Sorting out the confusion.
Using “For” at the Beginning of a Sentence
Would any grammarians complain if you wanted to make the bicycle sentence two sentences, as in “I was tired after my journey. For I had been forced to ride my bike for 20 miles”? Yes, here’s where opinions definitely differ.
The most liberal view comes from the American Heritage Guide to Contemporary Usage and Style and (3) tells us that “for” can be used in the middle of a sentence or to start a new one. It says, “All treatments are acceptable in standard usage.” So go ahead and write, “I used ‘for’ at the beginning of my sentence. For I felt like it.” This source does warn, though, that you won’t encounter “for” much in speech and informal writing because it “often lends a literary tone or note of formality to what is being said.”
The next two sources contradict each other: Garner's Modern American Usage (4) states, “‘For’ has always been proper at the beginning of an independent clause,” and it goes on to give three examples in which “for” begins a sentence, as in “For she certainly has worked very hard indeed.” The other source, the New Fowler’s Modern English Usage (5), says about “for,” “It cannot normally be placed at the beginning of a sentence. Its function is to introduce the ground or reason for something previously stated.” Yes? No? Who knows?
The Fourth Source
To solve this conundrum, we need to look at a fourth source, which is the only one to bring up an issue that seems to be at the heart of this problem: incomplete sentences, which are sentences that are missing something. The well-respected website from the Purdue University Online Writing Lab (6) offers various examples of incomplete sentences to avoid, and this list includes a sentence that starts with “for.” As most grammarians will suggest, this site advises you to rewrite sentence fragments. And you should rework an incomplete sentence unless you are trying to make your sentence stand out.
We now need to explore whether sentences that start with “for” are fragments. So we’re going to return to Garner's, the source that liked “for” at the beginning of a sentence, and use “because” instead. Garner (7) complains about sentence fragments that start with “because.” He calls this sentence an “ill-advised fragment”: “Because the industry stands at a very serious crossroads.” He explains that this sentence causes a miscue, meaning that readers could logically think that something else was going to follow the “because” statement.
Now let’s go back to one of the “for” sentences that he liked: “For she certainly has worked very hard indeed.” What happens when we change “for” to “because”? We end up with a fragment: “Because she certainly has worked very hard indeed.” So why does he like the “for” sentence and not the “because” sentence? It seems they’re essentially the same grammatically, so are these grammarians confused? Well, they’re certainly conflicted, and it would be easy to argue that statements beginning with “for” are fragments and are perhaps ill-advised.
Maybe sentences that start with “for” don’t cause miscues as much as sentences that start with “because.” It’s something to think about. Do you do a double take when you encounter a sentence that starts with “for”? Perhaps it depends on the person.
To conclude, if you think there’s a chance your sentence might be confusing or misleading, it’s a good idea to fix it. Even if you like starting a sentence with the word “for,” remember that your readers might consider your sentence a formal-sounding fragment, so it's a good idea to use the style sparingly.
The Curious Case of the Misplaced Modifier
This podcast was written by Bonnie Trenga, author of The Curious Case of the Misplaced Modifier, who blogs at sentencesleuth.blogspot.com, and I'm Mignon Fogarty, the author of the paperback book Grammar Girl's Quick and Dirty Tips for Better Writing.