What are the principles of the Church's social doctrine?

The Compendium of the Social Doctrine of the Church and later magisterial documents have identified and further developed four "principles of the Church's social doctrine": the dignity of the human person, the common good, subsidiarity and solidarity. Since these concepts are very different and can be associated with different traditions, it is not always clear how they should be interpreted. Based on magisterial documents, this paper delves deeper into the notion of a "principle of the Church's social doctrine", distinguishing the sense in which each of these principles may be called as such, and paying attention to the way in which human dignity can be considered a specific social principle.