45 Commas
Commas: these little demons haunt the nightmares of many a professor after an evening of reading student papers. It seems nearly impossible to remember and apply the seventeen or so comma rules that seem to given out as the standard. (For example: “Use commas to set off independent clauses joined by the common coordinating conjunctions.” or “Put a comma before the coordinating conjunction in a series.”)
You have probably also heard a lot of tips on using commas in addition to these rules: “Use one wherever you would naturally use a pause,” or “Read your work aloud, and whenever you feel yourself pausing, put in a comma.” These techniques help to a degree, but our ears tend to trick us, and we need other avenues of attack.
Perhaps the best and most instructive way for us to approach the comma is to remember its fundamental function: it is a separator. Once you know this, the next step is to determine what sorts of things generally require separation. This includes most transition words, descriptive words or phrases, adjacent items, and complete ideas (complete ideas contain both a subject and a verb).
Transition Words
Transition words add new viewpoints to your material; commas before and after transition words help to separate them from the sentence ideas they are describing. Transition words tend to appear at the beginning or in the middle of a sentence. By definition, a transition word creates context that links to the preceding sentence. Typical transition words that require commas before and after them include however, thus, therefore, also, and nevertheless.
- Therefore, the natural gas industry can only be understood fully through an analysis of these recent political changes.
- The lead prosecutor was prepared, however, for a situation like this.
Note: As was mentioned, these words require commas at the beginning or middle of a sentence. When they appear between two complete ideas, however, a period or semicolon is required beforehand:
- Clint had been planning the trip with his kids for three months; however, when work called he couldn’t say no.
- Sam was retired. Nevertheless, he wanted to help out.
As you can see from these examples, comma is always required after transition words.
Descriptive Phrases
Descriptive phrases often need to be separated from the things that they describe in order to clarify that the descriptive phrases are subordinate (i.e., they relate to the sentence context, but are less responsible for creating meaning than the sentence’s subject and verb). Descriptive phrases tend to come at the very beginning of a sentence, right after the subject of a sentence, or at the very end of a sentence.
- Near the end of the eighteenth century, James Hutton introduced a point of view that radically changed scientists’ thinking about geologic processes.
- James Lovelock, who first measured CFCs globally, said in 1973 that CFCs constituted no conceivable hazard.
- All of the major industrialized nations approved, making