Important comma information

UPDATED BELOW (12/14/16)

I ran across this blog post today, then read the unusually incisive (you know, for the Internet) comment, and decided that more research was necessary to really get to the bottom of things.

An hour and a half later, here are the facts.

According to Strunk and White (4th ed.), “If a dependent clause, or an introductory phrase requiring to be set off by a comma, precedes the second independent clause, no comma is needed after the conjunction.” Thus, for example: “The situation is perilous, but if we are prepared to act promptly, there is still one chance of escape.”

According to the Chicago Manual of Style (16th ed.), “When two conjunctions appear next to each other (e.g., and if, but if), they need not be separated by a comma.” Thus, “Burton examined the documents for over an hour, and if Smedley had not intervened, the forgery would have been revealed.” And, “They decided that if it rained, they would reschedule the game.”

The important thing to see here is that these are not the same rule.

S&W talks about dependent clauses or introductory phrases. Chicago is concerned with two conjunctions in a row. These two situations can, but certainly do not necessarily, coincide.

Here are a few examples that bear this out.

1: “The situation is perilous, but if we are prepared to act promptly, there is still one chance of escape.” [S&W & Chicago agree that no comma is necessary before if. I personally think the absence of the comma looks bad, but I am not a recognized authority on anything.]

2: “They decided that if it rained, they would reschedule the game.” [Chicago says this is correct. S&W does not appear to address this type of sentence and perhaps would insert a comma before if. If so, I’m on S&W’s side here.]

3: “Commas are great, and, in my opinion, we should use them as often as possible.” [S&W’s rule says that there needn’t be a comma before in. Chicago’s rule does not address this sentence. Based on similar sentences found in the Manual itself, I think Chicago would agree that I punctuated it correctly.]

I hope anyone at all in the world finds this helpful.

 

UPDATE: Through a combination of fortune and skill, I have recently acquired a copy of Bryan Garner’s Chicago Guide to Grammar, Usage, and Punctuation. I am sad to report that the section on commas is fully silent on this issue. –m.b.