The “topic sentence” that you should have at the beginning of every paragraph in an essay is probably misnamed—at least if you are writing to make an argument. In an argumentative essay, topic sentences need to do more than simply mention a “topic” for the paragraph. To be effective, a topic sentence should both state a specific main point for the paragraph and implicitly refer back to the essay’s thesis.
Just as the defense attorney explains why the witness’s testimony clears her client, the topic sentences of an essay should move your argument along, explaining how and why the forthcoming evidence supports your main point. If a paragraph lacks an argumentative topic sentence, it is merely dispensing information, which may well seem pointless to your readers.
To test whether a would-be topic sentence is actually doing its job, you might ask: does the sentence have a built-in answer to the “so what” question? If not, you probably need to revise. Often, you will need to write a somewhat more complex sentence that links together multiple concepts. (If you start applying this test, you might notice that no sentence that simply states a fact—that merely describes—can meet the “so what” criterion.)
Here, for instance, are a couple of weak topic sentences for a paragraph about the U.S. Constitution, in an essay that says it argues that the Constitution forged a legitimate representative government:
The convention that framed the Constitution met in Philadelphia.
The framers had difficulty figuring out a system of representation.
The first sentence above is merely a statement of fact—it doesn’t have any power to advance an argument. The second sentence at least includes an idea, that the issue of representation posed difficulties, but it is too vague: it neither attempts to explain why there was a problem nor why the problem mattered. Here, by contrast, is a sentence that could help advance the thesis in question:
The ratification debate and process allowed ordinary voters, including the majority of free men, to give the Constitution their approval.
This sentence works because it puts together two ideas—the ratification process and voter approval—and these ideas in turn help support the thesis. (I have to add, though, that this argument is far from airtight, historically speaking, given that the ratification process excluded the majority of the adult population, including all women and unfree servants and slaves.)
Topic sentences often need to do the additional work of helping make the transition from one paragraph to the next. You can usually make a transition with just a word or phrase that refers to the main idea of the previous paragraph. (Note that you do not need to make the transition twice—at both the end of one paragraph and the beginning of the next. On my essay rubric, I call this “overwriting” a transition.) But you usually need to gesture at the connections between each paragraph. Again, the purpose of doing so is to help move your argument along by connecting one idea to the next and explaining why each idea matters.
The well-written topic sentence thus plays a crucial role in the development of your essay’s argument. An essay without argumentative topic sentences will probably leave your reader unpersuaded and unsatisfied. You may be filling the pages, but you won’t be making your point.
Writing Handbook for History & Humanities by David J. Voelker is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.