An essential component of any theory of team reasoning is a formal definition of group rationality and of the collective interests that motivate the reasoning of team players. Eschewing the need to endow a group with its own preferences, this paper argues that an operational notion of coordination can serve such a role. Coordination is an intrinsically group-level concept that is complementary to, but distinct from, the intrinsically individual notion of performance. Both group rationality as manifest by coordination and individual rationality as manifest by performance are necessary for a full understanding of group behavior in social environments. Conditional game theory provides a flexible mathematical framework within which individuals may modulate their preferences in response to the social influence that others exert on them. As social influence diffuses throughout a social network, a comprehensive social model emerges that provides an operational definition of group rationality as well as an operational concept of augmented individual rationality that together establish a concept of coordinated reasoning.
