 Shared agency also has important normative implications. Institutions or laws established by everyone acting together have a status different from those that are, for example, imposed on a people by the dictates of one. And the nature of justification, be it epistemic or practical, might depend on whether it figures in the context of a shared enterprise. No wonder, then, that shared activity and intention is of interest for a variety of disciplines, including politics, social science, economics, ethics, law, epistemology (especially testimony and social epistemology), and psychology.