In Contrastive Rhetoric: Cross-Cultural Aspects of Second-Language Writing, Ulla Connor defines cohesion as "the use of explicit linguistic devices to signal relations between sentences and parts of texts." These cohesive devices are phases or words that help the reader associate previous statements with subsequent ones. In Cohesion in English, M.A. Halliday and Ruqaiya Hasan identify five general categories of cohesive devices that signal coherence in texts:
A text may be cohesive without necessarily being coherent: Cohesion does not spawn coherence. "Cohesion," Connor writes, "is determined by lexically and grammatically overt intersentential relationships, whereas coherence is based on semantic relationships."
Coherent texts make sense to the reader. In Text and Context: Explorations in the Semantics and Pragmatics of Discourse, Teun A. van Dijk (p. 93) argues convincingly that coherence is a semantic property of discourse formed through the interpretation of each individual sentence relative to the interpretation of other sentences, with "interpretation" implying interaction between the text and the reader. One method for evaluating a text's coherence is topical structure analysis.
A Topical Structure Analysis of Newspaper Editorials This paper analyzes the topical structure of accomplished essays and compares it with the topical structure tacitly preferred by assessors in their judgments of student essays. The central aim is to examine whether the same patterns of topical structure that are rewarded by assessors in student writing, as reported by previous studies, are in fact being used by professionals writing within a similar genre. The results of the comparison will help determine the extent to which essays written for such tests as Educational Testing Service's TOEFL Test of Written English, analyzed by Schneider and Connor (1991), are being evaluated in accordance with the unstated norms of topical structure in comparable accomplished prose. Read more ...