Grammar Series #2: Commas

In this post, I’m going to tackle what seems to be one of the more difficult elements of grammar…THE COMMA!

I had a high school English teacher whose biggest pet peeve was a misused comma. If Mrs. Henslee caught you misusing a comma, you could expect public humiliation and a verbal rebuking for your sins. I remember she used to say, exasperated, “It’s like you all take a handful of commas and just sprinkle them all over your papers.”

You may not have had a Mrs. Henslee to keep your writing in line, but proper comma use is important for the same reason proper grammar in general is important: if you can’t write or speak clearly and correctly, people tend to not take you very seriously. Let’s refer again to The Chicago Manual of Style for a little refresher:

“The comma, aside from its technical uses in mathematical, bibliographical, and other contexts, indicates the smallest break in sentence structure. Especially in spoken contexts, it usually denotes a slight pause.”

I’m going to stop right there.

Similar to the shoddy definition of a sentence I was fed as a grade-schooler, I was left similarly helpless with the line that “you put a comma anywhere you take a breath while reading.” From the excerpt above, it’s clear that yes, a comma typically indicates a pause, where one might typically take a breath if reading aloud. This definition is hardly complete, however, so we press on:

“In formal prose, however, logical considerations come first. Effective use of the comma involves good judgment, with ease of reading the end in view.”

This is a good reminder: another reason why correctness and clarity is vital when writing is that we want our readers to be able to easily read and understand what we’re saying (unless we’re James Joyce, and are deliberately working against standard form in order to challenge the reader due to aesthetic or artist goals; but we are not James Joyce).

Let’s get down to business, then. The following are also taken from Chicago, and cover some of the more common uses of commas:

Commas that set things off

Whenever a comma is used to set off an element such as a date or name, a second comma is required if the phrase or sentence continues beyond the elements being set off.

 July 22nd, 2011, is day on which I wrote this post.

Driving in Los Angeles, California, can be a frightful experience.

Commas with Relative Clauses

Wait, what? What’s a relative clause? Surprise! I feel it’s important to discuss comma use with relative clauses, so this post is going to be double-duty. Relative clauses aren’t too complicated, so let’s briefly take a look.

A relative clause begins with a relative pronoun: who, whose, whom, which, and that; or, they can begin with a relative adverb: where, when, and why. Or! A relative clause can also begin with an indefinite relative pronoun: whoever, whomever, whosever, whichever, whatever, and what (meaning “that which”). Why are these pronouns called “indefinite”? According to Understanding English Grammar:

[Indefinite pronouns] are called ‘indefinite’ because they have no specific referent; instead, they have a general, indefinite meaning. – p. 139

When dealing with technical terms, I find it helpful to examine what these words actually mean. says that “relative” can mean:

Something dependent upon external conditions for its specific nature, size, etc. (opposed to “absolute”).

This makes sense, because a relative clause basically exists to further define a noun or noun phrase. Relative clauses indicate that the nature of a sentence’s meaning depends on something external: a person (who/whose/whom, etc.), a thing (that/which, etc.), a time or place (where/when, etc.) or a motivation (why).

It’s helpful to remember that relative clauses are also called adjectival clauses; again, they exist to define.

Relative clauses can be broken into the subcategories of restrictive and nonrestrictive. I know this is a lot of terminology, but stay with me:  a restrictive relative clause is essential to the meaning of the sentence. That is, it “restricts” the sentence’s meaning.

A nonrestrictive relative clause is not essential to the meaning of the sentence, and if it is omitted, the sentence will still retain its meaning.

Now, back to commas. Understanding proper comma usage with relative clauses makes it easy to determine whether a relative clause is restrictive or nonrestrictive. If you noticed, restrictive relative clauses are not set off by commas but nonrestrictive relative clauses are.

You’ll see as we continue that it’s important to remember the distinction between a restrictive and nonrestrictive phrase, because that distinction helps determine proper comma use in a variety of situations.

Commas with Appositives

An appositive (that is, a word, abbreviation, phrase or clause that provides an explanatory equivalent to a noun) is normally set off by commas (if it is nonrestrictive).

My favorite poet, Billy Collins, is giving a talk at the university. (nounappositive)

Commas with Parenthetical Elements

If only a slight break is intended, commas should be used to set off a parenthetical element inserted into a sentence as an explanation or comment. If a stronger break is needed or if there are commas within the parenthetical element, em dashes or parentheses should be used.

All of the students, in spite of their fears, managed to pass the test.

Em dash or parentheses: All of the students – except for Monica, Chandler, Rachel and Joey – managed to pass the test.

Commas with Descriptive Adverbs

Commas are often used to set off adverbs such as however, therefore, and indeed. Again, if the adverb is essential to the sentence’s meaning (i.e. it’s restrictive), no commas are needed.

The information provided, however, was sadly insufficient. (nonrestrictive adv.)

The information provided was therefore insufficient. (restrictive adv.)

Commas with Independent Clauses joined by Conjunctions

When independent clauses are joined by and, but, or so, yet, or any other conjunctions, a comma usually precedes the conjunction. If the clauses are very short or closely connected, the comma may be omitted unless the clauses are part of a series.

I slammed the door, but the moth was already inside.

All of the shirts are somewhat discounted, and some of them are 50% off.

Comma Preceding a Main Clause: When you have a dependent clause before a main clause in a sentence, follow it with a comma.

If you accept the terms and conditions, you can use the device.

Comma Following a Main Clause: When you have a restrictive dependent clause following a main clause, you don’t need to precede it with a comma

You can use the device if you accept the terms and conditions.

If the dependent clause is nonrestrictive or merely parenthetical, add the comma.

I’d like a glass of water, if you don’t mind. (nonrestrictive dependent clause)

 Commas with “and if,” and the like: When two conjunctions appear next to each other, you don’t need to separate them with a comma.

I had been reading for over an hour, and if Jordan hadn’t interrupted me, I would have finished the book.

Commas with Coordinate Adjectives

As a general rule, when a noun is preceded by two or more adjectives that could, without affecting the meaning, be joined by and, the adjectives are normally separated by commas.

Willow was one of Buffy’s kindest, closest friends.

(adjs. could be connected by “and” and still make sense: Willow was one of Buffy’s kindest and closest friends.)

If, on the other hand, the adjectives are not coordinate (that is, if one or more of the adjectives are essential/linked to the noun being modified), no commas are used.

Some people do not excel in the traditional university setting.

(here, “university” technically modifies “setting”, but the words are linked to form one compound noun, defined by “traditional.” You wouldn’t say: “Some people do not excel in the traditional, university setting.” Another way to tell: “the traditional and university setting” doesn’t make sense.)

Commas with Repeated Adjectives/Adverbs

When an adjective or adverb is repeated before a noun, a comma normally appears between the two adjectives.

It was a hot, hot day.

I was very, very excited.

I could go on, but I think I’ve covered most of the big stuff.

In Brief…

We use commas all of the time. It’s important to know how to use them well. In general, commas set things off, introduce things, divide dependent and independent clauses, and divide descriptive elements (relative clauses, appositives, repeating adjectives, etc.) from the noun/phrase they are describing.

Remember: We do not want to divide restrictive information within a sentence, so we don’t use commas with restrictive clauses or essential defining elements (such as non-coordinate adjectives).

In closing, you’ve probably noticed that I’ve used a lot of indistinct language in this post, things like “in general,” “commonly,” or “often.” This is because grammar itself is a slippery subject and very hard to tie up in a nice, neat package. Walter Ong summarizes this struggle well, I think:

“The ‘rules’ of grammar in natural human languages are used first and can be abstracted from usage and stated explicitly in words only with difficulty and never completely.” – Orality and Literacy

A good grasp of grammar requires a combination of technical knowledge and gut intuition. There are always exceptions to the rule, particularly when it comes to poetry or non-technical prose in which style usually takes precedence to strict correctness. I believe that purpose, audience, and ease for the reader are the most important factors that determine how you write, and how strictly you write. When in doubt, rephrase!


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