Cohesion is the linguistic connectedness between sentences — the specific devices that link one sentence to the next so the reader can follow the thread. It is distinguished from coherence, which is the overall logical unity of a text. Cohesion is local; coherence is global.
M.A.K. Halliday and Ruqaiya Hasan identified five cohesive devices in Cohesion in English (1976):
- Reference — pronouns and demonstratives that point back to previously mentioned items. “The report was published. It showed…”
- Substitution — replacing a word or phrase with a substitute. “I’ll have a coffee. Make that two.”
- Ellipsis — omitting words that the reader can infer. “She wrote the first draft. He [wrote] the second.”
- Conjunction — transitional words and phrases that signal the logical relationship between sentences. “However,” “therefore,” “in contrast,” “for example.”
- Lexical cohesion — repeating key terms or using synonyms and related words to maintain the topic thread. A paragraph about “audience” that switches to “readers,” then “users,” then “the people you’re writing for” maintains cohesion through lexical variation.
Joseph Williams added a structural principle: the “old-before-new” contract. Each sentence should begin with information the reader already knows (from the previous sentence or from context) and end with new information. This creates a chain where the end of one sentence sets up the beginning of the next [@williams2006].
Too little cohesion makes prose feel choppy — the reader must infer connections the writer should have made explicit. Too much cohesion (excessive transitional phrases, mechanical repetition) makes prose feel labored. The goal is enough connection that the reader’s attention stays on the content, not on figuring out how the sentences relate.
Related terms
- coherence — the overall unity that cohesion supports
- transition — one of the primary cohesive devices
- paragraph — the unit where cohesion is most visible
- syntax — sentence structure contributes to cohesive flow