Essential and Nonessential
In order to use commas correctly in some circumstances, you need to know the grammatical concept of essential and nonessential.Some grammar books use the terms restrictive and nonrestrictive.
Here's the idea. We will define it in terms of phrases, but it applies to clauses as well:
An essential phrase is, well, essential to understanding the meaning of the sentence.
Examples: The underlined word, phrase or clause in the each sentence below is considered grammatically "essential":
Jarrett's dog Chubb likes books.
The book that Chubb was eating is overdue at the library.
In each case, you need the underlined words to understand the sentence. Those words are essential. From some of the exercises, we know that Jarrett has two dogs, so we need to know which dog this sentence refers to.
The book that Chubb was eating is overdue at the library.
This sentence is about a particular book -- the one Chubb was eating.
A nonessential phrase could be left out, and you would still understand the meaning of the sentence.
Basically,
a nonessential phrase adds something, elaborates, provides additional
detail, etc. It's nice, but not entirely necessary.
Examples: The underlined phrase (or clause) in each sentence below is considered grammatically "nonessential":
The book, which Chubb chewed all night, was due at the library yesterday.
Jarrett's bulldog, Chubb, likes books.
The book, which Chubb chewed all night, was due at the library yesterday.
This
sentence is about the fact that the book is due. The fact that Chubb
chewed it all night is extra detail; it is nonessential.
Jarrett's bulldog, Chubb, likes books.
This is where it gets tricky. Because Jarrett has only one bulldog, the name "Chubb" is nonessential. See how that works? Notice the commas. More on that follows.
Why the Distinction Matters
The distinction between essential and nonessential is all about commas -- when to use them, when to leave them out. The rules look simple, but they are subtle, so pay close attention.The Rules:
Rule 1: Do not use commas to set off an essential phrase.
Rule 2: Use commas to set off a nonessential phrase.
Rule 2: Use commas to set off a nonessential phrase.
Remember, the same rules apply to clauses and even to single words.
Examples of Rule 1 -- Do not use commas to set off an essential phrase:
We watched the award-winning movie "The Departed."
Lots of movies win awards. It is "essential" to know which one.
Lorraine drove her daughter Margie to school and her daughter Suzie to work. Lorraine has more than one daughter. The names are "essential."
Jarrett's neighbor Lisa watched from the hedge.Jarrett has neighbors on both sides. It is "essential" to know which one watched.
Examples of Rule 2 -- Use commas to set off a nonessential phrase:
The speaker was the winner of the 2007 Academy Award for leading actor, Forest Whittaker.
Lisa's cat, Mordred, watched from the shadows.
The planet closest to the sun, Mercury, has a surface temperature that ranges from -183 degrees to 427 degrees Celsius.
This
gets a bit picky, but, strictly speaking, there was only one such
winner in 2007. Thus, the name is "nonessential." I know, this is a bit
arcane, but, after all, it's grammar.
Lisa's cat, Mordred, watched from the shadows.
You
may know from some of the exercises that Lisa has only one cat. This makes the
cat's name "nonessential" to the meaning of the sentence. Her cat watched
from the shadows. Incidentally, that cat's name is Mordred. See how
that works?
The important thing is this: Notice the commas that surround "Mordred" like little mouse tails.
Lorraine and her husband, Charlie, worked in the garden.The important thing is this: Notice the commas that surround "Mordred" like little mouse tails.
Is Charlie essential or nonessential? Husbands want to know.
Alas, he is "nonessential" -- at least grammatically (and assuming that Lorraine has only one husband). Being nonessential, Charlie is awarded two commas. (See? There are advantages to being nonessential. Ask any husband.)
If she had more than one husband, Charlie would be even more nonessential as a husband, but his name would become essential in the sentence, to distinguish him from those other husbands who were not working in the garden. Bizarre, isn't it? But it's grammar!
Alas, he is "nonessential" -- at least grammatically (and assuming that Lorraine has only one husband). Being nonessential, Charlie is awarded two commas. (See? There are advantages to being nonessential. Ask any husband.)
If she had more than one husband, Charlie would be even more nonessential as a husband, but his name would become essential in the sentence, to distinguish him from those other husbands who were not working in the garden. Bizarre, isn't it? But it's grammar!
The planet closest to the sun, Mercury, has a surface temperature that ranges from -183 degrees to 427 degrees Celsius.
There
is only one planet closest to the sun, Mercury, so its name here is
"nonessential." Being nonessential, it is surrounded by mouse tails -- I
mean, commas. Perhaps we should think of these commas as comet tails. Nonessential comet tails.
In Brief
essential = no commas
nonessential = commas
To compensate for being nonessential, nonessential phrases get commas.
To deflate them a little for being so essential, essential phrases have their commas taken away from them.
nonessential = commas
To compensate for being nonessential, nonessential phrases get commas.
To deflate them a little for being so essential, essential phrases have their commas taken away from them.
Clauses receive the same treatment.
Almost an Exception
There is one situation in which a word looks like a nonessential phrase but isn't. This is unusual, but you need to know about it.Journalists value brevity. Short sentences matter. Go figure.
Some of these brief sentences produce odd expressions, like this:
Some of these brief sentences produce odd expressions, like this:
Lorraine and husband Charlie worked in the garden.
Here,
the fellow is just "husband Charlie," the way he might be "tall
Charlie" or "poor Charlie." "Husband" has become just another adjective
stuck before his name.
When Charlie is husbanded in this manner, he loses his commas and must garden without them.
Other times, such compacted sentences are not so odd. Compare:When Charlie is husbanded in this manner, he loses his commas and must garden without them.
A board member, Lorraine Carlton, spoke next.
Commas set of her "nonessential" name.
Board member Lorraine Carlton spoke next. Here,
Lorraine Carlton does not need commas. "Board member" is just an
adjective modifying her name. She might have been tall Lorraine, attorney Lorraine, beautiful Lorraine, etc.
That and Which
Now we get to the most important reason we pay attention to the difference between essential and nonessential: It tells you when to use that and when to use which in one of grammar's most troublesome distinctions.Most
of the examples we have used so far have been words or short phrases.
Life, alas, is not that simple. There are many more complicated
essential and nonessential things to deal with.
Still, it all comes down to the same two simple rules:
Rule 1: Do not use commas to set off an essential clause. Start such clauses with that.
Rule 2: Use commas to set off a nonessential clause. Start such clauses with which.
Rule 2: Use commas to set off a nonessential clause. Start such clauses with which.
Examples:
We had four hamburgers. The hamburger that was on the table is missing.
Everything in the second sentence is "essential." Hence "that" and no commas.
We had one hamburger. The hamburger, which was on the table, is missing.Because
they can't think of what else to call it, grammarians call the "which"
clause "nonessential." You can sort of see a logic here. There was only
one hamburger, so you don't have to tell which one was missing. The
only one was missing. So, they say, you DO need to start the clause
with "which" and precede it with a comma: "which was on the table."
So, sprinkle a few commas on that hamburger and pass it this way, please.
So, sprinkle a few commas on that hamburger and pass it this way, please.
Summary
If you can
Otherwise, use a "that" clause (without a comma).
Another Summary- leave out the clause and
- still understand the sentence
Otherwise, use a "that" clause (without a comma).
essential clause = that = no commas
nonessential clause = which = commas
A clause that needs no comma is essential.
Nonessential clauses, which need commas, often do not get them.
nonessential clause = which = commas
A clause that needs no comma is essential.
Nonessential clauses, which need commas, often do not get them.
Review
If you understand why some of the sentences below have commas inside them and others do not, you are ready for the exercises on essential and nonessential:Lorraine and husband Charlie gardened.
Lorraine and her husband gardened.
Lorraine and her husband, Charlie, gardened.
The book that was on the table fell on the floor.
He picked up the book that fell on the floor.
The book, which fell on the floor, was not damaged.
Thoreau's Walden, which was published in 1854, remains in print today.
Lorraine and her husband gardened.
Lorraine and her husband, Charlie, gardened.
The book that was on the table fell on the floor.
He picked up the book that fell on the floor.
The book, which fell on the floor, was not damaged.
Thoreau's Walden, which was published in 1854, remains in print today.
Practice using (or not using) commas in relation to essential and nonessential phrases (and clauses.)