Coherence and cohesion
Coherence and cohesion are important features of academic writing. They are common features tested in exams of academic English, including the IELTS test and the TOEFL test. Both of them are essential for aiding readability and idea communication. Coherence is about the unity of the ideas and cohesion the unity of structural elements. In other words, coherence refers to how the ideas of the text flow logically and make a text semantically meaningful as a whole. Cohesion is what makes the elements (e.g. the words, phrases, clauses, and sentences) of a text stick together to form a whole.
Let’s focus on the concept of coherence first.
What is coherence?
Many students have turned in papers only to have their teachers hand the papers back with comments that the writing doesn’t “flow.” However, what exactly is "flow"? Familiar though it may seem, many students actually do not know about its precise definition.
By “flow”, most readers mean what grammarians and linguists call coherence—the property of a text to hold together at the levels of sentences and paragraphs— to be logically ordered and connected. With coherence, the text is clear, consistent, and understandable. Just because an argument you’re making is clear in your own head, that doesn’t mean it’s automatically clear to people who are reading the written version of your argument.
Conscious effort is needed to bridge the gap. You need to put your ideas in a logical sequence, so that paragraphs of the document work together to provide a strong basis for accepting the main message. When a document flows logically, questions are raised in the readers’ minds and then answered. That helps your readers understand and remember what you want them to know.
More specifically, the reader’s understanding should always be borne in mind. On the text level, subject lines and headings should focus on the core message. On the paragraph level, each paragraph should have one single message, expressed by a topic sentence.
Within a paragraph, it has its internal structure, as described in the following sections.
Flow of information in paragraphs
Every paragraph has a structure. It is not just a random collection of sentences. The parts that make up the text are related in meaningful ways to each other.
In order for a paragraph to be easy to read, the information in it must flow easily from one sentence to the next. To do this it is important to structure your information clearly and signal exactly what you want to say by the use of signalling words.
Information structure
Most sentences in English have two parts: a theme (or topic) and a rheme (or comment) (McCarthy, 1991, p. 55). The theme is what you are writing about - it is shared information and it has been introduced to your reader. The rheme is what you are saying about the theme - it is new information, what you want to tell your reader.
In English, the theme usually comes at the beginning of the sentence and the rheme at the end. The decision about which part of the sentence to make the theme and which part to make the rheme depends on the information that needs to be communicated. This depends on the sentences that come before.
Look at the following short paragraphs:
a) I was born in Glasgow. Glasgow is the largest city in Scotland.
b) I was born in Glasgow. The largest city in Scotland is Glasgow.
All the sentences are grammatically correct but in example a, the information to be communicated, the rheme “the largest city in Scotland” is at the end of the sentence, which is preferred in English.
References:
https://writing.chalmers.se/chalmers-writing-guide/writing-a-text/coherence-cohesion/
https://www.myenglishpages.com/english/writing-cohesion-and-coherence-in-essays.php#cohesive_but_not_coherent_texts
https://www.eapfoundation.com/writing/cohesion/
http://www.uefap.com/writing/parag/par_flow.htm
https://courses.lumenlearning.com/suny-jefferson-collegecomposition/chapter/cohesion-what-do-people-mean-when-they-say-my-writing-doesnt-flow-open2010writingchapter9-pdf/
http://colelearning.net/who/module2/page46.html
