Abstract

Leading philosophical accounts of joint activity, such as Michael Bratman’s account of ‘shared intentional activity’, take joint activity to be the outcome of two or more agents having a ‘shared intention’, where this is a certain pattern of mutually known prior intentions that are directed toward a common goal. With Bratman’s account as a foil, I address two lacunas that are relatively unexplored in the philosophical literature. The first lacuna concerns how to make sense of the apparently joint cooperative activities of agents that lack the capacities for planning and “mindreading” that one must have in order to be a party to a shared intention. The second lacuna concerns how participants are able to coordinate their actions “online”—that is, during action execution as a joint activity unfolds—without recourse to plans that specify in advance what they should do. Chapters 2 and 3 focus on the first lacuna, while chapters 4 and 5 focus on the second. In chapter 2, I focus on why participants must have mutual or common knowledge of each other’s intentions and beliefs in order to have a shared intention: Why must these attitudes be “out in the open”? I argue that, if participants lack the concept of belief, then one of the two main motivations for the common knowledge requirement—to filter out certain cases that intuitively aren’t cases of genuine joint activity—actually dissipates. Furthermore, a kind of “openness” that only requires of participants that they have the concept of goal but not that of belief can satisfy the other main motivation, to make sense of the idea that joint activities are non-accidentally coordinated. In chapter 3, I offer an account of a kind of joint activity in which agents such as young children and some non-human primates could participate, given what we know about their socio-cognitive capacities. In chapter 4, I argue that ‘shared intention’-accounts are unable to say much about spontaneous or skilful joint action because of the following widely accepted constraint on what one can intend: while an agent might intend—in the sense of commit to a plan—that “we” do something together, an agent cannot intend to perform “our” joint action. I reject this constraint and argue that some joint actions are joint in virtue of each participant having what I call ‘socially extended intention-in-action’ that overlap. In chapter 5, I review empirical work on subpersonal enabling mechanisms for the coordination of joint action. The review provides clues to what it is that enables participants to successfully coordinate their actions in the absence of plan-like intentions or beyond what such intentions specify. While what I address are lacunas rather than problems, an upshot of this thesis is that leading philosophical accounts of joint activity may have less explanatory scope than one might otherwise be led to believe. The accounts of joint activity and joint action that are presented in this thesis are arguably applicable to many of the joint activities and joint actions of adult human beings. The account also helps us avoid the false dichotomy between a very robust form of joint activity and a mere concatenation of purely individualistic actions—a dichotomy that accounts such as Bratman’s arguably invite us to adopt.