The days were short, for/because it was now December.

[sitifan]

The days were short, for it was now December. (My bold.)
Source: A Practical English Grammar by A. J. Thomson & A. V. Martinet (1980).
Can I use "because" instead of "for" in the above sentence?

 

[teechar]

Of course! In fact, the use of "for" meaning because is mostly literary/poetic etc nowadays.
May I ask why you posted that particular sentence?

 

[sitifan]

Of course! In fact, the use of "for" meaning because is mostly literary/poetic etc nowadays.
May I ask why you posted that particular sentence?

Because I think it's not very idiomatic.
Can I omit the comma in the sentence below?
The days were short, because it was now December.

 

[teechar]

Yes, the sentence would be better without it.

 

[SoothingDave]

I'd probably say "as it was now December."

 

[jutfrank]

I'd probably say "as it was now December."

Yes, as. In fact, I'd go further and say because isn't right here.

 

[Annabel Lee]

Can I omit the comma in the sentence below?
The days were short, because it was now December.

I much prefer the sentence with "as" or "for" (instead of "because") and with the comma.

There isn't a strict relationship of cause or reason between "it was now December" and "The days were short."

Notice how grotesquely awkward it would be to cleft the "because"-clause:

? It was because it was now December that the days were short.
? It was now December. That was the reason the days were short.

The relationship of reason is looser, more circumstantial, and has to do with naturalness. Even "and" does the job:

It was now December and the days were short.
The days were short, it being now December.
It being now December, the days were short.

If I had to write the sentence with "because," I'd edit it to:

It was only natural that the days were short because it was now December.
The days were short, and it was only natural that they were because it was now December.

 

[Skrej]

'Since' also works well.

 

[teechar]

I disagree with @jutfrank and @Annabel Lee about the use of "because" in that sentence. I see nothing wrong with it. It's simply explanatory (yes, "as" can work there too). To me, there is nothing wrong with the use of "because" in such sentences.

 

[Skrej]

I didn't see anything wrong with 'because' either. All of them work in my opinion, although I agree 'for' does sound rather mawkish.

 

[Annabel Lee]

I can live with "because" in that sentence, but only with the comma before it.

The days were short, because it was now December.

With "for" or "as" or "since" introducing that clause, it has to be set off with a comma.

Would those who are OK with the "because" version without the comma also be OK with "because of"?

?? The days were short because of its now being December.

What we have here, in my opinion, is an epistemic clause, signaling that one fact can be inferred from another. Compare:

It was now December; therefore, the days were short.