Reflexively, the conversation itself may always be the topic of conversation. The processes of process control and production are then heterarchical, with no fixed ordering of levels of control. Biologically, this corresponds to the concept of a selfproductive network of processes (an autopoietic m-individual). Such a system is one that can support p-individuation, the evolution, through conversation of stable systems of belief (see also, Scott, 2000 and Scott, in press b).
Pask and colleagues (Pask, 1975, 1976; Pask, Scott and Kallikourdis, 1973; Pask, Kallikourdis and Scott, 1975) have developed methodologies for constructing models of the structure of bodies of knowledge. The basic idea is that a body of knowledge or subject matter consists of topics related one to another. Two basic forms of relations between topics are distinguished: entailment relations (hierarchical) and relations of analogy (heterarchical). A static representation of such relations is called an entailment structure.
Entailment structures reveal the “why” of knowledge, the conceptual structure of definitions and justifications that relate topics one to another. For a full semantics, the content of topics, their “how”, needs to be specified. This can be done operationally in the form of “task structures”, defined with respect to a canonical modelling facility. In Pask’s phrase, task structures show “what may be done”. They show the “procedural knowledge” or “performance competencies” that someone who understands a particular topic is deemed to have.
Task structures may be represented in a variety of ways, for example, as a precedence chart showing order relations between the goals and sub-goals of a task or as a flow chart showing a sequence of operations, tests, branches and iterations. The basic entailment structure model may be extended and elaborated in a number of ways. Any topic at the lowest level of an hierarchical entailment structure may be analysed further in order to reveal sub-topics (Pask’s term for such an analysis of a topic is “unzipping”).
Topics may be explained in terms of each other in different ways. If an entailment structure shows that topic A can be explained in terms of entailed topics B and C, then, in principle, topic B can be explained in terms of topics A and C and topic C can be explained in terms of topics A and B. If these local cycles are added to an entailment structure, the resulting form is what Pask refers to as an “entailment mesh”. As modelled thus far, the conversational domain, qua entailment mesh, is but a labyrinth of topics, albeit with extensible “edges”.
It does not represent the intuitive idea that a body of knowledge is coherent globally, as a totality, a memorable whole. Strawson (1992) expresses the general idea thus: “Let us imagine … the model of an elaborate network ….. such that the function of … each concept, could … be properly understood only by grasping its connections with the others … there will be no reason to worry if, in the process of tracing connections from one point to another of the network, we find ourselves returning to our starting point ….
the general charge of circularity would lose its sting for we might have moved in a wide, revealing, and illuminating circle”. As an example, within the domain “biology”, in explaining the topic “evolution” one may refer to the topic “cell”; conversely, in explaining the topic “cell”, one may refer to the topic “evolution”. It is only in recent years that mainstream analytic philosophers, like Strawson, have accepted the legitimacy of virtuous (i. e. , not vicious) circularities in conceptual systems (for recent formal work on “circularity”, see Barwise and Moss, 1996).
Pask models the global aspect of coherence by imagining that the edges of an entailment mesh extend until they meet. The meeting of opposing edges, top and bottom, left and right results in a closed form, a torus. A conversational domain can also be extended by analogy. However, for analogy relations to be coherent, the bodies of knowledge they are relating together must themselves be coherent (see also Scott, 1999, and Scott, in press b) Main points To learn a subject matter, students must learn the relationships among the concepts.
Explicit explanation or manipulation of the subject matter facilitates understanding (e. g. , use of teachback technique). Individuals differ in their preferred manner of learning relationships (serialists versus holists). Implications of Conversation Theory for Learning The critical method of learning according to conversation theory is “teachback” in which one person teaches another what they have learned. Thus, discussion must be a central component of any lesson.