2.6 Cohesion and Coherence
A text has texture, which is what holds the sentences of a text together as a semantic unit. Texture arises from the interaction of two components, cohesion and coherence. Cohesion refers to the degree to which sentences within a text hang together to form a unified whole. It has been metaphorically described as the "glue" that holds a text together and makes it interpretable. As such, cohesion is seen as the foundation on which the whole edifice of texture is built (Halliday & Hasan, 1985).
Halliday and Hasan (1976) identified three main types of cohesion as follows (see Table 2-1). Linguistic devices such as pronouns, synonyms, antonyms, and conjunctions help stitch a text together. They enable readers to track participants, detect logical-semantic relations, and identify thesis in the text.
Table 2-1 Types of Cohesion
Coherence, on the other hand, refers to the degree to which a text makes sense in particular social, cultural, and situational contexts. Frequently, the lack of coherence in a text "is reflected in, and is a reflection of, its accompanying lack of internal organization, its lack of cohesion" (Eggins, 2004, p. 29). However, it is important to note that a cohesive passage without coherence does not, technically, constitute a text. For example, the following string of sentences has high cohesion but no coherence because we cannot think of a situation where all the sentences taken together would make sense. It is thus not considered a text.
Tom Brady plays quarterback for the New England Patriots in Boston. He went swimming yesterday. Swimming in Florida can be both exciting and dangerous. Orlando is in Florida, and Florida is where Donald Trump resides.(https://www.daowen.com)
On the other hand, while a text is always coherent with respect to its context, it may not always be cohesive. For example, Text 2-4, an exchange between husband and wife, has no explicit cohesion, but has high coherence because we can think of a situation where both sentences taken together make sense. The scenario can be understood this way: the husband was expecting his business partner Ryan to come to his house at 6:00pm for a drink; so, when the wife told him someone was knocking on the door, he suspected it was Ryan but wanted to make sure; and one way for him to make sure is to check if it was 6 o'clock already. Here, the second sentence is interpreted in light of the context established by the first sentence.
Text 2-4
Wife: Honey, someone's knocking on the door.
Husband: What time is it?