Sentence Complexity and Embedding

Subordinate Noun Clauses

Independent v. Matrix Clauses

When most Americans learn about complex sentences in elementary school, they are often taught that a complex sentence consists of two clauses; one independent clause and one dependent clause.  They are then taught that an independent clause is one that can stand on its own, and that a dependent clause can’t stand on its own.  We used these definitions to help us understand the differences between compound sentences and complex sentences, and we used them again in looking at adverb clauses.  So far, this way of looking at and defining subordinate clauses has been helpful.  Now, suddenly, it is no longer helpful.

The descriptions from elementary school, like so many things we learned back then, are partial explanations that provide an introductory base to a much larger body of knowledge.  We must expand if we are to master the whole body of knowledge.  We have come to the point now where we need to learn that subordinate clauses don’t only attach to independent clauses; sometimes they attach to matrix clauses.  This is why this text has frequently used the term main clause instead of independent clause for the second clause in a complex sentence.  There are two types of main clauses.  One is the familiar independent clause, which can stand on its own.  The other is a matrix clause, which really can’t be said to stand on its own.

Let’s compare two sentences to see the differences more clearly:

Ben asked  |  why he had to take out the garbage.
Gary couldn’t take out the garbage  |  because he had a broken leg.

Both example sentences are complex sentences.  The two clauses in each sentence have been separated by a vertical line.  The main clause is the first clause in each sentence, and the subordinate (or dependent) clause is the second.  The first sentence contains a subordinate noun clause acting as a direct object; it tells what Ben asked.  The second sentence contains a subordinate adverb clause providing the cause of the action in the main clause.

When we look at the two main clauses, we get a different sense about the independence levels of each one.  In the second sentence, we really could just walk up to someone and make the statement saying, “Gary can’t take out the garbage.”  The listener would feel that we have finished our turn in the conversation with this statement.  If, however, we walked up to someone and said, “Ben asked,” a listener probably wouldn’t feel that the statement was completed.  This is because the verb asked is a transitive verb, and, therefore, is incomplete without a direct object.  The noun clause functions as the direct object, and it is only when a direct object is included that there is a sense that the main clause, Ben asked, can stand on its own.  But, of course, it isn’t on its own at all, is it?  It has a second clause attached, and that second clause seems necessary.

Now we see why linguists distinguish between matrix clauses and independent clauses.  Both types of clauses can carry subordinate clauses, so both are called main clauses, but independent clauses can stand on their own, while matrix clauses can’t. We can revise our clause chart to capture this new addition:

Fig. 12: Clause Types, revised

Finally, for those who might still wish to call all main clauses independent clauses, we can turn to a sentence that uses a noun clause as its subject to show that what remains after removing the subordinate clause isn’t something that can stand on its own:

            That we need money  |  is obvious.

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