Habermas sets out to define the term "public sphere." The terms "public" and "public sphere" have a variety of meanings. However, ordinary and scientific language cannot replace these terms with more precise ones. Despite the disintegration of public opinion, society still studies it.
Public means open to all, but also relates to the state. The public is a critical judge. The public sphere is a specific public domain, set against the private. The German word "Offentlichkeit" comes from the French adjective meaning "Public". There is no seventeenth-century word for the public sphere because it did not exist before the eighteenth century. In Germany, the public sphere emerged as part of civil society, the realm of commodity exchange and labor governed by its own laws.
Notions of public and private go back further than that, however. They are Greek categories with Roman additions. In ancient Greece, the polis-oikos division existed. Political life took place in the polis; the public sphere existed as a realm of discussion and common action. Citizens were free of productive labor, but their status depended on their role as the head of the oikos, or household. The Greek public sphere was the sphere of freedom and permanence, where distinction and excellence were possible.
Since the Renaissance, this Greek model was important and influential. Medieval categories of public and private came from Roman law. But they developed only with the rise of civil society and the modern state. For more than 100 years, the foundations of this sphere have been decomposing. Publicity is still important. By understanding it, we can understand a key category of our society.
In the middle ages, the public-private contrast from Roman law was familiar, but had no standard usage. The attempt to apply this distinction to the feudal system shows that ancient and modern public and private spheres did not exist. Various higher and lower powers existed, but there was no definite way for private people to enter the public sphere. The tradition of ancient German law did have a contrast comparable to the Roman tradition: that of common and particular. This was exactly reversed in feudalism; the common man is private, exemplified by the private soldier. One cannot show sociologically that the public sphere existed in the middle ages, but a publicity of representation did exist. This was a status attribute and not a social realm. The holder of office or power represented or displayed himself. The lord and master had an "aura" that he displayed before his subjects. Lordship was represented before the people. Representation was not about political communication but about social status.
Only after modern states had destroyed feudal power, helped by the development of a capitalist economy, could court sociability develop into the eighteenth century idea of a "good" society. For the first time, public and private spheres became separate in the modern sense. Bureaucracy, the church, and the army also became public institutions, separate from the increasingly private sphere of the court.