Parentheses Dos and Don’ts

A reader of this blog suggested this Eos Forum article as a possible blog post. The clever title of the piece really says it all: “Parentheses Are (Are Not) for References and Clarification (Saving Space).” It’s a short piece; I highly recommend taking the two minutes to click the link and read it. Yes, it’s five years old but, very alas, it is still as relevant today as it was then, at least in our field.

The basic point is this: parentheses should not be used to point out the opposite case, thus avoiding an additional phrase or sentence. Like this: “Dayside (nightside) values are indicated in red (blue).” The example in the Eos article is superb, with six “parenthetical opposite comments” in a single sentence. Space physicists do this quite a bit, and seeing the article author’s departmental affiliation, “Environmental Sciences,” I think it is ubiquitous across AGU disciplines.

I did a quick search about parentheses usage and, indeed, the Eos article author, Dr. Alan Robock of Rutgers University, is absolutely correct. I could not find any usage definition for parentheses that indicated it is acceptable for opposite meanings to be put in parentheses to save the writing of a follow-on sentence or phrase. The most common usage is to set apart an explanatory side comment, something that the author wants to de-emphasize because it doesn’t really fit the normal flow of the sentence. They are also used for citation call outs by some journals, although AGU uses brackets for this.

There are some that argue parenthetical side comments should be avoided altogether because if the text doesn’t normally fit well in the sentence, it shouldn’t be there at all. That is, the reader will still pass their eyes over the parenthetical text and be distracted by the less-than-fully relevant material embedded in the sentence. I completely agree with this for long parenthetical comments, those are very distracting. I am fine with short ones that provide some quick clarification, but even these could be avoided with a little bit of work rearranging the sentence. I am consciously avoiding parenthetical text in this blog post, actively revising sentences, often with commas, to embed the sidebar text naturally within each sentence. I feel like a Parentheses Ninja.


            I must admit that this was not on my grammatical radar screen and that I am probably guilty of including parenthetical opposite comments in papers. I am not going to embarrass myself and go through all of my published papers looking for this incorrect parentheses usage; I am pretty sure that I will find several instances of it. It has been brought to my attention, though, and now I will be on the lookout for it, as should all of you.

So, to JGR Space Physics authors: please avoid this incorrect usage of parentheses. Take the time to write out an additional phrase or second sentence to explain the opposite case rather than embed it within multiple parentheses. It is not only incorrect English usage but also confuses your readers, making them work harder to understand your study.

In addition, to JGR Space Physics reviewers: please feel empowered to request that this incorrect parentheses usage be changed. You will be doing all of us a favor because it will make the paper better.


5 thoughts on “Parentheses Dos and Don’ts

  1. I used to be a stickler for strictly proper English usage and get very wound up when someone did something I disagreed with. Then a couple of years ago I realised something; I was wrong. Yes, proper use of language is important but to refer to some ideal set of rules is silly. Language evolves, if it did not we would all still be talking about going to the shoppe to buy our groceries. The important part is that there is clarity and understanding on both sides rather than a rigid adherance to a rule book that was first written 100 years ago. In the case of parentheses does it matter that no one has set a rule over whether it can be used in a certain way? Just as court cases can define and change the way law is interpreted, common usage will change the meaning of words and punctuation. As long as the meaning is unambiguous does it really matter if parentheses are (not) used to describe different cases?

  2. Great point. Language of course changes but not always for the better. For example, the Oxford Dictionary has recently added “cakehole” as a real word ( My problem with the parenthetical opposite is that it requires multiple parenthetical comments sprinkled along the sentence and muddles the clarity of the original sentence. Because of the number of interruptions to the flow, I often have to read such text twice just to get the actual sentence’s meaning, let alone the opposite case version. Even though I have used it before, I find it to be inelegant. Thou art correct, though, language changes and rules come and go according the commonly-used vernacular. I’ll shut my cakehole now.

  3. Interesting reading. My suspicion is that some authors felt pressured to adopt this new way of using parentheses due to severe page restrictions in some journals, like Geophysical Research Letters. By using parentheses in the way described above, they found a way to include more information in the paper published in such journals. So perhaps one must consider the risk-reward when adopting such practices. I completely agree that doing so several times in a single sentence becomes unwieldy, confusing, and makes for very difficult reading.

  4. A similar situation can arise in theoretical discussions. Often there will be two solutions to an equation, or two quantities, that differ by having certain terms added in one case and subtracted in the other. The quadratic formula is an instance of the former, and the Elsaesser variables used in some theoretical discussions of the solar wind are an example of the latter. It’s clear enough when you have not more than one instance of a plus-or-minus sign on each side of the equation. But I have seen equations with multiple signs, where the reader is expected to choose either the upper sign or lower sign and use that sign consistently through the entire equation. That is the mathematical equivalent of opposite-case parentheses, and it gets confusing. Better to arrange the equation to use only one such sign if you can, or write out in separate equations if needed. If you are also presenting results where the plus-or-minus sign represents an error bar, then don’t use it in your equations.

  5. Pingback: Paper Titles | Notes from the JGR-Space Physics Editor-in-Chief

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