KISS Grammar Workbooks
Level Three Instructional Material

Clauses and Logic: 
Combining Main Clauses

     Although two or more main clauses can be combined into one sentence by using ", and," ", or," or ", but," three punctuation marks can also be used not only to combine the clauses, but also to direct readers to see specific logical relationships between the ideas expressed in the clauses.

Colons and Dashes to Indicate Further Details

     A colon or a dash can be used to indicate a "general/specific" relationship between the ideas in two main clauses:

The weather was nice -- it was sunny with a soft wind.
The payment is late: it was due two weeks ago.
In these examples, the first main clause makes a general statement, and the second provides more specific details.

Semicolons to Emphasize Contrasting Ideas

     Consider the following two sentences:

He went swimming. She did the dishes.
In effect, they simply state two facts. We can combine them with ", and" and a small "s," but they will still simply state two facts:
He went swimming, and she did the dishes.
There is, however, another way of combining the two, and it changes the meaning. When a semicolon is used between two main clauses, it suggests that the clauses embody contrasting ideas. Thus, we could write:
He went swimming; she did the dishes.
The semicolon invites the reader to think about the differences between the two main clauses, and, in this case, a little thought suggests that the underlying contrast here is that he is having fun, but she was stuck working in the kitchen.