This inquiry into local text structure has stayed close to the linguistic ground, concentrating on linguistic forms and categories. In this final chapter I widen the range of discussion to consider some of the organizing principles of discourse. I begin with hierarchical structure and functional units, and then discuss discourse relations. Finally, I comment on how the Discourse Modes pertain to discourse relations and to lexical patterns, which distinguish units at different levels of text structure.
Discourse is organized by its purpose, like many other human activities. To understand its structure we can turn to work in cognitive science on intentions and plans generally. Intentions have hierarchical structure, G. Miller, Galanter, & Pribram argue convincingly in an early study. They propose an abstract unit, the Test-Operate-Test-Exit or TOTE, to represent such structures. TOTE units can be used to model human intentional behavior: they represent a top level of control in planning and executing intentions. Intentions themselves are organized hierarchically into sub-goals, which in turn may have sub-goals, and so on. For instance, to hammer something once a person must plan and execute the two sub-goals of lifting and striking (1960:33):
Repeated hammering consists of many such steps, each with the same hierarchically organized sub-goals. More complex activities have many sub-goals. Even a relatively simple activity such as going to work has a number of