Some guides advise you to end each paragraph with a specific concluding sentence, in a sense, to treat each paragraph as a kind of mini-essay. But that’s not a widely held convention. Most well written academic pieces don’t adhere to that structure. The last sentence of the paragraph should certainly be in your own words (as in, not a quote), but as long as the paragraph succeeds in carrying out the task that it has been assigned by its key sentence, you don’t need to worry about whether that last sentence has an air of conclusiveness. For example, consider these paragraphs about the cold fusion controversy of the 1980s that appeared in a best-selling textbook12:
The experiment seemed straightforward and there were plenty of scientists willing to try it. Many did. It was wonderful to have a simple laboratory experiment on fusion to try after the decades of embarrassing attempts to control hot fusion. This effort required multi-billion dollar machines whose every success seemed to be capped with an unanticipated failure. ‘Cold fusion’ seemed to provide, as Martin Fleischmann said during the course of that famous Utah press conference, ‘another route’—the route of little science.
In that example, the first and last sentences in the paragraph are somewhat symmetrical: the authors introduce the idea of accessible science, contrast it with big science, and bring it back to the phrase “little science.” Here’s an example from the same chapter of the same book that does not have any particular symmetry13:
The struggle between proponents and critics in a scientific controversy is always a struggle for credibility. When scientists make claims which are literally ‘incredible’, as in the cold fusion case, they face an uphill struggle. The problem Pons and Fleischmann had to overcome was that they had credibility as electrochemists but not as nuclear physicists. And it was nuclear physics where their work was likely to have its main impact.
The last sentence of the paragraph doesn’t mirror the first, but the paragraph still works just fine. In general, every sentence of academic writing should add some unique content. Don’t trouble yourself with having the last sentence in every paragraph serve as a mini-conclusion. Instead, worry about developing each point sufficiently and making your logical sequence clear.
Conclusion: Paragraphs as Punctuation
To reiterate the initial point, it is useful to think of paragraphs as punctuation that organize your ideas in a readable way. Each paragraph should be an irreplaceable node within a coherent sequence of logic. Thinking of paragraphs as “building blocks” evokes the “five-paragraph theme” structure explained in Chapter 2: if you have identical stone blocks, it hardly matters what order they’re in. In the successful organically structured college paper, the structure and tone of each paragraph reflects its indispensable role within the overall piece. These goals—making every bit count and having each part situated within the whole—also anchor the discussion in the next chapter: how to write introductions and conclusions that frame—rather than simply book-end—your analysis.