Does membership in a political society, in and of itself, involve obligations to uphold that society’s political institutions? Margaret Gilbert offers a novel argument in defense of an affirmative answer to this question, which she labels the membership problem. Given a plausible construal of the concepts obligation, political society, and membership in a political society, Gilbert argues that it follows analytically that to be a member of a political society just is to have an obligation to uphold and support that society’s political institutions. The key to Gilbert’s argument is the idea of a joint commitment; those who jointly commit to X as a body thereby acquire obligations vis-à-vis the others with whom they jointly act. Social groups, including political societies, exist as the result of such a commitment amongst those who constitute them. In virtue of their joint commitment, agents form a plural subject, and so Gilbert titles her solution to the membership problem the plural subject theory of political obligation.

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Copyright © 2007, University of Notre Dame's Department of Philosophy. This article first appeared in Notre Dame Philosophical Reviews (2007).

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