According to many philosophers and scientists, human sociality is explained by our unique capacity to “share” attitudes with others. The conditions under which mental states are shared have been widely debated in the past two decades, focusing especially on the issue of their reducibility to individual intentionality and the place of collective intentions in the natural realm. It is not clear, however, to what extent these two issues are related and what methodologies of investigation are appropriate in each case. In (...) this article, I propose a solution that distinguishes between epistemic and ontological interpretations of the demand for the conditions of reduction of collective intentionality. While the philosophical debate has contributed important insights into the former, recent advances in the cognitive sciences offer novel resources to tackle the latter. Drawing on Michael Tomasello’s research in the ontogeny of shared intentionality in early instances of interaction based on joint attention, I propose an empirically informed argument of what it would take to address the ontological question of irreducibility, thus making a step forward in the naturalization of collective intentionality. (shrink)

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. (shrink)

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 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. Make the following experiment: say “It’s cold here” and mean “It’s warm here”. Can you do it?Ludwig Wittgenstein, Philosophical Investigations, 1953, §510.I can’t say “it’s cold here” and mean “it’s warm here”—at least, not without a little help from my friends.David Lewis, Convention. (shrink)

Among the many possible approaches to dealing with logical omniscience, I consider here awareness and impossible worlds structures. The former approach, pioneered by Fagin and Halpern, distinguishes between implicit and explicit knowledge, and avoids logical omniscience with respect to explicit knowledge. The latter, developed by Rantala and by Hintikka, allows for the existence of logically impossible worlds to which the agents are taken to have access; since such worlds need not behave consistently, the agents’ knowledge is fallible relative to logical (...) omniscience. The two approaches are known to be equally expressive in propositional systems interpreted over Kripke semantics. In this paper I show that the two approaches are equally expressive in propositional systems interpreted over Montague-Scott (neighborhood) semantics. Furthermore, I provide predicate systems of both awareness and impossible worlds structures interpreted on neighborhood semantics and prove the two systems to be equally expressive. (shrink)

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. (shrink)

This article focuses on the conventions that sustain social interaction and argues that they are central to Simon's decision-making theory. Simon clearly identifies two kinds of coordination by convention: behavioral mores that shape human actions, and shared mental models that govern human perceptions. This article argues that Poincaré–Carnap's conventionalism provides powerful support for Simon's theory; it contends that this theory offers a more convincing account of decision and coordination than Lewis' concept of convention. Simon's approach to applying conventionalist logic to (...) social interaction emphasizes the normative role played by mental models in solving coordination problems and considers rationality in terms of both cognitive and moral considerations. By connecting conventional phenomena to social identifications, Simon stresses the resulting complexity of coordination problems. (shrink)

This article presents a community-based account of salience as an alternative and a complement to the ‘natural salience’ approach which is endorsed by almost all game theorists who use this concept. While in the naturalistic approach, salience is understood as an objective and natural property of some entities, the community-based account claims that salience is a function of community membership. Building on David Lewis’s theory of common knowledge and on some of its recent refined accounts, I suggest that salience acts (...) as a correlating device in a correlated equilibrium. What is constitutive of salience is common understanding, the fact that agents have common knowledge that they share the same modes of reasoning with respect to a well-identified set of events. I argue that the basis for common understanding is community membership. The relevance of this account stems from the fact that it answers the objection that salience is either unnecessary or unable to account for coordination between rational agents. (shrink)

:Most game-theoretic accounts of institutions reduce institutions to behavioural patterns the players are incentivized to implement. An alternative account linking institutions to rule-following behaviour in a game-theoretic framework is developed on the basis of David Lewis’s and Ludwig Wittgenstein's respective accounts of conventions and language games. Institutions are formalized as epistemic games where the players share some forms of practical reasoning. An institution is a rule-governed game satisfying three conditions: common understanding, minimal awareness and minimal practical rationality. Common understanding has (...) a strong similarity with Ludwig Wittgenstein's concept of lebensform while minimal awareness and minimal practical rationality capture the idea that rule-following is community-based. (shrink)

This paper presents the results of an experiment on mutual versus common knowledge of advice in a two-player weak-link game with random matching. Our experimental subjects play in pairs for thirteen rounds. After a brief learning phase common to all treatments, we vary the knowledge levels associated with external advice given in the form of a suggestion to pick the strategy supporting the payoff-dominant equilibrium. Our results are somewhat surprising and can be summarized as follows: in all our treatments both (...) the choice of the efficiency-inducing action and the percentage of efficient equilibrium play are higher with respect to the control treatment, revealing that even a condition as weak as mutual knowledge of level 1 is sufficient to significantly increase the salience of the efficient equilibrium with respect to the absence of advice. Furthermore, and contrary to our hypothesis, mutual knowledge of level 2 induces, under suitable conditions, successful coordination more frequently than common knowledge. (shrink)

This paper examines a special kind of social preference, namely a preference to do one's part in a mixed-motive setting because the other party expects one to do so. I understand this expectation-based preference as a basic reactive attitude. Given this, and the fact that expectations in these circumstances are likely to be based on other people's preferences, I argue that in cooperation a special kind of equilibrium ensues, which I call a loop, with people's preferences and expectations mutually cross-referring. (...) As with a Lewis-norm, the loop can get started in a variety of ways. It is self-sustaining in the sense that people with social preferences have sufficient reason not to deviate. (shrink)

This paper examines the perceptual and reasoning processes that underpin regularities in behaviour. A distinction is made between situations as they are, or as described by an omniscient external observer, and situations as agents see or frame them. Different frames can stem from differences in culture, experience and personality, as well as from other context-specific factors. Drawing upon David Lewis’s Convention, I show that consistency between reasoning and experience does not preclude individuals from understanding the same state of affairs differently, (...) and that agents’ beliefs about others’ beliefs may well be wrong. As a result, cases may occur in which conventions are sustained by false but mutually consistent and self-confirming beliefs. (shrink)

The central philosophical task posed by conventions is to analyze what they are and how they differ from mere regularities of action and cognition. Subsidiary questions include: How do conventions arise? How are they sustained? How do we select between alternative conventions? Why should one conform to convention? What social good, if any, do conventions serve? How does convention relate to such notions as rule, norm, custom, practice, institution, and social contract? Apart from its intrinsic interest, convention is important because (...) philosophers frequently invoke it when discussing other topics. A favorite philosophical gambit is to argue that, perhaps despite appearances to the contrary, some phenomenon ultimately results from convention. Notable candidates include: property, government, justice, law, morality, linguistic meaning, necessity, ontology, mathematics, and logic. (shrink)

This dissertation is a contribution to the philosophy of language. Its central question is: In virtue of which facts do linguistic expressions mean what they do? E.g. why does “apple” mean apple in English? The question receives a systematic answer; in short: Linguistic expressions mean what they do because among their users, there are linguistic conventions and social norms to use and understand them in certain ways. The answer is clarified and defended as a central thesis. For in this form, (...) it is at best a slogan: What is meaning? What is it to use and understand expressions? What are conventions and social norms anyway? How does the use and understanding determine meaning? The goal of the dissertation consists in answering these questions. (shrink)

This paper aims to assess current theoretical findings on the origin of coordination by salience and suggests a way to clarify the existing framework. The main concern is to reveal how different coordination mechanisms rely on specific epistemic aspects of reasoning. The paper highlights the fact that basic epistemic assumptions of theories diverge in a way that makes them essentially distinctive. Consequently, recommendations and predictions of the traditional views of coordination by salience are, in principle, based on the processes related (...) to the agent’s presumptions regarding the cognitive abilities of a co-player. This finding implies that we should consider these theories as complementary, and not competitive, explanations of the same phenomenon. -/- . (shrink)