A piece of writing resembles a ladder its reader must climb. Its introduction acts as its base, where the reader begins the ascent; its top is the conclusion, the reader's destination after moving through its body. That body consists of rungs that, one by one, bring the reader closer to the piece of writing's conclusion and allows him or her to arrive there on solid footing. Those rungs are paragraphs. In The Elements of Style, William Strunk and E. B. White instruct, "Make the paragraph the unit of composition." Therefore, structuring your paragraphs well contributes immensely to effective writing.
Let's start at the beginning, with the paragraph's introductory sentence-usually a topic sentence, stating a new idea in the development of your thesis or subject. The break in text created by a new paragraph's indentation announces this change. Angela Lunsford and Robert Connors elaborate in The New St. Martin's Handbook: "Remember that a new paragraph often signals a pause in thought. Just as timing can make a crucial difference in telling a joke, so the pause signaled by a paragraph can lead readers to anticipate what is to follow . . ." If what follows does not present a new idea, readers are apt to be disappointed or confused.
The new idea expressed in the topic sentence should encapsulate the content of the ensuing paragraph. "Each paragraph should make one point, and every sentence in it should relate to that one point," declare Diana Roberts Wienbroer et al. in Rules of Thumb For Business Writers. The topic sentence provides the thematic baseline around which all other sentence in the paragraph must revolve.
Wienbroer et al. give a simple reason for placing the paragraph's declaration of intent at its start: most readers in a professional setting are pressed for time and want information presented to them as quickly and smoothly as possible. Beginning a paragraph with its topic tells the reader what to expect ahead, rather than making the reader guess at where your writing is going as he or she reads along. On the other hand, Lunsford and Connors argue rightly when they say, "When specific details add up to a generalization, putting the topic sentence at the end of the paragraph makes sense." This strategy suits works relying on inductive reasoning, moving from particular points toward a larger common idea; it can also lend variety to the structural pattern of your paragraphs. With the exception of legal writing or laboratory or survey reports, however, few occasions for inductive logic arise in professional writing.
Sometimes, instead of or in addition to staking out new territory for a composition, the first sentence of a paragraph connects the preceding paragraph to this new idea. "Link your paragraphs together with transitions-taking words or ideas from one paragraph and using them at the beginning of the next," suggests Rules of Thumb For Business Writers. Transition sentences at the beginning of a paragraph work best when the main idea of its paragraph grows out of, is a corollary of, or is an antithesis to that of the preceding paragraph. For example, the first sentence of this paragraph introduces the theme of the transition sentence by contrasting it with the preceding paragraphs' theme of making a break from the rest of the text.
The body of a paragraph works to support its topic statement. As you flesh out a paragraph, "ask yourself . . . how each sentence develops the paragraph topic," say Lunsford and Connors. Because, they assert, a paragraph "focuses on one main idea (unity); its parts are clearly related (coherence); and its main idea is supported with specifics (development)." Demonstrate explicitly and thoroughly how your details support your topic, especially where your interpretation of how they do is novel or counterintuitive. Drive the point home. Don't leave any gaps in your argument, assuming that you reader will be clever enough to carry your line of reasoning over them; readers don't expect to do your work for you, and your carefully built argument may appear to the reader like a house of cards.
"Within a paragraph, make sure that your sentences follow a logical sequence," Wienbroer et al. insist. "Each one should build upon the previous one and lead to the next." They recommend, "If you have trouble with paragraph organization, you can usually rely on this basic paragraph pattern:
A main point stated in one sentence
An explanation of any general words in your main point
An example or details that support your point
The reason each example or detail supports your point
A sentence to sum up"
You may also find it helpful to preface some supports, if they are different in kind, with an explanation of this difference to help the reader switch mental gears between them, or with transitions if they are similar in kind. "In acting as signposts, transitions such as after all, for example, indeed, so, and thus help readers follow the progression of one idea to the next within a paragraph," says The New St. Martin's Handbook. "Finally indicates that a last point is at hand; likewise, that a similar point is about to be made, and so on." Other common transitions include
Also In addition Additionally Furthermore
Moreover Similarly By comparison By contrast
However Nonetheless Still Therefore
In spite of Despite First (Second, etc.) To begin
Lastly To conclude In conclusion Next
"It is important to note," the Handbook cautions, "that transitions can only clarify connections between thoughts; they cannot create connections." As with linking supports to your paragraph's main idea, make the relationships between supports as explicit as possible if someone less familiar with your topic would not find them readily apparent. Transitions between similar supports, and introductions before supports of differing types, tell the reader that your argument in that paragraph is solid and cohesive because of its uniformity or in spite of its variety-they suggest that your supports are more than a random collection of incidences, that they form a trend of evidence of your topic statement's truth. Merely planting a transition word into a paragraph without explaining the connection could seem to your readers like hastily brushing over an incongruity in your argument and may raise doubts in their minds about your argument's validity.
Parallel structure provides another strategy for giving unity to a paragraph; "[e]xpress coordinate ideas in similar form," Strunk and White recommend. They illustrate this principle with the Sermon on the Mount, in which each sentence has two clause that start the same way: "Blessed are the [blank]; they shall [blank]." This device conveys the similarity between or among points more dramatically, embodying it through grammar and syntax.
The importance of unity in your paragraph necessitates avoiding digressions. Some of your supports-especially more complex, specialized, or arcane ones-may require more elaboration or explanation than usual, or may require you to define terms or supply background information. That's fine. Just keep such material to the minimum necessary to elucidate your topic; don't let it create a tangent that leads you away from your paragraph's line of thought. Habitually enclosing digressions in parentheses or pairs of dashes can assist you in limiting their length.
That leaves us with the concluding sentence. A concluding sentence should recap the paragraph's main point and summarize its content. "Sometimes you will want to state a topic sentence at the beginning of a paragraph and then refer to it in a slightly different form at the end," Lunsford and Connors suggest. Make sure this reiteration does differ in form, and maybe more than slightly. If you can't rephrase the main idea from a different angle, you'd be better off leaving the concluding sentence out than parroting to the reader what he or she has already read.
Best of all, the angle from which you rephrase your paragraph's main idea should be the body of the paragraph: state what about the main idea you have learned from your paragraph's material, what the reader can take away from the paragraph that he or she didn't know at the beginning. In addition, if the topic of the next paragraph derives from or relates to something in the current paragraph, your concluding sentence can lead into or set up the transition to or presentation of that idea in the following paragraph's introductory sentence.
If a work of writing is like a ladder, a paragraph is too: its first and last sentences are the two ends, and each sentence of its body forms a rung. A paragraph is a composition in miniature, a microcosm of the argument it is a part of. These smaller arguments, each about a different aspect of your subject or thesis, combine to make up your overall argument-only if they all function soundly will your audience be interested, informed, and influenced.