Commas are also employed to denote time-marking clauses, and in between independent clauses separated by an “or,” “and,” or “but.”
These standards are excellent advice when it comes to clarity.
However, they do not necessarily answer every question about proper comma usage in formal writing. This is especially true when it comes to clauses that start or end with “then.”
Do I Need a Comma Before “Then”?
In three instances, the answer is a very clear yes. In sentences that have conditional clauses (aka, “if/then” statements), you should put a comma before a “then” that separates those clauses. Also, if the “then” separates two independent clauses (clauses that could be grammatically complete sentences), there should also be a comma before it. Finally, if you are not putting an “and” or “but” before the “then,” even when you don’t have two independent clauses, it is best to put a comma for the sake of clarity.
Dividing Two Conditional Clauses
Conditional clauses describe cause and effect relationships. The comma helps to make it clear that the “then” is another way of saying “as a result of” an “if” statement.
For example, if you are trying to explain the consequences of an action, you might write, “If you refuse to take out the trash, then you will get in trouble with your parents.”
This also applies when the conditional clause is theoretical in nature.
An example of this is “If you refuse to take out the trash, then you might get in trouble with your parents.”
So, whether the effect is definite or simply a possibility, you should put a comma before the “then” in if/then sentences.
“Then” That Functions Like a Coordinating Conjunction
When “then” functions similarly to a coordinating conjunction, there should be a comma before it. Coordinating conjunctions join equal phrases, ideas, or parts of speech.
For example, you should put a comma in the following sentence.
“I graduated college, then I went to graduate school.” The comma is necessary because both clauses (which are independent clauses) have equal grammatical weight.
It is true that “then” is technically not a coordinating conjunction, in the above example or anywhere else.
In the example, it is actually an adverbial. However, its use is very similar to an “and” “but,” or “or.”
If it were in the same position as the “then” in our example, an “and,” “but,” or “or” would be a coordinating conjunction.
Because of the grammatical similarity, the use of the comma before this form of “then” is now used more often than not.
Is a Comma Necessary Before “And Then?”
What should you do with a “then” that divides an independent and a subordinate clause? Take a sentence like “He sped down the road and then was pulled over.” In that example, you do not need the comma.
However, you should use the comma if you are not using the “and,” such as when you write, “He sped down the road, then got pulled over.”
In this instance, the “then” still expresses cause and effect, even without the “if” of a conditional, causal clause.
Also, you would need a comma if you were making both clauses independent. An example of this would be if you wrote, “He sped down the road, then he got pulled over.”
What About a Comma Before a “Then” at the End of a Sentence?
This rule tends to trip up a lot of writers. However, it is easy to determine whether a comma is needed if you ask yourself whether the “then” a matter of time or consequence.
Let’s pretend that you have written, “Is Bob going to the party? I’m not going, then.”
The comma before “then” is necessary. This is because another way of saying these two sentences would be “If Bob is going to the party, then I am not going.” In that case, the “then” is clearly the result of an “if.”
However, if you are designating a time, a comma before your “then” would make things awfully unclear.
Take the following sentence. “You want to meet at five o’clock? Yes, let’s meet then.” Here, you are telling the reader that you want to meet at five o’clock.
However, let’s say you wrote, “You want to meet at five o’clock? Let’s meet, then.”
With the comma placed as it is, the reader may be confused whether you are agreeing on a time or merely agreeing to meet.
When navigating the often confusing rules of commas in the English language, it is important to remember that they exist primarily to make things clearer.
The rules and examples above should help sentences with “then” remain as clear as possible.
Hey fellow Linguaholics! It’s me, Marcel. I am the proud owner of linguaholic.com. Languages have always been my passion and I have studied Linguistics, Computational Linguistics and Sinology at the University of Zurich. It is my utmost pleasure to share with all of you guys what I know about languages and linguistics in general.