An interactional, conversational, dialogic, that is social, theory of culture requires a related theory of the set of interacting, conversing, dialoguing, people.
From Dewey onwards (at least), this theory often took the form of a theory of community. Most recently, Lave framed her attempt to understand learning as a divided, distributed process in terms of what she called a "community of practice" (1991).
The word community, because of its connotations indexing commonality, consensus, sharing (at least in America), is dangerous when the goal is precisely to index structured and profound difference among a particular set of people at a particular time.
The foundation of conversation is not sharing but dispute, the grounds of disputing, the areas where dispute has the best chance of producing a personal goal, etc., the authority patterns allowing some to (temporarily) settle disputes. Thus conversation is always political leading to the need for a theory of "polity."
POLITY would index the set of people who become (willingly or not, legitimately or not) participant within any particular setting.
Note that the polity, as constituted in earlier and more or less hegemonic conversations, is that which establishes who participates in its conversations, and particularly the mechanisms for inclusion and exclusion.
a POLITY OF PRACTICE would be the population that cannot escape what was constituted in previous conversations. For example:
think of what may happen in a routine classroom when a) the principal drops by, vs. b) when a janitor drops by. Both are outsiders to the most local polity (the teacher and her students), both will become temporary insiders but each method of participation will be different. Indeed it is by observing this difference that we might come to model the local construction of these differences.
a POLITY OF PRACTICE would include: