The paper argues that the specific kind of bond among persons that unifies and organizes political communities needs a eta-normative explanation based on the concept of political authority. I start by considering the nature and unifying principles of communities, i.e. not only political communities, but also families, companies, societies etc. I argue that any of these kinds of com-munity can only be explained by means of the concept of the good in action, since they emerge as byproducts of human actions and its focus on the good. Subsequently, I focus on the specific features of political communities and on the role of the common good as unifying principle.
