Discussion in this area continues to expand, and has influenced discussions in other disciplines including anthropology, developmental psychology, and economics. One general question is whether it is necessary to think in terms that go beyond the personal intentions of individual human beings properly to characterize what it is to act together. Bratman's account does not go beyond such personal intentions. Gilbert's account, with its invocation of joint commitment, does go beyond them. Searle's account does also, with its invocation of collective intentionality. The question of whether and how one must account for the existence of mutual obligations when there is a collective intention is another of the issues in this area of inquiry.