Introduction
Parallelism occurs when at least two parts of a sentence (clauses or phrases) have a similar form.
Here’s an example:
I love swimming, but I don’t like snorkeling.
Each clause uses a present participle (swimming, snorkeling) to create symmetry.
If the sentence had been I love swimming, but I don’t like to snorkel, it would be a case of faulty parallelism. Most cases of parallelism involve either a list or some form of comparison.
Recognizing faulty parallelism
The following examples illustrate some common causes of faulty parallelism.
Comparison
When we compare things, we often use conjunctions. What’s connected by the conjunctions needs to be parallel.
Monetarism is an economic policy that seeks to control the supply of money and preventing excessive inflation.
Correct: Monetarism is an economic policy that seeks to control the supply of money and to prevent excessive inflation.
At the same time, there’s no need to be too much of a stickler about parallelism. It may sound more natural to drop the last to and leave it implied.
Watch out especially for correlative conjunctions. Here’s an example:
Mrs. Twinklestar not only taught the children the history of windmills, but also the story of Don Quixote.
Correlative conjunction: not only … but also
Correct: Mrs. Twinklestar not only taught the children the history of windmills, but also read the story of Don Quixote.
Correct: Mrs. Twinklestar taught the children not only the history of windmills, but also the story of Don Quixote.
As you can see, when the correlative conjunction comes first then we need two verbs (taught, read), whereas if the verb comes first then the correlative conjunction can tie together the objects of the verb.
Lists
Lists are another form of comparison. Try to make sure that the items in the list have a similar structure:
In The Open Society & Its Enemies, Karl Popper argues that modern fascism has antecedents in Plato’s ideal republic, Hegel’s conception of history, and in the communist theories of Marx.
Correct: In The Open Society & Its Enemies, Karl Popper argues that modern fascism has antecedents in Plato’s ideal republic, Hegel’s conception of history, and Marx’s communist theories.
Correct: In The Open Society & Its Enemies, Karl Popper argues that modern fascism has antecedents in Plato’s ideal republic, in Hegel’s conception of history, and in Marx’s communist theories.
As you can see, either add “in” to every item in the list or only at the beginning.
Prepositions
Watch out when you use prepositions:
She went to the bookstore to buy books on fishing, coding, and on breastfeeding.
Correct: She went to the bookstore to buy books on fishing, coding, and breastfeeding.
Articles
Be consistent when you add articles (a, an, the) to the items in a list:
My friend Jack owns a turntable, an old cassette player, and surround sound system.
Correct: My friend Jack owns a turntable, an old cassette player, and a surround sound system.
That
Often two parts of a comparison start with that:
Kenneth said that he would come camping with us and he would bring some firewood.
Correct: Kenneth said that he would come camping with us and that he would bring some firewood.
Bulleted lists
Faulty parallelism is especially common when the items of a list are placed on separate lines. This is quite common in bureaucratic writing:
The governmental subcommittee on jargon-free communication has the following key objectives:
- Facilitating clear communication with all stakeholders
- We will initiate a review of all press releases issued by the previous government
- Craft letters of apology to anyone negatively impacted by the utilization of jargon
Here is a corrected version:
The governmental subcommittee on jargon-free communication has the following key objectives:
- Facilitating clear communication with all stakeholders
- Initiating a review of all press releases issued by the previous government
- Crafting letters of apology to anyone negatively impacted by the utilization of jargon
Obviously there is a lot more rewriting we could do here, but creating some parallel structure is a decent start.
Caution
Don’t overdo it. If a sentence is short, or the tone is more casual, you can cut back on the parallel elements:
She not only bought me a coffee, but also a cookie.
After all, normally you wouldn’t say, “She not only bought me a coffee, but she also bought me a cookie.”