Abstract

Historically considered, the concept of the topic sentence seems to be related to the concept of the topoi in classical rhetoric-in the sense of a topos or topic as subject matter treated in a speech or a portion of a discourse, as a method of reasoning about a subject, and as a place or heading from which arguments are drawn. All of these senses of the word seem to have been maintained in the kind of advice given by 19th-century textbook writers about methods of constructing paragraphs. In order to construct a paragraph, the advice goes, the writer should embody the main idea of the paragraph (its subject) in a topic sentence. Then, drawing upon a list of commonplace methods of reasoning about the subject (in the form of headings, such as comparison, contrast, and cause and effect, that label relationships), the writer should develop the central idea contained in the topic sentence into a unified and coherent paragraph. This connection between the topic sentence and the classical topoi is eminently suggestive, but however interesting it may be, the fact is that as an independent concept the topic sentence did not begin to emerge until the mid-19th century. It first appeared in Alexander Bain's discussion of the paragraph in 1866, and it attained fuller development in the late 19th and early 20th century. But the 19th-century conception of the topic sentence has come under considerable attack in recent years because of its deductive origins and because one kind of research has revealed that many contemporary professional writers do not use topic sentences in their writing. I would like to argue, however, that in some kinds of writing the topic sentence can be a valuable rhetorical strategy because it can help writers to organize their ideas and it can help readers to follow the logical development of the writer's ideas. As a means of developing my argument, I would like to look briefly at the origin and development of the concept of the topic sentence, consider the criticisms that have been made of the topic sentence in the 20th century, and then, drawing upon readability research that discusses the topic sentence and schema theory, argue that this kind of research supports the value of using topic sentences in expository prose.