In this paper we present a brief overview of logic-based belief change, a research area concerned with the question of how a rational agent ought to change its mind in the face of new, possibly conflicting, information. Our intention is to provide the reader with a basic introduction to the work done in this area over the past 30 years. In doing so we hope to sketch the main historical results, provide appropriate pointers to further references, and discuss some current (...) developments. We trust that this will spur on the interested reader to learn more about the topic, and perhaps to join us in the further development of this exciting field of research. (shrink)

Most approaches to iterated belief revision are accompanied by some motivation for the use of the proposed revision operator (or family of operators), and typically encode enough information in the epistemic state of an agent for uniquely determining one-step revision. But in those approaches describing a family of operators there is usually little indication of how to proceed uniquely after the first revision step. In this paper we contribute towards addressing that deficiency by providing a formal framework which goes beyond (...) the first revision step in two ways. First, the framework is obtained by enriching the epistemic state of an agent starting from the following intuitive idea: we associate to each world x two abstract objects x⁺ and x⁻, and we assume that, in addition to preferences over the set of worlds, we are given preferences over this set of objects as well. The latter can be considered as meta-information encoded in the epistemic state which enables us to go beyond the first revision step of the revision operator being applied, and to obtain a unique set of preferences over worlds. We then extend this framework to consider, not only the revision of preferences over worlds, but also the revision of this extended structure itself. We look at some desirable properties for revising the structure and prove the consistency of these properties by giving a concrete operator satisfying all of them. Perhaps more importantly, we show that this framework has strong connections with two other types of constructions in related areas. Firstly, it can be seen as a special case of preference aggregation which opens up the possibility of extending the frame-work presented here into a full-fledged framework for preference aggregation and social choice theory. Secondly, it is related to existing work on the use of interval orderings in a number of different contexts. (shrink)

We provide a formal study of belief retraction operators that do not necessarily satisfy the postulate. Our intuition is that a rational description of belief change must do justice to cases in which dropping a belief can lead to the inclusion, or ‘liberation’, of others in an agent's corpus. We provide two models of liberation via retraction operators: ρ-liberation and linear liberation. We show that the class of ρ-liberation operators is included in the class of linear ones and provide axiomatic (...) characterisations for each class. We show how any retraction operator can be ‘converted’ into either a withdrawal operator ) or a revision operator via the Harper Identity and the Levi Identity respectively. (shrink)

In studies of multi-agent interaction, especially in game theory, the notion of equilibrium often plays a prominent role. A typical scenario for the belief merging problem is one in which several agents pool their beliefs together to form a consistent "group" picture of the world. The aim of this paper is to define and study new notions of equilibria in belief merging. To do so, we assume the agents arrive at consistency via the use of a social belief removal function, (...) in which each agent, using his own individual removal function, removes some belief from his stock of beliefs. We examine several notions of equilibria in this setting, assuming a general framework for individual belief removal due to Booth et al. We look at their inter-relations as well as prove their existence or otherwise. We also show how our equilibria can be seen as a generalisation of the idea of taking maximal consistent subsets of agents. (shrink)

Philosophers of modern logic have cherished no project more dearly than that of extensional reduction. Despite occasional protests that this project was ill-conceived from the start, or that it fails to account for important areas of experience and thought, the extensionalist mills have been grinding away anyhow. Their grinding has brought with it a number of important technical successes, replete with philosophical claims that light has finally been shed on areas hitherto buried in incomprehensible darkness.

Most belief change operators in the AGM tradition assume an underlying plausibility ordering over the possible worlds which is transitive and complete. A unifying structure for these operators, based on supplementing the plausibility ordering with a second, guiding, relation over the worlds was presented in Booth et al. (Artif Intell 174:1339-1368, 2010). However it is not always reasonable to assume completeness of the underlying ordering. In this paper we generalise the structure of Booth et al. (Artif Intell 174: 1339-1368, 2010) (...) to allow incomparabilities between worlds. We axiomatise the resulting class of belief removal functions, and show that it includes an important family of removal functions based on finite prioritised belief bases. (shrink)

Human lives are radically uncertain. Making sense of such uncertainties is the hallmark of wisdom. Sense-making requires narratives, putting them in the center stage of human everyday decision-making. Yet what if radical uncertainty is a narrative itself? Moreover, do laypeople always consider such narratives irrational? Here we pose these questions to enrich a theory of choice under uncertainty.

One of the most dominant approaches to semantics for relevant (and many paraconsistent) logics is the Routley-Meyer semantics involving a ternary relation on points. To some (many?), this ternary relation has seemed like a technical trick devoid of an intuitively appealing philosophical story that connects it up with conditionality in general. In this paper, we respond to this worry by providing three different philosophical accounts of the ternary relation that correspond to three conceptions of conditionality. We close by briefly (...) discussing a general conception of conditionality that may unify the three given conceptions. (shrink)

As the expansion of the Internet and the digital formatting of all kinds of creative works move us further into the information age, intellectual property issues have become paramount. Computer programs costing thousands of research dollars are now copied in an instant. People who would recoil at the thought of stealing cars, computers, or VCRs regularly steal software or copy their favorite music from a friend's CD. Since the Web has no national boundaries, these issues are international concerns. The contributors-philosophers, (...) legal theorists, and business scholars, among others-address questions such as: Can abstract ideas be owned? How does the violation of intellectual property rights compare to the violation of physical property rights? Can computer software and other digital information be protected? And how should legal systems accommodate the ownership of intellectual property in an information age? Intellectual Property is a lively examination of these and other issues, and an invaluable resource for librarians, lawyers, businesspeople, and scholars. (shrink)

Community Partnered Participatory Research is grounded in the ethical principle of respect for persons participating in the research enterprise. The critical importance of respect for person...

Hastings Center Report, Volume 52, Issue 1, Page 51-58, January/February 2022.

This book is a collection of secondary essays on America's most important philosophic thinkers—statesmen, judges, writers, educators, and activists—from the colonial period to the present. Each essay is a comprehensive introduction to the thought of a noted American on the fundamental meaning of the American regime.

Moritz Schlick’s interpretation of the causality principle is based on Schlick’s understanding of quantum mechanics and on his conviction that quantum mechanics strongly supports an empiricist reading of causation in his sense. The present paper compares the empiricist position held by Schlick with Bas van Fraassen’s more recent conception of constructive empiricism. It is pointed out that the development from Schlick’s understanding of logical empiricism to constructive empiricism reflects a difference between the understanding of quantum mechanics endorsed by Schlick (...) and the understanding that had been established at the time of van Fraassen’s writing. (shrink)