Abstract
<jats:p>The article discusses the semiotic features of argumentative text and parameters of its analytical understanding. The author also describes the semiological, pragmatic and psychological parameters of natural language reasoning as components of the text system. These parameters have the characteristics of an open system operating within a labile rhetorical situation. The article characterizes the logical characteristics of reasoning and the perspectives of applying traditional logical systems to its analysis. Abduction is described separately and its interpretative limitations are explained. As an alternative, an extensional system is proposed that provides a detailed description of the extension of scholastic syllogistics as a base, and as an applied component; the system takes into account peculiarities of vocabulary and grammar in the formulation of judgments that make up the syllogism. The article explains ways of obtaining an unambiguous composition of the premises of the syllogism for which a verbalized conclusionserves as a basis. The proposed algorithm is applicable for exchanging information in a closed mode from unauthorized persons.</jats:p>