I'm finding conflicting guidelines about the use of commas with subordinate clauses. What are the rules?

Also, which of the following is correct, and why?

  • Some of what Mike did needs to be adjusted.
  • Some of what Mike did, needs to be adjusted.

closed as general reference by FumbleFingers, MetaEd, Hellion, kiamlaluno, Kris Dec 21 '12 at 6:05

This question is too basic; it can be definitively and permanently answered by a single link to a standard internet reference source designed specifically to find that type of information. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Don't use a comma here because there's no need for it. The reader isn't led down a garden path to misunderstanding. There's no way that a native speaker will think that "did needs" go together. Sloppy readers will misunderstand even the clearest of sentences. I'm generally not a sloppy reader, but I misread a sentence in a paper I edited last night. I was probably too tired to notice that "MMP" and "MMPAC" are different abbreviations. That was the reader's (my) fault, not the writer's. – user21497 Dec 20 '12 at 10:11
  • I'm curious as to what "conflicting guidelines" you've come across so far...? – Hellion Dec 21 '12 at 19:16

Comma usage in English language is a difficult problem to resolve. There are rules, there are rules against those rules and there are recommendations.

In situations like these, the best you can do is use your common sense and ask yourself: does a comma here helps the reader understand the sentence?

In your sentence it's definitely not required, but I'd say it's "legally optional", as it tells the reader which part of the sentence the "did" belongs to. Not that it's ambiguous, but it could possibly belong to the second part of the sentence. If your brain reads too fast, it could interpret it as:

Some of what Mike, did need to be adjusted.

I know, I know, I'm exaggerating here, but you get the point.

The problem arises when you put the comma where it absolutely cannot be. From the history of the questions on this site, I expect that sometimes in 2013 a user will post the following sentence:

Some of that, Mike did, needs to be, adjusted.

Again, I'm exaggerating here, but again, you get the point.

TL;DR: Put a comma wherever it helps the reader parse the sentence. Never put a comma anywhere blindly just because it audibly fits.

  • 1
    The problem, of course, is knowing how a comma might help someone else parse a sentence. Generally one only knows how it might help oneself. Since usage is far from stable, as you point out, this means there are many conflicting theories in play, because there are many contradictory rules being used various speakers, all of whom believe their rule is standard. My solution would be to go by intonation, rather than "common sense". – John Lawler Dec 20 '12 at 14:53

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