Author Archives: Rachael Cayley

This post is the third in a series of posts on comma use. The first post dealt with commas and coordinating conjunctions. The second dealt with non-standard commas and punctuating for length. Today’s entry will discuss the way that some commas work best in pairs. Compare these three sentences:

This innovative new technique, developed by Woljert, has altered the way this surgery is performed.

This innovative new technique, developed by Woljert has altered the way this surgery is performed.

This innovative new technique developed by Woljert, has altered the way this surgery is performed.

The first sentence clearly conveys its meaning to the reader: there is an innovative new technique that has altered the way some surgery is performed. The reader is also given supplementary information: this technique was developed by some researcher named Woljert. This element (‘developed by Woljert’) either takes two commas (as in the first sentence) or takes no commas (‘This innovative new technique developed by Woljert has altered the way this surgery is performed.’). A single comma here (as in both the second and third sentences) will throw off your readers because it doesn’t clarify the grammatical role of the adjacent information.

When clauses like this appear at the beginning or end of a sentence, the need for paired commas is obviated:

According to Chen, this new technique is very valuable.

This new technique is very valuable, according to Chen.

This new technique, according to Chen, is very valuable.

In each of the first two sentences, an additional comma becomes unnecessary because of the placement of the clause at the beginning or end of the sentence. In the third sentence, we see the need for two commas to clarify the role of this brief interruption. (Of course, you will have noticed that the first sentence sounds much better than the other two. You don’t generally want to give this sort of unimportant information such a prominent place at the end of the sentence. Similarly, you don’t generally want to interrupt a sentence in this fashion unless the interruption itself is significant.)

This use of one comma instead of two (or none) isn’t a particularly grammatically complex issue, but it is a frequent occurrence in the student writing I see. And while it isn’t fatal, it does make your reader’s life more difficult. In lots of cases, this mistake may just be random carelessness; it’s certainly easy to miss a comma here or there. But if you repeatedly use a single comma when two (or none) are needed, you  may be experiencing some confusion between restrictive and nonrestrictive clauses: not knowing whether to use no commas (as you would for a restrictive clause) or two commas (as you would for a nonrestrictive clause), maybe you split the difference and use just one. Come back for the next comma post, in which I will try to sort out the difference between restrictive and nonrestrictive clauses. As I will stress then, this distinction is most crucially an issue of punctuation, but I will also touch on the persistent dilemma experienced by writers trying to choose between ‘which’ and ‘that’.

This post is the second in a series of posts on comma use. The first post dealt with commas and coordinating conjunctions.

Today’s topic is the practice of putting commas in sentences as a response to the length of the sentence. Consider this example:

The purpose of these focus groups was to improve the understanding of the nature of risk and autonomy during outpatient treatment, and focus on exploring the role of the hospital and the professional team in identifying and balancing treatment efficacy and patient comfort.

The comma after ‘treatment’ is, as your grammar book will tell you, unnecessary. Indeed, putting a comma there might cause some readers to think that ‘focus on exploring’ is the start of an independent clause. To illustrate the redundancy of this comma, consider the same punctuation pattern in a very simple sentence:

I went to the store for milk, and eggs.

This sentence will look wrong to most of us since it separates ‘milk’ and ‘eggs’ when they are obviously meant to go together. There is no reason for a comma between ‘I went to the store for’ and ‘eggs’. We wouldn’t say ‘I went to the store for, eggs’. (We would, however, say, ‘I went to the store for milk, eggs, and avocados’ because we punctuate lists of three or more items differently than we do pairs. For more on lists, see here, here, and here.)

What, then, do we think about the comma usage in our first example? The grammar books suggest it is wrong. The analogy with a short sentence suggests that it is wrong. (Of course, I would certainly acknowledge that it is possible to refuse the logic that says ‘wrong in a short sentence, therefore wrong in a long sentence’. In fact, we do sometimes use punctuation differently in short and long sentences; Veni, vidi, vici invariably comes up in such discussions.) But whether it is wrong or not, this is a pattern of comma use that you will see in lots of respectable places.

My response to this uncertainty is to characterize this usage as non-standard rather than as wrong. This assessment alerts students to the fact that the usage may be ambiguous for some readers and may be out of place in some sentences. However, to me, the most salient thing about this type of comma use is that it is generally better to leave it in place than to remove it without further alteration of the sentence. Simply removing it may make your sentence more ‘correct’ but will likely also make it harder to read. Let’s look at our first example again, now with the non-standard comma removed:

The purpose of these focus groups was to improve the understanding of the nature of risk and autonomy during outpatient treatment and focus on exploring the role of the hospital and the professional team in identifying and balancing treatment efficacy and patient comfort.

You can immediately see that this isn’t a good solution. The new sentence is much harder to read and, in fact, some might even read ‘outpatient treatment and focus’ as a single phrase and thus become confused about the sentence structure. What are our options when a pattern of comma usage isn’t standard and yet removing the comma only makes things worse?

The simplest revision would look something like this:

The purpose of these focus groups was both to improve the understanding of the nature of risk and autonomy during outpatient treatment and to focus on exploring the role of the hospital and the professional team in identifying and balancing treatment efficacy and patient comfort.

Using ‘both’ serves to alert the reader that a pair is coming; since the reader is expecting the writer to offer a dual purpose, the reader will be anticipating a compound structure. The repetition of the ‘to’ (‘both to improve and to focus’) will be another hint to the reader as to how to read the sentence. Notice all the ‘ands’ in our example sentence; repeating an element like ‘to’ signals to the reader which ‘and’ is doing the heavy lifting.

Another option would be to restructure the sentence so that it explicitly anticipates the two purposes:

These focus groups had two main purposes: to improve the understanding of the nature of risk and autonomy during outpatient treatment and to focus on exploring the role of the hospital and the professional team in identifying and balancing treatment efficacy and patient comfort.

In this case, the reader encounters ‘to improve’ and then ‘to focus’ with a prior understanding that there are two purposes; by providing that explicit information, the writer makes very certain that the reader will know how to read the sentence. The only downside to this structure is the possibility that it could overemphasize something that might actually be trivial:

The trip to the store had two main purposes: milk and eggs.

But in our original example, the writer seems to be giving important information about the current research, suggesting that the extra emphasis provided by the colon is warranted.

In sum, I think it is valuable to be aware of this pattern of comma use as non-standard. With that knowledge, you may go on using the comma in this way or you may choose to rephrase. My point is that, in many cases, the optimal solution won’t be to remove this comma without also altering the sentence in other ways. In some cases, of course, simple removal will work, but in more cases, when we punctuate for length, we are responding to a valuable intuition that the sentence won’t work without some additional aid for the reader.

Our next comma post will look at the importance of understanding when a comma can stand alone and when it needs a partner.

I am going to start this discussion of commas by showing a simple pattern of comma use:

Some educators believe in using inductive methods in the classroom, and others maintain that a ‘top-down’ approach is more effective.

In this compound sentence, the comma separates the two independent clauses, indicating that we must read each one separately; the ‘and’ following a comma tells us that the next word (in this case, ‘others’) is the beginning of a new independent clause. The crucial issue here is the presence of a coordinating conjunction. A coordinating conjunction is strong enough to join two independent clauses with only a comma. There are seven coordinating conjunctions: and, but, so, or, nor, for, yet. Only those seven words can give us the compound-sentence-with-comma pattern found in the above example. I have listed them in a way that approximately reflects the frequency of their appearance in this capacity. Obviously, these are words with many other roles to play in our writing, but I am speaking here of their use as coordinating conjunctions. We use ‘and’ and ‘but’ all the time; we use ‘so’ and ‘or’ often; and we rarely (outside of literary writing) use ‘nor’, ‘for’, and ‘yet’. We can also write them in a different order so as to get a mnemonic: for, and, nor, but, or, yet, so. The resulting FANBOYS, despite being a somewhat silly word—I confess to having spent a fair amount of time rearranging those seven letters in an attempt to find a more dignified term—is a handy way to check if a sentence can be punctuated as a compound sentence.

Now that we understand this simple pattern of comma use in compound sentences, we can look at some related comma errors.

One such error is the comma splice: the placement of two independent clauses together with a comma and NO conjunction whatsoever. Here is an example:

The simulation of physical systems is a crucial part of scientific discovery, experience shows that conducting this simulation precisely and efficiently is essential.

This type of error—which is relatively rare—can be easily fixed in a number of ways, including the simple addition of ‘and’ before ‘experience’:

The simulation of physical systems is a crucial part of scientific discovery, and experience shows that conducting this simulation precisely and efficiently is essential.

What if we had attempted to correct this sentence by replacing the comma with an ‘and’? Note the ambiguity of a compound sentence without the comma:

The simulation of physical systems is a crucial part of scientific discovery and experience shows that conducting this simulation precisely and efficiently is essential.

Here it would be easy to read ‘scientific discovery and experience’ as a single phrase and thus miss the true structure of the sentence. Remembering that we always need a comma before a coordinating conjunction in a compound sentence will save us from this potential ambiguity.

Lastly, I would like to look at a related comma error that is very common: the practice of using commas to separate independent sentences joined by conjunctive adverbs (e.g., however, therefore, accordingly, finally, instead, nevertheless, specifically, thus) or transitional expressions (e.g., equally important, for example, in fact, on the contrary, on the other hand). Compare these two sentences:

Low levels of ROS are used in redox signalling reactions that are essential for cellular homeostasis, but high levels of ROS initiate an intracellular response that leads to oxidative stress.

Low levels of ROS are used in redox signalling reactions that are essential for cellular homeostasis, however high levels of ROS initiate an intracellular response that leads to oxidative stress.

The first sentence is correct, but the second one is not. Here is a corrected version of the second sentence:

Low levels of ROS are used in redox signalling reactions that are essential for cellular homeostasis; however, high levels of ROS initiate an intracellular response that leads to oxidative stress.*

In order to understand this distinction, we have to see the difference between ‘but’ and ‘however’. This distinction can seem opaque since the two terms have a similar meaning. However, we now know that ‘but’ is a coordinating conjunction, which means that it is strong enough to connect two independent clauses. Other words or phrases—such as conjunctive adverbs or transitional expressions—will fail at this particular task. Knowing that only coordinating conjunctions work in this sentence pattern and being able to remember the seven coordinating conjunctions (hence the value of the mnemonic, however lame) will allow you to avoid this particular type of comma error.

Let’s look at a final example of this type of error:

The design process of a UAV starts with a pre-specified mission agenda, consequently, following conventional design methods will lead to an airplane that is only suited to achieving the primary mission.

If you find that sort of sentence in your own writing, you can do one of three things:

1. Use a semicolon.

The design process of a UAV starts with a pre-specified mission agenda; consequently, following conventional design methods will lead to an airplane that is only suited to achieving the primary mission.

This is by far the easiest and most effective solution. The semicolon probably best reflects the close relationship that the original sentence was trying to create.

2. Use a coordinating conjunction to preserve the original sentence pattern.

The design process of a UAV starts with a pre-specified mission agenda, and following conventional design methods will lead to an airplane that is only suited to achieving the primary mission.

This solution is grammatically correct but may not retain the original meaning. In this case, for instance, replacing ‘consequently’ with ‘and’ is a clear alteration of the original meaning.

3. Use a period.

The design process of a UAV starts with a pre-specified mission agenda. Consequently, following conventional design methods will lead to an airplane that is only suited to achieving the primary mission.

This is probably the least effective solution. Although it is grammatically correct, it does not express the close relationship between the two parts of the sentence. In general, replacing these sort of commas with periods can lead to unnecessarily short sentences and thus choppiness.

In sum, understanding the proper use of coordinating conjunctions will allow you to construct correct compound sentences and will allow you to avoid problems with comma use preceding conjunctive adverbs and transitional expressions.

The next comma post will look at how commas are used as a way to cope with long sentences.

* Comma use after introductory elements will be discussed in a future post.