There is no good human life outside of a state, and the good state enables us to live well together - so says Constitutivism, the theory developed in this book. Reinvigorating Aristotelian ideas, the author asks in what sense citizens of modern, populous and pluralistic societies share a common good.

While we can easily find examples of cooperation that benefit each member, such as insurances, the idea that persons could share a common good became puzzling with modernity - a puzzlement epitomised in Margaret Thatcher's 'What is society? There is no such thing!' Aristotle describes the state as the end of human development, both chronologically and normatively, but modern philosophers, from Thomas Hobbes to Carl Schmitt, conceive the relation between state and citizen as instrumental. Either the state is a means of advancing each member's individual good or the individual is a means of advancing some collective good. From both perspectives, the Aristotelian idea that human individuals somehow realise their own good in realising some communal good appears metaphysically puzzling, even nonsensical.

This puzzlement, the author argues, results from our profoundly modern understanding of rational actions, which we generally see as means toward outcomes. If we allow that not only outcomes but also histories and identities can be good reasons for actions, then it makes sense to see a person's good and the common good of their political community as constitutive of one another, as Aristotle thought. Building on this idea, the author argues that individual actions and lives exist only in conjunction with a political community. In designing our institutions, we hence also give ourselves an identity and, in that sense, constitute ourselves as persons. Her arguments shed new light on a range of traditional topics of political theory, such as the justification of state authority or the question of how to justify or challenge the design of social institutions.