grammaticality - Because as a preposition

Recently, I have seen discussions that state that "because" is always a preposition. Can someone shed light on this idea? Thank you.

UPDATE:

The question that prompted me to post this question: Is "which" a preposition? Because because

I posted this question for several reasons:

1) I have seen this topic come up in comments before. I don't remember the original posts that led to the comments...perhaps another user can recall.

2) I could not follow all of the reasoning in the referenced article (Language log) and am hoping a user can bring the discussion "down to earth" for the rest of us mortals.

3) Language is not set in stone, and I have the feeling that other words will soon change use. I think it's important to see how people discuss the words that are changing and to understand these inevitable changes.

4) I think it would help us have a better understanding of ideas such as "preposition" and "Subordinate conjunction" and "conjunction."

Answer

Conventionally because is considered a conjunction, because it links (or conjoins) two clauses. The argument against its classification as a conjunction is that because operate like other subordinating or coordinating conjunctions but does operate like prepositions.

This post on the Language Log demonstrates that because is not a conjunction by comparing it to that (subordinating conjunction) and and (coordinating conjunction). I summarize the argument below.

Typical subordinating conjunction: that

• That can be omitted from a sentence and the sentence's meaning generally remains the same.


• The clauses cannot be rearranged and maintain meaning: "[clause 1] that [clause 2]" != "that [clause 2], [clause 1]".


• Complements follow that.


• If because is omitted from a sentence the meaning does not remain the same.



• With because the clauses can be rearranged.


• Adjuncts generally follow because.

Typical coordinating conjunction: and

• The two clauses joined by and can be rearranged and the meaning stays the same.


• And cannot start a sentence.


• Rearranging the clauses changes the meaning with because.



• Because can start a sentence.

Because does not act like conjunctions, and thus is not a conjunction. It does, however, act like prepositions.

Prepositions can introduce noun-phrases, clauses, preposition phrases, and nothing, depending on the preposition. Because has long introduced clauses and preposition phrases (with of) and more recently also introduces noun-phrases.