Grammar Basics – The Comma in a Compound Sentence

Welcome back to my crash course in basic Grammar. Today’s blog is centered around the comma in a compound sentence.

First, let’s define what a compound sentence is.

According the Chicago Manual of Style, (the end-all authority,) a compound sentence joins clauses by using a coordinating conjunction. (Coordinating conjunctions include words such as and, but, or, so, and yet.)

The rule is:

IF you have two independent clauses joined with the coordinating conjunction, there IS a comma.

The easiest way I know how to explain an independent clause is that it can stand alone – it expresses a complete thought. (It is really a stand-alone sentence, but it is joined with another complete thought in one sentence.)

For instance: The Uber didn’t get there, so we took a taxi.

‘The Uber didn’t get there,’ is a complete sentence, and so is, ‘We took a taxi.’ They are joined by the coordinating conjunction, so.

Because the two joined clauses are both independent, you use a comma before the conjunction. Think of it as though neither of these clauses needs the other. Therefore, the comma separates them.

Conversely, IF you have an independent clause joined with a dependent clause, there is NOT a comma.

A dependent clause does NOT express a complete thought on its own. It needs the other part of the sentence – the independent clause to make it a complete sentence.

Because the two joined clauses NEED one another to express the thought, there is NOT a comma. (I think of it as a form of codependency.)

For instance: We will sign the proposal if you accept all of our demands.

‘We will sign the proposal,’ is an independent clause – it expresses a complete thought.

‘You accept all of our demands, is NOT a complete thought, therefore it DEPENDS on the first part of the sentence. They are joined by the coordinating junction, OR, and no comma is appropriate in this instance.

I use this rule on a daily basis. You do too. Some of us learned this a long time ago in high school English, while some of us still struggle with it. In my editing process, I read each sentence one at a time. I evaluate any sentences where there is a coordinating conjunctionand, but, or, so, and yet, and I look at both of the clauses.

Are they both independent? (Could they both stand alone?)

IF yes, then there IS a comma before the ‘and,’ ‘but,’ etc.

Is one of the clauses dependent? (Does it need the other part of the sentence to make sense?)

IF yes, then there IS NOT a comma before the coordinating conjunction.

Tomorrow, we will talk about a few other kinds of compound sentences – but I wanted to illustrate this one first. I think it is in this instance where folks have the most errors.

Until next time,

~Mustang Patty~

Published by Mustang Patty

I am finally a full-time author, who writes legal thrillers, how-to- books, short stories, flash fiction, a tiny bit of poetry, and Blog posts. My published works include 'Guilty until Proven Innocent,' 'Innocent for the Moment,' and 'Moment by Moment.' This is a trilogy called the Jill Adair Series. Additionally, I've written a collection of short stories about my dogs, Howie and Bernie - with a 2nd Collection coming in late 2021. I'm also coordinating an Anthology of Short Stories called, '2021 Indie Authors Short Story Anthology.' This book will be available on Amazon.com on August 1st of 2021. (The 2020 Indie Authors Short Story Anthology is currently available on Amazon.com - the collection includes 30 stories, written by 18 different Authors from three continents.) I am married to my wonderful hubby of over 37 years, and I have two grown children, named Heather and Gregory. I've been blessed with two beautiful grandbabies, Heather Rose and Logan Ernest.

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