Expository text grammar and disciplinary knowledge (presupposition)
The paper describes the expository text as the model of disciplinary knowledge. Consideration is given to the type of epistemic modality associated with presupposition, i.e., knowledge known and relevant to the participants of communication. Text analysis functional methods are used to study expository texts from Russian textbooks on Social Sciences and Physics for secondary school. It has been found that presupposition is most often expressed through modal constructions referring to a reader (personal pronouns) occupying an initial or non-initial position in the text. The didactic function of the expressed presupposition is to actualize the reader’s knowledge necessary for text comprehension. At the same time, the expressed presupposition allows presenting a model of knowledge and a knowledge-building process by mapping a knowledge structure. The expressed presupposition represents the epistemic relations (1) between the familiar and unfamiliar parts of disciplinary knowledge and (2) between familiar parts of everyday life and unfamiliar disciplinary knowledge. The expressed presupposition presents the knowledge-building process by affecting the text deployment. The initial presupposition can occur as a global topic sentence expressing the most significant referents and determining the thematic text structure. Also, the initial presupposition can convey familiar segments of knowledge and set an information context to introduce unfamiliar significant referents in the following sentences. The non-initial presupposition expands the information context and tends to elaborate and detail the topic. To conclude, there is a correlation between the text-deployment potential of the expressed presupposition and the epistemic potential of the familiar knowledge.