How to avoid faulty parallelism

There is an error in each of the following sentences. Let’s quickly study them and identify the problems.

She sells oranges, mangoes and apple.

We enjoyed eating, swimming and to play table tennis.

They planned to sweep the room, to clean the rug and changing the curtains.

They not only commended the student but also giving him N100,000.

– Truncated plural flow

For the first sentence, it is understandable that the person involved is a fruit seller, that is a fruiterer. And the three fruits she sells are clearly identified. Structure-wise, however, the statement is a victim of what grammarians call faulty parallelism, which occurs when two or more coordinated elements in a sentence fail to maintain matching grammatical structures. Simply put, a sentence that harbours faulty parallelism violates the principle of parallelism.

The problem centres on the use of ‘apple’ when the other two fruits are correctly given as ‘oranges’ and ‘mangoes’. In other words, the plural trend already established with ‘oranges’ and ‘mangoes’ should apply to ‘apple’ too. Of course, it is not possible that the trader sells just an apple. Rather, she sells apples. So, the plural structure should be maintained throughout:

She sells oranges, mangoes and apple. (Wrong)

She sells oranges, mangoes and apples. (Correct)

– Gerund or to-infinitive?

In the second sentence, the writer fails to consolidate the gerund structure he/she initiated at the beginning through the middle of the sentence. A gerund is a verb form ending in -ing that functions as a noun in a sentence. On the other hand, the to-infinitive is a verb form made up of ‘to’ plus the base form of a verb. The writer shifted from the gerunds ‘eating’ and ‘swimming’ to the to-infinitive ‘play’, thus also injuring the spirit of parallelism:

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We enjoyed eating, swimming and to play table tennis. (Wrong)

We enjoyed eating, swimming and playing table tennis. (Correct)

– From gerund to to-infinitive: What is sauce for the goose …

The error in the third sentence is similar to what we have in the second above. The writer begins well with to-infinitive clauses but gets it twisted when he introduces a gerund. Now, if we insist the gerund structure should not be abruptly aborted in the preceding sentence, we should say the same of the to-construction too. After all, what is sauce for the goose is sauce for the gander. (Hope you know that ‘what is good for the goose is good for the gander’ is a substandard saying):

They planned to sweep the room, to clean the rug and changing the curtains. (Wrong)

They planned to sweep the room, to clean the rug and to change the curtains. (Correct)

They planned to sweep the room, clean the rug and change the curtains. (Correct)

They planned sweeping the room, cleaning the rug and changing the curtains. (Correct)

– Faulty parallelism

As earlier noted, in all the three sentences analysed, the error involved is called faulty parallelism. According to experts, when ideas are joined by coordinating conjunctions (like and, or, or but), correlative conjunctions (such as neither…nor or not only…but also), or placed in a list, they are expected to mirror one another grammatically. Breaking this pattern creates a structural mismatch that destabilises the sentence, often forcing readers to pause and re-read to parse the intended meaning. You should, therefore, always be careful and take a second look at your constructions. Much of faulty parallelism can be detected and corrected during proofreading.