Social epistemology is a many-splendored subject. Different theorists adopt different approaches and the options are quite diverse, often orthogonal to one another. The approach I favor is to examine social practices in terms of their impact on knowledge acquisition . This has at least two virtues: it displays continuity with traditional epistemology, which historically focuses on knowledge, and it intersects with the concerns of practical life, which are pervasively affected by what people know or don't know. In making this choice, (...) I am not blind to the allure of alternative approaches. In this paper I explain and motivate the knowledge-centered approach by contrasting it with a newly emerging alternative that has a definite appeal of its own. According to this alternative, the chief dimension of social epistemological interest would be rationality rather than knowledge. (shrink)

It is argued in this paper that there can be both normative and nonnormative, merely factual group beliefs. The former involve the whole social group in question, while the latter only relate to the distributions of personal beliefs within the group. The paper develops a detailed theory, called the positional account of group beliefs, to explicate normative, group-involving group beliefs. Normative group beliefs are characterized within this approach in terms of joint acceptances of views by the group members — or (...) their representatives — acting in their right positions and tasks, and in a sense creating group commitments for all the members to accept (and keep accepting) the view in question. Also aggregate accounts of group belief are considered in the paper, especially the shared we-belief approach. Such aggregate accounts purport to account for merely factual group beliefs. (shrink)

This paper extends earlier work by its authors on formal aspects of the processes of contracting a theory to eliminate a proposition and revising a theory to introduce a proposition. In the course of the earlier work, Gardenfors developed general postulates of a more or less equational nature for such processes, whilst Alchourron and Makinson studied the particular case of contraction functions that are maximal, in the sense of yielding a maximal subset of the theory (or alternatively, of one of (...) its axiomatic bases), that fails to imply the proposition being eliminated. In the present paper, the authors study a broader class, including contraction functions that may be less than maximal. Specifically, they investigate "partial meet contraction functions", which are defined to yield the intersection of some nonempty family of maximal subsets of the theory that fail to imply the proposition being eliminated. Basic properties of these functions are established: it is shown in particular that they satisfy the Gardenfors postulates, and moreover that they are sufficiently general to provide a representation theorem for those postulates. Some special classes of partial meet contraction functions, notably those that are "relational" and "transitively relational", are studied in detail, and their connections with certain "supplementary postulates" of Gardenfors investigated, with a further representation theorem established. (shrink)

In this incisive new book one of Britain's most eminent philosophers explores the often overlooked tension between voluntariness and involuntariness in human cognition. He seeks to counter the widespread tendency for analytic epistemology to be dominated by the concept of belief. Is scientific knowledge properly conceived as being embodied, at its best, in a passive feeling of belief or in an active policy of acceptance? Should a jury's verdict declare what its members involuntarily believe or what they voluntarily accept? And (...) should statements and assertions be presumed to express what their authors believe or what they accept? Does such a distinction between belief and acceptance help to resolve the paradoxes of self-deception and akrasia? Must people be taken to believe everything entailed by what they believe, or merely to accept everything entailed by what they accept? Through a systematic examination of these problems, the author sheds new light on issues of crucial importance in contemporary epistemology, philosophy of mind, and cognitive science. (shrink)

In this paper, we present several extensions of epistemic logic with update operators modelling public information change. Next to the well-known public announcement operators, we also study public substitution operators. We prove many of the results regarding expressivity and completeness using so-called reduction axioms. We develop a general method for using reduction axioms and apply it to the logics at hand.

In an information state where various agents have both factual knowledge and knowledge about each other, announcements can be made that change the state of information. Such informative announcements can have the curious property that they become false because they are announced. The most typical example of that is 'fact p is true and you don't know that', after which you know that p, which entails the negation of the announcement formula. The announcement of such a formula in a given (...) information state is called an unsuccessful update. A successful formula is a formula that always becomes common knowledge after being announced. Analysis of information systems and 'philosophical puzzles' reveals a growing number of dynamic phenomena that can be described or explained by unsuccessful updates. This increases our understanding of such philosophical problems. We also investigate the syntactic characterization of the successful formulas. (shrink)

Draft as of 2001 of a book chapter a^ppeared in 2005. This paper gives an account of the belief/ acceptance distrinction applied to the issue of collective beliefs and intentionality in terms of the "doctrinal dilemma" proposed by some legal theorists.

In 1985 Alchourrón, Gärdenfors and Makinson presented their now classic theory of theory change . In 1988 Adam Grove, generalizing David Lewis's theory of counterfactuals, presented a model theory suitable for the AGM theory. Although AGM and Grove mentioned object languages, neither used them. But recently, Maarten de Rijke has shown how object languages can be brought into the picture. In the present paper we take de Rijke's idea further, addressing the question whether there is a particular doxastic or epistemic (...) logic implicit in AGM. (shrink)

Logical puzzles like the doctrinal paradox raise the problem of how to aggregate individual judgements into a collective judgement, or alternatively, how to merge collectively inconsistent knowledge bases. In this paper, we view judgement aggregation as a function on propositional logic valuations, and we investigate how logic constrains judgement aggregation. In particular, we show that there is no non-dictatorial decision method for aggregating sets of judgements in a logically consistent way if the decision method is local, i.e., only depends on (...) the individual judgements on the proposition under consideration. (shrink)

Taken as a model for how groups should make collective judgments and decisions, the ideal of deliberative democracy is inherently ambiguous. Consider the idealised case where it is agreed on all sides that a certain conclusion should be endorsed if and only if certain premises are admitted. Does deliberative democracy recommend that members of the group debate the premises and then individually vote, in the light of that debate, on whether or not to support the conclusion? Or does it recommend (...) that members individually vote on the premises, and then let their commitment to the conclusion be settled by whether or not the group endorses the required premises? Is deliberative democracy to enforce the discipline of reason at the individual level, as in the first possibility, or at the collective level, as in the second? (shrink)

We construct logical languages which allow one to represent a variety of possible types of changes affecting the information states of agents in a multi-agent setting. We formalize these changes by defining a notion of epistemic program. The languages are two-sorted sets that contain not only sentences but also actions or programs. This is as in dynamic logic, and indeed our languages are not significantly more complicated than dynamic logics. But the semantics is more complicated. In general, the semantics of (...) an epistemic program is what we call aprogram model. This is a Kripke model of ‘actions’,representing the agents' uncertainty about the current action in a similar way that Kripke models of ‘states’ are commonly used in epistemic logic to represent the agents' uncertainty about the current state of the system. Program models induce changes affecting agents' information, which we represent as changes of the state model, called epistemic updates. Formally, an update consists of two operations: the first is called the update map, and it takes every state model to another state model, called the updated model; the second gives, for each input state model, a transition relation between the states of that model and the states of the updated model. Each variety of epistemic actions, such as public announcements or completely private announcements to groups, gives what we call an action signature, and then each family of action signatures gives a logical language. The construction of these languages is the main topic of this paper. We also mention the systems that capture the valid sentences of our logics. But we defer to a separate paper the completeness proof. (shrink)

Belief is not a unified phenomenon. In this paper I argue, as a number of other riters argue, that one should distinguish a variety of belief-like attitudes: believing proper - a dispositional state which can have degrees - holding true - which can occur without understanding what one believes - and accepting - a practical and contextual attitude that has a role in deliberation and in practical reasoning. Acceptance itself is not a unified attitude. I explore the various relationships and (...) differences between these doxastic attitudes, and claim that although acceptance is distinct from belief, it rests upon it, and is therefore a species of belief. (shrink)