In this paper I develop an account of member obligation: the obligations that fall on the members of an obligated collective in virtue of that collective obligation. I use this account to argue that unorganized collections of individuals can constitute obligated agents. I argue first that, to know when a collective obligation entails obligations on that collective’s members, we have to know not just what it would take for each member to do their part in satisfying the collective obligation, but also what they should do if they cannot do their part because others will not do theirs. I go on to argue (contra recent proposals) that it is not good enough for members in this situation to reasonably believe that others will not do their part. Rather, for a member of an obligated collective to permissibly escape doing her part in a collective obligation, she must both reasonably doubt that others will do their part and stand ready to act in case others do as well.
This necessary condition for collective obligation points the way to plausible sufficient conditions – conditions that, I argue, allow unstructured collectives to bear obligations. For (a) if a collective’s members are individually obligated to be ready to do their part, in a given collective action, and (b) if that individual readiness makes it sufficiently likely that the collective will in fact act, then it is hard to see what could block an attribution of collective obligation. In particular, in that case there ought to be no additional objection that there is no existing, organized “agent” on which the obligation might fall. For agents are, simply, things that can act. To be able to act is just to be able to succeed by trying. Unstructured collectives try to do something, I argue, when each member acts on their willingness to do their part in that thing if others do theirs; sometimes they succeed, producing a collective action. Some unstructured collectives, therefore, can succeed by trying; therefore, they can act; therefore they are agents.