This article analyzes the key features of social sin in light of both recent pronouncements by the Roman Magisterium and selected passages from the theological work (mainly the Summa Theologiae) of Thomas Aquinas. In part 1, the social dimension of sin is highlighted in several documents of the Second Vatican Council, and in many magisterial pronouncements which, after the Second Vatican Council, have contributed to the clarification and development of the concept of social sin, the principal one (which will be used as the main point of reference for the purposes of this writing) is the postsynodal apostolic exhortation Reconciliation and Penance of December 2, 1984. Part 2 investigates the concept of sin and its affiliates in Thomass Summa. My fundamental argument throughout is that the social dimension of sin does not exclude, but instead is rooted in, the free will of each man who remains responsible for all human action attributable to him.
Maurizio Ragazzi, "The Concept of Social Sin in Its Thomistic Roots," Journal of Markets & Morality 7, no. 2 (Fall 2004): 363-408