comma before 'that' [pronoun; comma splice]: played better, that is

[marylou2010]

Dear all

I've tried to consult the Internet but could not find an answer: Do I use a comma before the phrase "that is why" or not?

Example: He played better (,) that is why he had won.

Thanks a lot for your help!

 

[Cenzontle]

I think you need something "stronger" than a comma.
He played better, and that is why he had (?) won.
He played better; that's why he won.
He played better—that's why he won.

 

[marylou2010]

Hello Cenzontle

Thanks a lot. I made up the example as I wondered whether or not I should use a comma before the phrase "that is why" in the middle of a sentence. Maybe the example is not the best. Is there a general rule for using or leaving out the comma before the phrase "that is why"? Thanks a lot and sorry for the confusing example.

 

[lucas-sp]

Is there a general rule for using or leaving out the comma before the phrase "that is why"?

No. It will always depend on the sentence.

The basic rules of grammar and comma use always apply. In the sentence you cited you have two independent clauses linked by a comma - which is a comma splice (a kind of run-on sentence). So Cenzontle is absolutely right.

But look at:

I wanted to be early for my flight, so I drove. Ironically, that's why I ended up being late - there was a massive traffic jam on the highway.

No comma splice there.

 

[Cenzontle]

There is nothing special about "that is why", except that (1) it begins a clause, and (2) it refers to the preceding clause.
So there are two complete clauses. If you join two "independent" clauses with a comma, that's called a '"comma splice", and it's usually considered wrong.
When two clauses are joined by "and", I think it's a good idea to put a comma before "and" (but some writers don't follow this rule, especially when the clauses are short).
The semicolon ( ; ) is accepted for joining clauses that are closely related in meaning, such as by cause and effect.
The dash (—) in this context is less formal than the semicolon.

 

[e2efour]

Just in case you're not aware of this, you can use which instead of that -- with a comma before it.

 

[marylou2010]

Thanks a lot to all of you! E2four, I wasn't aware of this option