The most significant innovation in the history of ideas about justice, at least in modern times and perhaps in the entirety of that history, has been the development of the idea of social justice. This idea is an outgrowth of the notion that human beings are capable of reshaping the terrain of their social world to conform to an intentional design – a notion that first appeared in ancient Athens, but gained widespread acceptance only in the eighteenth century. Rooted in the postulate that all human beings are equal in worth, the modern idea of social justice has spawned a series of perceptions of and theories about justice that are intertwined closely with recent and contemporary institutions and practices. Whether we conceive of these theories and perceptions as causes or as consequences of the innovations that have accompanied them, it is impossible to understand the modern world without them.