On avoiding Oz

A correspondent writes to ask whether the conjunctions because, since, as, and for are interchangeable - as in She was late for class because/since/as/for her alarm clock was broken. And he adds: 'The reason I ask is that I would like to be able to use any one of them to connect clauses rather than being limited to because, which might create wizard-of-oz prose.' (He's recalling the words in the song - 'because, because, because...'.)

They can all be used, indeed, but there are frequency, stylistic, and contextual differences. Because ('cos) is by far the commonest. In one corpus study, the percentage ratio between the four conjunctions was: 77 (because), 12 (for), 5 (as) and 6 (since). For is used in more formal style, and is very rare in speech. As and since are much more common in writing, but are often avoided because of the occasional ambiguity with their temporal meaning.

As they were near the window, they heard noises
Since they left, there have been many arguments.

Corpus studies also show positional variation. All clauses are more commonly found in final position (i.e. after the main clause) - because clauses overwhelmingly so, especially in speech. As clauses tend to be more evenly balanced between initial and final position.

Note also that, if stylistic variation is the aim, English provides several other alternatives for expressing reason, such as:

With the bad weather coming, I've decided to close the store. (= Because the bad weather is coming...)
What with the bad weather coming...
Seeing (that) the bad weather is coming...

And there are more complex (and often more formal) constructions such as:

Inasmuch as the bad weather is coming...
By virtue of the bad weather...
In view of the bad weather...
On account of the bad weather...
Owing to the bad weather...
Due to the bad weather...

Plenty of choice, then, for the aspiring stylist.