Normally, the rule for correlative conjunctions is that the two elements being combined must be parallel in structure. But I believe there are cases this rule is broken, but I'm not sure why they're still considered correct.

Examples of correlative conjunctions are:

  • not only...but also...
  • neither...nor...
  • either...nor...
  • both...and...
  • between...and...
  • at once...and...
  • just as...so...
  • as...as...
  • as many...as...
  • so...that...

There are many more correlative conjunctions, but these will suffice.

Here's how the parallelism rule works:

  1. He is NOT ONLY happy BUT ALSO tired. = correct because "happy" and "tired" are both adjectives and thus parallel

  2. They are EITHER going to swim OR going to drown. = correct. The verb phrases are parallel.

But here are cases when the elements are NOT parallel, which is what confuses me. Why do these cases break the parallelism rule?

  1. He is AS strong AS an ox. = correct, yet "strong" (adjective) is not parallel to "an ox" (noun). What gives?

  2. I was SO happy THAT I could scream. = correct, yet "happy" (adj.) and "I could scream" are not parallel.

  3. NOT ONLY did he cheat on this exam BUT he ALSO cheated on all exams. = correct, yet "did he cheat on this exam" seems inverted, using a verb-subject structure, rather than the subject-verb structure in the second half. So it's not perfectly parallel, yet I know the sentence is fine. How do you explain this?

  4. Twice as many people inhabit China as inhabit India. = correct, yet "people inhabit China" doesn't seem parallel to "inhabit India." The "inhabit" carries over, so that's good. Maybe there is an implied "people" that also carries over to the second half? Not sure.

Would the following be considered correct?

A) Twice as many people inhabit China as people inhabit India.

B) Twice as many people inhabit China as people who inhabit India.

How do you explain these exceptions to the parallelism rule? Thanks!

  • 1
    "as ADJ as" is not a correlative structure (as you indicate with your example "as strong as an ox"). Why do you expect it to be?
    – herisson
    Commented Apr 28, 2017 at 0:45
  • There's something wrong with "I was so happy that I could scream". Consider "I was so happy that I could swim the river." "I was so happy that I could scream when I finally got the tape off my mouth." Also "either . . . nor" is a problem.
    – Xanne
    Commented Apr 28, 2017 at 1:22
  • @Xanne What's wrong with "I was so happy that I could scream"? Scream in joy because I'm so happy. Seems fine. Yes, "either...nor" is wrong because it should be "either...or" (not NOR).
    – Peter
    Commented Apr 28, 2017 at 1:32
  • @sumelic If it's not correlative, how would you use "as...as" as a correlative? "He is as strong a person as his brother is." That's correlative, right? But "strong a person" doesn't seem parallel to "his brother is." The first correlative is missing the subject, because it appeared completely before the first "as."
    – Peter
    Commented Apr 28, 2017 at 1:35
  • Related: What defines a correlative?
    – herisson
    Commented Apr 28, 2017 at 1:49

3 Answers 3

  1. He is as strong as an ox. It is a simile, not a correlative conjunction. Because we can also write it as, 'He is strong as an ox.' The second 'as' is unnecessary, though it would be if it was part of a correlative conjunction.

Other examples: She ran like the wind. (implying speed) His reply was cold as ice. (implying lack of feeling)

In similes, adjectives and verbs are compared to nouns, so this sentence is doesn't violate the rule of parallelism.

  1. I was so happy that I could scream. Again, it's not a correlative conjunction. 'So' is an adverb describing 'happy'. How happy? Very happy.

'That I could scream' is an adverbial clause that describes 'happy' as well. How happy was I? I was happy enough to scream.

  1. NOT ONLY did he cheat on this exam BUT he ALSO cheated on all exams. First, this sentence is awkward if you omit 'the' before exams. It should read:

'Not only did he cheat on this exam, but he also cheated on all (of) the exams.'

Now, if we are putting to question the inversion, we have to first ask whether the dependent clause can be written in a subject-verb manner. So let's try.

'He not only cheated on this exam, but he also cheated on all the exams.' Here we have an exact parallel between conjoined parts of the sentence. We can omit 'also' to make the sentence flow smoothly, using the conjoining words 'not only' and 'but'.

'He not only cheated on this exam, but he cheated on all the exams.'

  1. Twice as many people inhabit China as inhabit India. For convenience's sake, the subject 'people' is omitted in the second part of the sentence. But if we write this sentence in its entirety, we get the following:

'Twice as many people live in China as people live in India.'

By writing out the full sentence, we can see that rule of parallelism is upheld.

  1. "He is as strong as an ox" is an example of a simile. It is a comparison. If you wanted to phrase it as correlative, you could say, "He is as strong as an ox is strong." The last "is strong" is understood.
  2. "I could scream" is a an adjectival phrase. Subject, adverb, verb together are serving as an adjective, correlative to "happy".
  3. The inversion "did he cheat" rather that "he did cheat" is just for emphasis. The correlative is still there. Another example: "Can Kristofferson play the guitar?" "Can he?" in a tone meaning he certainly can.
  4. The parallel is inhabit to inhabit. This is another example of a word being omitted, yet the sense of it is understood. You are comparing a number (twice as many) to another number (one) which is understood by the context. Neither of your redrafts is as clear and graceful as the original sentence.

English does not always make sense.

  • 1. You're saying "He is as strong as an ox" is NOT correlative? I thought because "is strong" is implied, the sentence is still correlative. But if we include "if strong," the sentence would then be comparing "strong" with "an ox is strong." How is that parallel? 2. How is "I could scream" an adjectival phrase? I thought adjectival phrases were things like "running down the street," as in "the boy running down the street." If I wrote "I was so happy that ADJECTIVE," it would be wrong. For example, "I was so happy that JOYFUL" is wrong.
    – Peter
    Commented Apr 28, 2017 at 1:28
  • 3. What do you mean for emphasis? If I wrote, "Not only HE DID cheat on this exam, but he also cheated on all exams," wouldn't that be wrong? 4. I see the parallelism with "inhabit." But I thought the whole element after each part of the correlative conjunction needed to be parallel, not just the verb.
    – Peter
    Commented Apr 28, 2017 at 1:29
  • #1 is a comparison, not a correlative. It is taking a known quality of ox, strength, and comparing the man's strength to the ox's. ...... Your other comments seem to go to what sounds graceful to a native speaker rather than to strict parallelism.
    – Theresa
    Commented Apr 28, 2017 at 1:35
  • So how does "He is as strong as an ox is strong" suddenly become correlative? Isn't it still comparing the quality of an ox to the quality of the man? Also, I just looked up adj. phrase - Google said adj. phrase needs to begin with a word that can function as adjective, but "I could scream" starts with "I," which cannot be an adjective.
    – Peter
    Commented Apr 28, 2017 at 1:38

Correlative conjunctions work together and relate one sentence element to another. As far as I know, the connected elements just need to carry equal importance. It is prudent -- but not required -- to make sure the sentence structures they connect have a parallel structure (i.e. be similar in length or grammatical structure). There is no requirement that these elements be of the same type.

Sentence elements can be nouns, adjectives, adverbs, or entire clauses. For example:

I’m going not only to the concert, but also backstage! [directional prepositional phrase -> directional adverbial objective]

I’d no sooner lie to you than strangle a puppy. [clause -> clause]

Neither Norway nor Switzerland is in the European Union. [noun -> noun]

In sport, what counts is not the winning but the taking part. [gerund -> gerund]

The only other rule I am aware of is that a verb that follows two subjects must agree with the second subject, NOT the first:

Neither the manager nor his assistants are here today.

  • I've corrected the classifications (some will not like 'gerund'), and you see that parallelism is stronger than you claim. Commented Sep 4, 2017 at 16:41

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