Ordinary common knowledge is formally expressed by strong probabilistic common belief. How strong exactly? The question can be answered by drawing from the similar equivalence, recently explored, between plain and probabilistic individual beliefs. I argue that such a move entails that common knowledge displays a double fragility: as a description of a collective state and as a phenomenon, because it can respectively disappear as group size increases, or more worryingly as the epistemic context changes. I argue that despite this latter (...) fragility, the effects of common knowledge on action are robust. Unfortunately, this in turn leads to a third fragility, that of the concept of common knowledge, which threatens to collapse on probabilistic common belief. This also reveals a disanalogy between the individual and the collective cases. I finally pinpoint the subtle difference entailed by the two concepts, expressed in terms of the attitude towards contrary evidence or of the agents’ awareness. As a result, common knowledge can be defended as a concept, which refers to a fragile yet distinct collective attitude. (shrink)

Are individuals responsible for the consequences of actions taken by their community? What about their community's inaction or its attitudes? In this innovative book, Larry May departs from the traditional Western view that moral responsibility is limited to the consequences of overt individual action. Drawing on the insights of Arendt, Jaspers, and Sartre, he argues that even when individuals are not direct participants, they share responsibility for various harms perpetrated by their communities.

Social action is central to social thought. This centrality reflects the overwhelming causal significance of action for social life, the centrality of action to any account of social phenomena, and the fact that conventions and normativity are features of human activity. This book provides philosophical analyses of fundamental categories of human social action, including cooperative action, conventional action, social norm governed action, and the actions of the occupants of organizational roles. A distinctive feature of the book is that it applies (...) these theories of social action categories to some important moral issues that arise in social contexts such as the collective responsibility for environmental pollution, humanitarian intervention, and dealing with the rights of minority groups. Avoiding both the excessively atomistic individualism of rational choice theorists and implausible collectivist assumptions, this important book will be widely read by philosophers of the social sciences, political scientists and sociologists. (shrink)

_ Convention_ was immediately recognized as a major contribution to the subject and its significance has remained undiminished since its first publication in 1969. Lewis analyzes social conventions as regularities in the resolution of recurring coordination problems-situations characterized by interdependent decision processes in which common interests are at stake. Conventions are contrasted with other kinds of regularity, and conventions governing systems of communication are given special attention.

Most reductionist accounts of intentional joint action include a condition that it must be common knowledge between participants that they have certain intentions and beliefs that cause and coordinate the joint action. However, this condition has typically simply been taken for granted rather than argued for. The condition is not necessary for ensuring that participants are jointly responsible for the action in which each participates, nor for ensuring that each treats the others as partners rather than as social tools. It (...) is thus something of a mystery why the condition is so widely accepted. By rejecting three arguments that could potentially support it, I argue that reductionists should get rid of the condition. I show that two of the arguments fail. While the third argument is intuitively compelling, it builds on key premises that are unavailable to the reductionist. (shrink)

Human beings act together in characteristic ways that matter to us a great deal. This book explores the conceptual, metaphysical and normative foundations of such sociality. It argues that appeal to the planning structures involved in our individual, temporally extended agency provides substantial resources for understanding these foundations of our sociality.

This paper offers a comparison of three different kinds of collective attitudes: aggregate, common, and corporate attitudes. They differ not only in their relationship to individual attitudes—e.g., whether they are “reducible” to individual attitudes—but also in the roles they play in relation to the collectives to which they are ascribed. The failure to distinguish them can lead to confusion, in informal talk as well as in the social sciences. So, the paper’s message is an appeal for disambiguation.

Are individuals responsible for the consequences of actions taken by their community? What about their community's inaction or its attitudes? In this innovative book, Larry May departs from the traditional Western view that moral responsibility is limited to the consequences of overt individual action. Drawing on the insights of Arendt, Jaspers, and Sartre, he argues that even when individuals are not direct participants, they share responsibility for various harms perpetrated by their communities.

This is a revision of game theory which takes account of agents' own descriptions of their situations, and which allows people to reason as members of groups.

This book offers original accounts of a number of central social phenomena, many of which have received little if any prior philosophical attention. These phenomena include social groups, group languages, acting together, collective belief, mutual recognition, and social convention. In the course of developing her analyses Gilbert discusses the work of Emile Durkheim, Georg Simmel, Max Weber, David Lewis, among others.

Philosophers have proposed accounts of shared intentions that aim at capturing what makes a joint action intentionally joint. On these accounts, having a shared intention typically presupposes cognitively and conceptually demanding theory of mind skills. Yet, young children engage in what appears to be intentional, cooperative joint action long before they master these skills. In this paper, I attempt to characterize a modest or ‘lite’ notion of shared intention, inspired by Michael Bacharach’s approach to team–agency theory in terms of framing, (...) group identification and team reasoning. I argue that the account of shared intentions this approach yields is less cognitively and conceptually demanding than other accounts and is thus applicable to the intentional joint actions performed by young children. I also argue that it has limitations of its own and that considering what these limitations are may help us understand why we sometimes need to take other routes to shared intentions. (shrink)

What is law (and why should we care)? -- Crazy little thing called "law" -- Austin's sanction theory -- Hart and the rule of recognition -- How to do things with plans -- The making of a legal system -- What law is -- Legal reasoning and judicial decision making -- Hard cases -- Theoretical disagreements -- Dworkin and distrust -- The economy of trust -- The interpretation of plans -- The value of legality.

One does not simply predict where the other will go, which is wherever the first predicts the second to predict the first to go, and so ad infinitum. Not "What would I do if I were she?" but "What would I do if I were she wondering what she would do if she were wondering what I would do if I were she...?".

Shared agency is of central importance in our lives in many ways. We enjoy engaging in certain joint activities with others. We also engage in joint activities to achieve complex goals. Current approaches propose that we understand shared agency in terms of the more basic phenomenon of shared intention. However, they have presented two antagonistic views about the nature of this phenomenon. Some have argued that shared intention should be understood as being primarily a structure of attitudes of individual participants (...) and their interrelations (Bratman, Searle, Tuomela and Miller). Others have claimed that shared intention should be regarded as being primarily a normative transaction which gives rise to interpersonal obligations (Gilbert). In contrast to these approaches, I propose a compromise view. I argue that shared intention involves a complex socio-psychological structure which ensures, in the absence of special circumstances, the existence of relevant moral obligations. My argument involves two main steps. First, I show that shared intention includes important relations of mutual reliance between the participants. Then, I argue that the existence of these relations of mutual reliance in shared intention helps us explain why, failing special circumstances, shared intention generates those obligations. This provides, in my view, a solution to the vexed question of the relation between shared intention and interpersonal obligations. (shrink)

The everyday concept of a social group is approached by examining the concept of going for a walk together, an example of doing something together, or "shared action". Two analyses requiring shared personal goals are rejected, since they fail to explain how people walking together have obligations and rights to appropriate behavior, and corresponding rights of rebuke. An alternative account is proposed: those who walk together must constitute the "plural subject" of a goal. The nature of plural subjecthood, the thesis (...) that social groups are plural subjects, and the relation of these ideas to Rousseau's and Hobbes 's, are briefly explored. (shrink)

David Lewis is widely credited with the first formulation of common knowledge and the first rigorous analysis of convention. However, common knowledge and convention entered mainstream game theory only when they were formulated, later and independently, by other theorists. As a result, some of the most distinctive and valuable features of Lewis' game theory have been overlooked. We re-examine this theory by reconstructing key parts in a more formal way, extending it, and showing how it differs from more recent game (...) theory. In contrast to current theories of common knowledge, Lewis' theory is based on an explicit analysis of the modes of reasoning that are accessible to rational individuals and so can be used to analyse the genesis of common knowledge. Lewis' analysis of convention emphasises the role of inductive reasoning and of salience in the maintenance of conventions over time. Footnotes Earlier versions of this paper were presented at the 13th Amsterdam Colloquium at the University of Amsterdam, at a workshop on social norms at Wissenschaftskolleg zu Berlin, and at seminars at Tilburg University and the University of Bristol. We are grateful for comments from participants at those meetings, from two anonymous referees, and from Michael Bacharach, Nick Bardsley, Cristina Bicchieri, Luc Bovens, Simon Grant, David McCarthy, Shepley Orr, Brian Skyrms, Peter Vanderschraaf, Peter Wakker and Jörgen Weibull. Robert Sugden's work was supported by the Leverhulme Trust. (shrink)

Two partners plan to rob a bank. The first recruits a driver while the second purchases a shotgun from a gun dealer. The driver knows he’s taking part in a robbery, although not a bank robbery. The gun dealer should have checked his customer’s police record before the sale, but failed to do so. The bank is robbed, a guard is killed, and the robbers escape, only to be caught later. “They committed bank robbery,” a prosecutor will say. But does (...) “they” include the gun dealer, whose lax standards made the robbery possible? “They conspired to rob the bank”—but does “they” here include the driver, who didn’t know it was a bank they were robbing? “They killed a bank guard”—but does it matter which robber inside the bank pulled the trigger? (shrink)

What is involved when a group of agents decide to do something together? Joint action by a team appears to involve more than just the union of simultaneous individual actions, even when those actions are coordinated. We would not say that there is any teamwork involved in ordinary automobile traffic, even though the drivers act simultaneously and are coordinated (one hopes) by the traffic signs and rules of the road. But when a group of drivers decide to do something together, (...) such as driving somewhere as a convoy, it appears that the group acts more like a single agent with beliefs, goals, and intentions of its own, over and above the individual ones. [more]. (shrink)

This paper offers an analysis of the logical form of plural action sentences that shows that collective actions so ascribed are a matter of all members of a group contributing to bringing some event about. It then uses this as the basis for a reductive account of the content of we-intentions according to which what distinguishes we-intentions from I-intentions is that we-intentions are directed about bringing it about that members of a group act in accordance with a shared plan.

This collection of essays by one of the most prominent and internationally respected philosophers of action theory is concerned with deepening our understanding of the notion of intention. In Bratman's view, when we settle on a plan for action we are committing ourselves to future conduct in ways that help support important forms of coordination and organization both within the life of the agent and interpersonally. These essays enrich that account of commitment involved in intending, and explore its implications for (...) our understanding of temptation and self-control, shared intention and shared cooperative activity, and moral responsibility. The essays offer extensive discussions of related views by, among others, Donald Davidson, Hector-Neri Castañeda, Christine Korsgaard, Harry Frankfurt, and P. F. Strawson. This collection will be a valuable resource for a wide range of philosophers and their students. (shrink)

Most definitions of cooperation provide sufficient but not necessary conditions. This paper describes a form of minimal cooperation, corresponding to mass actions implying many agents, such as demonstrations. It characterizes its intentional, epistemic, strategic, and teleological aspects, mostly obtained from weakening classical concepts. The rationality of minimal cooperation turns out to be part of its definition, whereas it is usually considered as an optional though desirable feature. Game-theoretic concepts thus play an important role in its definition. The paper concludes by (...) answering concrete questions about what should and should not be called cooperation. (shrink)

This book develops a view of logic as a theory of information-driven agency and intelligent interaction between many agents - with conversation, argumentation and games as guiding examples. It provides one uniform account of dynamic logics for acts of inference, observation, questions and communication, that can handle both update of knowledge and revision of beliefs. It then extends the dynamic style of analysis to include changing preferences and goals, temporal processes, group action and strategic interaction in games. Throughout, the book (...) develops a mathematical theory unifying all these systems, and positioning them at the interface of logic, philosophy, computer science and game theory. A series of further chapters explores repercussions of the 'dynamic stance' for these areas, as well as cognitive science. (shrink)

Defined and formalized several decades ago, widely used in philosophy and game theory, the concept of common knowledge is still considered as problematic, although not always for the right reasons. I suggest that the epistemic status of a group of human agents in a state of common knowledge has not been thoroughly analyzed. In particular, every existing account of common knowledge, whether formal or not, is either too strong to fit cognitively limited individuals, or too weak to adequately describe their (...) state. I provide a realistic definition of common knowledge, based on a formalization of David Lewis’ seminal account and show that it is formally equivalent to probabilistic common belief. This leads to a philosophical analysis of common knowledge which answers several common criticisms and sheds light on its nature. (shrink)

University of Cologne, Germany Joint action and group agency have emerged as focuses of attention in recent social theory and philosophy but they have rarely been connected with one another. The argument of this article is that whereas joint action involves people acting together to achieve any sort of result, group agency requires them to act together for the achievement of one result in particular: the construction of a centre of attitude and agency that satisfies the usual constraints of consistency (...) and rationality in adequate measure. The main discovery in the recent theory of group agency is that this result is not easily achieved; no regular voting procedure will ensure, for example, that a group of individually consistent agents will display consistency in group judgments. Key Words: groups • group agents • collective agents • joint action • joint intention. (shrink)

Two approaches to instrumental rationality Suppose I intend end E, believe that a necessary means to E is M, and believe that M requires that I intend M. My attitudes concerning E and M engage a basic requirement of practical rationality, a requirement that, barring a change in my cited beliefs, I either intend M or give up intending E.2 Call this the Instrumental Rationality requirement – for short, the IR requirement.

What is required for several agents to intentionally φ together? I argue that each of them must believe or assume that their φ-ing is a single end that each intends to contribute to. Various analogies between intentional singular action and intentional joint action show that this doxastic single end condition captures a feature at the very heart of the phenomenon of intentional joint action. For instance, just as several simple actions are only unified into a complex intentional singular activity if (...) the agent believes or assumes that there is a single end that each action is directed to, so several agents’ actions are only unified into an intentional joint activity if each agent believes or assumes that there is a single end that each intends to contribute to. Influential accounts of intentional joint action, including Christopher Kutz’s and Michael Bratman’s, implicitly include this condition only if participants must intend to contribute to the end under the same conception. While such a requirement successfully rules out some counterexamples, it also makes the accounts unable to appropriately accommodate and explain clear cases of intentional joint action that they ought to be able to accommodate and explain. (shrink)

Writers on collective action are in broad agreement that in order for a group of agents to form a collective intention, the members of that group must have beliefs about the beliefs of the other members. But in spite of the fact that this so-called "interactive knowledge" is central to virtually every account of collective intention, writers on this subject have not offered a detailed account of the nature of interactive knowledge. In this paper, we argue that such an account (...) is necessary for any adequate analysis of collective intention. Furthermore, we argue that an application of Robert Aumann's theory of interactive knowledge may be used to address several puzzling features of collective intention. CiteULike Connotea Del.icio.us What's this? (shrink)

Given the premise that joint action plays some role in explaining how humans come to understand minds, what could joint action be? Not what a leading account, Michael Bratman's, says it is. For on that account engaging in joint action involves sharing intentions and sharing intentions requires much of the understanding of minds whose development is supposed to be explained by appeal to joint action. This paper therefore offers an account of a different kind of joint action, an account compatible (...) with the premise about development. The new account is no replacement for the leading account; rather the accounts characterise two kinds of joint action. Where the kind of joint characterised by the leading account involves shared intentions, the new account characterises a kind of joint action involving shared goals. (shrink)

This chapter aims at investigating the phenomenology of joint action and at gaining a better understanding of (1) how the sense of agency one experiences when engaged in a joint action differs from the sense of agency one has for individual actions and (2) how the sense of agency one experiences when engaged in a joint action differs according to the type of joint action and to the role one plays in it.