Theories of team agency
In decision theory, it is almost universally presupposed that agency is invested in individuals: each person acts on her own preferences and beliefs. A person’s preferences may take account of the effects of her actions on other people; she may, for example, be altruistic or have an aversion to inequality. Still, these are her preferences, and she chooses what she most prefers. Opposing this orthodoxy is a small body of literature which allows teams of individuals to count as agents, and which seeks to identify distinctive modes of team reasoning that are used by individuals as members of teams. This idea has been around for some time, having been proposed in different forms by David Hodgson (1967), Donald Regan (1980), Margaret Gilbert (1989), Susan Hurley (1989), Robert Sugden (1993, 2003), Martin Hollis (1998) and Michael Bacharach (1999, 2006). Closely related, but less directly concerned with decision theory, is the literature of collective intentions, exemplified by the work of Raimo Tuomela and Kaarlo Miller (1988), John Searle (1990) and Michael Bratman (1993). These ideas have yet to capture the attention of mainstream decision theory. There seems to be a suspicion either that team reasoning is a particular case of individual reasoning, distinguished only by the particular assumptions it makes about preferences, or that it is not reasoning in the true sense of the word. The main contribution of the present paper is to represent team reasoning explicitly, as a mode of reasoning in which propositions are manipulated according to well-defined rules—an approach that has previously been used by Natalie Gold and Christian List (2004). Our basic building block is the concept of a schema of practical reasoning, in which conclusions about what actions should be taken are inferred from explicit premises about the decision environment and about what agents are seeking to achieve. We use this theoretical framework to compare team reasoning with the individual reasoning of standard decision theory, and to compare various theories of team agency and collective intentionality.