08.2.2 Commas

Incorrect use—or non-use—of commas is the most common grammatical error made by students.

Pay particular attention to points i. and ii.

(The next most common error is the insertion of an apostrophe into the possessive word “its”, as in the incorrect example, “it’s use is significant.”) Commas should enable fluent reading. They should, for example, be used in cases of syntactical ambiguity where otherwise the reader would not construe the text correctly on a first reading. Two problematic uses should be noted:

i. When a pair of commas does the job of parentheses, be sure not to omit the second of the pair:

On the third time of asking, however, he accepted.

She was offended when, for example, he asked intrusive personal questions.

ii. Essential (defining) clauses should not be set off with commas. In the following example the specific book in question is being defined (Metzger wrote many others):

Bruce Metzger’s book The Text of the New Testament was first published in 1964.

Nonessential clauses (clauses that may be omitted without affecting the meaning of the sentence) should be set off with commas. In the following example the book in question is already fully defined: