Many people were somewhat surprised that the American Dialect Society's "Word of the Year" was because in its use before a noun or noun phrase, as in "Because Science" (to choose a recent Slate headline). It is perhaps unprecedented for a word in a minor part-of-speech category, in this case preposition, to be chosen over an emergent or fashionable word in one of the major categories. Here are some recent winners:
2012 - hashtag (noun)
2011 - occupy (verb)
2010 - app (noun)
2009 - tweet (noun and verb)
2008 - bailout (noun)
2007 - subprime (adjective)
2006 - plutoed (past participle of a verb)
2005 - truthiness (noun)
You'll note that I referred to because as a preposition, which warrants some explanation given the remarkable fact that seemingly every dictionary on the market, as far as I can tell, disagrees. For example, the American Heritage Dictionary, whose entry is representative, reports that because is a conjunction, but also that there is a word spelled because of that is a preposition. Both claims are flamingly and demonstrably wrong and here's why.
Traditional grammar recognizes that conjunctions come in two varieties: subordinating conjunctions and coordinating conjunctions. But because isn't like either.
The classic subordinating conjunction is that (that can also be a pronoun, an adjective, or an adverb, but those are different usages). As a conjunction, that introduces a subordinate clause, as in Ted says that the world is flat—clauses that are nearly always what is called a complement. In other words, they are required or specifically licensed by the foregoing main clause word, in this case says. That is meaningless in its own right, and often omissible: Ted says the world is flat is a grammatical alternative. Also, shifting that and the clause it introduces to the beginning often sounds pretty weird. That the world is flat, Ted says only makes sense in certain special contexts in which different things Ted says are being contrasted with one another.
None of this holds for because, as seen in a sentence like Ted is mocked because he holds ridiculous beliefs. Here, because introduces a clause that is never a complement; rather it is always an optional adjunct. Because is not meaningless, but contributes a crucial logical relation of cause or reason. The word can never be omitted without radical change to the meaning and, usually, the grammatical integrity of the sentence: Ted is ridiculed he holds ridiculous beliefs is not grammatical. And shifting it to the front is perfectly natural: Because he holds ridiculous beliefs, Ted is mocked.
The classic "coordinating conjunction" is and, as in Roses are red and violets are blue. Switching the positions of the two clauses separated by the and normally gives a grammatical result with the same truth conditions: Violets are blue and roses are red is true if and only if Roses are red and violets are blue is true. Preposing the and plus what follows it is not permitted: And violets are blue, roses are red is totally ungrammatical.
The opposite of all of this holds for because. The sentence Roses are red because violets are blue may express a strange claim, but it has a completely different meaning from Violets are blue because roses are red (the causal arrow is reversed). Also, Because violets are blue, roses are red is a grammatical, alternative way of expressing the same thing as Roses are red because violets are blue.
Why then do all dictionaries make the self-evidently false claim that because is a conjunction, and therefore either like that or like and? In short, they are all followers of a tradition that has needed rethinking for 200 years (some would say it's more like 2,000 years, because it originates in classical times). They are respecting an ancient analysis that doesn't work. It is based on the vague assertion that a conjunction is a word that "joins" two elements together. Very little thought is required to see that if using C to join A together with B means simply forming the sequence "A C B," then almost anything can be called a conjunction; no stricter or more tightly framed definition has been given.
Which brings us to the similarly mindless claim that there is a preposition spelled because of. First off, I would never claim that a dictionary should not recognize something as a word if it has a space in it; I think Santa Cruz is best thought of as a word, and there are certainly space-containing words that are not proper nouns. But because of isn't one of them. There is no preposition because of. These are two separate words, with their own functions, capable of being widely separated by other words.
Of, naturally, is indeed a preposition. It is the commonest and most stereotypical of all prepositions in English. But what about because? Contrary to what all the dictionaries tell us, it is also a preposition. To explain:
1. Some prepositions can occur with no complement, as in: We went in ;
2. Some can occur with a noun phrase (NP), as in: We went through the front door;
3. Some can occur with a clause, as in: My son is waiting for me to pick him up;
4. And some can occur with a preposition phrase (PP) that begins with of, as in: They did it out of ignorance.
The change that has caught the eye of the American Dialect Society is simply that because has picked up the extra privilege already possessed by many other prepositions: it now allows a noun phrase (NP) as complement. So, in the following table of prepositions (the rows) and their complement categories (the columns), a single entry has been changed (✓ means 'grammatically permitted,' * means 'grammatically forbidden,' and % means 'grammatically permitted in some semantically limited contexts'):
The language has simply added to its stock of grammatical possibilities a single check mark, replacing the second asterisk in the last row. And if you would like the dictionary to cover (as Wiktionary does) the colloquial use of because on its own, as an imperiously uninformative answer to a why question—as in, "Why do I have to eat my vegetables? Because!"—then we can get rid of the first asterisk as well, and the relevant line will look like this:
Because is a preposition that is sometimes used with no complement, sometimes (in the new usage that the ADS has just recognized) with an noun phrase complement, sometimes (much more commonly) with an of-PP complement , and sometimes with a clause. That's an accurate classification, which dictionaries ought to adopt because, well … because syntax.
A version of this post originally appeared on Language Log.