Punctuating and Formatting Correctly in Relation to Parentheses
Parentheses (or round brackets) are used with considerable frequency in academic and scientific writing, but the punctuation and formatting that some scholars use in relation to parentheses are inappropriate, inconsistent and sometimes misleading. I am not referring here to specialised uses of parentheses in, for instance, mathematical equations or textual studies, but to the more general use of parentheses in the running text of a wide range of scholarly documents. Effective punctuation and formatting around and within parentheses in this context are, in fact, fairly straightforward, but the presence of the parentheses can confuse matters or make what is correct look awkward or incorrect, so a few basic rules may simplify matters.
Parentheses can be used within parenthetical clauses marked by dashes (en rules and em rules), and dashes can be used within parentheses. ‘Three kinds of birds returned in the spring – robins, chickadees (the smallest) and sparrows – and then left again in the fall’ demonstrates the correct format for the first, and ‘three kinds of birds returned in the spring (robins, chickadees – the smallest – and sparrows) and left again in the fall’ shows correct usage for the second.
A comma or semicolon should precede an opening parenthesis only in a numbered list when the numerals are enclosed in parentheses, as they are in this example: ‘Four conditions were created for the experiment: (1) darkness inside, (2) darkness outside, (3) artificial lighting inside and (4) daylight outside.’ Neither a comma nor a semicolon should ever precede a closing parenthesis. ‘After crawling through the window (on the third floor), she unlocked the door’ demonstrates the correct way to punctuate if a sentence requires a comma immediately after a set of parentheses. ‘After crawling through the window (on the third floor,) she unlocked the door’ is incorrect. In such a construction, the comma properly belongs to the surrounding sentence, not to the parenthetical material, so it should appear after the closing parenthesis.
Full stops as well as question and exclamation marks should be used in the same way, following a closing parenthesis if they belong to the sentence as a whole and preceding a closing parenthesis only if they belong particularly or solely to the parenthetical material. The first situation is demonstrated by ‘I worked for days to polish my thesis, yet my external examiner had the audacity to say something truly insulting (“It doesn’t look like you proofread this at all”)!’ The correct format for the second is shown in ‘It may be November, but it was as warm as summer yesterday (can you believe it?).’ In the case of a full stop, ‘belonging’ to the parenthetical material means that material forms a complete sentence and the parenthetical construction as a whole is separate from other sentences, as the final sentence of this paragraph is. (For this reason, one or more full sentences within parentheses should never be embedded in another sentence.)
In British English, parentheses can be used within parentheses in normal running prose when necessary, as in ‘(34 men (50%) and 34 women (50%)).’ In American English, however, square brackets are generally used within parentheses – ‘(34 men [50%] and 34 women [50%])’ – and, if needed, parentheses are then used within those interior square brackets, square brackets within those parentheses and so on. Whichever form of English you are using, it is usually best to keep double bracketing to a minimum, especially in the main text of a document, where rewording or rearranging parenthetical material to avoid double bracketing is a preferable option. Similarly, it is best if parentheses do not appear back to back, and if they must, that this usage be kept to a minimum as well. Although this principle applies to all brackets in general contexts, some specialised uses (in mathematical and legal contexts for instance) may require a back-to-back format, just as they may require a specific order for the use of brackets.
