Writing Parallel ListsIn a parallel list, all the list items start with the same type of word. The term "parallel list" is most commonly used in relation to bullet points, but it also applies to lists written out as sentences and also with terms such as "either/or" and "neither/nor" (called correlative conjunctions).
Example of a Parallel List with Bullet PointsHere is an example of a parallel list with bullet points: The list above is parallel because all the list items start with a verb that gives an order (i.e., an imperative verb). Here is a similar example with a non-parallel list: The list above has been marked as wrong because it is non-parallel. A non-parallel structure does not always create a grammar error (as in this case), but we have marked it as wrong because it is not as slick or as clear as the parallel version. You should strive to keep your lists parallel.
Examples of Parallel Lists in Normal TextsEach of these examples has a parallel list:
- I would advise visitors to avoid bathing in the river, driving in the town, and eating in the local tapas bar. (This list is parallel because each list item starts with a word ending "-ing." These words are called gerunds.)
- Our mouthwash helps to fight plaque, tooth decay, and bad breath. (This list is parallel because each list item starts with a noun phrase.)
- Please do not light fires, damage trees, or leave litter. (This list is parallel because each list item starts with a verb giving an order.)
- I would advise visitors to avoid bathing in the river, driving in the town, and the local tapas bar. (This list is non-parallel because the last list item does not start with a word ending "-ing." Nevertheless, the list reads fine. We have marked this as wrong because writers should strive to make all lists parallel to assist their readers.)
- Our mouthwash helps to fight plaque, tooth decay, and freshens breath. (This list is non-parallel. It is unquestionably wrong because the third list item has a logic flaw with the introduction "Our mouthwash helps to fight." Creating such logic flaws is one of the risks of using non-parallel structures. This is a genuine example from a mouthwash bottle.)
- Please do not light fires, damage trees, and take your litter home. (This list is non-parallel. It is unquestionably wrong because the third list item has a logic flaw with the introduction "Please do not." This is a genuine example from a sign at a camping site.)
Example of a Parallel Structure with a Correlative ConjunctionCorrelative conjunctions are used in pairs to link equivalent elements in a sentence. Common examples are "either/or," "neither/nor," and "not only/but also."
Here is an example of a parallel structure with a correlative conjunction:
- He must either sell his watch or apply for a loan. (This sentence has a parallel structure because the words after "either" and "or" are both verbs.)
- He must sell either his watch or apply for a loan. (This sentence has a non-parallel structure because "either" is followed by a noun phrase while the "or" is followed by a verb.)
Advantages of Parallel ListsHere are four advantages of parallel lists:
(1) Parallel lists are easier to read because, after reading the first list item, readers anticipate the grammatical structure of the following list items.
(2) Parallel lists are less likely to include logic flaws with the list introduction.
(3) Parallel lists will portray you as a clear thinker.
(4) Parallel lists are often easier to write because the text structure has already been established, leaving writers with only the words to find.
Disadvantages of Parallel ListsHere is a disadvantage of a parallel list:
(1) Parallel lists can sometimes be difficult to write because the information in at least one list item does not easily fit into the chosen structure.
(When this happens, you should endeavour to find the right words or switch to a structure that fits every list item.)