In this paper I present a dynamic-epistemic hybrid logic for reasoning about information and intention changes in situations of strategic interaction. I provide a complete axiomatization for this logic, and then use it to study intentions-based transformations of decision problems.

In this paper I study two ways of transforming decision problems on the basis of previously adopted intentions, ruling out incompatible options and imposing a standard of relevance, with a particular focus on situations of strategic interaction. I show that in such situations problems arise which do not appear in the single-agent case, namely that transformation of decision problems can leave the agents with no option compatible with what they intend. I characterize conditions on the agents’ intentions which avoid such (...) problematic scenarios, in a way that requires each agent to take account of the intentions of others. (shrink)

Different versions of the idea that individualism about agency is the root of standard game theoretical puzzles have been defended by Regan 1980, Bacharach, Hurley, Sugden :165–181, 2003), and Tuomela 2013, among others. While collectivistic game theorists like Michael Bacharach provide formal frameworks designed to avert some of the standard dilemmas, philosophers of collective action like Raimo Tuomela aim at substantive accounts of collective action that may explain how agents overcoming such social dilemmas would be motivated. This paper focuses on (...) the conditions on collective action and intention that need to be fulfilled for Bacharach’s “team reasoning” to occur. Two influential approaches to collective action are related to the idea of team reasoning: Michael Bratman’s theory of shared intention and Raimo Tuomela’s theory of a we-mode of intending. I argue that neither captures the “agency transformation” that team reasoning requires. That might be an acceptable conclusion for Bratman but more problematic for Tuomela, who claims that Bacharach’s results support his theory. I sketch an alternative framework in which the perspectival element that is required for team reasoning - the ‘we-perspective’ - can be understood and functionally characterized in relation to the traditional distinction between mode and content of intentional states. I claim that the latter understanding of a collective perspective provides the right kind of philosophical background for team reasoning, and I discuss some implications in relation to Tuomela’s assumption that switching between individual and collective perspectives can be a matter of rational choice. (shrink)

Philosophical accounts of collective intentionality typically rely on members to form a personal intention of sorts, viewed as a mental state. This tendency is opposed by recent economic literature on team-directed reasoning, which focuses on the reasoning process leading up to the formation of the members’ intentions. Our formal analysis bridges these paradigms and criticizes the team- directed reasoning account on two counts: first, team-directed reasoning is supposed to transcend traditional game and decision theory by adopting a certain collectivistic reasoning (...) method. However, we show that team-directed reasoning yields the same action recommendations as a certain I-mode we-intention type. Accordingly, an important part of we-mode reasoning can be reduced to I-mode reasoning with certain preferences. Second, contrary to the claims of team-directed-reasoning theorists, we refute that team-directed reasoning surpasses pro-group intentions in selecting cooperatively rational solutions. That is, in some scenarios team-directed reasoning fails to guarantee successful cooperation whereas pro-group intentions succeed in doing so. We therefore propose to revise team-directed reasoning and introduce a third we-intention type, called participatory intentions. We prove that participatory intentions guarantee that a best group action is performed whenever either team-directed reasoning or pro-group intentions do. (shrink)

Many philosophers are convinced that rationality dictates that one’s overall set of intentions be consistent. The starting point and inspiration for our study is Bratman’s planning theory of intentions. According to this theory, one needs to appeal to the fulfilment of characteristic planning roles to justify norms that apply to our intentions. Our main objective is to demonstrate that one can be rational despite having mutually inconsistent intentions. Conversely, it is also shown that one can be irrational despite having a (...) consistent overall set of intentions. To overcome this paradox, we argue that it is essential for a successful planning system that one’s intentions are practically consistent rather than being consistent or applying an aggregation procedure. Our arguments suggest that a new type of norm is needed: whereas the consistency requirement focuses on rendering the contents of one’s intentions consistent, our new practical consistency requirement demands that one’s intentions be able to simultaneously and unconditionally guide one’s action. We observe that for intentions that conform to the ‘own-action condition’, the practical consistency requirement is equivalent to the traditional consistency requirement. This implies that the consistency requirement only needs to be amended in scenarios of choice under uncertainty. (shrink)