Frankly, I don’t think teachers really discuss the purpose of punctuation—including the comma. We don’t use punctuation when we speak, but when we write, we can’t use inflections, pauses, emphases, drama. We’re stuck with what written language can do, thus the need for punctuation. Punctuation is our friend, there to help our text make sense and be clear.
And the comma? It has one use: to separate for clarity. That’s it. Find a sentence with a comma anywhere (well, anywhere that’s using it correctly) and you’ll see it do its work.
And there are only four kinds of texts that need separation: items in a list, complete sentences joined with a conjunction, “conventions” like city and state or name and title, and “what you can take out” (introductory phrases and appositives).
Yep, that’s it. Just four. Some examples may help make this more clear.
Oxford, the Serial Killer:
Take a simple sentence like “Johnny went shopping and bought cereal, toothpaste, and lettuce.” It needs those commas or else “Johnny went shopping and bought cereal toothpaste and lettuce.” In this case, “cereal” becomes an adjective. And “cereal toothpaste” sounds really gross—raisin bran flavored Crest.
Eats Shoots and Leaves? (Excellent book, BTW. Check it out). It goes something like this: a panda walks into a bar, orders a meal, eats it, shoots the bartender, and leaves the bar. When asked why he did that, the panda answered, “Haven’t you read the description of a panda? It says “A panda eats, shoots and leaves.”
And what about that “Oxford comma,” the one that’s “optional” in a list? Well frankly it shouldn’t be optional. Case in point: I’m reading along last night, loving my Neil Gaiman, and I read this: “A falling girder in Manhattan closed a street for two days. It killed two pedestrians, an Arab taxi driver and the taxi driver’s passenger.” I read it two, three times and dog-eared the corner. Comma error.
The problem? Four people were killed: two pedestrians, a taxi driver, and the taxi driver’s passenger. But that’s not what the text says. It says only two died: the taxi driver and his passenger, who happened to be out of their vehicle at the time. Without the Oxford comma, the phrase “an Arab taxi driver and the taxi driver’s passenger” is an appositive, a phrase set off to describe the word “pedestrians.” Because almost any list you make can be misread as a word followed by an appositive, that Oxford comma should never really be optional. Remember—separation for clarity.
Comma Conventions...or...Punctuation Party:
So what about conventional uses like city and state? Well, if you’re from the US, it might seem obvious that East Lansing, Michigan is a city and a state and the comma isn’t needed. But if you’re from Siberia or Timbuktu, East Lansing Michigan could be the name of a city in New Jersey for all they know. Then sometimes convention calls for that separation just to make meaning clear. Bill Cosby (and his apparently clueless editor) clearly doesn’t know this rule, because I highly doubt that his book is about some kinky sexual practice.
And complete sentences with a conjunction? Well, in writing, ALL complete sentences are separated in some way, usually by a period. It makes it clear to the reader that we’re making two points, not one. Most people don’t have trouble with this rule except that many love the comma so much they put it before EVERY conjunction—which leaves your poor reader hanging.
- “He had cereal, and a sandwich.”
- “He was in love, but hated it.”
- “She felt hungry, so ate a sandwich.”
The real confusion comes with the “things you can take out” rule. But if you remember the PURPOSE of the comma—to separate—it gets easier.
Try this one on for size:
When Amy went to the store for her mother she felt that if she had gone sooner she could have gotten a good deal on tomatoes the little roma ones which was an easy trade-off since the tornado hit right at the time had she gone earlier she could have been there.Without commas, this thing is nearly impossible to read. Commas separate and make it easier because there are parts you can take out.
When Amy went to the store for her mother, she felt that, if she had gone sooner, she could have gotten a good deal on tomatoes, the little roma ones, which was an easy trade-off since the tornado hit right at the time, had she gone earlier, she could have been there.Here’s the trick: Use parentheses instead.
(When Amy went to the store for her mother) she felt that (if she had gone sooner) she could have gotten a good deal on tomatoes (the little roma ones) [which was an easy trade-off since the tornado hit right at the time (had she gone earlier) she could have been there].If using parentheses instead works, you’re using them correctly. Here it works just fine because “She felt that she could have gotten a good deal on tomatoes” makes perfect sense. You can take the rest out. What’s the deal with the square brackets? Well the entire phrase starting with “which” could also be taken out, but that’s another grammar lesson (that vs. which).
Let’s do this in the other direction (from a student’s paper in my technical writing class):
The purpose of this memo, is to recommend a website for your review, that is well designed, and easy to navigate, that will be valuable to review, during the development of the new website for MAVADE Technologies.So let’s try the parentheses trick:
(The purpose of this memo) is to recommend a website for your review (that is well designed) and easy to navigate (that will be valuable to review) during the development of the new website for MAVADE Technologies.Hmm. “is to recommend a website for your review and easy to navigate during the development of the new website…”—yeah, this isn’t working. What if we just get rid of that first comma after memo?
The purpose of this memo is to recommend a website for your review (that is well designed) and easy to navigate (that will be valuable to review) during the development of the new website for MAVADE Technologies.Nope, still not working. Maybe like this:
The purpose of this memo is to recommend a website for your review that is well designed and easy to navigate (that will be valuable to review during the development of the new website for MAVADE Technologies).Ah, yes, that works. So this sentence should really only have one comma! All those places you may have the urge to pause—no comma unless it needs separation. (Although commas could go around “for your review” and that would be acceptable).
Obviously the issue of commas can get complicated if you try lots of variety in your sentence structure. But remember the PURPOSE of the comma is to separate and make things clear. That’s all. Nothing more. So overusing commas makes writing murky as does underuse. Find that middle happy ground. Like in all of life, moderation is the key.
The internet is chock-full of great comma info. I especially like this NYTimes article and the example below, where real-life comma use matters.
Quote from Globe and Mail article:
"A grammatical blunder may force Rogers Communications Inc. to pay an extra $2.13-million to use utility poles in the Maritimes after the placement of a comma in a contract permitted the deal's cancellation...Language buffs take note — Page 7 of the contract states: The agreement “shall continue in force for a period of five years from the date it is made, and thereafter for successive five year terms, unless and until terminated by one year prior notice in writing by either party.” ...The validity of the contract and the millions of dollars at stake all came down to one point — the second comma in the sentence. Had it not been there, the right to cancel wouldn't have applied to the first five years of the contract and Rogers would be protected from the higher rates it now faces. Based on the rules of punctuation,” the comma in question “allows for the termination of the [contract] at any time, without cause, upon one-year's written notice,” the regulator said."We also can keep in mind the fact that the absence or presence of a comma in the Second Amendment to the Constitution makes a big difference as well. It says:
A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed.With the parentheses trick, this says “A well regulated militia (being necessary to the security of a free state) (the right of the people to keep and bear arms) shall not be infringed.” So technically the sentence says a well regulated militia shall not be infringed. The phrase “the right of the people to keep and bear arms” modifies “being necessary to the security of a free state” which modifies “a well regulated militia”—so essentially it’s the right to have a militia that is guaranteed—not the right to bear arms. If the comma were not there after arms, it would read “the right of the people to keep and bear arms shall not be infringed”—but that’s not what it says. However, this has been debated ad nauseum, and gun-lovers just ignore that last comma.
Commas really matter—and often. They can even save lives! A comma is the difference between “Let's eat Grandma!” and “Let's eat, Grandma!”
And if you’re ever in doubt, play it safe and rewrite the sentence—or just rebel and use a dash.