5.6 Punctuating Correctly and Consistently: Errors and Preferences

Punctuation may seem a tiny matter, but even the tiniest mark of punctuation can have a striking effect on the meaning of a sentence, and the ultimate goal of punctuation should always be clarity of communication and ease of reading. There is no one single system of correct punctuation in the English language, however, so there is considerable room for author preferences and individual styles, yet the punctuation used in a sentence (or an entire thesis) must function effectively. I therefore deal here with situations in which punctuation tends to be problematic for many academic and scientific authors or in which punctuation can be treated in more than one way. In some cases, the focus is on correct usage and the patterns that are required in formal English prose, while in others the options are considered and the importance of adopting a particular approach or style throughout a thesis is emphasised. Please note that this section focuses on punctuation in the normal running text of a doctoral thesis, so for advice on punctuating references and quotations, see Chapters 7 and 8 below. It also focuses on general contexts, but certain disciplines, topics and material will require special punctuation procedures (an exclamation mark, for example, has specific meanings in mathematics, where it is a factorial sign, and computing, where it is a delimiter symbol). You are probably already aware of any specialised uses in your own discipline, but as a good starting place for further advice, see Chapters 13 and 14 of Butcher et al. (2006), Chapter 14 of the Chicago Manual of Style (2003) and Chapters 13 and 14 of Ritter (2005). For more information on the general rules of punctuation in English, see, for instance, the Penguin Guide to Punctuation (Trask, 1997).

5.6.1 Commas, Semicolons and Colons

Commas. Although commas indicate the shortest pause and smallest break possible in a sentence’s structure, their appropriate use also tends to present significant difficulties for authors, particularly, I suspect, because commas are used in so many different situations and are often governed by author and style preferences rather than by strict rules of correct usage. Some functions of the comma are more straightforward than others, but, generally speaking, variations are possible in many instances where a comma might be used depending on the precise meaning, context and sentence structure. A comma almost always appears after ‘yes’ or ‘no,’ for instance – ‘Yes, I agree’ or ‘No, I don’t think so’ – and a comma usually follows a name in a direct address (e.g., ‘Sarah, will you please pass the pepper’) or in a salutation in correspondence (Dear Sarah,). In formal business letters in American English, however, a colon is often used instead of the comma (Dear Sarah:), and there is a tendency in both British and American English for punctuation to be omitted from letters; if it is not, a comma should also precede the final signature (Yours sincerely,). A comma follows an exclamatory ‘oh’ or ‘ah’ as well, but only if a pause is intended – ‘Oh, what a lovely day!’ but ‘Oh no!’ – and a comma should not be included after either of them in a vocative construction (Oh cruel master!).

A comma is also used after other introductory parts of sentences, such as an initial adverb – ‘However, my findings did not confirm this’ or ‘Accordingly, I conducted the trial a second time’ – but a comma does not follow the adverb if it modifies an adjective or another adverb (e.g., ‘However hard she tries, she will not finish her thesis this month’), although in such cases a comma generally does follow the entire opening clause (after ‘tries’ here). Introductory adverbial clauses and indeed all initial dependent or subordinate clauses (clauses, that is, that are dependent upon the main clause that follows; see Section 5.4.5) are generally followed by a comma –‘After writing all night, I was exhausted’ or ‘If he had been digging all day, he would be exhausted.’ The comma is not necessary, however, if the introductory phrase is short, particularly if it indicates time or location (On Sunday she goes to church), or if the dependent clause immediately precedes the verb it modifies (Out of the forest walked the woman they were seeking). The comma is also not required if the dependent clause follows the main clause and is restrictive (or defining), which is to say that it cannot be removed without significantly altering the sentence’s meaning – ‘He was exhausted after digging all day’ – but if the dependent clause that follows is nonrestrictive (or nondefining), which means that it adds supplementary information that is not strictly essential to the sentence’s meaning, a comma should be used (He was exhausted, if you ask me).

This pattern of usage also applies to other restrictive and nonrestrictive clauses, such as relative or parenthetical clauses: if the clause is necessary to the meaning of a sentence (restrictive), no comma is needed before it and no comma is needed after it either if it appears in the middle of the sentence (The people who live there enjoy mild weather every day), but if the clause is supplementary, a comma should precede the relative or parenthetical clause and follow it as well if the clause appears in the middle of the sentence (The people, who speak the southern dialect, enjoy mild weather every day). In restrictive relative clauses, either ‘which’ or ‘that’ is acceptable – ‘She focussed on her topic with an intensity which I thought extraordinary’ or ‘She focussed on her topic with an intensity that I thought extraordinary’ – but in nonrestrictive clauses ‘that’ should not be used and ‘which’ is the correct choice (The thesis, which was very well written, was submitted to the committee). In American English there is a tendency to use ‘that’ instead of ‘which’ for restrictive relative clauses, so if you are following the conventions of American English, it is a good idea to use ‘that’ for all such clauses. Finally, if the meaning is clear, the word ‘that’ is not strictly necessary – ‘the book I wrote’ is as correct as ‘the book that I wrote’ – and sometimes such wording can be smoother and less cumbersome.

The same general principles of comma use apply to words, phrases, clauses or abbreviations in apposition: no commas are required around the appositive part of the sentence if it is restrictive and therefore essential to the sentence. In the case of a name, for example, this means that the appositive part specifies which one of more than one person or thing is intended: ‘The medieval poet Langland wrote Piers Plowman.’ If, however, the name and the ‘medieval poet’ are transposed in the sentence, the ‘medieval poet’ becomes nonrestrictive, providing supplementary information about the named poet, and should therefore be enclosed in commas: ‘Langland, the medieval poet, wrote Piers Plowman.’ In such constructions, a pair of en rules or em rules (see Section 5.6.4) or a pair of parentheses (see Section 5.6.5) can instead surround the nonrestrictive material, but they indicate a relationship between that material and the surrounding text that is not as close as that implied by commas: ‘Langland (the medieval poet) wrote Piers Plowman.’ Parenthetical adverbs or interjections that appear mid-sentence are similarly enclosed in commas – ‘The questionnaires, therefore, were recirculated,’ ‘It is uncertain, however, whether all the participants could be located’ and ‘That, indeed, was the last thing we expected’ – but if the adverb is essential to the meaning of the clause or sentence, no commas should be used: ‘The participants were found and the questionnaires were therefore recirculated’ and ‘The lecture was indeed too long.’ Commas should not be used for an appositive or parenthetical phrase that is part of a name, so ‘Bob, the carpenter from the shop, built the house’ is correct with commas, but ‘Bob the carpenter built the house’ is correct without them.

When presenting a series or list of three or more items (words, phrases or clauses) in which the final item is preceded by a conjunction (‘and’ or ‘or), commas are used after the items that are not followed by a conjunction, but whether or not a comma (known as a ‘serial comma’) should appear before the conjunction is in most cases a matter of choice (on lists, see also Section 5.5.2). No comma is required for correct English usage – ‘She bought milk, juice and coffee’ and ‘Dave cooked the steaks, Samantha prepared the vegetables and Adam poured the wine’ – even if the last item is a compound joined by a conjunction: ‘She bought milk, juice and tea and coffee.’ It is equally correct, however, to use a serial comma: ‘She bought milk, juice, and coffee,’ ‘Dave cooked the steaks, Samantha prepared the vegetables, and Adam poured the wine’ and ‘She bought milk, juice, and tea and coffee.’ The serial comma is used particularly in American English and by US publishers, but it is also used by Oxford University Press (hence its alternative name ‘Oxford comma’) and some other UK publishers, so the use of British or American English does not necessarily decide the issue, though you may want to use this distinction if your department or university guidelines call for a particular form of English, but give no advice on the use of the serial comma. On the other hand, if you want to keep punctuation to a minimum, you may choose not to use serial commas, but if you tend to use a lot of compounds joined by conjunctions in series, using serial commas may well be the best choice to ensure clarity of communication. Whether you choose to use the serial comma or not, your usage should remain consistent throughout your thesis, although if the serial comma is not normally used, it can still be used occasionally to avoid ambiguity and confusion. When a compound item joined by a conjunction appears before the main conjunction in a list, for example, using a comma before that main conjunction can help clarify the author’s meaning: in ‘They brought root beer, vanilla and chocolate ice cream, and cookies,’ for instance, the serial comma is necessary before the final ‘and’ to avoid the implication that the ‘cookies,’ too, were ‘vanilla and chocolate.’

When one (or more) of the items in a series or list is long and complex or uses additional punctuation, semicolons instead of commas should be used between the items (see below), in which case a final semicolon should appear where the serial comma normally would even if serial commas are not generally used in the thesis. If, on the other hand, conjunctions are used between all items in a list or series – ‘the options are juice or wine or beer’ – no commas are needed, but they can be used if the items are particularly long or complex and the commas will help clarify the meaning. As I mentioned in my discussion of lists in Section 5.5.2, it is important to ensure that only items that share a valid syntactical relationship with the introductory part of the sentence be linked with commas and a final conjunction: for example, ‘The thesis must be well written, thoroughly proofread and use a serial comma consistently’ is poorer style than ‘The thesis must be well written and thoroughly proofread, and use a serial comma consistently’ because the third item (use a serial comma consistently) does not work grammatically with the introductory ‘The thesis must be.’ When an ampersand (&) is used instead of ‘and’ in a series (a usage that is generally only acceptable in parenthetical and supplementary materials), the use of a serial comma before it can be determined by usage elsewhere in the thesis (‘She bought milk, juice, & coffee’ or ‘She bought milk, juice & coffee’). Finally, although the abbreviation ‘etc.’ should also be avoided in the running text of formal prose, when it is used to end a series in parenthetical material or tables, it should be preceded by a comma if a serial comma is used elsewhere in the thesis (She bought milk, juice, coffee, etc.), but not if a serial comma is not usually used in the thesis (She bought milk, juice, coffee etc.). If the sentence continues after the series, ‘etc.’ is often but not necessarily followed by a comma (She bought milk, juice, coffee etc., although she didn’t need to buy anything). When an English equivalent of ‘etc.’ (‘and so forth,’ ‘and so on’ or ‘and the like’) is used in the main text instead of ‘etc.,’ it, too, should be preceded by a comma or not according to the use of serial commas elsewhere in the thesis: ‘She bought milk, juice, coffee, and the like’ or ‘She bought milk, juice, coffee and so on.’ (For more information on using the ampersand and ‘etc.,’ see Section 6.3.)

Unlike the serial comma, the use of which is dependent on preferences and meaning, a comma splice is an error and must be avoided. A comma splice occurs when two main clauses (whether they share a subject or have different subjects) are joined together into one sentence via a comma alone, as in ‘I love buying old books, I go to the used bookshop almost every weekend’ or ‘We were delighted, one of the younger members even shouted out with glee.’ A semicolon can be used instead of the comma (e.g., ‘I love buying old books; I go to the used bookshop almost every weekend’) to fix the problem, or a full stop and capital can be added to divide the incorrect sentence into two: ‘We were delighted. One of the younger members even shouted out with glee.’ Alternatively, the comma can be retained and a conjunction (‘and,’ ‘or,’ ‘but’ etc.) added between the two clauses – ‘We were delighted, and one of the younger members even shouted out with glee’ – but if a conjunction is used and the independent clauses are short and closely connected, the comma may not be necessary (He bought coffee and she brought cream). Similarly, the comma may not be necessary if the sentence’s clauses form a compound predicate (two or more verbs with the same subject) instead of independent clauses, but the conjunction is required in such cases: ‘I love buying old books and I go to the used bookshop almost every weekend.’ If there is any potential for confusion, however, a comma should be used: for example, if the comma were not included in ‘Spike did not recognise the woman who walked through the door, and barked,’ the sentence would imply that the woman walking through the door (rather than the dog named Spike) was doing the barking. A comma splice also occurs when two main clauses are linked only by an adverb or adverbial phrase (‘She was afraid, nevertheless she stood her ground’ or ‘The instructor intimidated him, as a result he dropped the course’). The best solution to this problem is to use a semicolon instead of the comma, and often a comma after the adverb or adverbial phrase is appropriate as well (‘She was afraid; nevertheless she stood her ground’ or ‘The instructor intimidated him; as a result, he dropped the course’).

Commas can also be used between two or more adjectives preceding a noun, but rules and conventions for this usage vary considerably. The Chicago Manual of Style (2003), for instance, explains that if the adjectives ‘could, without affecting the meaning, be joined by and, the adjectives are normally separated by commas,’ but ‘if the noun and the adjective immediately preceding it are conceived as a unit . . . , no comma should be used’ (p.250). Following this method, ‘faithful, sincere friend’ bears a comma, but ‘many young friends’ does not. New Hart’s Rules (Ritter, 2005, Section 4.3.4), on the other hand, suggests an approach based on the type of adjective used, with adjectives such as ‘big,’ ‘tiny,’ ‘happy’ and ‘sad’ being gradable or qualitative adjectives, while adjectives such as ‘white,’ ‘black,’ ‘English’ and ‘treacherous’ are classifying adjectives. According to this system (Ritter, 2005, Section 4.3.4), ‘a comma is needed to separate two or more qualitative adjectives’ (such as ‘a short, thick tree’) but ‘no comma is needed to separate adjectives of different types’ (a big black cat) or to separate classifying adjectives that ‘relate to different classifying systems’ (‘annual environmental damage’ or ‘English Renaissance love poets’). Whichever system is used, when an adjective is repeated before a noun – ‘many, many tourists visit the Grand Canyon’ – a comma is usually inserted between the two instances. Exceptions can be made to these rules, however, so do check to see if your department or university has preferences with regard to the use of commas between adjectives (in technical writing, for example, commas are often kept to a bare minimum), and if there are no guidelines to follow, it is often better to use fewer commas than more (some authors will use none at all between adjectives), much as it is better to use one or two adjectives perfect for the context rather than a long string of them.

Commas are often used around interjected phrases beginning with ‘not’ or ‘not only’ (e.g., ‘The student himself, not his supervisor, led the meeting’), but they are not as necessary when the clauses are short, simple and closely related (The dog was not white but black). The principle is similar with ‘the more . . ., the more,’ ‘the more . . ., the less’ and similar statements. A comma should be used between longer clauses, but not between short phrases: for example, ‘the more I learn about the thesis process, the less intimidated I feel,’ but ‘the more the merrier.’ Commas are often used to introduce brief quoted material as well as direct speech (‘According to Taylor, “the results could be reproduced”’ and ‘Tiffany replied, “Not today”’), but if a conjunction such as ‘that’ or ‘whether’ is used before the quotation, no comma is required (Taylor argued that ‘the results could be reproduced’), and if the quotation is longer or the context more formal, a colon should be used instead of a comma (see the discussion of colons below, and for more information on punctuating quotations, see Chapter 8). Maxims and proverbs are usually treated much as quotations and appositives are, making use of commas when necessary to clarify the sense: ‘Samantha’s personal motto, “early to bed, early to rise,” is not mine,’ but ‘The motto “early to bed, early to rise” is one I should observe more often.’ A comma is also used to introduce a question in running text – ‘He asked her, how will the changes affect the thesis?’ – and although no initial capital is required to begin the question, if the question is long or contains internal punctuation, an initial capital can be helpful: ‘He asked her, If I follow these guidelines, how will the changes affect the thesis?’ Notice that quotation marks are not required around the question (though they can be used to indicate direct speech), and when the question is indirect, neither the comma nor the question mark is needed either: ‘He is wondering how the changes will affect the thesis.’

Commas are frequently used to indicate the omission of a word or words, but the missing element(s) must be obvious from the context and the words that are provided in the sentence: for example, ‘in the evergreens there are four nests of robins; in the deciduous trees, five of sparrows; in the marsh snags, six of chickadees,’ in which the words ‘there are . . . nests’ are represented by each of the commas. The commas may be omitted, however, if the meaning is clear without them: ‘the robins returned in March, the chickadees in April and the sparrows in May.’ This sort of elliptical structure can be difficult to perfect and tends to be either underused or overused by authors, so do check any usage of this kind in your thesis carefully to be sure that it is as concise as it can be without omitting essential information. You should also ensure that you have used commas properly in numerals (to mark the ‘thousands,’ for instance, in numbers such as ‘272,098,’ ‘11,354,209’ and ‘2,524,307,099’), dates (after the day in March 17, 2011 in American English, for example: for more information on punctuation in both numbers and dates, see Section 6.4 below), and addresses and place names (in running text, for instance, commas are used to separate addresses and place names: ‘750, Richmond Road, Victoria, British Columbia). References also make use of commas: commas appear between the dates of sources written by the same author in parenthetical author–date references – ‘(Pearsall, 1987, 1996, 2001, 2006)’ – and (usually without spaces) between the numerals used for numerical in-text references: ‘(8,9,12,16,18).’ They also appear in various places (depending on the referencing system and style used) in full bibliographical references, whether those references are provided in notes or in a list (see Chapter 7 for more information on punctuating references). Many of the instances in which commas are used may seem simple or obvious, but errors and inconsistencies associated with the use of commas arise with surprising frequency in scholarly writing, so it is important to remain alert to the small details of comma use as well as to the larger patterns as you draft, proofread and revise your thesis chapters.