Grammar: Commas


Page contents:

joining commas
listing commas
the serial comma
isolating commas

   pausing
   introductory adverbs and phrases
   mid-sentence adverbs
   conjunctive adverbs
   essential and inessential clauses
   apposition

the elliptical comma
direct address
direct speech
fused sentences
sentence fragments

 

Joining Commas

Joining commas join independent (sentence-like) clauses that have intervening conjunctions such as and, but, for and while, and their use is often
discretionary – 

      I asked him several times to turn down the volume, but he ignored me.

The conjunction but joins two independent clauses, and in this example the comma is optional; it does no harm, but the sentence is sufficiently 
short to cope without it. The longer the clause preceding the conjunction, however, the greater the need for a comma –

      I asked him several times in the course of the afternoon to turn down the  
      volume of his damned stereo, but he ignored me.

 

Listing Commas

Listing commas separate items, actions or ideas in a series and are used to avoid unnecessary repetitions of the conjunctions and and or. For
example, instead of writing –

      She climbed into the car and fastened her seat belt and started the engine
      and drove off

we write – 

      She climbed into the car, fastened her seat belt, started the engine and
      drove off.

The listing comma is also used after all but the last in a string of adjectives –

      After the match, he took a long, hot, relaxing bath.

A comma may also be used to separate two adjectives –

      After the match, he took a hot, relaxing bath

but it is generally omitted when the adjectives are strongly related or frequently used together –

      After the match, he took a long hot bath.

      Good old George!

      Their daughter, Lizzie, is a lovely little thing.

 

The Serial Comma

In British English, we do not generally use a listing comma after the penultimate item or phrase in a list or series of actions  

      He said his favourite writers were Robert Harris, C. J. Sansom and
      Elizabeth Speller.

      He buttoned his coat, pulled down his cap, hunched his shoulders and
      stepped out into the rain.

In American English, however, it is standard practice to use one –

      He said his favourite writers were Robert Harris, C. J. Sansom, and
      Elizabeth Speller.

      He buttoned his coat, pulled down his cap, hunched his shoulders, and
      stepped out into the rain.

In this capacity, the listing comma is called a serial comma. It is also known as the Oxford comma and the Harvard comma because of its traditional
use in the presses of those universities. Opinion on its use is divided, but in most cases it is difficult to see what purpose the serial 
comma can serve.
The conjunction, usually
and or or, is sufficient to indicate the separation of the last two items without a preceding comma. In fact, the serial comma
can cause ambiguity by being mistaken for an isolating comma –

      The company is to open new outlets in Bangor, North Wales and Liverpool.

Here we have one listing comma in an easily understood sentence involving new outlets in three places: (a) Bangor in Northern Ireland, (b) North 
Wales and (c) Liverpool. If the the writer had meant Bangor in North Wales, then North Wales would have been cordoned off with isolating commas
to give us new outlets in two places –

      The company is to open new outlets in Bangor, North Wales, and Liverpool.

The problem is that we cannot be sure that the commas are indeed isolating commas, for if they are meant to be listing commas – the second being
a serial comma – we are back with new outlets in three places.

This said, there are two circumstances in which the serial comma avoids rather than creates ambiguity. The first is with lists whose penultimate items
are composites (paired items), such that two conjunctions appear towards the end of the sentence. A commonly cited example is –

      My favourite breakfast is coffee, bacon and eggs and toast.

The question is, which two items are paired, bacon and eggs with the toast served separately, or eggs and toast with the bacon served separately? 
A serial comma avoids the confusion –

      My favourite breakfast is coffee, bacon and eggs, and toast.
      (Bacon and eggs paired)

      My favourite breakfast is coffee, bacon, and eggs and toast.
      (Eggs and toast paired)

The second circumstance in which the serial comma is recommended is when the listed items might otherwise be misconstrued as appositives (two 
or more words or phrases that have the same referent, such as actor, Derek Jacobi or US President, Barak Obama) –

      Included among the photographers exhibits were cross-dressers, Mike
      Tyson and Arnold Schwarzenegger.

A serial comma after Mike Tyson would avoid the ambiguity and possibly a couple of libel suits, or even black eyes.

Verdict: avoid the serial comma except where necessary.

 

Isolating Commas

The purpose of isolating commas is to cordon off information that is not essential to the sentence, whether a clause, a phrase or a single word –

      They discussed the problem for hours but, as usual, found no solution.

      Suddenly, there came a clap of thunder.

      I think, nevertheless, that you should let the matter rest.

      Larks, which nest on the ground, fly higher than most other birds.

In each of these cases, we can remove what comes between the commas (or what comes before the only comma) without damaging the basic
sentence –

      They discussed the problem for hours but found no solution.

      There came a clap of thunder.

      I think that you should let the matter rest.

      Larks fly higher than most other birds.

There are circumstances, however, in which these comma omissions can cause problems.


Pausing

Very often, what resemble isolating commas are used instead to indicate speech-like pauses –

      They discussed the problem for hours, but as usual, found no solution.

The sentence is now grammatically questionable. Instead of dividing it into its logical components, the commas are used to indicate the way in
which the sentence would be spoken. This time, the removal of the words they enclose results in nonsense 
 

      They discussed the problem for hours found no solution.1

But this practice might be defended on the grounds that it makes for easier reading. Many readers, that is, interpret commas as pausing points,
so 
that their logical use often interrupts the flow of the sentence –

      Karen stepped out of the door and, checking her purse for the key, closed
      it quietly behind her.
(Correct)

There are two natural pausing points in this sentence, the first after door and the second after key, but many people will also pause after and
because they feel compelled to by the comma. The author of a popular novel, therefore, whose business after all is to entertain rather than
enlighten, would be more likely to write –

      Karen stepped out of the door, and checking her purse for the key, closed
      it quietly behind her.
(Substandard, but a more accurate representation of speech patterns)2

Thus correct grammar is sacrificed for the sake of optimum communication (and consequently the sale of more books). An undergraduate writing
an essay, on the other hand, would be better advised to keep to the grammatical rule.

Pausing commas really add nothing to the clarity of sentences, yet some people are fond of inserting them between the subject and verb –

      The more experienced members of the party, gave warning that the weather 
      conditions were about to 
deteriorate. (Pointless comma)

A pausing comma was once used to precede that clauses, but the practice is now obsolete –

      We can no longer say with the conviction we used to, that the British health
      service is the best in the world.
(Obsolete comma)


Introductory adverbs and phrases

Introductory adverbs are traditionally followed by commas –

      Suddenly, there came a clap of thunder.

      Outside, the temperature had dropped considerably.

      Nevertheless, I think you should let the matter rest.

But with the current fashion of minimal punctuation, they are now often omitted –

      Suddenly there came a clap of thunder.

      Outside the temperature had dropped considerably.

      Nevertheless I think you should let the matter rest.

In these examples, the omissions create no difficulties because the sentences can be read in only one way, but this is not always the case 

      Outside Lauras new car shone in the sunlight.

This time, the absence of an isolating comma after the introductory adverb Outside invites the reader to construct the introductory phrase Outside 
Laura's new car and therefore to expect something to happen in a road or in a car park. Only upon reaching the verb shone does he realise the
error and discover that the observer is indoors. He then has to re-read the sentence, mentally inserting a comma where the writer should
 have put
it in the first place –

      Outside, Lauras new car shone in the sunlight.

Again –

      Originally we planned to visit the British Museum. However we decided
      to go to the Victoria and Albert instead. 

The writer can get away without a comma in the first sentence but not in the second. The word however is meant to serve as a conjunctive adverb

      However, we decided to go...

but without the comma it appears initially to be a relative adverb –     

      However we decided to go... (on foot, by bus, by taxi?)

Isolating commas, then, should be used where there would otherwise be an introductory word-phrase ambiguity. Here are a few more examples 
where the missing commas cause confusion –

      Beneath the ground shook twenty miles from the volcano.

      After all he had been through a great deal.

      From two children start to mix with other children and make friends.

      Until the rain stopped the builders had nothing to do.

      Ten minutes after she returned with the tickets.

      Twelve months before he had taken up his new appointment.


Mid-sentence adverbs

Apart from conjunctive adverbs, the practice of enclosing mid-sentence adverbs in commas is all but obsolete –

      After a great deal of persuasion, he agreed, reluctantly, to help.

We would write in this way today only if we wished to emphasise the adverb. Otherwise, we would omit the commas and place the adverb after the
pronoun
he –

      After a great deal of persuasion, he reluctantly agreed to help.


Conjunctive adverbs

Conjunctive adverbs (words and expressions such as however, indeed, in fact, moreover, namely, therefore and thus) are not usually isolated when
they appear between the subject and verb –

      I nevertheless think that you should let the matter rest.

      We therefore recommend that you always clean the product after use.

The exception is when the subject requires emphasis or exclusivity, but note how this isolation can create the impression of arrogance or conceit –

      I, nevertheless, think that you should let the matter rest.

Conjunctive adverbs are traditionally isolated when they appear between the main verb and that clauses –

      I think, nevertheless, that you should let the matter rest.

      We recommend, therefore, that you always clean the product after use.

      The patron saint of Ireland was, in fact, a Briton.

But the trend is changing –

      I think nevertheless that you should let the matter rest.

      We recommend therefore that you always clean the product after use.

      The patron saint of Ireland was in fact a Briton.
 

Essential and inessential clauses

An essential clause is an integral part of a sentence and is not, therefore, enclosed in commas. An inessential clause adds supplementary or
by-the-way information that is not necessary to the sentence and must, therefore, be enclosed in commas. In either case, the clause might
comprise exactly the same words, so that it is the commas (or their absence) that give the subject of the sentence its meaning. For example,
if we take the sentence 

      People should not throw stones

and amend it to 

      People who live in glasshouses should not throw stones

we will have added an essential clause. The underlined clause is essential because it alters the essence of the subject; the original subject people
is changed to some people, namely those who live in glasshouses. For this reason, essential clauses are also known as defining clauses or
restrictive clauses because they help define or in some way restrict the subject. As an essential part of a sentence, then, such a clause must not
be cordoned off with commas.

On the other hand, if we amend our original sentence to 

      People, who live in glasshouses, should not throw stones

we will have added an inessential clause. The commas make all the difference. By isolating the clause from the rest of the sentence, we show that
it has no effect on the subject; it merely adds ancillary or incidental information about the subject (in this case, the incorrect information that all
people live in glasshouses) 

      People (who, by the way, live in glasshouses) should not throw stones.

The basic sentence remains the same: People should not throw stones. Hence inessential clauses are also known as non-defining clauses, non-
restrictive clauses and commenting clauses.

Again 

      Larks that nest on the ground fly higher than most other birds

is very different in meaning from 

      Larks, which nest on the ground, fly higher than most other birds.3

In the first sentence, the underlined words form an essential clause; we do not mean all larks, but only those that nest on the ground. In the
second 
sentence, the underlined words form an inessential clause; this time we do mean all larks, simply adding that these birds happen to
nest on the 
ground.

In distinguishing essential and inessential clauses, then, the humble comma assumes enormous importance, radically changing the meaning of
sentences that can have exactly the same words.


Apposition

An appositive is a noun or noun phrase that describes another. In the phrase Oscar Peterson, the Canadian jazz pianist, for example, the noun
phrase 
the Canadian jazz pianist is the appositive of  and in apposition to  Oscar Peterson.4 

An appositive can be just one word 

      President Obama wins the Democratic primary in New Hampshire
     
(President is the appositive of Obama)

or many 

      The president recently visited New Orleans, the city which suffered
      catastrophic damage when Hurricane Katrina struck in 2005
     
(The underlined is the appositive of New Orleans)

There can also be more than one appositive 

      President Obama, one-time Senator of Illinois and civil-rights attorney
      in Chicago, wins the democratic primary in New Hampshire.

As we have just seen, commas are not normally used to isolate appositives that are titles or epithets 

      President Obama waved to the crowd.

      Richard the Lionheart ruled England between 1189 and 1199.

      Dennis the Menace first appeared in The Beano in March 1951.

Nor are they used, as in the above three examples, when the appositive is restrictive. This same rule is explained in essential and inessential
clauses
, namely, that commas must not be used when the element in some way restricts the noun or noun phrase. In other words, commas are
omitted when the word or words provide information that is essential to the sentence.

For example, the appositive the Lionheart restricts the subject Richard. We do not mean any Richard, nor even any king called Richard. We are 
restricting Richard to that particular king known as the Lionheart. As an essential part of the sentence, therefore, the appositive must not be 
isolated by commas.

On the other hand, commas are required to isolate appositives that are non-restrictive: appositives that give us useful but inessential information 

      Richard I, the Lionheart, ruled England between 1189 and 1199.

This time, the Lionheart is non-restrictive because it is not an essential part of the sentence  

      Richard I ruled England between 1189 and 1199.

We know already which king called Richard is being referred to because the restriction is in the Roman numeral after his name. The Lionheart
merely gives us additional but unnecessary information.

Another example might serve to drive the point home 

      My sister Mary is a fashion designer in London.

Assuming the writer to be grammatically competent, we can tell immediately from this sentence that she has more than one sister. There are no 
commas enclosing the appositive Mary, which means it is restrictive – restricting sister to the one called Mary in distinction to her other sisters
(say) Kate and Louise.
 If the writer had had only one sister, she would be more likely to have written My sister is a fashion designer in London (the
essential sentence) or, if she had wished to add the useful but inessential detail of her sister's name 

      My sister, Mary, is a fashion designer in London.

But note that the second comma is omitted with the use of the possessive apostrophe 

      My sister, Marys job is fashion designer.

With restrictive appositives, of course, there would be no commas 

      My sister Marys job is fashion designer.

(See appositives in The Apostrophe.)

 

The Elliptical Comma

In formal English, an ellipsis is the omission of a duplicated word or words. For example, instead of writing 

      Anne works in local government and her partner works in industry

we can economise by omitting the repetition of works 

      Anne works in local government and her partner, in industry.

Traditionally, as above, the ellipsis is preceded by a comma, but the rule is often ignored today. It should at any rate be ignored where an unsightly
number of commas would otherwise appear 

      Mark ordered a prawn biriani, Dawn, a vegetable korma, Jane,
      a chicken tikka and Paul, a beef madras.

The inclusion here of both listing and elliptical commas (the latter avoiding the repetition of ordered) is rather ungainly. The sentence is better
expressed with listing commas only 

      Mark ordered a prawn biriani, Dawn a vegetable korma, Jane
      a chicken tikka and Paul a beef madras.

 

Direct Address

Commas are also used to mark off people’s names when they are directly addressed, wherever the name appears in the sentence 

      John, Im not sure that its such a good idea after all.

      Im not sure, John, that its such a good idea after all.

      Im not sure that its such a good idea after all, John.

 

Direct Speech

Opinion is divided on this use of the comma. It is traditional to use one when announcing a quotation 

      Socrates said, ‘No one does wrong willingly

but the modern tendency is to do without it 

      Socrates said No one does wrong willingly.

(See direct speech and reproduced text.)

But a comma should be used after an introductory phrase, whether or not what follows is a quotation 

      According to Socrates, no one does wrong willingly.

(See introductory adverbs and phrase above.)

 

Fused Sentences

A fused or run-on sentence is a grammatical error in which two or more sentences are incorrectly written as one. Instead of a full stop or semicolon,
the writer uses a comma or nothing at all 

      You need take no action, however you might wish to keep
      this letter for your records.

Corrected 

      You need take no action. However, you might wish to keep this letter
      for your records.

Or take this notice that appeared in the staff car park of a further education college one Monday morning 

                    NO PARKING
      RESERVED FOR INSPECTORS

'Quite right!' some would say; inspectors should take their chances parking along with everyone else.

Unlike most punctuation errors, sentence fusion is common among writers of all educational backgrounds 

      Tesco is a major retailer that sells everything from groceries to electrical
      equipment it also has its own finance scheme with the Royal Bank of
      Scotland. 

      (BTEC First Diploma student)

Corrected 

      Tesco is a major retailer that sells everything from groceries to electrical
      equipment. It also has its own finance scheme with the Royal Bank of
      Scotland.

      Council employees are now given the opportunity to develop themselves
      through training more so than before, this is identified in the appraisal
      process which every member of staff now goes through each year, these
      are mainly appraisee led. 

      (MBA student)

Corrected 

      Council employees are now given the opportunity to develop themselves
      through training more so than before. This is identified in the appraisal
      process which every member of staff now goes through each year. These
      are mainly appraisee led.

      The results of the survey showed the possibilities of upward mobility, the
      managerial group particularly showed the transition from social grade C
      to B. 

      (HNC Business student)

Corrected 

      The results of the survey showed the possibilities of upward mobility. The
      managerial group particularly showed the transition from social grade C
      to B.

      The prolonged recession didn't radicalise most voters (it never does),
      rather it made 
them more cautious.
      (Neil Kinnock)5

Corrected 

      The prolonged recession didn't radicalise most voters (it never does);
      it made them more cautious. 

      (Note that the semicolon makes the adverb rather unnecessary.)

However, it is often better to keep the sentence as one by means of a conjunction 

      You need take no action, but you might wish to keep this letter for your
      records

or a change of tense 

      The results of the survey showed the possibilities of upward mobility, the
      managerial group particularly showing the transition from social grade C
      to B.

Even novelists sometimes fuse their sentences, especially in dialogue, though whether through ignorance of grammar or a self-appointed artistic
licence is anyone’s guess 

      She knew all she had to know, she had experienced all she had to experience,
      she was fulfilled in a kind of bitter ripeness, there remained only to fall from
      the tree into death. 

      (D. H. Lawrence, Women in Love)

 

Sentence Fragments (Incomplete Sentences)

By definition, an incomplete ‘sentence’, or sentence fragment, has one or more of its necessary components missing, usually the subject, verb or
both 

      Like this sentence.

The fragment often belongs to another sentence (usually the one before) and is the opposite of the fused sentence; instead of two sentences in one
(with a comma in place of a full stop), we get one sentence in two (with a full stop in place of a comma) 

      Most services of the NHS are free at the point of delivery. Although
      charges are sometimes made for such things as cosmetic surgery.

Corrected 

      Most services of the NHS are free at the point of delivery, although
      charges are sometimes made for such things as cosmetic surgery.

Unlike fused sentences, however, sentence fragments have legitimate uses. They are perfectly acceptable in speech and written dialogue, for
example, especially in direct questions and answers 

      Where are you off to this year? (Complete)
      Rome. (Fragment)
      Why Rome again? (Fragment)
      Because its so beautiful. (Fragment)

They are also used in narrative to emulate disjointed thoughts. The justification is that since, for the most part, we neither speak nor think in
perfect sentences, it would be misleading of writers to portray us as if we did 

      I searched the wardrobe. Nothing. The dresser, then? Damn! Someone
      had been here before me. Someone. But who?

Sentence fragments are common, too, in journalistic articles as short exclamations, usually following one or two lengthy sentences 

      How things have changed!

      So much for justice!

and as a means of emphasis 

      Its remarkable that almost every smoker we meet says that he or she
      intends to kick the habit. They remind me of the words of St Augustine:
      God grant me chastity and continence. Only not yet.

In more formal scripts, such as academic essays, sentence fragments are usually confined to titles and headings. The only exceptions are the 
occasional sentences that begin with conjunctions, typically And, But, For, Or and Yet. Although this is technically incorrect, there has hardly
been a writer who has not begun a sentence in this way, and
 the practice can make for easier reading when the preceding sentence is lengthy
or the subject matter intellectually demanding 

      A few examples of Hegels dialectic may serve to make it more intelligible.
      He begins the argument of his logic by the assumption that the Absolute
      is Pure Being; we assume that it just is, without assigning any qualities to
      it. But pure being without any qualities is nothing; therefore we are led to
      the antithesis: The Absolute is Nothing’.
      (Bertrand Russell) 6

Russell might have chosen to open his last sentence with However, but too many of these conjunctive adverbs tend to irritate readers. On
occasions such as this, then, it makes sense to allow ease of reading to override grammatical correctness. Similarly,
But may be used to open
paragraphs (such as the next) that make a counterpoint to the one before and where an optional conjunctive adverb would again be in danger of
becoming repetitious.

But sentence fragments are used with far less excuse simply to create a spurious sense of importance 

      But there is no one set of skills which can guarantee success. Just as
      there is no one perfect essay. And no perfect answer for any topic.

This passage, which ironically appears in a book on how to write essays, does not contain one legitimate sentence. There might be an excuse
for opening the passage with a conjunction, but it should otherwise comprise one sentence
, not three 

      But there is no one set of skills which can guarantee success, just as
      there is no one perfect essay and no perfect answer for any topic.

Apart from the legitimate exceptions explained above, sentence fragments are substandard English. They are the hallmarks of advertising and
the popular press, where 
information is fed to readers in small, easily digested portions. They will almost certainly patronise educated readers.

 

____________

1 It might be argued that the first comma is a joining comma, giving us the basic sentence They discussed the problem for hours, but found no solution
   But the addition of as usual would then either require another two commas for isolation, giving us the rather inelegant They discussed the problem for
   hours, but, as usual, found no solution 
or, since the addition is sufficiently short, require no commas at all: They discussed the problem for hour, but
   as usual found no solution
.
2 Authors are not always consistent with this use of commas, as the following two excerpts show: (a) Helen rose languidly and, stooping to the lunch 
   basket at her 
feet, produced from it a battered-looking watermelon 
(M. M. Kaye, Death in KashmirMinotaur, New York, 2009, p. 93); (b) She
   shivered, and closing the 
curtains against the white night, fell into an easy sleep
 (Ibid., p. 104).
Note that with animals and things, in distinction to people, essential clauses take the relative pronoun that and inessential clauses, which (see that, which
    and who
).
4 Sources disagree about whether the appositive is always the descriptive element. If we change the order of the elements to The Canadian jazz pianist, 
   Oscar Peterson, some sources now regard Oscar Peterson as the appositive while others still take it to be the noun phrase. We assume here that either 
   element can be construed as the appositive of the other.
5 Neil Kinnock writing for BBC News, 22 February 2000. Accessed 03.09.03.
6 Bertrand Russell, History of Western Philosophy, Unwin University Books, London, 1961, p. 704.