The Colon and the Semicolon Compared

Since the use of the colon and the semicolon, although simple in principle, presents so many difficulties to uncertain punctuators, it will be helpful to contrast them here. Consider first the following two sentences:

Lisa is upset. Gus is having a nervous breakdown.

The use of two separate sentences suggests that there is no particular connection between these two facts: they just happen to be true at the same time. No particular inference can be drawn, except perhaps that things are generally bad. Now see what happens when a semicolon is used:

Lisa is upset; Gus is having a nervous breakdown.

The semicolon now suggests that the two statements are related in some way. The likeliest inference is that the cause of Lisa's annoyance and the cause of Gus's nervous breakdown are the same. Perhaps, for example, both are being disturbed by building noise next door. (Remember, a semicolon connects two sentences which are related.) Now try it with a colon:

Lisa is upset: Gus is having a nervous breakdown.

This time the colon shows explicitly that Gus's nervous breakdown is the reason for Lisa's distress: Lisa is upset because Gus is having a nervous breakdown. (Remember, a colon introduces an explanation or elaboration of what has come before.)

Consider another example:

I have the answer. Mike's solution doesn't work.

Here we have two independent statements: my answer and Mike's solution may possibly have been directed at the same problem, but nothing implies this, and equally they may have been directed at two entirely distinct problems. Now, with a semicolon:

I have the answer; Mike's solution doesn't work.

The semicolon shows that the two statements are related, and strongly implies that Mike and I were working on the same problem. Finally, with a colon:

I have the answer: Mike's solution doesn't work.

This time the use of the colon indicates that the failure of Mike's solution is exactly the answer which I have obtained: that is, what I have discovered is that Mike's solution doesn't work.

If you understand these examples, you should be well on your way to using colons and semicolons correctly.

Summary of colons and semicolons:

• Use a colon to separate a general statement from following specifics.
• Use a semicolon to connect two complete sentences not joined by and, or, but, yet or while.

Copyright © Larry Trask, 1997

Maintained by the Department of Informatics, University of Sussex