 Most of the views canvassed here emphasize as a condition for shared activity fairly robust forms of integration between participants. Before continuing in this vein, it bears mention that the focus on the participants and how they are related might lead us to neglect other important conditions for shared activity. Epstein 2015 argues that the metaphysical grounds for some forms of shared activity, such as that involved in some cases of group action, involve a variety of conditions that are not themselves relations between members of the group, but often can determine how those members are related. These might include historical conditions that determine the structure and membership criteria for the group. Or, the grounds might include external conditions such as the actions of some designated individual (such as a sergeant at arms) not a part of the collective body but who for example must convene a meeting in order that the members of the body may collectively take some action. 