This volume of original essays assesses Nozick's analyses of knowledge and evidence and his approach to skepticism. Several of the contributors claim that Nozick has not succeeded in rebutting the skeptic; some offer fresh accounts of skepticism and its flaws; others criticize Nozick's externalist accounts of knowledge and evidence; still others welcome externalism but attempt to replace Nozick's accounts of knowledge and evidence with more plausible analyses.

The Description for this book, The Analysis of Knowing: A Decade of Research, will be forthcoming.

Change, Choice and Inference develops logical theories that are necessary both for the understanding of adaptable human reasoning and for the design of intelligent systems. The book shows that reasoning processes - the drawing on inferences and changing one's beliefs - can be viewed as belonging to the realm of practical reason by embedding logical theories into the broader context of the theory of rational choice. The book unifies lively and significant strands of research in logic, philosophy, economics and artificial (...) intelligence. It elaborates on the relevant theories and provides a mathematically precise foundation for the thesis that large parts of theoretical reason can be subsumed under practical reason. (shrink)

The paper attacks the widely held view that belief revision theories, as they have been studied in the past two decades, are founded on the Principle of Informational Economy. The principle comes in two versions. According to the first, an agent should, when accepting a new piece of information, aim at a minimal change of his previously held beliefs. If there are different ways to effect the belief change, then the agent should, according to he second version, give up those (...) beliefs that are least entrenched. Although widely proclaimed by belief revision theorists, I argue that both versions of the principle are dogmas that are not (and perhaps should not be) adhered to. I substantiate this claim with two simple mathematical observations, and I defend it against four possible objections that involve contractions, reconstructions, dispositions, and truths. (shrink)

In this exciting and original introduction to epistemology, Michael Williams explains and criticizes traditional philosophical theories of the nature, limits, methods, possibility, and value of knowing. All the main contemporary perspectives are explored and questioned, and the author's own theories put forward, making this new book essential reading for anyone, beginner or specialist, concerned with the philosophy of knowledge.

Edmund Gettier is Professor Emeritus at the University of Massachusetts, Amherst. This short piece, published in 1963, seemed to many decisively to refute an otherwise attractive analysis of knowledge. It stimulated a renewed effort, still ongoing, to clarify exactly what knowledge comprises.

Meets what? Ranking theory is, as far as I know, the only existing theory suited for underpinning Keith Lehrer’s account of knowledge and justification. If this is true, it’s high time to bring both together. This is what I shall do in this paper. However, the result of defining Lehrer’s primitive notions in terms of ranking theory will be disappointing: justified acceptance will, depending on the interpretation, either have an unintelligible structure or reduce to mere acceptance, and in the latter (...) interpretation knowledge will reduce to true belief. Of course, this result will require a discussion of who should be disappointed. So, the plan of the paper is simple: In section 1 I shall briefly state what is required for underpinning Lehrer’s account and why most of the familiar theories fail to do so. In section 2 I shall briefly motivate and introduce ranking theory. Basing Lehrer’s account on it will be entirely straightforward. Section 3 proves the above-mentioned results. Section 4, finally, discusses the possible conclusions. (shrink)

In earlier papers (Lindström & Rabinowicz, 1989. 1990), we proposed a generalization of the AGM approach to belief revision. Our proposal was to view belief revision as a relation rather thanas a function on theories (or belief sets). The idea was to allow for there being several equally reasonable revisions of a theory with a given proposition. In the present paper, we show that the relational approach is the natural result of generalizing in a certain way an approach to belief (...) revision due to Adam Grove. In his (1988) paper, Grove presents two closely related modelings of functional belief revision, one in terms of a family of "spheres" around the agent's theory G and the other in terms of an epistemic entrenchment ordering of propositions. The "sphere"-terminology is natural when one looks upon theories and propositions as being represented by sets of possible worlds. Grove's spheres may be thought of as possible "fallback" theories relative to the agent's original theory: theories that he may reach by deleting propositions that are not "sufficiently" entrenched (according to standards of sufficient entrenchment of varying stringency). To put it differently, fallbacks are theories that are closed upwards under entrenchment The entrenchment ordering can be recovered from the family of fallbacks by the definition: A is at least as entrenched as B iff A belongs to every fallback to which B belongs. To revise a theory T with a proposition A, we go to the smallest sphere that contain A-worlds and intersect it with A. The relational notion of belief revision that we are interested in, results from weakening epistemic entrenchment by not assuming it to be connected. I.e., we want to allow that some propositions may be incomparable with respect to epistemic entrenchment. As a result, the family of fallbacks around a given theory will no longer have to be nested. This change opens up the possibility for several different ways of revising a theory with a given proposition. (shrink)

Nozick analyzes fundamental issues, such as the identity of the self, knowledge and skepticism, free will, the foundations of ethics, and the meaning of life.

Counterfactuals is David Lewis' forceful presentation of and sustained argument for a particular view about propositions which express contrary to fact conditionals, including his famous defense of realism about possible worlds and his theory of laws of nature.

In this impressive second edition of Theory of Knowledge, Keith Lehrer introduces students to the major traditional and contemporary accounts of knowing. Beginning with the traditional definition of knowledge as justified true belief, Lehrer explores the truth, belief, and justification conditions on the way to a thorough examination of foundation theories of knowledge,the work of Platinga, externalism and naturalized epistemologies, internalism and modern coherence theories, contextualism, and recent reliabilist and causal theories. Lehrer gives all views careful examination and concludes that (...) external factors must be matched by appropriate internal factors to yield knowledge. This match of internal and external factors follows from Lehrer’s new coherence theory of undefeated justification. In addition to doing justice to the living epistemological traditions, the text smoothly integrates several new lines that will interest scholars. Also, a feature of special interest is Lehrer’s concept of a justification game.This second edition of Theory of Knowledge is a thoroughly revised and updated version that contains several completely new chapters. Written by a well-known scholar and contributor to modern epistemology, this text is distinguished by clarity of structure, accessible writing, and an elegant mix of traditional material, contemporary ideas, and well-motivated innovation. (shrink)

This work, written from a neo-Pyrrhonian perspective, is an examination of contemporary theories of knowledge and justification. It takes ideas primarily found in Sextus Empiricus's Outlines of Pyrrhonism, restates them in a modern idiom, and then asks whether any contemporary theory of knowledge meets the challenges they raise. The first part, entitled "Gettier and the Problem of Knowledge," attempts to rescue our ordinary concept of knowledge from those philosophers who have assigned burdens to it that it cannot bear. Properly understood, (...) Fogelin shows that the concept of knowledge is unproblematic. The second part of this study, called "Agrippa and the Problem of Justification," examines Agrippa's contribution to Pyrrhonism, a systematic reduction of its procedures which came to be known as the "Five Modes Leading to the Suspension of Belief." These modes present a completely general procedure for refuting any claim a dogmatist might make. Though largely unnoticed, there is, according to Fogelin, an uncanny resemblance between problems posed by Agrippa's "Five Modes" and those that contemporary epistemologists address under the heading of a theory of justification. Fogelin examines the strongest contemporary theories of justification--in both foundationalist and anti-foundationalist forms. The conclusion is that recent philosophical writings on justification have made no significant progress in responding to the Pyrrhonian problems these writings have addressed. (shrink)

David Lewis (1941-2001) was Class of 1943 University Professor of Philosophy at Princeton University. His contributions spanned philosophical logic, philosophy of language, philosophy of mind, philosophy of science, metaphysics, and epistemology. In On the Plurality of Worlds, he defended his challenging metaphysical position, "modal realism." He was also the author of the books Convention, Counterfactuals, Parts of Classes, and several volumes of collected papers.

The recently offered, Purported counter-Examples to justified, True belief analyses of knowledge are looked at with some care and all found to be either incoherent or inconclusive. It is argued that justified, True belief analyses are based on sound insight into the concept of knowledge. The distinction between having been justified in claiming to know something and actually having known it is used in an effort to get the discussion of knowledge back on the right track.

Change in View offers an entirely original approach to the philosophical study of reasoning by identifying principles of reasoning with principles for revising one's beliefs and intentions and not with principles of logic. This crucial observation leads to a number of important and interesting consequences that impinge on psychology and artificial intelligence as well as on various branches of philosophy, from epistemology to ethics and action theory. Gilbert Harman is Professor of Philosophy at Princeton University. A Bradford Book.

This book is the first complete survey and critical appraisal of the large body of research that has appeared during approximately the last decade concerning the analysis of knowing. Robert K. Shope pays special attention to the social aspects of knowing and proposes a new formulation of the fundamental structure of the Gettier problem. Originally published in 1983. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University (...) Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905. (shrink)

This paper studies the idea of conservatism with respect to belief change strategies in the setting of unary, iterated belief revision functions (based on the conclusions of Rott, ‘Coherence and Conservatism in the Dynamics of Belief, Part I: Finding the Right Framework’, Erkenntnis 50, 1999, 387–412). Special attention is paid to the case of ‘basic belief change’ where neither the (weak) AGM postulates concerning conservatism with respect to beliefs nor the (stong) supplementary AGM postulates concerning dispositional coherence need to be (...) satisfied. One‐step belief change generated by ‘basic entrenchment’ is combined with a natural conservative method of revising entrenchment relations. A logical characterization of this method is presented, and it is compared with three other methods known from the literature which I call ‘external’, ‘radical’ and ‘moderate’ belief revision. While conservative belief change turns out to be incoherent in its treatment of the recency of information, moderate belief change is more satisfactory in this respect. (shrink)

This volume represents the most comprehensive and authoritative collection of canonical readings in theory of knowledge. It is ideal as a reader for all courses in epistemology.

Volumes I and II provided a completely new translation of the philosophical works of Descartes, based on the best available Latin and French texts. Volume III contains 207 of Descartes' letters, over half of which have previously not been translated into English. It incorporates, in its entirety, Anthony Kenny's celebrated translation of selected philosophical letters, first published in 1970. In conjunction with Volumes I and II it is designed to meet the widespread demand for a comprehensive, authoritative and accurate edition (...) of Descartes' philosophical writings in clear and readable modern English. (shrink)

In this important new text, Keith Lehrer introduces students to the major traditional and contemporary accounts of knowing. Beginning with the accepted definition of knowledge as justified true belief, Lehrer explores the truth, belief and justification conditions on the way to a thorough examination of foundation theories of knowledge, externalism and naturalized epistemologies, internalism and modern coherence theories as well as recent reliabilist and causal theories. Lehrer gives all views careful examination and concludes that external factors must be matched by (...) appropriate internal ones to yield knowledge. Readers of Professor Lehrer's earlier book _Knowledge_ will want to know that this text adopts the framework of that classic text. But _Theory of Knowledge_ is a completely rewritten and updated version of that book that has been simplified throughout for student use. (shrink)

In this paper we present a new modeling for belief revision that is what we term irrevocable. This modeling is of philosophical interest since it captures some features of suppositional reasoning, and of formal interest since it is closely connected with AGM, yet provides for iterated belief revision. The analysis is couched in terms of dynamic doxastic logic.

Isaac Levi's new book develops further his pioneering work in formal epistemology, focusing on the problem of belief contraction, or how rationally to relinquish old beliefs. Levi offers the most penetrating analysis to date of this key question in epistemology, offering a completely new solution and explaining its relation to his earlier proposals. He mounts an argument in favor of the thesis that contracting a state of belief by giving up specific beliefs is to be evaluated in terms of the (...) value of the information lost by doing so. The rationale aims to be thoroughly decision theoretic. Levi spells out his goals and shows that certain types of recommendations are obtained if one seeks to promote these goals. He compares his approach to his earlier account of inductive expansion. The recommendations are for "mild contractions." These are formally the same as the "severe withdrawals" considered by Pagnucco and Rott. The rationale, however, is different. A critical part of the book concerns the elaboration of these differences. The results are relevant to accounts of the conditions under which it is legitimate to cease believing and to accounts of conditionals. Mild Contraction will be of great interest to all specialists in belief revision theory and to many students of formal epistemology, philosophy of science, and pragmatism. (shrink)

Postulational approaches attempt to understand the dynamics of belief revision by appealing to no more than the set of beliefs held by an agent and the logical relations between them. It is argued there that such an approach cannot work. A proper account of belief revision must also appeal to the arguments supporting beliefs, and recognize that those arguments can be defeasible. If we begin with a mature epistemological theory that accommodates this, it can be seen that the belief revision (...) operators on which the postulational theories are based are ill-defined. It is further argued that there is no way to repair the definitions so as to retain the spirit of those theory. Belief revision is better studied from within an independently motivated epistemological theory. (shrink)

Der Aufsatz stellt einige Überlegungen zu internalistischen Lösungsversuchen für das sog. Gettier-Problem an. Dieses Problem besteht darin, daß die klassische Definition von Wissen als gerechtfertigte wahre Meinung unzureichend ist. Ausgehend von naheliegenden Ideen, die an wohlbekannten Beispielen scheitern, unterbreite ich einen eigenen Vorschlag zur Lösung des Problems. Anschließend diskutiere ich den prominenten Ansatz von Keith Lehrer und zeige seine Unzulänglichkeit, aber auch, wie er modifiziert werden kann, um eine befriedigende Lösung des Gettier-Problems zu ergeben. Externalistische Analysen des Wissensbegriffs, die als (...) das entscheidende Kriterium für Wissen ansehen, daß die fragliche Meinung in der richtigen Weise durch den entsprechenden Sachverhalt verursacht ist, werden in diesem Aufsatz nicht behandelt.The subject of this article are internalistic solutions of the Gettier problem. The problem is that the traditional definition of knowledge as justified true belief is unsatisfying. Starting from natural proposals to solve the problem, which are refuted by well-known counterexamples, I arrive at a suggestion of my own. Then I discuss the prominent solution of Keith Lehrer and show that it is unsatisfactory, but also, how it can be modified to yield a correct analysis of knowledge. Externalistic solutions to the problem, which demand that the belief in question be caused in some appropriate way to count as knowledge, are not discussed in this paper. (shrink)

Dynamic doxastic logic (DDL) is used in connexion with theories of belief revision. Here we try to show that languages of DDL are suitable also for discussing aspects of default logic. One ingredient of our analysis is a concept of coherence-as-ratifiability.