To think about something critically, to be able to ask questions and evaluate their answers, involves what is called coherence. We pose and reply to questions with words, of course, and in the study of language, whether written or spoken, coherence is of primary importance. We make sense of things by understanding how they belong together, how they stick or cling together, the original meaning of the verb cohere. When someone answers a question with ideas which don’t cohere, their reply may be said to be inconsistent, incongruous—incoherent.
The principle of coherence controls the way we draft sentences and paragraphs because both of those literary devices are means by which we compose and promulgate our thoughts critically. Paragraphs are nothing more than a set of sentences written around one idea, and traditional writing manuals (among them The Technique of Composition by Kendall Taft et al. [1964], which defines a unified paragraph as one whose details “belong together,” and hence my use of that same phrase above) will regularly identify a number of techniques to achieve a coherent paragraph: logical order, grammatical transitions, and repeating phraseology, for example. Since we can learn to do the same by imitating our betters, here is an example from a major twentieth-century philosopher in which we may see how the first three sentences of a paragraph cling tightly together. The result is that we readers can push out from harbor confidently into the open ocean of an unfamiliar and difficult subject:
Philosophy arises from an unusually obstinate attempt to arrive at real knowledge. What passes for knowledge in ordinary life suffers from three defects: it is cocksure, vague, and self-contradictory. The first step towards philosophy consists in becoming aware of these defects, not in order to rest content with a lazy scepticism, but in order to substitute an amended kind of knowledge which shall be tentative, precise, and self-consistent.
These three sentences constitute the opening of a nine-sentence long paragraph by the British philosopher Bertrand Russell in his Outlines of Philosophy (1927). Russell was known for his acute and pristine prose (he was a mathematician and logician, as well as a philosopher), and if we take the time to briefly analyze the way these three sentences cohere, we will understand how the technique of logical arrangement works and how to employ it ourselves.
His first sentence marks the unitary topic of the paragraph; it will stand as what is called the controlling idea, to which the ideas in every subsequent sentence in the paragraph must belong. Philosophy, it says, has something to do with real knowledge. The second sentence then picks up this idea of real knowledge and contrasts it with knowledge in ordinary life (let’s call it ordinary knowledge), identifying three characteristics (defects) of the way we usually think about things: we are often cocksure, vague, and self-contradictory. Notice thus far this order of ideas: philosophy and real knowledge, ordinary knowledge and its defects. Let’s label the scheme A, A, B, B.
Russell’s third sentence, however, is the jewel in the crown over this passage. It begins by connecting the idea of philosophy (A) with the idea of defects (B), using exactly the same two words used previously to tie the first two sentences together. This third sentence, however, continues with the introduction of lazy scepticism as a synonym for the idea previously named ordinary knowledge (B), and the sentence completes its logical arrangement by contrasting the ordinary characteristics of cocksure, vague, and self-contradictory with philosophy’s real knowledge (A): tentative, precise, and self-consistent. Note that these three terms correspond, word for word, as the opposite of the earlier-named three defects. Where the compositional design of the first two sentences is A, A, B, B, a simple arrangement to introduce the ideas which develop the controlling idea, the culminating third sentence rearranges the scheme into A, B, B, A in order to put those ideas into gear.
That’s just beautifully done, and all of it a masterful display of coherence, of choosing ideas that belong with one another and holding them together under an intelligible design. What is unknown will always appear difficult to us at first (here both content and form), but although these technical matters of composition will be important to the conscientious writer, it matters little whether a reader knows of or about them. What the tailor has done to make that dress drape so finely at shoulder, waist, and leg matters to the tailor; it is the integrity of the work that matters to us who observe it. Truth, what Russell calls here real knowledge, must likewise assume such integrity of workmanship. This should be the concern of every craft, but perhaps of the craft of language most of all, because the integrity—the coherence—of what we write and speak reveals the quality of our knowledge, whether it be merely ordinary and vague, or ultimately real and precise.
***