that non-p. Knowledge and justified allowance function here as some pseudo-theoretical concepts which allow only some partial and conditional definitions by some “empirical” terms and logical conditions. (shrink)
Ockham appeared to maintain that God necessarily knows all true propositions, including future contingent propositions, despite the fact that such propositions have determinate truth values. While some commentators believe that Ockham’s attempt to reconcile divine omniscience with the contingency of true future propositions amounts to little more than a simple-minded assertion of Ockham’s Christian faith, I argue that Ockham’s position is more sophisticated than this and rests on attributing to God a dual knowledge property: God not only knows every (...) true proposition, but knows its modal properties as well. Future contingent propositions are determinately true when actualized, not timelessly, and God’s knowledge of their truth values is knowledge of when the truth value of a proposition is actually determined. (shrink)
Classical modal logics, based on the neighborhood semantics of Scott and Montague, provide a generalization of the familiar normal systems based on Kripke semantics. This paper defines AGM revision operators on several first-order monotonic modal correspondents, where each first-order correspondence language is defined by Marc Pauly’s version of the van Benthem characterization theorem for monotone modal logic. A revision problem expressed in a monotone modal system is translated into first-order logic, the revision is performed, and the (...) new belief set is translated back to the original modal system. An example is provided for the logic of Risky Knowledge that uses modal AGM contraction to construct counter-factual evidence sets in order to investigate robustness of a probability assignment given some evidence set. A proof of correctness is given. (shrink)
Several justification logics have evolved, starting with the logicLP, (Artemov 2001). These can be thought of as explicit versions of modal logics, or logics of knowledge or belief, in which the unanalyzed necessity (knowledge, belief) operator has been replaced with a family of explicit justification terms. Modal logics come in various strengths. For their corresponding justification logics, differing strength is reflected in different vocabularies. What we show here is that for justification logics corresponding to modal (...) logics extending T, various familiar extensions are actually conservative with respect to each other. Our method of proof is very simple, and general enough to handle several justification logics not directly corresponding to distinct modal logics. Our methods do not, however, allow us to prove comparable results for justification logics corresponding to modal logics that do not extend T. That is, we are able to handle explicit logics of knowledge, but not explicit logics of belief. This remains open. (shrink)
We propose a novel interpretation of natural-language questions using a modal predicate logic of knowledge. Our approach brings standard model-theoretic and proof-theoretic techniques from modal logic to bear on questions. Using the former, we show that our interpretation preserves Groenendijk and Stokhof's answerhood relation, yet allows an extensional interpretation. Using the latter, we get a sound and complete proof procedure for the logic for free. Our approach is more expressive; for example, it easily treats complex questions with (...) operators that scope over questions. We suggest a semantic criterion that restricts what natural-language questions can express. We integrate and generalize much previous work on the semantics of questions, including Beck and Sharvit's families of subquestions, non-exhaustive questions, and multi-party conversations. (shrink)
We extend Moss and Parikh’s bi-modal system for knowledge and effort by means of hybrid logic. In this way, some additional concepts from topology related to knowledge can be captured. We prove the soundness and completeness as well as the decidability of the extended system. Special emphasis will be placed on algebras.
We present a cut-free tableau calculus with histories and variables for the EXPTIME-complete multi-modal logic of common knowledge (LCK). Our calculus constructs the tableau using only one pass, so proof-search for testing theoremhood of ϕ does not exhibit the worst-case EXPTIME-behaviour for all ϕ as in two-pass methods. Our calculus also does not contain a “finitized ω-rule” so that it detects cyclic branches as soon as they arise rather than by worst-case exponential branching with respect to the size (...) of ϕ. Moreover, by retaining the rooted-tree form from traditional tableaux, our calculus becomes amenable to the vast array of optimisation techniques which have proved essential for “practical” automated reasoning in very expressive description logics. Our calculus forms the basis for developing a uniform framework for the family of all fix-point logics of common knowledge. However, there is still no “free lunch” as, in the worst case, our method exhibits 2EXPTIME-behaviour. A prototype implementation can be found at twb.rsise.anu.edu.au which allows users to test formulae via a simple graphical interface. (shrink)
We present a framework for intensional reasoning in typed -calculus. In this family of calculi, called Modal Pure Type Systems (MPTSs), a propositions-as-types-interpretation can be given for normal modal logics. MPTSs are an extension of the Pure Type Systems (PTSs) of Barendregt (1992). We show that they retain the desirable meta-theoretical properties of PTSs, and briefly discuss applications in the area of knowledge representation.
This is indeed a very nice draft that I have read with great pleasure, and that has helped me to better understand the completeness proof for LCC. Modal fixed point logic allows for an illuminating new version (and a further extension) of that proof. But still. My main comment is that I think the perspective on substitutions in the draft paper is flawed. The general drift of the paper is that relativization, (predicate) substitution and product update are general operations (...) on models, and that it is important to check whether given logical languages are closed under these operations. FO logic is closed under relativization, predicate substitution and product constructions (such as those involved in relative interpretation). The minimal modal logic is closed under relativization, which explains the reduction of epistemic logic (withhout common knowledge) + public announcement to epistemic logic simpliciter (as observed in Van Benthem, [2]). The reduction breaks down as soon as one adds common knowledge. The minimal modal logic is also closed under substitution, which explains the reduction of epistemic logic plus (publicly observable) factual change to epistemic logic simpliciter, via the following reduction axioms (I use !p := φ for the operation of publicly changing the truth value of p to φ): [!p := φ]p ↔ φ [!p := φ]q ↔ q (p and q syntactically different ) [!p := φ]¬ψ ↔ ¬[!p := φ]ψ [!p := φ](ψ1 ∧ ψ2) ↔ [!p := φ]ψ1 ∧ [!p := φ]ψ2 [!p := φ][i]ψ ↔ [i][!p := φ]ψ Unlike the case of relativisation, this can be extended to the case of epistemic logic with common knowledge, by means of: [!p := φ]CGψ ↔ CG[!p := φ]ψ We get the following.. (shrink)
The theory of rough sets starts with the notion of an approximation space , which is a pair ( U , R ), U being the domain of discourse, and R an equivalence relation on U . R is taken to represent the knowledge base of an agent, and the induced partition reflects a granularity of U that is the result of a lack of complete information about the objects in U . The focus then is on approximations of (...) concepts on the domain, in the context of the granularity. The present article studies the theory in the situation where information is obtained from different sources. The notion of approximation space is extended to define a multiple-source approximation system with distributed knowledge base , which is a tuple , where N is a set of sources and P ranges over all finite subsets of N . Each R P is an equivalence relation on U satisfying some additional conditions, representing the knowledge base of the group P of sources. Thus each finite group of sources and hence individual source perceives the same domain differently (depending on what information the group/individual source has about the domain), and the same concept may then have approximations that differ with the groups. In order to express the notions and properties related with rough set theory in this multiple-source situation, a quantified modal logic LMSAS D is proposed. In LMSAS D , quantification ranges over modalities, making it different from modal predicate logic and modal logic with propositional quantifiers. Some fragments of LMSAS D are discussed and it is shown that the modal system KTB is embedded in LMSAS D . The epistemic logic is also embedded in LMSAS D , and cannot replace the latter to serve our purpose. The relationship of LMSAS D with first and second-order logics is presented. Issues of expressibility, axiomatization and decidability are addressed. (shrink)
Many powerful logics exist today for reasoning about multi-agent systems, but in most of these it is hard to reason about an infinite or indeterminate number of agents. Also the naming schemes used in the logics often lack expressiveness to name agents in an intuitive way.To obtain a more expressive language for multi-agent reasoning and a better naming scheme for agents, we introduce a family of logics called term-modal logics. A main feature of our logics is the use of (...)modal operators indexed by the terms of the logics. Thus, one can quantify over variables occurring in modal operators. In term-modal logics agents can be represented by terms, and knowledge of agents is expressed with formulas within the scope of modal operators. (shrink)
In order to capture the concept of common knowledge, various extensions of multi-modal epistemic logics, such as fixed-point ones and infinitary ones, have been proposed. Although we have now a good list of such proposed extensions, the relationships among them are still unclear. The purpose of this paper is to draw a map showing the relationships among them. In the propositional case, these extensions turn out to be all Kripke complete and can be comparable in a meaningful manner. (...) F. Wolter showed that the predicate extension of the Halpern-Moses fixed-point type common knowledge logic is Kripke incomplete. However, if we go further to an infinitary extension, Kripke completeness would be recovered. Thus there is some gap in the predicate case. In drawing the map, we focus on what is happening around the gap in the predicate case. The map enables us to better understand the common knowledge logics as a whole. (shrink)
The problems we deal with concern reasoning about incomplete knowledge. Knowledge is understood as ability of an ideal rational agent to make decisions about pieces of information. The formalisms we are particularly interested in are Moore's autoepistemic logic (AEL) and its variant, the logic of acceptance and rejection (AEL2). It is well-known that AEL may be seen as the nonmonotonic KD45 modal logic. The aim is to give an appropriate modal formalization for AEL2.
Contextual type theories are largely explored in their applications to programming languages, but less investigated for knowledge representation purposes. The combination of a constructive language with a modal extension of contexts appears crucial to explore the attractive idea of a type-theoretical calculus of provability from refutable assumptions for non-monotonic reasoning. This paper introduces such a language: the modal operators are meant to internalize two different modes of correctness, respectively with necessity as the standard notion of constructive verification (...) and possibility as provability up to refutation of contextual conditions. (shrink)
A duality between Pawlak's knowledge representation systems and certain information systems of logical type, called bi-consequence systems is established. As an application a first-order characterization of some informational relations is given and a completeness theorem for the corresponding modal logic INF is proved. It is shown that INF possesses finite model property and hence is decidable.
We extend our general approach to characterizing information to multi-agent systems. In particular, we provide a formal description of an agent''s knowledge containing exactly the information conveyed by some (honest) formula . Only knowing is important for dynamic agent systems in two ways. First of all, one wants to compare different states of knowledge of an agent and, secondly, for agent a''s decisions, it may be relevant that (he knows that) agent b does not know more than . (...) There are three ways to study the question whether a formula can be interpreted as minimal information. The first method is semantic and inspects minimal models for (with respect to some information order on states). The second one is syntactic and searches for stable expansions, minimal with respect to some language *. The third method is a deductive test, known as the disjunction property. We present a condition under which the three methods are equivalent. Then, we show how to construct the order by collecting layered orders. Focusing on the multi-agent case we identify languages * for various orders , and show how they yield different notions of honesty for different multi-modal systems. We then provide several tools for studying honesty types and illustrate their usefulness on a number of examples, for three modal systems of particular interest. Finally, we relate the different notions of minimal knowledge, and describe possible patterns of honesty for these systems. (shrink)
In this paper we investigate first order common knowledge logics; i.e., modal epistemic logics based on first order logic with common knowledge operators. It is shown that even rather weak fragments of first order common knowledge logics are not recursively axiomatizable. This applies, for example, to fragments which allow to reason about names only; that is to say, fragments the first order part of which is based on constant symbols and the equality symbol only. Then formal (...) properties of "quantifying into" epistemic contexts are investigated. The results are illustrated by means of epistemic representations of Nash Equilibria for finite games with mixed strategies. (shrink)
We present a modal logic for the class of subset spaces based on discretely descending chains of sets. Apart from the usual modalities for knowledge and effort the standard temporal connectives are included in the underlying language. Our main objective is to prove completeness of a corresponding axiomatization. Furthermore, we show that the system satisfies a certain finite model property and is decidable thus.
Spatial objects may not only be perceived visually but also by touch. We report recent experiments investigating to what extent prior object knowledge acquired in either the haptic or visual sensory modality transfers to a subsequent visual learning task. Results indicate that even mental object representations learnt in one sensory modality may attain a multi-modal quality. These findings seem incompatible with picture-based reasoning schemas but leave open the possibility of modality-specific reasoning mechanisms.
I develop an epistemic focal bias account of certain patterns of judgments about knowledge ascriptions by integrating it with a general dual process framework of human cognition. According to the focal bias account, judgments about knowledge ascriptions are generally reliable but systematically fallible because the cognitive processes that generate them are affected by what is in focus. I begin by considering some puzzling patters of judgments about knowledge ascriptions and sketch how a basic focal bias account seeks (...) to account for them. In doing so, I argue that the basic focal bias account should be integrated in a more general framework of human cognition. Consequently, I present some central aspects of a prominent general dual process theory of human cognition and discuss how focal bias may figure at various levels of processing. On the basis of this discussion, I attempt to categorize the relevant judgments about knowledge ascriptions. Given this categorization, I argue that the basic epistemic focal bias account of certain contrast effects and salient alternatives effects can be plausibly integrated with the dual process framework. Likewise, I try to explain the absence of strong intuitions in cases of far-fetched salient alternatives. As a manner of conclusion, I consider some methodological issues concerning the relationship between cognitive psychology, experimental data and epistemological theorizing. (shrink)
We extend our general approach to characterizing information to multi-agent systems. In particular, we provide a formal description of an agent's knowledge containing exactly the information conveyed by some (honest) formula φ. Only knowing is important for dynamic agent systems in two ways. First of all, one wants to compare different states of knowledge of an agent and, secondly, for agent a's decisions, it may be relevant that (he knows that) agent b does not know more than φ. (...) There are three ways to study the question whether a formula φ can be interpreted as minimal information. The first method is semantic and inspects 'minimal' models for φ (with respect to some information order ≤ on states). The second one is syntactic and searches for stable expansions, minimal with respect to some language $\scr{L}^{\ast}$ . The third method is a deductive test, known as the disjunction property. We present a condition under which the three methods are equivalent. Then, we show how to construct the order ≤ by collecting 'layered orders'. Focusing on the multi-agent case we identify languages $\scr{L}^{\ast}$ for various orders ≤, and show how they yield different notions of honesty for different multi-modal systems. We then provide several tools for studying honesty types and illustrate their usefulness on a number of examples, for three modal systems of particular interest. Finally, we relate the different notions of minimal knowledge, and describe possible patterns of honesty for these systems. (shrink)
Berkeley's idealism started a revolution in philosophy. As one of the great empiricist thinkers he not only influenced British philosophers from Hume to Russell and the logical positivists in the twentieth century, he also set the scene for the continental idealism of Hegel and even the philosophy of Marx. -/- There has never been such a radical critique of common sense and perception as that given in Berkeley's Principles of Human Knowledge (1710). His views were met with disfavour, and (...) his response to his critics was the Three Dialogues between Hylas and Philonous. -/- This edition of Berkeley's two key works has an introduction which examines and in part defends his arguments for idealism, as well as offering a detailed analytical contents list, extensive philosophical notes and an index. (shrink)
Judging by our folk appraisals, then, knowledge and action are intimately related. The theories of rational action with which we are familiar leave this unexplained. Moreover, discussions of knowledge are frequently silent about this connection. This is a shame, since if there is such a connection it would seem to constitute one of the most fundamental roles for knowledge. Our purpose in this paper is to rectify this lacuna, by exploring ways in which knowing something is related (...) to rationally acting upon it, defending one particular proposal against anticipated objections. (shrink)
In this new volume in the Oxford Psychology Series, the author presents a highly readable account of the cognitive unconscious, focusing in particular on the problem of implicit learning. Implicit learning is defined as the acquisition of knowledge that takes place independently of the conscious attempts to learn and largely in the absence of explicit knowledge about what was acquired. One of the core assumptions of this argument is that implicit learning is a fundamental, "root" process, one that (...) lies at the very heart of the adaptive behavioral repertoire of every complex organism. The author's goals are to outline the essential features of implicit learning that have emerged from the many studies that have been carried out in a variety of experimental laboratories over the past several decades; to present the various alternative perspectives on this issue that have been proposed by other researchers and to try to accommodate these views with his own; to structure the literature so that it can be seen in the context of standard heuristics of evolutionary biology; to present the material within a functionalist approach and to try to show why the experimental data should be seen as entailing particular epistemological perspectives; and to present implicit processing as encompassing a general and ubiquitous set of operations that have wide currency and several possible applications. Chapter 1 begins with the core problem under consideration in this book, a characterization of "implicit learning" as it has come to be used in the literature. Reber puts this seemingly specialized topic into a general framework and suggests a theoretical model based on standard heuristics of evolutionary biology. In his account, Reber weaves a capsule history of interest in and work on the cognitive unconscious. Chapter 2 turns to a detailed overview of the experimental work on the acquisition of implicit knowledge, which currently is of great interest. Chapter 3 develops the evolutionary model within which one can see learning and cognition as richly intertwining issues and not as two distinct fields with one dominating the other. Finally, Chapter 4 explores a variety of entailments and speculations concerning implicit cognitive processes and their general role in the larger scope of human performance. (shrink)
In this paper I assume that we have some intuitive knowledge—i.e. beliefs that amount to knowledge because they are based on intuitions. The question I take up is this: given that some intuition makes a belief based on it amount to knowledge, in virtue of what does it do so? We can ask a similar question about perception. That is: given that some perception makes a belief based on it amount to knowledge, in virtue of what (...) does it do so? A natural idea about perception is that a perception makes a belief amount to knowledge in part by making you sensorily aware of the concrete objects it is about. The analogous idea about intuition is that an intuition makes a belief amount to knowledge in part by making you intellectually aware of the abstract objects it is about. I expand both ideas into fuller accounts of perceptual and intuitive knowledge, explain the main challenge to this sort of account of intuitive knowledge (i.e. the challenge of making sense of intellectual awareness), and develop a response to it. (shrink)
1 Knowledge and Justification This book is an investigation of one central problem which arises in the attempt to give a philosophical account of empirical ...
This book presents an attempt to develop a theory of knowledge and a philosophy of mind using ideas derived from the mathematical theory of communication developed by Claude Shannon. Information is seen as an objective commodity defined by the dependency relations between distinct events. Knowledge is then analyzed as information caused belief. Perception is the delivery of information in analog form (experience) for conceptual utilization by cognitive mechanisms. The final chapters attempt to develop a theory of meaning (or (...) belief content) by viewing meaning as a certain kind of information-carrying role. (shrink)
In “The Myth of Factive Verbs” (Hazlett 2010), I had four closely related goals. The first (pp. 497-99, p. 522) was to criticize appeals to ordinary language in epistemology. The second (p. 499) was to criticize the argument that truth is a necessary condition on knowledge because “knows” is factive. The third (pp. 507-19) – which was the intended means of achieving the first two – was to defend a semantics for “knows” on which <S knows p> can be (...) true even if p isn’t true. The fourth (Ibid.) – which seemed necessary for the success of the third – was to defend a pragmatic account of the fact that utterances of <S knows p> typically imply p, on which the implication in those cases is down to conversational implicature. In this paper I’ll go after these goals again, with an emphasis on the second. Our topic will be whether the factivity of “knows” (whatever this amounts to) supports the truth condition on knowledge. A new goal will be to defend my argument against some criticisms from John Turri (2011) and Savas Tsohatzidis (forthcoming). We’ll first look at the truth condition (§1) and factive presupposition (§§2 – 3), before turning to replies to Turri and Tsohatzidis (§§4 – 7). (shrink)
Self-knowledge is based on several different forms of information, so distinct that each one essentially establishes a different 'self. The ecological self is the self as directly perceived with respect to the immediate physical environment; the interpersonal self, also directly perceived, is established by species-specific signals of emotional rapport and communication; the extended self is based on memory and anticipation; the private self appears when we discover that our conscious experiences are exclusively our own; the conceptual self or 'self-concept' (...) draws its meaning from a network of socially-based assumptions and theories about human nature in general and ourselves in particular. Although these selves are rarely experienced as distinct (because they are held together by specific forms of stimulus information), they differ in their developmental histories, in the accuracy with which we can know them, in the pathologies to which they are subject, and generally in what they contribute to human experience. (shrink)
Intuitively, there is a difference between knowledge and mere belief. Contemporary philosophical work on the nature of this difference has focused on scenarios known as “Gettier cases.” Designed as counterexamples to the classical theory that knowledge is justified true belief, these cases feature agents who arrive at true beliefs in ways which seem reasonable or justified, while nevertheless seeming to lack knowledge. Prior empirical investigation of these cases has raised questions about whether lay people generally share philosophers’ (...) intuitions about these cases, or whether lay intuitions vary depending on individual factors (e.g. ethnicity) or factors related to specific types of Gettier cases (e.g. cases that include apparent evidence). We report an experiment on lay attributions of knowledge and justification for a wide range of Gettier Cases and for a related class of controversial cases known as Skeptical Pressure cases, which are also thought by philosophers to elicit intuitive denials of knowledge. Although participants rated true beliefs in Gettier and Skeptical Pressure cases as being justified, they were significantly less likely to attribute knowledge for these cases than for matched true belief cases. This pattern of response was consistent across different variations of Gettier cases and did not vary by ethnicity or gender, although attributions of justification were found to be positively related to measures of empathy. These findings therefore suggest that across demographic groups, laypeople share similar epistemic concepts with philosophers, recognizing a difference between knowledge and justified true belief. (shrink)
The Gettier Problem is the problem of revising the view that knowledge is justified true belief in a way that is immune to Gettier counter-examples. The “Gettier Problem problem”, according to Lycan, is the problem of saying what is misguided about trying to solve the Gettier Problem. In this paper I take up the Gettier Problem problem. I distinguish giving conditions that are necessary and sufficient for knowledge from giving conditions that explain why one knows when one does (...) know. I argue that the problem with the Gettier Problem is that it requires us to articulate conditions that suffice for knowledge even if those conditions are non-explanatory. After defending this view, I take up two related methodological issues, one about the evidence that can be given in favor of an account of knowledge, and one about the role that investigating justification might play in investigating knowledge. (shrink)
