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Stalnaker (Context, Oxford University Press, Oxford, 2014) defends two ideas about common ground. The first is that the common ground of a conversation is definable in terms of an iterated propositional attitude of acceptance, so that p is common ground iff p is commonly accepted. The second is the idea that the "default setting" of conversational acceptance is belief, so that as a default, what is accepted in conversation coincides with what is (commonly) believed. In this paper, I argue that we should favor a pair of contrasting theses instead. First, I argue that we should identify the common ground with what is common knowledge about what is accepted, so that p is common ground iff it is common knowledge that p is accepted. Thus the attitude that is iterated in the definition of common ground is not acceptance but knowledge. Second, I argue that the "default setting" for conversational acceptance is not belief, but knowledge. [ABSTRACT FROM AUTHOR]

Domain adaptation aims to alleviate the impact of distribution differences when migrating knowledge from the source domain to the target domain. However, two issues remain to be addressed. One is the difficulty of learning both marginal and specific knowledge at the same time. The other is the low quality of pseudo labels in target domain can constrain the performance improvement during model iteration. To solve the above problems, we propose a domain adaptation method called Joint Marginal and Central Sample Learning (JMCSL). This method consists of three parts which are marginal sample learning (MSL), central sample learning (CSL) and unified strategy for multi-classifier (USMC). MSL and CSL aim to better learning of common and specific knowledge. USMC improves the accuracy and stability of pseudo labels in the target domain. Specifically, MSL learns specific knowledge from a novel triple distance, which is defined by sample pair and their class center. CSL uses the closest class center and the second closest class center of samples to retain the common knowledge. USMC selects label consistent samples by applying K-Nearest Neighbors (KNN) and Structural Risk Minimization (SRM), while it utilizes the class centers of both two domains for classification. Finally, extensive experiments on four visual datasets demonstrate that JMCSL is superior to other competing methods. [ABSTRACT FROM AUTHOR]

Axel Seemann's book, "The Shared World: Perceptual Common Knowledge, Demonstrative Communication, and Social Space," explores the concept of joint attention and its relationship to perceptual common knowledge, demonstrative communication, and social space. The book combines philosophical analysis with empirical research in developmental psychology and social neuroscience. Seemann argues that joint perceptual capacities, including joint perception, joint attention, and perceptual common knowledge, play a central role in our ability to perceive a shared world. The book offers a unified account of joint perceptual capacities and their significance in understanding the relation between mind and world. The text discusses the concept of joint perception and its role in successful demonstrative communication, proposing a social disjunctivism approach that emphasizes the importance of joint perception and common knowledge of reference. The text also explores the idea of a social spatial framework and its role in joint attention, highlighting the connection between perception, attention, and communication. The author supports their arguments with empirical evidence and acknowledges the challenges of reconciling philosophical debates. Overall, this text offers valuable insights into the relationship between perception, communication, and the shared world. [Extracted from the article]

We show that knowledge satisfies interpersonal independence, meaning that a non-trivial sentence describing one agent’s knowledge cannot be equivalent to a sentence describing another agent’s knowledge. The same property of interpersonal independence holds, mutatis mutandis, for belief. In the case of knowledge, interpersonal independence is implied by the fact that there are no non-trivial sentences that are common knowledge in every model of knowledge. In the case of belief, interpersonal independence follows from a strong interpersonal independence that knowledge does not have. Specifically, there is no sentence describing the beliefs of one person that implies a sentence describing the beliefs of another person. [ABSTRACT FROM AUTHOR]

I argue that joint attention solves the "base problem" as it arises for Schiffer's and Lewis's theories of common knowledge. The problem is that an account is needed of the perceptual base of some forms of common knowledge that gets by without itself invoking common knowledge. The paper solves the problem by developing a theory of joint attention as consisting in the exercise of joint know-how involving particular and sometimes distal targets and arguing that certain joint perceivers can always have a minimal form of propositional common knowledge about the location of these targets. On such a view, perceptual common knowledge is based on the experience of a process that is maintained by way of perceivers' exercise of an object-involving form of joint know-how. Some reductive theories of collective intentionality require that agents' intentions and subplans are common knowledge (or "out in the open") between them. For these theories the base problem arises again. The enacted theory of joint attention can solve the problem. The argument is exactly parallel to the common knowledge case. The openness of joint agents' intentions and meshing subplans is explained by appeal to their practical knowledge of how to maintain the process by way of which they pursue the collective intention. They can then make this knowledge explicit by linguistic communication. When they succeed in communicating knowledge of their meshing subplans as pursued in a joint action context, they necessarily have this knowledge in common. For theories of collective intentionality that include a common knowledge condition, the experience of participating in a perceptually constituted joint action provides the base that renders harmless the regress that otherwise threatens reductive analyses. [ABSTRACT FROM AUTHOR]

Some arguments against the assumption that ordinary people may share common knowledge are sound. The apparent cost of such arguments is the rejection of scientific theories that appeal to common knowledge. My proposal is to accept the arguments without rejecting the theories. On my proposal, common knowledge is shared by ideally rational people, who are not just mathematically simple versions of ordinary people. They are qualitatively different from us, and theorizing about them does not lead to predictions about our behavior. Nevertheless, models of action that assume common knowledge have a role to play in our understanding of collective rationality. [ABSTRACT FROM AUTHOR]

This study explores enablers that help researchers to undertake collaborative transdisciplinary work with non-academic actors to co-produce knowledge on complex climate risks in African cities. Enablers were explored using a qualitative case study approach and expansive learning theory, which emphasises the embeddedness of practices in cultural and historical contexts. Concepts associated with expansive learning helped to consider relational enablers, namely: (i) capabilities required by researchers to understand the perspectives, values and motives of non-academic actors and make their own explicit; (ii) characteristics of spaces that allowed diverse participants to engage with perspectives, values and motives of others; and (iii) knowledge of the motivation behind different practices of non-academic actors, as embedded in different contexts. Findings highlight the importance of researchers' intentional efforts to engage non-academic actors in their city contexts and respond to local priorities. Design elements that enabled relational work included explicit co-production framings, sharing experiences and opportunities for understanding various actor groups through structured activities and informal dialogues. The study highlights the situated and dialectical relationship between growing relational capabilities of researchers and their engagement in transdisciplinarity, provided spaces were created for reflection on activities. Relational enablers helped researchers to understand the heterogeneous experiences of actors working in African cities and tensions that influence their practices including traditional knowledge paradigms and siloed ways of working. The "champions" identified by researchers were those non-academic actors who took agency to engage with these tensions and begin transforming their practices towards multi-actor transdisciplinary knowledge co-production. [ABSTRACT FROM AUTHOR]

We explore the relationship between evidence and knowledge when knowledge is described by a standard partition over a finite state space, and evidence is represented by a state-dependent collection of finite sets of messages. When the collection is measurable with respect to the partition, there is evidence for an event only if the event is self-evident—i.e., known at every one of its states. Thus, an event is commonly known in and only if there is mutual evidence that implies that the event has occurred, and all knowledge can be proved only when the agent is informed about the state or knows nothing. The existence of partial provability outside these two extremes hinges on the non monotonic nature of provability. [ABSTRACT FROM AUTHOR]

In his “Common knowledge” (2016) and The Transmission of Knowledge (2021), John Greco proposes a novel account of hinge propositions. Central to it is the idea that they are items of common knowledge – that is, of knowledge that is already present in the system, freely available to anyone, without having to figure it out by oneself or having to be taught it by others. As such, they are not subject to any quality control at all. Furthermore, they figure in a subject’s cognitive economy as items of procedural, mostly tacit knowledge, which is operative in the execution of actions and various cognitive tasks. After introducing the basics of Greco’s account, I consider it from a systematic and historical perspective and argue that, while instructive, it is wanting in several respects. Whereas some, among the myriad hinges Wittgenstein considers in On Certainty (1969), may be known, there is no need to make them the content of a different kind of knowledge. Furthermore, we cannot have (evidential) justification and, a fortiori, knowledge of at least some other propositions that Wittgenstein considered as hinges. In passing, I also show that Greco’s account aligns much more with G. E. Moore’s ideas about the epistemic status of his truisms in “A defence of common sense” (1925) and the premises of his celebrated “Proof of an external world” (1939), than with Wittgenstein’s account of hinges and their epistemic significance in On Certainty. [ABSTRACT FROM AUTHOR]

In this paper, we propose a dynamic epistemic framework to capture the knowledge evolution in multi-agent systems where agents are not able to observe. We formalize multi-agent conformant planning with group knowledge, and reduce planning problems to model checking problems. We prove that multi-agent conformant planning with group knowledge is Pspace-complete on the size of dynamic epistemic models. We also consider the alternative Kripke semantics, and show that for each Kripke model with perfect recall and no miracles, there is an equivalent dynamic epistemic model and vice versa. [ABSTRACT FROM AUTHOR]

Common knowledge, that is, a common understanding of environmental conditions, task objectives, coordination rules, etc., can greatly improve the collaborative efficiency of swarm robots. In many complex task scenarios, it is impossible to assume there is a central facility (e.g., a powerful robot or a back-end server that can communicate effectively with everyone) responsible for maintaining the collective's common knowledge. Instead, we must maintain it in a decentralized way. Blockchain has been proved to be an effective means of meeting this demand. It can even tolerate malicious or malfunctioning individuals to a certain extent, which is an important capability for swarm robots to operate in an open or hostile environment. However, current widely-accepted Blockchain techniques, such as Ethereum, use the proof-of-work mechanism as the basis of reaching consensus, which has to consume huge computing resources and is not suitable for swarm robots. In this paper, we present a fast and robust solution for maintaining common knowledge in swarm robots based on Hashgraph, a lightweight consensus technology being originally proposed for fully-connected, well-conditioned networks. We successfully improve its kernel mechanisms to adapt it to swarm robots with limited communication capabilities. And we novelly introduce the concept of Ranger Robot, a special kind of robot that can significantly accelerate the formation of consensus in sparsely-distributed or physically-partitioned robot swarms. Furthermore, we design a knowledge validation algorithm to enable the robot swarm to recognize attacks from a special kind of malicious robot called Byzantine robots. The results of a set of experiments based on both simulated and real robots show that our solution can greatly reduce computing overhead and accelerate the formation of consensus in comparison with solutions based on the original Hashgraph. [ABSTRACT FROM AUTHOR]

The article deals with infinitary modal logic. We first discuss the difficulties related to the development of a satisfactory proof theory and then we show how to overcome these problems by introducing a labelled sequent calculus which is sound and complete with respect to Kripke semantics. We establish the structural properties of the system, namely admissibility of the structural rules and of the cut rule. Finally, we show how to embed common knowledge in the infinitary calculus and we discuss first-order extensions of infinitary modal logic. [ABSTRACT FROM AUTHOR]

This paper reveals a serious flaw in the consequentialist solution to the inefficacy problem in moral philosophy. The consequentialist solution is based on expected utility theory. In current philosophical literature, the debate focuses on the empirical plausibility of the solution. Most philosophers consider the cases of collective actions as of the same type as a horse-racing game, where expected utility theory is adequate to solve the choice problem. However, these cases should be considered as of the same type as a coordination game, where the assumption of common knowledge is also required. However, the assumption is implausible—it is impossible to obtain common knowledge of rationality in cases such as voting. [ABSTRACT FROM AUTHOR]

To understand lying, we naturally focus on small scale lies involving one speaker, one listener, one assertion. This methodology confers artificial plausibility upon the requirement that liars intend to deceive. For it excludes principal-agent conflicts that emerge from linguistic division of labor. When an employee lies for her boss, she need not inherit his motive to deceive. She displays loyalty even if her lie does not deceive. Focus on a single lie in isolation also blinds us to tactical deceptions such as telling a lie which is intended to be caught to advance another lie. Many of these complexities arise from situations that approximate common knowledge without quite crystallizing into this uniform transparency. [ABSTRACT FROM AUTHOR]

I articulate the question of the value of common knowledge, or the question of why common knowledge is preferred to mere widespread knowledge. I argue that common knowledge often enjoys instrumental value lacked by widespread knowledge, and present a case that suggests that common knowledge sometimes enjoys non-instrumental value lacked by widespread knowledge. But I articulate some doubts about whether we should draw that conclusion from the case. [ABSTRACT FROM AUTHOR]

In a Bayesian dialogue two individuals report their Bayesian updated belief about a certain event back and forth, at each step taking into account the additional information contained in the updated belief announced by the other at the previous step. Such a process, which operates through a reduction of the set of possible states of the world, converges to a commonly known posterior belief, which can be interpreted as a dynamic foundation for Aumann's agreement result. Certainly, if two individuals have diverging interests, truthfully reporting one's Bayesian updated belief at every step might not be optimal. This observation could lead to the intuition that always truthfully reporting one's Bayesian updated belief were the best that two individuals could do if they had perfectly coinciding interests and these were in line with coming to know the truth. This article provides an example which shows this intuition to be wrong. In this example, at some step of the process, one individual has an incentive to deviate from truthfully reporting his Bayesian updated belief. However, not in order to hide the truth, but to help it come out at the end: to prevent the process from settling into a commonly known belief—the "Aumann conditions"—on a certain subset of the set of possible states of the world (in which the process then would be blocked), and this way make it converge to a subset of the set of possible states of the world on which it will be commonly known whether the event in question has occurred or not. The strategic movement described in this example is similar to a conversational implicature: the correct interpretation of the deviation from truthfully reporting the Bayesian updated belief thrives on it being common knowledge that the announced probability cannot possibly be the speaker's Bayesian updated belief at this step. Finally, the argument is embedded in a game-theoretic model. [ABSTRACT FROM AUTHOR]

Salience reasoning, many have argued, can help solve coordination problems, but only if such reasoning is supplemented by higher-order predictions, e.g. beliefs about what others believe yet others will choose. In this paper, I will argue that this line of reasoning is self-undermining. Higher-order behavioral predictions defeat salience-based behavioral predictions. To anchor my argument in the philosophical literature, I will develop it in response and opposition to the popular Lewisian model of salience reasoning in coordination games. This model imports the problematic higher-order beliefs by way of a 'symmetric reasoning' constraint. In the second part of this paper, I will argue that a player may employ salience reasoning only if she suspends judgment about what others believe yet others will do. [ABSTRACT FROM AUTHOR]

Joint attention customarily refers to the coordinated focus of attention between two or more individuals on a common object or event, where it is mutually "open" to all attenders that they are so engaged. We identify two broad approaches to analyse joint attention, one in terms of cognitive notions like common knowledge and common awareness, and one according to which joint attention is fundamentally a primitive phenomenon of sensory experience. John Campbell's relational theory is a prominent representative of the latter approach, and the main focus of this paper. We argue that Campbell's theory is problematic for a variety of reasons, through which runs a common thread: most of the problems that the theory is faced with arise from the relational view of perception that he endorses, and, more generally, they suggest that perceptual experience is not sufficient for an analysis of joint attention. [ABSTRACT FROM AUTHOR]

We study shared intentions in what we call loose groups. These are groups that lack a codified organizational structure, and where the communication channels between group members are either unreliable or not completely open. We start by formulating two desiderata for shared intentions in such groups. We then argue that no existing account meets these two desiderata, because they assume either too strong or too weak an epistemic condition, that is a condition on what the group members know and believe about what the others intend, know, and believe. We propose an alternative, pooled knowledge, and argue that it allows formulating conditions on shared intentions that meet the two desiderata. [ABSTRACT FROM AUTHOR]

This paper provides a critical reconstruction of Sugden's intellectual itinerary with respect to his theory of team reasoning, starting from the beginning of his reflection in the early 1980s to his latest contributions in 2015. My reconstruction follows both a historical and an interpretative approach to show the continuity of different lines of thought, developed in different moments, notwithstanding the changes in the aims and scope of the theory from one period to another. I divide the evolution of Sugden's team reasoning into four main stages. The first includes some works prior to 1993, and the second is from 1993 to 2000. The third and fourth stages are from 2001 to 2007 and from 2008 to 2015, respectively. [ABSTRACT FROM AUTHOR]

In the era when human activities can fundamentally alter the planetary climate system, a stable climate is a global commons. However, the need to develop the economy to sustain the growing human population poses the Climate Commons Dilemma. Although citizens may need to support policies that forgo their country's economic growth, they may instead be motivated to grow their economy while freeriding on others' efforts to mitigate the ongoing climate change. To examine how to resolve the climate commons dilemma, we constructed a Climate Commons Game (CCG), an experimental analogue of the climate commons dilemma that embeds a simple model of the effects of economic activities on global temperature rise and its eventual adverse effects on the economy. The game includes multiple economic units, and each participant is tasked to manage one economic unit while keeping global temperature rise to a sustainable level. In two experiments, we show that people can manage the climate system and their economies better when they regarded the goal of environmentally sustainable economic growth as a singular global goal that all economic units collectively pursue rather than a goal to be achieved by each unit individually. In addition, beliefs that everyone shares the knowledge about the climate system help the group coordinate their economic activities better to mitigate global warming in the CCG. However, we also found that the resolution of the climate commons dilemma came at the cost of exacerbating inequality among the economic units in the current constrains of the CCG. [ABSTRACT FROM AUTHOR]

Using animals and their products to treat patients suffering from a range of health conditions has a long history and is still common in many parts of the world. We investigated such zootherapeutic uses among two tribes who inhabit different areas of North-East India: the Tangsa and the Wancho. Overexploitation of the animals they use, however, could endanger some species' survival and create imbalances in the ecosystem that ultimately could affect humans and animals of the region. In order to find solutions how humans and animals can continue to coexist harmoniously, it is essential to know which species and their products are sought after by the local healers. We found that the Tangsa make greater use of animals than Wancho and use predominantly a variety of mammals (47%) followed by birds (16%) of the 55 species of animals considered therapeutic by them. The Wancho informed us of using 20 species, of which birds and their products account for 37%, while mammals and insects feature in 26% and 21%, respectively. In both tribes, the remainder are distributed across different animal taxa. To treat ailments and diseases like joint, bone and muscle pains, Tangsa prefer to use the body fats of tiger, civet, hornbill, eagle and python. Wancho do not use any animal fats very often and prefer animal parts and marrow to be given to a sick person in cooked or roasted form. The bile of bears is used by both Tangsa and Wancho in that it is supposed to ameliorate pain-causing conditions such as stomach, head and toothaches and to reduce labour pains. The use of leeches to remove blood clots and the consumption of earthworms to ward off malaria has been recorded only from the Wancho, while Tangsa treat malaria sufferers with tortoise carapace extracts. The use of the flesh of roasted bat wings fed to children older than 4 years of age to stop bed-wetting seems unique to the Tangsa. Being aware of such folk medicinal traditions is important not just with regard to safeguarding the animal resource, but also in connection with the introduction of possible alternative treatment methods not involving animal zootherapies. [ABSTRACT FROM AUTHOR]

Standard game theory cannot explain the selection of payoff-dominant outcomes that are best for all players in common-interest games. Theories of team reasoning can explain why such mutualistic cooperation is rational. They propose that teams can be agents and that individuals in teams can adopt a distinctive mode of reasoning that enables them to do their part in achieving Pareto-dominant outcomes. We show that it can be rational to play payoff-dominant outcomes, given that an agent group identifies. We compare team reasoning to other theories that have been proposed to explain how people can achieve payoff-dominant outcomes, especially with respect to rationality. Some authors have hoped that it would be possible to develop an argument that it is rational to group identify. We identify some large—probably insuperable—problems with this project and sketch some more promising approaches, whereby the normativity of group identification rests on morality. [ABSTRACT FROM AUTHOR]

In this essay, I consider a kind of social group that I call 'epistemic'. It is constituted by its members' possession of perceptually grounded common knowledge, which endows them with a particular kind of epistemic authority. This authority, I argue, is invoked in the activity of 'joint reminiscing'—of remembering together a past jointly experienced event. Joint reminiscing, in turn, plays an important role in the constitution of social and personal identity. The notion of an epistemic group, then, is a concept that helps explain an important aspect of a subject's understanding of who she is. [ABSTRACT FROM AUTHOR]

In many everyday activities, individuals have a common interest in coordinating their actions. Orthodox game theory cannot explain such intuitively obvious forms of coordination as the selection of an outcome that is best for all in a common-interest game. Theories of team reasoning provide a convincing solution by proposing that people are sometimes motivated to maximize the collective payoff of a group and that they adopt a distinctive mode of reasoning from preferences to decisions. This also offers a compelling explanation of cooperation in social dilemmas. A review of team reasoning and related theories suggests how team reasoning could be incorporated into psychological theories of group identification and social value orientation theory to provide a deeper understanding of these phenomena. [ABSTRACT FROM AUTHOR]

Contagion models have been used to study the spread of social behavior among agents of a networked population. Examples include information diffusion, social influence, and participation in collective action (e.g., protests). Key players, which are typically agents characterized by structural properties of the underlying network (e.g., high degree, high core number or high centrality) are considered important for spreading social contagions. In this paper, we ask whether contagions can propagate through a population that is devoid of key players. We justify the use of Erdős-Rényi random graphs as a representation of unstructured populations that lack key players, and investigate whether complex contagions—those requiring reinforcement—can spread on them. We demonstrate that two game-theoretic contagion models that utilize common knowledge for collective action can readily spread such contagions, thus differing significantly from classic complex contagion models. We compare contagion dynamics results on unstructured networks to those on more typically-studied, structured social networks to understand the role of network structure. We test the classic complex contagion and the two game-theoretic models with a total of 18 networks that range over five orders of magnitude in size and have different structural properties. The two common knowledge models are also contrasted to understand the effects of different modeling assumptions on dynamics. We show that under a wide range of conditions, these two models produce markedly different results. Finally, we demonstrate that the disparity between classic complex contagion and common knowledge models persists as network size increases. [ABSTRACT FROM AUTHOR]

The concept of social capital has gained lots of attention as an important instrument to induce collective action on Common Pool Resources management. However, evidence demonstrated amply that social capital alone was not always enough to encourage collective action. There were other factors needed as a leverage to activate social capital but research regarding this issue is still limited. This research was intended to elucidate how to strengthen the role of social capital and the preconditions required to encourage community members to conduct collective action. The research was carried out using survey methods at the eastern coastal area of East Sinjai sub district, South Sulawesi, Indonesia. The research results show that strong social capital, indicated by high value score of trust, norm and networking would not always engender collective action in natural resource management. In order to achieve collective action, social capital had to be activated to function optimally. This was done through the intervention of symbolic power which is inherent in role models to initiate and mobilize action in mangrove management. The process to convince people to perform collective action was a crucial one which had to be resolved and is known as common knowledge. External support from local governments could facilitate the emergence of symbolic power through provision of enabling conditions for leadership promotion. [ABSTRACT FROM AUTHOR]

Biondi et al. (Phys A 391(22):5532-5545, 2012) develop an analytical model to examine the emergent dynamic properties of share market price formation over time, capable to capture important stylized facts. These latter properties prove to be sensitive to regulatory regimes for fundamental information provision, as well as to market confidence conditions among actual and potential investors. We comparatively assess accounting models belonging to two main families: historical cost accounting and mark-to-market (fair value) accounting regimes. Regimes based upon mark-to-market measurement of traded security, while generating higher linear correlation between market prices and fundamental signals, also involve higher market instability and volatility. These regimes also incur more relevant episodes of market exuberance and vagary in some regions of the market confidence space, where lower market liquidity further occurs. [ABSTRACT FROM AUTHOR]

In this paper I scrutinize the 'rational beliefs' in the concept of rationalizability in strategic games [Bernheim (Econometrica 52:1007-1028, 1984), Pearce (Econometrica 52:1029-1051, 1984)]. I illustrate through an example that a rationalizable strategy may not be supported by a 'rational belief', at least under one plausible interpretation of 'rational belief'. I offer an alternative formulation of 'rational belief' in the concept of rationalizability, which yields a novel epistemic interpretation of the notion of point-rationalizability. [ABSTRACT FROM AUTHOR]

In Aumann (Games Econ Behav 8(1):6-19, , Games Econ Behav 23(1):97-105, ), time is assumed implicitly in the description of games of perfect information, and it is part of the epistemic distinction between ex-ante and ex-post knowledge. We show that ex-post knowledge in these papers can be expressed by ex-ante knowledge and therefore epistemically, time is irrelevant to the analysis. Furthermore, we show that material rationality by weak dominance and by expectation can be expressed in terms of the timeless strategic form of the game. [ABSTRACT FROM AUTHOR]

We overview the most prominent logics of knowledge and action that were proposed and studied in the multiagent systems literature. We classify them according to these two dimensions, knowledge and action, and moreover introduce a distinction between individual knowledge and group knowledge, and between a nonstrategic an a strategic interpretation of action operators. For each of the logics in our classification we highlight problematic properties. They indicate weaknesses in the design of these logics and call into question their suitability to represent knowledge and reason about it. This leads to a list of research challenges. [ABSTRACT FROM AUTHOR]

The article studies common knowledge in communication networks with a fixed topological structure. It introduces a non-trivial principle, called the Ryōan-ji axiom, which captures logical properties of common knowledge of all protocols with a given network topology. A logical system, consisting of the Ryōan-ji axiom and two additional axioms, is proven to be sound and complete. [ABSTRACT FROM AUTHOR]

When states of the world are normally distributed, the sequential exchange and revision of beliefs converges to agreement in finitely many rounds of communication. Public information may reduce the information shared by individuals after the revision of beliefs. [ABSTRACT FROM AUTHOR]

Strawson style counterexamples to Grice's account of communication show that a communicative intention has to be overt. Saying what overtness consists in has proven to be difficult for Gricean accounts. In this paper, I show that a common explanation of overtness, one that construes it in terms of a network of shared beliefs or knowledge, is mistaken. I offer an alternative, collectivist, model of communication. This model takes the utterer's communicative intention to be a we-intention, a kind of intention with a distinctive content that cannot be reduced to an intention in favor of an individual action. I show that the collectivist model can explain overtness in terms of a general feature of we-intentions, namely the requirement that the participants in a shared activity are to intend to act in accordance with meshing subplans. [ABSTRACT FROM AUTHOR]

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This paper studies Aumann's agreeing to disagree theorem from the perspective of dynamic epistemic logic. This was first done by Dégremont and Roy (J Phil Log 41:735-764, ) in the qualitative framework of plausibility models. The current paper uses a probabilistic framework, and thus stays closer to Aumann's original formulation. The paper first introduces enriched probabilistic Kripke frames and models, and various ways of updating them. This framework is then used to prove several agreement theorems, which are natural formalizations of Aumann's original result. Furthermore, a sound and complete axiomatization of a dynamic agreement logic is provided, in which one of these agreement theorems can be derived syntactically. These technical results are used to show the importance of explicitly representing the dynamics behind the agreement theorem, and lead to a clarification of some conceptual issues surrounding the agreement theorem, in particular concerning the role of common knowledge. The formalization of the agreement theorem thus constitutes a concrete example of the so-called dynamic turn in logic. [ABSTRACT FROM AUTHOR]

We study how asymmetric information affects the set of rationalizable solutions in a linear setup where the outcome is determined by forecasts about this same outcome. The unique rational expectations equilibrium is also the unique rationalizable solution when the sensitivity of the outcome to agents’ forecasts is less than one, provided that this sensitivity is common knowledge. Relaxing this common knowledge assumption, multiple rationalizable solutions arise when the proportion of agents who know the sensitivity is large, and the uninformed agents believe it is possible that the sensitivity is greater than one. Instability is equivalent to existence of some kind of sunspot equilibria. [ABSTRACT FROM AUTHOR]

The problem of cooperation for rational actors comprises two sub problems: the problem of the intentional object (under what description does each actor perceive the situation?) and the problem of common knowledge for finite minds (how much belief iteration is required?). I will argue that subdoxastic signalling can solve the problem of the intentional object as long as this is confined to a simple coordination problem. In a more complex environment like an assurance game signals may become unreliable. Mutual beliefs can then bolster the earlier attained equilibrium. I will first address these two problems by means of an example, in order to draw some more general lessons about combining evolutionary theory and rationality later on. [ABSTRACT FROM AUTHOR]

The interaction between participation and the emergence of common knowledge is the subject matter of this paper. A case study of a single class provides the focal point of analysis. During the semester the students participated in a blogging activity. As a result of their participation, the students create and distribute knowledge. The online efforts of the students can be described as participation in both a discourse and knowledge community. At one level, blogging is an activity composed of writing, reading, and commenting, and at a second level, the students share their thoughts in their own voices. At a third level, over the course of the semester, the student posts and commentary form a commons of information that can be mined later in the semester for other kinds of learning activities. Knowledge creation, distribution, and accumulation are analyzed in terms of student participation at both the level of individual events and from the perspective of an ongoing community. [ABSTRACT FROM AUTHOR]

Famously, Kripke has argued that the central portion of the Philosophical Investigations describes both a skeptical paradox and its skeptical solution. Solving the paradox involves the element of the community, which determines correctness conditions for rule-following behavior. What do such conditions precisely consist of? Is it accurate to say that there is no fact to the matter of rule following? How are the correctness conditions sustained in the community? My answers to these questions revolve around the idea (cf. P.I. §§198, 199) that a rule is followed insofar as a convention is in place. In particular, I consider the game-theoretic definition of convention offered by David Lewis and I show that it illuminates essential aspects of the communitarian understanding of rule-following. [ABSTRACT FROM AUTHOR]

In this paper I present a more refined analysis of the principles of deductive closure and positive introspection. This analysis uses the expressive resources of logics for different types of group knowledge, and discriminates between aspects of closure and computation that are often conflated. The resulting model also yields a more fine-grained distinction between implicit and explicit knowledge, and places Hintikka's original argument for positive introspection in a new perspective. [ABSTRACT FROM AUTHOR]

In this paper, we extend Aumann's (Ann Stat 4:1236-1239, ) probabilistic agreement theorem to situations in which agents' prior beliefs are represented by a common neo-additive capacity. In particular, we characterize the family of updating rules for neo-additive capacities, which are necessary and sufficient for the impossibility of 'agreeing to disagree' on the values of posterior capacities as well as on the values of posterior Choquet expectations for binary acts. Furthermore, we show that generalizations of this result to more general acts are impossible. [ABSTRACT FROM AUTHOR]

We study the relationship between common knowledge and the sequence of iterated mutual knowledge from a topological point of view. It is shown that common knowledge is not equivalent to the limit of the sequence of iterated mutual knowledge. On that account the new epistemic operator limit knowledge is introduced and analyzed in the context of games. Indeed, an example is constructed where the behavioral implications of limit knowledge of rationality strictly refine those of common knowledge of rationality. More generally, it is then shown that limit knowledge of rationality is capable of characterizing any solution concept for some appropriate epistemic-topological conditions. Finally, some perspectives of a topologically enriched epistemic framework for games are discussed. [ABSTRACT FROM AUTHOR]

This article deals with the fact that most children in Africa are taught in a language neither they nor their teachers master, resulting in poor education outcomes. While there are also donor interests and donor competition involved in retaining ex-colonial languages, as well as an African elite that may profit from this system, one of the main reasons why teaching in ex-colonial languages persists lies in the fact that a large proportion of the general public still believes that the best way to learn a foreign language is to have it as a language of instruction. By contrast, research studies conducted in Africa, as well as examples from Asian countries such as Sri Lanka and Malaysia, have shown that children actually learn mathematics and science much better in local and familiar languages. Though the recent World Bank Education Strategy policy paper is entitled Learning for All, it does not specify which language learning should take place in. A claim one often hears in countries of so-called Anglophone Africa is that English is the language of science and technology, and that teaching these subjects through English (instead of teaching English as a subject in its own right as a foreign language) is best. The monolingual island of Zanzibar is in fact about to reintroduce English as the language of instruction in maths and science from grade 5 onwards in primary school. The author of this paper suggests that when it comes to language policy, some African and some Asian countries could learn from each other. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]