What emphasis does Habermas place on the "structural" in his work?
Habermas makes it clear that he is dealing with a specific cultural structure, and the socio-economic structures that make it possible. The change he depicts is not one that can be charted through the actions of individuals, but by considering broader phenomena. Amongst the structures he considers are those of publicity, economics, the mass media and the modern "culture industry". But Habermas is not a structuralist thinker in the philosophical sense. The Structural Transformation is also a deeply historical work; Habermas considers the structures of publicity within the context of their development over time. The work contains a range of historical detail about the history of advertising, of public relations and German politics. This is a work about theoretical and cultural structures, but one that never presents them as static constructions.
How do the public and private realms relate to one another in Habermas's model?
The public and private realms have only existed separately since the end of the middle ages. The public realm, or "public authority" includes the state and the apparatus of government, and the royal court. The private realm, also known as "society", includes civil society, and the private space of the family. The key opposition is between economy and family on one hand, and state on the other. The prototype of the public sphere, the literary public sphere, operated in the private realm; the political public sphere operated in the public domain. Essentially, it represented the needs and demands of civil society to the state, and provided a bridge linking public and private. Membership in the public sphere depended on one's economic position, and role as a property owner within the family. Without a grounding in the private sphere, one could not participate in the public sphere.
But this relationship changes. The modern world is characterized by a blurring of the distinction between public and private, as states begin to interfere in the economy and interest groups from civil society take over some of the state's roles. A larger, indistinct mass of "society" emerges where what is public and what is private becomes unclear. The categories that explain the concept of publicity in the eighteenth century no longer apply.
Does Habermas want to reconstruct the eighteenth century public sphere today?
No. Although the latter sections of the work make it clear that Habermas views the modern situation, in which rational-critical debate is almost absent, the mass media operates and political parties and interest groups try to construct and manipulate publicity, unfavorably, he does not argue for a return to previous structures. Indeed, he makes it clear that such a return is not viable; to attempt to restore the old structures of the public sphere would damage those that still exist. The transformation that he analyses is not reversible, but nor is it inevitable that the bourgeois public sphere will be annihilated. Habermas recognizes that the socio-economic conditions that produced the bourgeois public sphere no longer exist, but asks whether it is possible to reproduce it in very different conditions. He argues that a critically debating public is vital to the success of all democratic state, but not that this public must be the same as in the eighteenth century.