Despite the apparent simplicity of these correlative conjunctions, there is uncertainty and disagreement over the suitability of their use and the correctness of their placement. Much of this discord pertains to the need for parallelism and sentence balance. I’ll look at that later in the post, but first I’ll give an overview of how the conjunctions are used.
Not only is this post quite long and detailed, it also lacks images, so I’ve folded it up and divided it into three general sections: Usage, Parallelism, Opinions.
Writers typically, but not always, use both parts of the set, i.e. (1) not only, and (2) but (also). The first part is occasionally written not just or not alone, while the second part is commonly seen in the forms but . . . too and but . . . as well. These variants offer different nuances but not very different meanings.
It was not just a big bear, but a grumpy one as well.
Not alone did she win the race, but she also beat the record.
He not only used a fictitious example, but he reproduced it too.
But (also) is the most common root form, so I’ll focus on it in this discussion. Where the alternatives are not mentioned, consider them implied. When but is included you can either add also (or its alternatives) or not; both forms are common and standard. Hence the parentheses in but (also), which could also be written as (but) also, since but sometimes doesn’t appear either.
He not only used a fictitious example, but he also reproduced it.
He not only used a fictitious example, he also reproduced it.
Rowers not only face backward, they race backward.
The last example, from the New Yorker, is effective because of its succinctness and punchy rhythm. Adding but would impair it, while adding also would do little or nothing to improve it. Doing without but or also tends to reduce formality, or to reduce stiffness in formal prose, and can benefit short and straightforward constructions. Here are a few more:
“Borges not only wrote stories but transformed them” (The Mirror Man documentary)
“The shape of Cleopatra’s nose influences not only wars, but ideologies” (Arthur Koestler, The Sleepwalkers)
“The omission of the also is not only frequent but Standard” (Kenneth G. Wilson, Columbia Guide to Standard American English)
“Not only are there verbs with similar meanings and different past-tense forms, there are verbs with different meanings and the same past-tense forms. (Steven Pinker, Words and Rules)
But (also) can appear by itself, without being preceded by not only:
“It depends on your point of view, but also on where you live.” (Don Watson, Weasel Words)
“The article, based on a lengthy interview with Kidd, but also on discussions with other figures in Joyce and general editorial scholarship, contained the essentials of the row which was then inevitable.” (Bruce Arnold, The Scandal of Ulysses; my underlines)
Not only could have been inserted as follows:
“The article, based not only on a lengthy interview with Kidd, but also on discussions with other figures…”
But whether this is preferable to the original is a matter of taste, not correctness.
Using not only . . . but (also) to frame parallel sentence parts can heighten clarity, reduce ambiguity, and lend elegance to one’s style. Nonetheless, many skilled writers eschew precise parallelism at no significant cost. It’s only when faulty parallelism is flagrant that most readers tend to notice it, or to notice that something has gone awry.
Short sentences derive force from simplicity and a lack of elaborate rhetorical devices, whereas longer sentences often need more emphasis on balance, to help the reader keep track of structure and constituent parts. Balance is boosted by careful placement of sentence elements.
Not only does the number of migrations vary with the month, but also with the type of species.
Not only does the number of migrations vary with the month, (but) it also varies with the type of species.
The number of migrations varies not only with the month, but also with the type of species.
These examples show the general benefit of careful placement of the correlative conjunctions. Though none is likely to confuse people, the third is the tidiest. Some style authorities consider this tidiness an essential point of courtesy, but sentence structure is not something most readers pay much attention to – unless it’s a mess. To take a closer look at not only . . . but (also) in the context of parallelism and sentence balance, consider the following example:
The controversy not only damages sales but also shareholder confidence.
That is, [subject] not only [verb, noun] but also [noun]. Many readers don’t notice that the correlated sentence parts are mismatched, some notice but don’t care, and others notice and care a little, or care very much. If you want to offset criticism from purists, you could reposition not only from its contentious position before the verb, to immediately before the element it qualifies:
The controversy damages not only sales but also shareholder confidence.
[subject, verb] not only [noun] but also [noun]
or you could repeat the verb or insert another suitable one:
The controversy not only damages sales but also damages shareholder confidence.
The controversy not only damages sales but also undermines shareholder confidence.
[subject] not only [verb, noun] but also [verb, noun]
Or you could simply use and:
The controversy damages sales and shareholder confidence.
Each option brings subtle differences to the structure and stress of the sentence. Here’s an interesting example from George Orwell’s “Down the Mine”:
Occasionally, of course, the charge is too powerful, and then it not only brings the coal out but brings the roof down as well.
The phrasal verbs bring out and bring down add further internal symmetry and counterpoint to Orwell’s sentence.
Usage commentators disagree on whether not only and but (also) should frame parallel elements. Some grammarians advise strict adherence to parallelism; others are more relaxed about it. Here is H. W. Fowler in A Dictionary of Modern English Usage:
Not only out of its place is like a tintack loose on the floor; it might have been most serviceable somewhere else, & is capable of giving acute & undeserved pain where it is.
Bryan A. Garner in A Dictionary of Modern American Usage is equally severe, instructing that not only . . . but (also) “must frame syntactically identical sentence parts”. The advice in Merriam-Webster’s Dictionary of English Usage is more moderate. Reporting many literary and historical examples of non-parallel usage, it concludes:
So long as you take care that the groups of words joined by the conjunctions are not so dissimilar as to call attention to themselves, you need not worry all the time about achieving precise parallelism. It is more important for your sentence to sound natural and to make sense.
Not only and but (also) certainly have their uses, but they tend to be overworked in over-baked prose, where they occasionally fudge the contents or lead the reader astray. If you use them and you find the result awkward or ambiguous, try to recast the elements as I have shown, to improve the structure and balance of your sentence, and remember that and can often suffice for more complex constructions.