Usually, when a dependent clause precedes an independent clause, a comma should separate the two clauses. Are there exceptions to this?

Question

I was recently asked if a comma should always follow a dependent clause if the dependent clause precedes an independent clause. At first glance, I thought this was true, especially since I can't seem to think of any counterexamples, but English grammar has been known to have exceptions to some of its rules. For example, a comma usually isn't used when an independent clause precedes a dependent clause, but there are times when this shouldn't be the case. If I were to say that "Louise didn't go to Bob's house because she forgot the cookies," it's unclear what I mean. One interpretation is that Louise didn't go to Bob's house, and her reason for this was not because she forgot the cookies. Another interpretation is that Louise didn't go to Bob's house, and her reason for this was that she forgot the cookies. So, to remove the ambiguity, we could add a comma: "Louise didn't go to Bob's house, because she forgot the cookies." This means that Louise didn't go to Bob's house, and her reason for this was because she forgot the cookies.

Are there any sentences where, for the sake of clarity, it would be better to omit a comma after a dependent clause when the dependent clause precedes the independent clause?

Answer 1

The rule-of-thumb for commas after most 'introductory elements' is that one should usually be included, but that for short examples, the comma is optional. See the comma after introductory elements thread, Kolln's balanced advice.

Surely this makes sense. Of course there will be exceptions.

(Note that a comma would change the meaning with the previous example, from 'Of course there will be exceptions to the rule-of-thumb for commas after most 'introductory elements' is that one should usually be included to 'Of course, there will be exceptions to the caveat for short examples, the comma is optional'.)

With a dependent clause, this is rarely the case, but

• As he left he sneezed.
• As he drew she shot.

(showing mere synchronicity, but where the simultaneity needs stressing ... there being no contrast as with a though-clause, balancing as with because- and so that- clauses, or temporal break as with after-, since- and before- clauses)

seem reasonable candidates.

Answer 2

One good counterexample is this sentence from a translation of Kant:

That all our knowledge begins with experience there can be no doubt.

Commas are generally not used in this sort of preposing construction. The subordinate clause "that all our knowledge begins with experience" is not an adjunct modifying the sentence but a complement of the noun "doubt," one that has been shifted to the start of the sentence.

This is a somewhat formal usage, but in this case the comma is omitted regardless of the length of the subordinate clause.

A similar phenomenon occurs in this line from Robert Frost:

Whose woods these are I think I know.