And here is the much-derided Mr. Strunk's take on the problem (http://www.bartleby.com/141/strunk.html):
 




Two-part sentences of which the second member is introduced by as (in the sense of because), for, or, nor, and while (in the sense of and at the same time) likewise require a comma before the conjunction.

 

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.

 





The situation is perilous, but if we are prepared to act promptly, there is still one chance of escape.

Two-part sentences of which the second member is introduced by as (in the sense of because), for, or, nor, and while (in the sense of and at the same time) likewise require a comma before the conjunction. 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. 
 





The situation is perilous, but if we are prepared to act promptly, there is still one chance of escape.
 
Although Strunk doesn't address the issue directly, what if his sentence had read: 
 

"The situation is perilous, because if we aren't prepared to act promptly, there will be no chance of escape."
 
It seems to me that the comma does belong before the "because" here even though "because" can be construed as restrictive.
 
Geoff Layton


 
> Date: Wed, 13 Apr 2011 09:43:45 -0500
> From: [log in to unmask]
> Subject: Re: Punctuation Question
> To: [log in to unmask]
> 
> Martha's _Rhetorical Grammar_ offers a solution here. She points out that a comma places focus on the word in front of it (in speech, "the pause," the slight raise in pitch and accent). In this case it preserves some focus for the end of the main clause, which would receive end forcus if the because clause was moved to the front of the sentence. I always enjoyed telling my students that the comma between a main clause and a subordinate one following it was optional -- trust your ear -- it's a rhetorical choice.
> 
> Dave Sawyer
> Dept. of English (Retired)
> ________________________________________
> From: Assembly for the Teaching of English Grammar [[log in to unmask]] On Behalf Of Karl Hagen [[log in to unmask]]
> Sent: Wednesday, April 13, 2011 8:35 AM
> To: [log in to unmask]
> Subject: Re: Punctuation Question
> 
> I would suspect the writer is not making any conscious decision at all
> about syntactic analysis (e.g., deciding that "because" is a
> coordinator). More likely, he is punctuating on feel, and inserted the
> comma because he hears a slight pause in his mental reading of the
> sentence and wants to convey that pause.
> 
> On 4/13/2011 4:16 AM, T. J. Ray wrote:
> > I believe you're right in thinking he feels this is a coordinate
> > conjunction. My understanding is that
> > "because" clauses are dependent and hence should not be preceded with a
> > comma. I just
> > wanted a number of opinions before I bring it to the committee's
> > attention, folks who evidently
> > don't see a problem with it as no one had marked any of these before I
> > saw the MSS.
> >
> > Thanks for your time.
> >
> >
> > On Wednesday 04/13/2011 at 5:43 am, "Dixon, Jack" wrote:
> >> Focusing on the obvious, I suspect the writer believes that "because"
> >> functions as a coordinating conjunction rather than a subordinating.
> >> Does the student punctuate most subordinating clauses that follow the
> >> independent clause this way, or do he make this mistake with "because"
> >> only?
> >>
> >> I seem to remember that Martha Kolln in _Rhetorical Grammar_ addresses
> >> the few instances when terminal subord. clauses are set off with commas.
> >>
> >> ________________________________________
> >> From: Assembly for the Teaching of English Grammar
> >> [[log in to unmask]] On Behalf Of T. J. Ray [[log in to unmask]]
> >> Sent: Tuesday, April 12, 2011 8:10 PM
> >> To: [log in to unmask]
> >> Subject: Punctuation Question
> >>
> >> I have a doctoral student who produces sentences like the following:
> >>
> >> "This quatrain cannot be read in isolation at all, because the syntax
> >> is
> >> inherent and incomplete on its own."
> >>
> >> My question is not a search for whatever he meant to say but is about
> >> his punctuation: the comma. Comments are welcome.
> >>
> >> T. J.
> >>
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