The semicolon (;) is a curious punctuation mark that could be described as neither fish nor fowl. To quote Harry Shaw’s Punctuate It Right, “It is a stronger mark than the comma, signifying a greater break or longer pause between sentence elements. But it is weaker than the period and other terminal marks (question mark, exclamation point) and cannot be used to end a sentence.” Indeed, as Shaw points out, even its name is misleading, since the semicolon does not play the introductory role of the colon and might more aptly be termed a “semi-period” or “double-comma.”
This ambiguity does nothing to inspire confidence in writers, who often wonder when to use the semicolon, and having wondered, move on without it. In doing so, however, they are denying themselves an important bridge and separator.
As a bridge, the semicolon can link two independent clauses that would otherwise have to stand alone as sentences or rely on a comma and conjunction to connect them. Here is one example:
Karen was drawn to Princeton’s beautiful campus. Its call proved irresistible.
Karen was drawn to Princeton’s beautiful campus, and its call proved irresistible.
Karen was drawn to Princeton’s beautiful campus; its call proved irresistible.
As you can see, the semicolon combines continuity and economy in a way that neither of the other possibilities achieves. The semicolon is also commonly used to link two independent clauses that are separated by a conjunctive adverb such as “indeed,” “however,” or “then.” For instance, one could say, “The exam was difficult; indeed, I barely passed it.”
In its role as a separator, the semicolon can bring clarity to a series of elements in which commas are incorporated, as in, “The committee included Mei Hu, a professor of molecular biology and prolific author; Daniel Robertson, an epidemiologist with extensive field experience; and Susan Bronfman, a senior official at the World Health Organization.” The exclusive use of commas in this instance would unnecessarily complicate the task of differentiating members of the committee.
So be kind to the semicolon. It may never win a popularity contest, but it has a place in every writer’s toolbox.