Serial comma

"Oxford comma" redirects here. For the song by Vampire Weekend, see Oxford Comma (song).

The serial comma (also known as the Oxford comma or Harvard comma, and sometimes referred to as the series comma) is the comma used immediately before a coordinating conjunction (usually and or or, and sometimes nor) preceding the final item in a list of three or more items. For example, a list of three countries can be punctuated as either "Portugal, Spain, and France" (with the serial comma) or as "Portugal, Spain and France" (without the serial comma).^[1][2][3]

Opinions vary among writers and editors on the usage or avoidance of the serial comma. In American English, the serial comma is standard usage^[4] in non-journalistic writing that follows the Chicago Manual of Style. Journalists, however, usually follow the AP Stylebook, which advises against it. It is used less often in British English,^[5][6] where it is standard usage to leave it out, with some notable exceptions such as Fowler's Modern English Usage.^[7] In many languages (e.g., French,^[8] German,^[9] Italian,^[10] Polish,^[11] Spanish^[12]) the serial comma is not the norm and may even go against punctuation rules. It may be recommended in many cases, however, to avoid ambiguity or to aid prosody.

Arguments for and against

Common arguments for consistent use of the serial comma:

1. Use of the comma is consistent with conventional practice.^[13]
2. It better matches the spoken cadence of sentences.^[14]
3. It can resolve ambiguity (see examples below).^[15]
4. Its use is consistent with other means of separating items in a list (for example, when semicolons are used to separate items, a semicolon is consistently included before the last item, even when and or or is present).^[16]

Common arguments against consistent use of the serial comma:

1. Use of the comma is inconsistent with conventional practice.^[17]
2. The comma may introduce ambiguity (see examples below).
3. It is redundant in a simple list, because the and or the or is often meant to serve (by itself) to mark the logical separation between the final two items,^[18] unless, of course, the final two items are not truly separate items but are two parts of a compound single item.
4. Where space is at a premium, the comma adds unnecessary bulk to the text.

Many sources are against both automatic use and automatic avoidance of the serial comma, making recommendations in a more nuanced way (see Usage and subsequent sections).

Ambiguity

Resolving ambiguity

The style that always uses the serial comma may be less likely to result in ambiguity. Consider the apocryphal book dedication quoted by Teresa Nielsen Hayden:^[19]

To my parents, Ayn Rand and God.

There is ambiguity about the writer's parentage, because Ayn Rand and God can be read as in apposition to my parents, leading the reader to believe that the writer claims Ayn Rand and God are her parents. A comma before and removes the ambiguity:

To my parents, Ayn Rand, and God.

An example collected by Hayden was found in a newspaper account of a documentary about Merle Haggard:

Among those interviewed were his two ex-wives, Kris Kristofferson and Robert Duvall.^[20]

which may be taken to mean that Kris Kristofferson and Robert Duvall were Haggard's ex-wives. A serial comma would preclude this reading:

Among those interviewed were his two ex-wives, Kris Kristofferson, and Robert Duvall.

Consider also:

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

Three foods are listed, but it is uncertain which are the second and third. Adding a serial comma removes this ambiguity. With a comma after eggs, the foods are:

1. Coffee
2. Bacon and eggs
3. Toast

With a comma after bacon:

1. Coffee
2. Bacon
3. Eggs and toast

Writers who normally avoid the serial comma often use one in these circumstances, though sometimes re-ordering the elements of such a list can help as well.

Creating ambiguity

In some circumstances the serial-comma convention can introduce ambiguity. An example would be a dedication reading:

To my mother, Ayn Rand, and God

The serial comma after Ayn Rand creates ambiguity about the writer's mother because it uses punctuation identical to that used for an appositive phrase, leaving it unclear whether this is a list of three people (1, my mother; 2, Ayn Rand; and 3, God) or of only two people (1, my mother, who is Ayn Rand; and 2, God). Without a serial comma, the above dedication would read To my mother, Ayn Rand and God, a phrase ambiguous only if the reader is prepared to accept the unlikely interpretation my mother, who is both Ayn Rand and God.

This ambiguity does not exist under style recommendations that recommend that appositives be enclosed in parentheses, as in

To my mother (Ayn Rand) and God

Nor does the ambiguity arise when the phrase is written

To my mother Ayn Rand, and God

Unresolved ambiguity

The Times once published an unintentionally humorous description of a Peter Ustinov documentary, noting that "highlights of his global tour include encounters with Nelson Mandela, an 800-year-old demigod and a dildo collector".^[21] This would still be ambiguous if a serial comma were added, as Mandela could then be mistaken for a demigod, although he would be precluded from being a dildo collector.

Or consider

They went to Oregon with Betty, a maid, and a cook.

This is ambiguous because it is unclear whether "a maid" is an appositive describing Betty, or the second in a list of three people. On the other hand, removing the final comma:

They went to Oregon with Betty, a maid and a cook.

leaves the possibility that Betty is both a maid and a cook (with "a maid and a cook" read as a unit, in apposition to Betty). So in this case neither the serial-comma style nor the no-serial-comma style resolves the ambiguity. A writer who intends a list of three distinct people (Betty, maid, cook) may create an ambiguous sentence, regardless of whether the serial comma is adopted. Furthermore, if the reader is unaware of which convention is being used, both versions are always ambiguous.

These forms (among others) would remove the ambiguity:

• 1 person
  • They went to Oregon with Betty, who was a maid and a cook.
  • They went to Oregon with Betty, both a maid and a cook.
• 2 people
  • They went to Oregon with Betty (a maid) and a cook.
  • They went to Oregon with Betty—a maid—and a cook.
  • They went to Oregon with Betty, a maid, and with a cook.
  • They went to Oregon with the maid Betty and a cook.
  • They went to Oregon with a cook and Betty, a maid.
• 3 people
  • They went to Oregon with Betty as well as a maid and a cook.
  • They went to Oregon with Betty and a maid and a cook.
  • They went to Oregon with Betty, one maid and a cook.
  • They went to Oregon with a maid, a cook, and Betty.

In general

• The list x, y and z is unambiguous if y and z cannot be read as in apposition to x.
• Equally, x, y, and z is unambiguous if y cannot be read as in apposition to x.
• If neither y nor y[,] and z can be read as in apposition to x, then both forms of the list are unambiguous; but if y or y[,] and z can be read as in apposition to x, then both forms of the list are ambiguous.
• x and y and z is unambiguous.

Usage

The Chicago Manual of Style, Strunk and White's Elements of Style, most authorities on American English and Canadian English, and some authorities on British English (for example, Oxford University Press and Fowler's Modern English Usage) recommend the use of the serial comma. Newspaper style guides (such as those published by The New York Times, The Los Angeles Times, the Associated Press, The Times newspaper in the United Kingdom, and the Canadian Press) recommend against it, possibly for economy of space.^[22]

The differences of opinion on the use of the serial comma are well characterized by Lynne Truss in her popularized style guide Eats, Shoots & Leaves: "There are people who embrace the Oxford comma, and people who don't, and I'll just say this: never get between these people when drink has been taken."^[23]

In Australia, Canada, South Africa and the United Kingdom, the serial comma tends not to be used in non-academic publications unless its absence produces ambiguity. Many academic publishers (for example, Cambridge University Press, for books published in the UK) also avoid it,^[5] though some academic publishing houses in these countries do use it. The Australian Government Publishing Service's Style Manual for Authors, Editors and Printers (6th edition, 2002) recommends against it, except "to ensure clarity" (p. 102).

Style guides supporting mandatory use

The following style guides support mandatory use of the serial comma:

The United States Government Printing Office's Style Manual

After each member within a series of three or more words, phrases, letters, or figures used with and, or, or nor.

• "red, white, and blue"
• "horses, mules, and cattle; but horses and mules and cattle"
• "by the bolt, by the yard, or in remnants"
• "a, b, and c"
• "neither snow, nor rain, nor heat"
• "2 days, 3 hours, and 4 minutes (series); but 70 years 11 months 6 days (age)"^[24]

Wilson Follett's Modern American Usage: A Guide (Random House, 1981), pp. 397–401

What, then, are the arguments for omitting the last comma? Only one is cogent – the saving of space. In the narrow width of a newspaper column this saving counts for more than elsewhere, which is why the omission is so nearly universal in journalism. But here or anywhere one must question whether the advantage outweighs the confusion caused by the omission ...

The recommendation here is that [writers] use the comma between all members of a series, including the last two, on the common-sense ground that to do so will preclude ambiguities and annoyances at a negligible cost.^[25]

The Chicago Manual of Style, 15th edition (University of Chicago Press, 2003), paragraph 6.19

When a conjunction joins the last two elements in a series, a comma ... should appear before the conjunction. Chicago strongly recommends this widely practiced usage....

• "She took a photograph of her parents, the president, and the vice president."
• "I want no ifs, ands, or buts."
• "The meal consisted of soup, salad, and macaroni and cheese."

The Elements of Style (Strunk and White, 4th edition 1999), Rule 2

In a series of three or more terms with a single conjunction, use a comma after each term except the last.

For example, "red, white, and blue."

The American Medical Association Manual of Style, 9th edition (1998) Chapter 6.2.1

Use a comma before the conjunction that precedes the last term in a series.

• Outcomes result from a complex interaction of medical care and genetic, environmental, and behavioral factors.
• The physician, the nurse, and the family could not convince the patient to take his medication daily.
• While in the hospital, these patients required neuroleptics, maximal observation, and seclusion.

The Publication Manual of the American Psychological Association, 6th edition (2010) Chapter 4.03

Use a comma between elements (including before and and or) in a series of three or more items.

• the height, width, or depth
• in a study by Stacy, Newcomb, and Bentler

The Oxford Style Manual, 2002, Chapter 5, section 5.3 Comma

For a century it has been part of OUP style to retain or impose this last serial (or series) comma consistently, [...] but it is commonly used by many other publishers both here and abroad, and forms a routine part of style in US and Canadian English. [...] Given that the final comma is sometimes necessary to prevent ambiguity, it is logical to impose it uniformly, so as to obviate the need to pause and gauge each enumeration on the likelihood of its being misunderstood – especially since that likelihood is often more obvious to the reader than the writer. (pp. 121–122)

The CSE Manual for Authors, Editors, and Publishers (Council of Science Editors, 7th edition, 2006), Section 5.3.3.1

To separate the elements (words, phrases, clauses) of a simple series of more than 2 elements, including a comma before the closing “and” or “or” (the so-called serial comma). Routine use of the serial comma helps to prevent ambiguity.

Garner's American Usage (Oxford, 2003)

Whether to include the serial comma has sparked many arguments. But it's easily answered in favor of inclusion because omitting the final comma may cause ambiguities, whereas including it never will.

MLA Style Manual and Guide to Scholarly Publishing (Modern Language Association 2008). 3.4.2.b

Use commas to separate words, phrases, and clauses in a series.

Most college writing handbooks in the U.S. also advocate use of the serial comma.^[26]

Style guides opposing mandatory use

The Times style manual^[27]

Avoid the so-called Oxford comma; say "he ate bread, butter and jam" rather than "he ate bread, butter, and jam".

The New York Times stylebook^[28]

In general, do not use a comma before and or or in a series: The snow stalled cars, buses and trains.

The Economist style manual^[29]

Do not put a comma before and at the end of a sequence of items unless one of the items includes another and. Thus 'The doctor suggested an aspirin, half a grapefruit and a cup of broth. But he ordered scrambled eggs, whisky and soda, and a selection from the trolley.'

The AP Stylebook

Use commas to separate elements in a series, but do not put a comma before the conjunction in a simple series: The flag is red, white and blue. He would nominate Tom, Dick or Harry.

Put a comma before the concluding conjunction in a series, however, if an integral element of the series requires a conjunction: I had orange juice, toast, and ham and eggs for breakfast.

Use a comma also before the concluding conjunction in a complex series of phrases: The main points to consider are whether the athletes are skillful enough to compete, whether they have the stamina to endure the training, and whether they have the proper mental attitude.

The Australian Government Publishing Service's Style Manual for Authors, Editors and Printers

A comma is used before and, or, or etc. in a list when its omission might either give rise to ambiguity or cause the last word or phrase to be construed with a preposition in the preceding phrase: "There were many expeditions, including those of Sturt, Mitchell, Burke and Wills, and Darling." "The long days at work, the nights of intense study, and inadequate food eventually caused them serious health problems." "The sea, the perfume of wisteria, or a summer lunch: any of these revived memories of an easier time." "We needed to know how to get there, what time to get there, the number of participants, etc." Generally, however, a comma is not used before and, or or etc. in a list: "John, Warren and Peter came to dinner." "Fruit, vegetables or cereals may be substituted." "Why not hire your skis, boots, overpants etc.?"

The Guardian Style Guide^[30]

A comma before the final "and" in lists: straightforward ones (he ate ham, eggs and chips) do not need one, but sometimes it can help the reader (he ate cereal, kippers, bacon, eggs, toast and marmalade, and tea), and sometimes it is essential:

compare
I dedicate this book to my parents, Martin Amis, and JK Rowling

with

I dedicate this book to my parents, Martin Amis and JK Rowling

University of Oxford Writing and Style Guide^[31][32]

As a general rule, do not use the serial/Oxford comma: so write 'a, b and c' not 'a, b, and c'. But when a comma would assist in the meaning of the sentence or helps to resolve ambiguity, it can be used – especially where one of the items in the list is already joined by 'and' They had a choice between croissants, bacon and eggs, and muesli.

The Cambridge Guide to English Usage^[33]

In British practice there's an Oxford/Cambridge divide … In Canada and Australia the serial comma is recommended only to prevent ambiguity or misreading.

References

1. ^ The terms Oxford comma and Harvard comma come from Oxford University Press and Harvard University Press, where serial-comma use is the house style.
2. ^ Sometimes, the term also denotes the comma that might come before etc. at the end of a list (see the Australian Government Publishing Service's Style Manual for Authors, Editors, and Printers, below). Such an extension is reasonable, since etc. is the abbreviation of the Latin phrase et cetera (lit. and other things).
3. ^ The serial comma sometimes refers to any of the separator commas in a list, but this is a rare, old-fashioned usage. Herein, the term is used only as defined above.
4. ^ Truss, Lynn (2004). Eats, Shoots & Leaves: The Zero Tolerance Approach to Punctuation. New York: Gotham Books. p. 84. ISBN 1-592-40087-6. 
5. ^ ^{a b} Butcher, Judith; Drake, Caroline; Leach, Maureen (2006). Butcher's copy-editing: the Cambridge handbook for editors, copy-editors and proofreaders (4 ed.). Cambridge University Press. p. 156. ISBN 9780521847131. 
6. ^ The Oxford Style Manual, 2002: "The presence or lack of a comma before and or or ... has become the subject of much spirited debate. For a century it has been part of OUP style ..., to the extent that the convention has come to be called the 'Oxford comma'. But it is commonly used by many other publishers here and abroad, and forms a routine part of style in US and Canadian English" (p. 121).
7. ^ Truss, Lynn (2004). Eats, Shoot & Leaves: The Zero Tolerance Approach to Punctuation. New York: Gotham Books. p. 84. ISBN 1-592-40087-6. 
8. ^ Grevisse, Maurice; revised by André Goosse (1988). "Ponctuation: la virgule dans la coordination" (in French). Le bon usage: grammaire française (12th ed.). Paris-Gembloux: Duculot. pp. §124 (c) Remarque 1. ISBN 2-8011-0588-0. 
9. ^ Institut für Deutsche Sprache (IDS) Mannheim (2006). "„Deutsche Rechtschreibung. Regeln und Wörterverzeichnis“ – Überarbeitetes Regelwerk (Fassung 2006)" (in German) (PDF). pp. § 72, p. 79. http://www.ids-mannheim.de/service/reform/regeln2006.pdf. Retrieved 2009-03-12. 
10. ^ Accademia della Crusca (2002). "Domande ricorrenti: Uso della virgola prima della congiunzione e" (in Italian). http://www.accademiadellacrusca.it/faq/faq_risp.php?id=6234&ctg_id=93. Retrieved 2008-02-16. 
11. ^ Polański, E. (editor) (2006). Wielki słownik ortograficzny PWN z zasadami pisowni i interpunkcji, 2nd ed., Warsaw: Polish Scientific Publishers PWN. ISBN 978-83-01-14571-2.
12. ^ Real Academia Española (October 2005). "Diccionario panhispánico de dudas: coma² §1.2.1" (in Spanish). http://buscon.rae.es/dpdI/SrvltGUIBusDPD?lema=coma2#121. Retrieved 2007-03-20. 
13. ^ The Oxford Style Manual, 2002: "But it is commonly used by many other publishers here and abroad, and forms a routine part of style in US and Canadian English" (p. 121).
14. ^ The Oxford Style Manual, 2002; from discussion of the serial comma: "If the last item in a list has emphasis equal to the previous ones, it needs a comma to create a pause of equal weight to those that came before" (p. 121). The University of Oxford itself is quite distinct from Oxford University Press, and gives different advice. See University of Oxford Writing and Style Guide, below in this article.
15. ^ The Oxford Style Manual, 2002; from discussion of the serial comma: "The last comma serves also to resolve ambiguity, particularly when any of the items are compound terms joined by a conjunction" (p. 122).
16. ^ The Oxford Style Manual, 2002; in discussion of the semicolon, examples are given in which complex listed items are separated by semicolons, with the same structure and on the same principles as are consistently recommended for use of the comma as a list separator in the preceding section (pp. 124–5)
17. ^ Ridout, R., and Witting, C., The Facts of English, Pan, 1973, p. 79: "Usually in such lists 'and' is not preceded by a comma, [...]".
18. ^ Implicit in the treatment given in The Australian Government Publishing Service's Style Manual for Authors, Editors and Printers, 6th edition, Wiley, 2002, on p. 102. The exception discussed (see Usage, below) makes sense only on the assumption of this argument.
19. ^ Nielsen Hayden, Teresa (1994). Making Book. Framingham, Massachusetts: The NESFA Press. pp. 143. 
20. ^ Making Light, October 21, 2010
21. ^ "Planet Ustinov", Nov 22, 1998
22. ^ Bryan A. Garner (2003). Garner's Modern American Usage. New York: Oxford University Press. p. 654. ISBN 0-19-516191-2. 
23. ^ Lynne Truss (2004). Eats, Shoots & Leaves: The Zero Tolerance Approach to Punctuation. Gotham. ISBN 1592400876. http://books.google.com/?id=c3ETv37GqfcC&pg=PA84&dq=oxford+comma. 
24. ^ "8. Punctuation" (PDF). GPO Style Manual (30th ed.). Washington, DC: U.S. Government Printing Office. 2008. p. 201 §8.42. ISBN 978-0-16-081813. http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=2008_style_manual&docid=f:chapter8.pdf#page=9. Retrieved 9 June 2010. 
25. ^ The Case of the Serial Comma-Solved!
26. ^ Andy Gramlich, Commas: the biggest little quirks in the English language. Hohonu 2005, Volume 3, Number 3. http://www.uhh.hawaii.edu/academics/hohonu/writing.php?id=82
27. ^ "Online Style Guide - P". London: The Times. 2005-12-16. pp. (see punctuation/commas). http://www.timesonline.co.uk/tol/tools_and_services/specials/style_guide/article986734.ece. Retrieved 2008-03-22. 
28. ^ Perlman, Merrill (2007-03-06). Talk to the Newsroom: Director of Copy Desks Merrill Perlman. The New York Times 
29. ^ "Research Tools – Economist.com – Economist.com". The Economist. http://www.economist.com/research/styleGuide/index.cfm?page=805695. 
30. ^ "Guardian and Observer style guide: O". The Guardian (London). 2008-12-19. http://www.guardian.co.uk/styleguide/o. Retrieved April 1, 2010. 
31. ^ "Writing and style guide". University of Oxford. http://www.ox.ac.uk/branding_toolkit/writing_and_style_guide/punctuation.html. Retrieved 2008-12-31. 
32. ^ Public Affairs Directorate Writing and Style Guide, May 2009
33. ^ Peters, Pam (2004). The Cambridge Guide to English Usage. Cambridge, England: Cambridge University Press. ISBN 0-521-62181-X.