When I’m line editing a manuscript, one of my top priorities is making sure the relationships between sentences are logical and clear to the reader. If you set up one idea in Sentence A and then introduce another one in Sentence B, the reader should be able to tell how they relate to each other—is Idea B supporting evidence for Idea A, a caveat or counterexample, a second example of the same phenomenon, or something else?
To show these connections, authors often use what Pamela Haag calls “switchtrack words” (112). If Idea B supports or furthers Idea A, you might use “therefore,” “similarly,” “additionally,” or “for example” in your second sentence; if Idea B sets up a contrast, you might say “but,” “yet,” “however,” or “conversely.” Haag writes that these words “perform the micro-work of flow by steering your prose (and reader) from one stance to the next” (114).
Underusing these words can lead to writing that sounds disjointed because you’re not showing the reader the connections between your ideas. But using a switchtrack word doesn’t automatically make the relationship clear—if the reader can’t tell what is being supported, built on, or contradicted, they still won’t get what you’re trying to convey. I often see this problem when authors pile up consecutive “but”/”however” sentences: “Idea A. However, Idea B. Yet Idea C. But Idea D.” The relationship between A and B might be perfectly clear, but once you get to the second contradiction, it falls apart—is C contradicting A or B? And the more complex each sentence is (in terms of both concepts and syntax), the more careful you need to be to show exactly what element of the first sentence is being supported or contradicted in the second one. For the same reason, starting a paragraph with a switchtrack word can be confusing, especially if the previous paragraph has its own set of relationships between ideas.
Haag, Pamela. Revise: The Scholar-Writer’s Essential Guide to Tweaking, Editing, and Perfecting Your Manuscript. New Haven: Yale University Press, 2021).